1//////////////////////////////////////////////////////////////////////
   2// LibFile: shapes2d.scad
   3//   This file includes redefinitions of the core modules to
   4//   work with attachment, and functional forms of those modules
   5//   that produce paths.  You can create regular polygons
   6//   with optional rounded corners and alignment features not
   7//   available with circle().  The file also provides teardrop2d,
   8//   which is useful for 3D printable holes.  
   9//   Many of the commands have module forms that produce geometry and
  10//   function forms that produce a path. 
  11// Includes:
  12//   include <BOSL2/std.scad>
  13// FileGroup: Basic Modeling
  14// FileSummary: Attachable circles, squares, polygons, teardrop.  Can make geometry or paths.
  15// FileFootnotes: STD=Included in std.scad
  16//////////////////////////////////////////////////////////////////////
  17
  18use <builtins.scad>
  19
  20
  21// Section: 2D Primitives
  22
  23// Function&Module: square()
  24// Synopsis: Creates a 2D square or rectangle.
  25// SynTags: Geom, Path, Ext
  26// Topics: Shapes (2D), Path Generators (2D)
  27// See Also: rect()
  28// Usage: As a Module
  29//   square(size, [center], ...);
  30// Usage: With Attachments
  31//   square(size, [center], ...) [ATTACHMENTS];
  32// Usage: As a Function
  33//   path = square(size, [center], ...);
  34// Description:
  35//   When called as the built-in module, creates a 2D square or rectangle of the given size.
  36//   When called as a function, returns a 2D path/list of points for a square/rectangle of the given size.
  37// Arguments:
  38//   size = The size of the square to create.  If given as a scalar, both X and Y will be the same size.
  39//   center = If given and true, overrides `anchor` to be `CENTER`.  If given and false, overrides `anchor` to be `FRONT+LEFT`.
  40//   ---
  41//   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
  42//   spin = Rotate this many degrees around the Z axis after anchor.  See [spin](attachments.scad#subsection-spin).  Default: `0`
  43// Example(2D):
  44//   square(40);
  45// Example(2D): Centered
  46//   square([40,30], center=true);
  47// Example(2D): Called as Function
  48//   path = square([40,30], anchor=FRONT, spin=30);
  49//   stroke(path, closed=true);
  50//   move_copies(path) color("blue") circle(d=2,$fn=8);
  51function square(size=1, center, anchor, spin=0) =
  52    let(
  53        anchor = get_anchor(anchor, center, [-1,-1], [-1,-1]),
  54        size = is_num(size)? [size,size] : point2d(size)
  55    )
  56    assert(all_positive(size), "All components of size must be positive.")
  57    let(
  58        path = [
  59            [ size.x,-size.y],
  60            [-size.x,-size.y],
  61            [-size.x, size.y],
  62            [ size.x, size.y],
  63        ] / 2
  64    ) reorient(anchor,spin, two_d=true, size=size, p=path);
  65
  66
  67module square(size=1, center, anchor, spin) {
  68    anchor = get_anchor(anchor, center, [-1,-1], [-1,-1]);
  69    rsize = is_num(size)? [size,size] : point2d(size);
  70    size = [for (c = rsize) max(0,c)];
  71    attachable(anchor,spin, two_d=true, size=size) {
  72        if (all_positive(size))
  73            _square(size, center=true);
  74        children();
  75    }
  76}
  77
  78
  79
  80// Function&Module: rect()
  81// Synopsis: Creates a 2d rectangle with optional corner rounding.
  82// SynTags: Geom, Path
  83// Topics: Shapes (2D), Paths (2D), Path Generators, Attachable
  84// See Also: square()
  85// Usage: As Module
  86//   rect(size, [rounding], [chamfer], ...) [ATTACHMENTS];
  87// Usage: As Function
  88//   path = rect(size, [rounding], [chamfer], ...);
  89// Description:
  90//   When called as a module, creates a 2D rectangle of the given size, with optional rounding or chamfering.
  91//   When called as a function, returns a 2D path/list of points for a square/rectangle of the given size.
  92// Arguments:
  93//   size = The size of the rectangle to create.  If given as a scalar, both X and Y will be the same size.
  94//   ---
  95//   rounding = The rounding radius for the corners.  If negative, produces external roundover spikes on the X axis. If given as a list of four numbers, gives individual radii for each corner, in the order [X+Y+,X-Y+,X-Y-,X+Y-]. Default: 0 (no rounding)
  96//   chamfer = The chamfer size for the corners.  If negative, produces external chamfer spikes on the X axis. If given as a list of four numbers, gives individual chamfers for each corner, in the order [X+Y+,X-Y+,X-Y-,X+Y-].  Default: 0 (no chamfer)
  97//   atype = The type of anchoring to use with `anchor=`.  Valid opptions are "box" and "perim".  This lets you choose between putting anchors on the rounded or chamfered perimeter, or on the square bounding box of the shape. Default: "box"
  98//   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
  99//   spin = Rotate this many degrees around the Z axis after anchor.  See [spin](attachments.scad#subsection-spin).  Default: `0`
 100// Anchor Types:
 101//   box = Anchor is with respect to the rectangular bounding box of the shape.
 102//   perim = Anchors are placed along the rounded or chamfered perimeter of the shape.
 103// Example(2D):
 104//   rect(40);
 105// Example(2D): Anchored
 106//   rect([40,30], anchor=FRONT);
 107// Example(2D): Spun
 108//   rect([40,30], anchor=FRONT, spin=30);
 109// Example(2D): Chamferred Rect
 110//   rect([40,30], chamfer=5);
 111// Example(2D): Rounded Rect
 112//   rect([40,30], rounding=5);
 113// Example(2D): Negative-Chamferred Rect
 114//   rect([40,30], chamfer=-5);
 115// Example(2D): Negative-Rounded Rect
 116//   rect([40,30], rounding=-5);
 117// Example(2D): Default "box" Anchors
 118//   color("red") rect([40,30]);
 119//   rect([40,30], rounding=10)
 120//       show_anchors();
 121// Example(2D): "perim" Anchors
 122//   rect([40,30], rounding=10, atype="perim")
 123//       show_anchors();
 124// Example(2D): "perim" Anchors
 125//   rect([40,30], rounding=[-10,-8,-3,-7], atype="perim")
 126//       show_anchors();
 127// Example(2D): Mixed Chamferring and Rounding
 128//   rect([40,30],rounding=[5,0,10,0],chamfer=[0,8,0,15],$fa=1,$fs=1);
 129// Example(2D): Called as Function
 130//   path = rect([40,30], chamfer=5, anchor=FRONT, spin=30);
 131//   stroke(path, closed=true);
 132//   move_copies(path) color("blue") circle(d=2,$fn=8);
 133module rect(size=1, rounding=0, atype="box", chamfer=0, anchor=CENTER, spin=0) {
 134    errchk = assert(in_list(atype, ["box", "perim"]));
 135    size = [for (c = force_list(size,2)) max(0,c)];
 136    if (!all_positive(size)) {
 137        attachable(anchor,spin, two_d=true, size=size) {
 138            union();
 139            children();
 140        }
 141    } else if (rounding==0 && chamfer==0) {
 142        attachable(anchor, spin, two_d=true, size=size) {
 143            square(size, center=true);
 144            children();
 145        }
 146    } else {
 147        pts_over = rect(size=size, rounding=rounding, chamfer=chamfer, atype=atype, _return_override=true);
 148        pts = pts_over[0];
 149        override = pts_over[1];
 150        attachable(anchor, spin, two_d=true, size=size,override=override) {
 151            polygon(pts);
 152            children();
 153        }
 154    }
 155}
 156
 157
 158
 159function rect(size=1, rounding=0, chamfer=0, atype="box", anchor=CENTER, spin=0, _return_override) =
 160    assert(is_num(size)     || is_vector(size,2))
 161    assert(is_num(chamfer)  || is_vector(chamfer,4))
 162    assert(is_num(rounding) || is_vector(rounding,4))
 163    assert(in_list(atype, ["box", "perim"]))
 164    let(
 165        anchor=_force_anchor_2d(anchor),
 166        size = [for (c = force_list(size,2)) max(0,c)],
 167        chamfer = force_list(chamfer,4), 
 168        rounding = force_list(rounding,4)
 169    )
 170    assert(all_nonnegative(size), "All components of size must be >=0")
 171    all_zero(concat(chamfer,rounding),0) ?
 172        let(
 173             path = [
 174                 [ size.x/2, -size.y/2],
 175                 [-size.x/2, -size.y/2],
 176                 [-size.x/2,  size.y/2],
 177                 [ size.x/2,  size.y/2],
 178             ]
 179        )
 180        rot(spin, p=move(-v_mul(anchor,size/2), p=path))
 181    :
 182    assert(all_zero(v_mul(chamfer,rounding),0), "Cannot specify chamfer and rounding at the same corner")
 183    let(
 184        quadorder = [3,2,1,0],
 185        quadpos = [[1,1],[-1,1],[-1,-1],[1,-1]],
 186        eps = 1e-9,
 187        insets = [for (i=[0:3]) abs(chamfer[i])>=eps? chamfer[i] : abs(rounding[i])>=eps? rounding[i] : 0],
 188        insets_x = max(insets[0]+insets[1],insets[2]+insets[3]),
 189        insets_y = max(insets[0]+insets[3],insets[1]+insets[2])
 190    )
 191    assert(insets_x <= size.x, "Requested roundings and/or chamfers exceed the rect width.")
 192    assert(insets_y <= size.y, "Requested roundings and/or chamfers exceed the rect height.")
 193    let(
 194        corners = [
 195            for(i = [0:3])
 196            let(
 197                quad = quadorder[i],
 198                qinset = insets[quad],
 199                qpos = quadpos[quad],
 200                qchamf = chamfer[quad],
 201                qround = rounding[quad],
 202                cverts = quant(segs(abs(qinset)),4)/4,
 203                step = 90/cverts,
 204                cp = v_mul(size/2-[qinset,abs(qinset)], qpos),
 205                qpts = abs(qchamf) >= eps? [[0,abs(qinset)], [qinset,0]] :
 206                    abs(qround) >= eps? [for (j=[0:1:cverts]) let(a=90-j*step) v_mul(polar_to_xy(abs(qinset),a),[sign(qinset),1])] :
 207                    [[0,0]],
 208                qfpts = [for (p=qpts) v_mul(p,qpos)],
 209                qrpts = qpos.x*qpos.y < 0? reverse(qfpts) : qfpts,
 210                cornerpt = atype=="box" || (qround==0 && qchamf==0) ? undef
 211                         : qround<0 || qchamf<0 ? [[0,-qpos.y*min(qround,qchamf)]]
 212                         : [for(seg=pair(qrpts)) let(isect=line_intersection(seg, [[0,0],qpos],SEGMENT,LINE)) if (is_def(isect) && isect!=seg[0]) isect]
 213              )
 214            assert(is_undef(cornerpt) || len(cornerpt)==1,"Cannot find corner point to anchor")
 215            [move(cp, p=qrpts), is_undef(cornerpt)? undef : move(cp,p=cornerpt[0])]
 216        ],
 217        path = deduplicate(flatten(column(corners,0)),closed=true),
 218        override = [for(i=[0:3])
 219                      let(quad=quadorder[i])
 220                      if (is_def(corners[i][1])) [quadpos[quad], [corners[i][1], min(chamfer[quad],rounding[quad])<0 ? [quadpos[quad].x,0] : undef]]]
 221      ) _return_override ? [reorient(anchor,spin, two_d=true, size=size, p=path, override=override), override]
 222                       : reorient(anchor,spin, two_d=true, size=size, p=path, override=override);
 223
 224
 225// Function&Module: circle()
 226// Synopsis: Creates the approximation of a circle.
 227// SynTags: Geom, Path, Ext
 228// Topics: Shapes (2D), Path Generators (2D)
 229// See Also: ellipse(), circle_2tangents(), circle_3points()
 230// Usage: As a Module
 231//   circle(r|d=, ...) [ATTACHMENTS];
 232//   circle(points=) [ATTACHMENTS];
 233//   circle(r|d=, corner=) [ATTACHMENTS];
 234// Usage: As a Function
 235//   path = circle(r|d=, ...);
 236//   path = circle(points=);
 237//   path = circle(r|d=, corner=);
 238// Description:
 239//   When called as the built-in module, creates a 2D polygon that approximates a circle of the given size.
 240//   When called as a function, returns a 2D list of points (path) for a polygon that approximates a circle of the given size.
 241//   If `corner=` is given three 2D points, centers the circle so that it will be tangent to both segments of the path, on the inside corner.
 242//   If `points=` is given three 2D points, centers and sizes the circle so that it passes through all three points.
 243// Arguments:
 244//   r = The radius of the circle to create.
 245//   d = The diameter of the circle to create.
 246//   ---
 247//   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
 248//   spin = Rotate this many degrees around the Z axis after anchor.  See [spin](attachments.scad#subsection-spin).  Default: `0`
 249// Example(2D): By Radius
 250//   circle(r=25);
 251// Example(2D): By Diameter
 252//   circle(d=50);
 253// Example(2D): Fit to Three Points
 254//   pts = [[50,25], [25,-25], [-10,0]];
 255//   circle(points=pts);
 256//   color("red") move_copies(pts) circle();
 257// Example(2D): Fit Tangent to Inside Corner of Two Segments
 258//   path = [[50,25], [-10,0], [25,-25]];
 259//   circle(corner=path, r=15);
 260//   color("red") stroke(path);
 261// Example(2D): Called as Function
 262//   path = circle(d=50, anchor=FRONT, spin=45);
 263//   stroke(path);
 264function circle(r, d, points, corner, anchor=CENTER, spin=0) =
 265    assert(is_undef(corner) || (is_path(corner,[2]) && len(corner) == 3))
 266    assert(is_undef(points) || is_undef(corner), "Cannot specify both points and corner.")
 267    let(
 268        data = is_def(points)?
 269                assert(is_path(points,[2]) && len(points) == 3)
 270                assert(is_undef(corner), "Cannot specify corner= when points= is given.")
 271                assert(is_undef(r) && is_undef(d), "Cannot specify r= or d= when points= is given.")
 272                let( c = circle_3points(points) )
 273                assert(!is_undef(c[0]), "Points cannot be collinear.")
 274                let( cp = c[0], r = c[1]  )
 275                [cp, r] :
 276            is_def(corner)?
 277                assert(is_path(corner,[2]) && len(corner) == 3)
 278                assert(is_undef(points), "Cannot specify points= when corner= is given.")
 279                let(
 280                    r = get_radius(r=r, d=d, dflt=1),
 281                    c = circle_2tangents(r=r, pt1=corner[0], pt2=corner[1], pt3=corner[2])
 282                )
 283                assert(c!=undef, "Corner path cannot be collinear.")
 284                let( cp = c[0] )
 285                [cp, r] :
 286            let(
 287                cp = [0, 0],
 288                r = get_radius(r=r, d=d, dflt=1)
 289            ) [cp, r],
 290        cp = data[0],
 291        r = data[1]
 292    )
 293    assert(r>0, "Radius/diameter must be positive")
 294    let(
 295        sides = segs(r),
 296        path = [for (i=[0:1:sides-1]) let(a=360-i*360/sides) r*[cos(a),sin(a)]+cp]
 297    ) reorient(anchor,spin, two_d=true, r=r, p=path);
 298
 299module circle(r, d, points, corner, anchor=CENTER, spin=0) {
 300    if (is_path(points)) {
 301        c = circle_3points(points);
 302        check = assert(c!=undef && c[0] != undef, "Points must not be collinear.");
 303        cp = c[0];
 304        r = c[1];
 305        translate(cp) {
 306            attachable(anchor,spin, two_d=true, r=r) {
 307                if (r>0) _circle(r=r);
 308                children();
 309            }
 310        }
 311    } else if (is_path(corner)) {
 312        r = get_radius(r=r, d=d, dflt=1);
 313        c = circle_2tangents(r=r, pt1=corner[0], pt2=corner[1], pt3=corner[2]);
 314        check = assert(c != undef && c[0] != undef, "Points must not be collinear.");
 315        cp = c[0];
 316        translate(cp) {
 317            attachable(anchor,spin, two_d=true, r=r) {
 318                if (r>0) _circle(r=r);
 319                children();
 320            }
 321        }
 322    } else {
 323        r = get_radius(r=r, d=d, dflt=1);
 324        attachable(anchor,spin, two_d=true, r=r) {
 325            if (r>0) _circle(r=r);
 326            children();
 327        }
 328    }
 329}
 330
 331
 332
 333// Function&Module: ellipse()
 334// Synopsis: Creates the approximation of an ellipse or a circle.
 335// SynTags: Geom, Path
 336// Topics: Shapes (2D), Paths (2D), Path Generators, Attachable
 337// See Also: circle(), circle_2tangents(), circle_3points()
 338// Usage: As a Module
 339//   ellipse(r|d=, [realign=], [circum=], [uniform=], ...) [ATTACHMENTS];
 340// Usage: As a Function
 341//   path = ellipse(r|d=, [realign=], [circum=], [uniform=], ...);
 342// Description:
 343//   When called as a module, creates a 2D polygon that approximates a circle or ellipse of the given size.
 344//   When called as a function, returns a 2D list of points (path) for a polygon that approximates a circle or ellipse of the given size.
 345//   By default the point list or shape is the same as the one you would get by scaling the output of {{circle()}}, but with this module your
 346//   attachments to the ellipse will retain their dimensions, whereas scaling a circle with attachments will also scale the attachments.
 347//   If you set `uniform` to true then you will get a polygon with congruent sides whose vertices lie on the ellipse.  The `circum` option
 348//   requests a polygon that circumscribes the requested ellipse (so the specified ellipse will fit into the resulting polygon).  Note that
 349//   you cannot gives `circum=true` and `uniform=true`.  
 350// Arguments:
 351//   r = Radius of the circle or pair of semiaxes of ellipse 
 352//   ---
 353//   d = Diameter of the circle or a pair giving the full X and Y axis lengths.  
 354//   realign = If false starts the approximate ellipse with a point on the X+ axis.  If true the midpoint of a side is on the X+ axis and the first point of the polygon is below the X+ axis.  This can result in a very different polygon when $fn is small.  Default: false
 355//   uniform = If true, the polygon that approximates the circle will have segments of equal length.  Only works if `circum=false`.  Default: false
 356//   circum = If true, the polygon that approximates the circle will be upsized slightly to circumscribe the theoretical circle.  If false, it inscribes the theoretical circle.  If this is true then `uniform` must be false.  Default: false
 357//   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
 358//   spin = Rotate this many degrees around the Z axis after anchor.  See [spin](attachments.scad#subsection-spin).  Default: `0`
 359// Example(2D): By Radius
 360//   ellipse(r=25);
 361// Example(2D): By Diameter
 362//   ellipse(d=50);
 363// Example(2D): Anchoring
 364//   ellipse(d=50, anchor=FRONT);
 365// Example(2D): Spin
 366//   ellipse(d=50, anchor=FRONT, spin=45);
 367// Example(NORENDER): Called as Function
 368//   path = ellipse(d=50, anchor=FRONT, spin=45);
 369// Example(2D,NoAxes): Uniformly sampled hexagon at the top, regular non-uniform one at the bottom
 370//   r=[10,3];
 371//   ydistribute(7){
 372//     union(){
 373//       stroke([ellipse(r=r, $fn=100)],width=0.05,color="blue");
 374//       stroke([ellipse(r=r, $fn=6)],width=0.1,color="red");
 375//     }
 376//     union(){
 377//       stroke([ellipse(r=r, $fn=100)],width=0.05,color="blue");
 378//       stroke([ellipse(r=r, $fn=6,uniform=true)],width=0.1,color="red");
 379//     }
 380//   }
 381// Example(2D): The realigned hexagons are even more different
 382//   r=[10,3];
 383//   ydistribute(7){
 384//     union(){
 385//       stroke([ellipse(r=r, $fn=100)],width=0.05,color="blue");
 386//       stroke([ellipse(r=r, $fn=6,realign=true)],width=0.1,color="red");
 387//     }
 388//     union(){
 389//       stroke([ellipse(r=r, $fn=100)],width=0.05,color="blue");
 390//       stroke([ellipse(r=r, $fn=6,realign=true,uniform=true)],width=0.1,color="red");
 391//     }
 392//   }
 393// Example(2D): For odd $fn the result may not look very elliptical:
 394//    r=[10,3];
 395//    ydistribute(7){
 396//      union(){
 397//        stroke([ellipse(r=r, $fn=100)],width=0.05,color="blue");
 398//        stroke([ellipse(r=r, $fn=5,realign=false)],width=0.1,color="red");
 399//      }
 400//      union(){
 401//        stroke([ellipse(r=r, $fn=100)],width=0.05,color="blue");
 402//        stroke([ellipse(r=r, $fn=5,realign=false,uniform=true)],width=0.1,color="red");
 403//      }
 404//    }
 405// Example(2D): The same ellipse, turned 90 deg, gives a very different result:
 406//   r=[3,10];
 407//   xdistribute(7){
 408//     union(){
 409//       stroke([ellipse(r=r, $fn=100)],width=0.1,color="blue");
 410//       stroke([ellipse(r=r, $fn=5,realign=false)],width=0.2,color="red");
 411//     }
 412//     union(){
 413//       stroke([ellipse(r=r, $fn=100)],width=0.1,color="blue");
 414//       stroke([ellipse(r=r, $fn=5,realign=false,uniform=true)],width=0.2,color="red");
 415//     }
 416//   }
 417module ellipse(r, d, realign=false, circum=false, uniform=false, anchor=CENTER, spin=0)
 418{
 419    r = force_list(get_radius(r=r, d=d, dflt=1),2);
 420    dummy = assert(is_vector(r,2) && all_positive(r), "Invalid radius or diameter for ellipse");
 421    sides = segs(max(r));
 422    sc = circum? (1 / cos(180/sides)) : 1;
 423    rx = r.x * sc;
 424    ry = r.y * sc;
 425    attachable(anchor,spin, two_d=true, r=[rx,ry]) {
 426        if (uniform) {
 427            check = assert(!circum, "Circum option not allowed when \"uniform\" is true");
 428            polygon(ellipse(r,realign=realign, circum=circum, uniform=true));
 429        }
 430        else if (rx < ry) {
 431            xscale(rx/ry) {
 432                zrot(realign? 180/sides : 0) {
 433                    circle(r=ry, $fn=sides);
 434                }
 435            }
 436        } else {
 437            yscale(ry/rx) {
 438                zrot(realign? 180/sides : 0) {
 439                    circle(r=rx, $fn=sides);
 440                }
 441            }
 442        }
 443        children();
 444    }
 445}
 446
 447
 448// Iterative refinement to produce an inscribed polygon
 449// in an ellipse whose side lengths are all equal
 450function _ellipse_refine(a,b,N, _theta=[]) =
 451   len(_theta)==0? _ellipse_refine(a,b,N,lerpn(0,360,N,endpoint=false))
 452   :
 453   let(
 454       pts = [for(t=_theta) [a*cos(t),b*sin(t)]],
 455       lenlist= path_segment_lengths(pts,closed=true),
 456       meanlen = mean(lenlist),
 457       error = lenlist/meanlen
 458   )
 459   all_equal(error,EPSILON) ? pts
 460   :
 461   let(
 462        dtheta = [each deltas(_theta),
 463                  360-last(_theta)],
 464        newdtheta = [for(i=idx(dtheta)) dtheta[i]/error[i]],
 465        adjusted = [0,each cumsum(list_head(newdtheta / sum(newdtheta) * 360))]
 466   )
 467   _ellipse_refine(a,b,N,adjusted);
 468
 469
 470
 471
 472function _ellipse_refine_realign(a,b,N, _theta=[],i=0) =
 473   len(_theta)==0?
 474         _ellipse_refine_realign(a,b,N, count(N-1,180/N,360/N))
 475   :
 476   let(
 477       pts = [for(t=_theta) [a*cos(t),b*sin(t)],
 478              [a*cos(_theta[0]), -b*sin(_theta[0])]],
 479       lenlist= path_segment_lengths(pts,closed=true),
 480       meanlen = mean(lenlist),
 481       error = lenlist/meanlen
 482   )
 483   all_equal(error,EPSILON) ? pts
 484   :
 485   let(
 486        dtheta = [each deltas(_theta),
 487                  360-last(_theta)-_theta[0],
 488                  2*_theta[0]],
 489        newdtheta = [for(i=idx(dtheta)) dtheta[i]/error[i]],
 490        normdtheta = newdtheta / sum(newdtheta) * 360,
 491        adjusted = cumsum([last(normdtheta)/2, each list_head(normdtheta, -3)])
 492   )
 493   _ellipse_refine_realign(a,b,N,adjusted, i+1);
 494
 495
 496
 497function ellipse(r, d, realign=false, circum=false, uniform=false, anchor=CENTER, spin=0) =
 498    let(
 499        r = force_list(get_radius(r=r, d=d, dflt=1),2),
 500        sides = segs(max(r))
 501    )
 502    assert(all_positive(r), "All components of the radius must be positive.")
 503    uniform
 504      ? assert(!circum, "Circum option not allowed when \"uniform\" is true")
 505        reorient(anchor,spin,
 506            two_d=true, r=[r.x,r.y],
 507            p=realign
 508              ? reverse(_ellipse_refine_realign(r.x,r.y,sides))
 509              : reverse_polygon(_ellipse_refine(r.x,r.y,sides))
 510        )
 511      : let(
 512            offset = realign? 180/sides : 0,
 513            sc = circum? (1 / cos(180/sides)) : 1,
 514            rx = r.x * sc,
 515            ry = r.y * sc,
 516            pts = [
 517                for (i=[0:1:sides-1])
 518                let (a = 360-offset-i*360/sides)
 519                [rx*cos(a), ry*sin(a)]
 520            ]
 521        ) reorient(anchor,spin, two_d=true, r=[rx,ry], p=pts);
 522
 523
 524// Section: Polygons
 525
 526// Function&Module: regular_ngon()
 527// Synopsis: Creates a regular N-sided polygon.
 528// SynTags: Geom, Path
 529// Topics: Shapes (2D), Paths (2D), Path Generators, Attachable
 530// See Also: debug_polygon(), circle(), pentagon(), hexagon(), octagon(), ellipse(), star()
 531// Usage:
 532//   regular_ngon(n, r|d=|or=|od=, [realign=]) [ATTACHMENTS];
 533//   regular_ngon(n, ir=|id=, [realign=]) [ATTACHMENTS];
 534//   regular_ngon(n, side=, [realign=]) [ATTACHMENTS];
 535// Description:
 536//   When called as a function, returns a 2D path for a regular N-sided polygon.
 537//   When called as a module, creates a 2D regular N-sided polygon.
 538// Arguments:
 539//   n = The number of sides.
 540//   r/or = Outside radius, at points.
 541//   ---
 542//   d/od = Outside diameter, at points.
 543//   ir = Inside radius, at center of sides.
 544//   id = Inside diameter, at center of sides.
 545//   side = Length of each side.
 546//   rounding = Radius of rounding for the tips of the polygon.  Default: 0 (no rounding)
 547//   realign = If false, vertex 0 will lie on the X+ axis.  If true then the midpoint of the last edge will lie on the X+ axis, and vertex 0 will be below the X axis.    Default: false
 548//   align_tip = If given as a 2D vector, rotates the whole shape so that the first vertex points in that direction.  This occurs before spin.
 549//   align_side = If given as a 2D vector, rotates the whole shape so that the normal of side0 points in that direction.  This occurs before spin.
 550//   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
 551//   spin = Rotate this many degrees around the Z axis after anchor.  See [spin](attachments.scad#subsection-spin).  Default: `0`
 552// Named Anchors:
 553//   "tip0", "tip1", etc. = Each tip has an anchor, pointing outwards.
 554//   "side0", "side1", etc. = The center of each side has an anchor, pointing outwards.
 555// Example(2D): by Outer Size
 556//   regular_ngon(n=5, or=30);
 557//   regular_ngon(n=5, od=60);
 558// Example(2D): by Inner Size
 559//   regular_ngon(n=5, ir=30);
 560//   regular_ngon(n=5, id=60);
 561// Example(2D): by Side Length
 562//   regular_ngon(n=8, side=20);
 563// Example(2D): Realigned
 564//   regular_ngon(n=8, side=20, realign=true);
 565// Example(2D): Alignment by Tip
 566//   regular_ngon(n=5, r=30, align_tip=BACK+RIGHT)
 567//       attach("tip0", FWD) color("blue")
 568//           stroke([[0,0],[0,7]], endcap2="arrow2");
 569// Example(2D): Alignment by Side
 570//   regular_ngon(n=5, r=30, align_side=BACK+RIGHT)
 571//       attach("side0", FWD) color("blue")
 572//           stroke([[0,0],[0,7]], endcap2="arrow2");
 573// Example(2D): Rounded
 574//   regular_ngon(n=5, od=100, rounding=20, $fn=20);
 575// Example(2D): Called as Function
 576//   stroke(closed=true, regular_ngon(n=6, or=30));
 577function regular_ngon(n=6, r, d, or, od, ir, id, side, rounding=0, realign=false, align_tip, align_side, anchor=CENTER, spin=0, _mat, _anchs) =
 578    assert(is_int(n) && n>=3)
 579    assert(is_undef(align_tip) || is_vector(align_tip))
 580    assert(is_undef(align_side) || is_vector(align_side))
 581    assert(is_undef(align_tip) || is_undef(align_side), "Can only specify one of align_tip and align-side")
 582    let(
 583        sc = 1/cos(180/n),
 584        ir = is_finite(ir)? ir*sc : undef,
 585        id = is_finite(id)? id*sc : undef,
 586        side = is_finite(side)? side/2/sin(180/n) : undef,
 587        r = get_radius(r1=ir, r2=or, r=r, d1=id, d2=od, d=d, dflt=side)
 588    )
 589    assert(!is_undef(r), "regular_ngon(): need to specify one of r, d, or, od, ir, id, side.")
 590    assert(all_positive([r]), "polygon size must be a positive value")
 591    let(
 592        inset = opp_ang_to_hyp(rounding, (180-360/n)/2),
 593        mat = !is_undef(_mat) ? _mat :
 594            ( realign? zrot(-180/n) : ident(4)) * (
 595                !is_undef(align_tip)? rot(from=RIGHT, to=point2d(align_tip)) :
 596                !is_undef(align_side)? rot(from=RIGHT, to=point2d(align_side)) * zrot(180/n) :
 597                1
 598            ),
 599        path4 = rounding==0? ellipse(r=r, $fn=n) : (
 600            let(
 601                steps = floor(segs(r)/n),
 602                step = 360/n/steps,
 603                path2 = [
 604                    for (i = [0:1:n-1]) let(
 605                        a = 360 - i*360/n,
 606                        p = polar_to_xy(r-inset, a)
 607                    )
 608                    each arc(n=steps, cp=p, r=rounding, start=a+180/n, angle=-360/n)
 609                ],
 610                maxx_idx = max_index(column(path2,0)),
 611                path3 = list_rotate(path2,maxx_idx)
 612            ) path3
 613        ),
 614        path = apply(mat, path4),
 615        anchors = !is_undef(_anchs) ? _anchs :
 616            !is_string(anchor)? [] : [
 617            for (i = [0:1:n-1]) let(
 618                a1 = 360 - i*360/n,
 619                a2 = a1 - 360/n,
 620                p1 = apply(mat, polar_to_xy(r,a1)),
 621                p2 = apply(mat, polar_to_xy(r,a2)),
 622                tipp = apply(mat, polar_to_xy(r-inset+rounding,a1)),
 623                pos = (p1+p2)/2
 624            ) each [
 625                named_anchor(str("tip",i), tipp, unit(tipp,BACK), 0),
 626                named_anchor(str("side",i), pos, unit(pos,BACK), 0),
 627            ]
 628        ]
 629    ) reorient(anchor,spin, two_d=true, path=path, extent=false, p=path, anchors=anchors);
 630
 631
 632module regular_ngon(n=6, r, d, or, od, ir, id, side, rounding=0, realign=false, align_tip, align_side, anchor=CENTER, spin=0) {
 633    sc = 1/cos(180/n);
 634    ir = is_finite(ir)? ir*sc : undef;
 635    id = is_finite(id)? id*sc : undef;
 636    side = is_finite(side)? side/2/sin(180/n) : undef;
 637    r = get_radius(r1=ir, r2=or, r=r, d1=id, d2=od, d=d, dflt=side);
 638    check = assert(!is_undef(r), "regular_ngon(): need to specify one of r, d, or, od, ir, id, side.")
 639            assert(all_positive([r]), "polygon size must be a positive value");
 640    mat = ( realign? zrot(-180/n) : ident(4) ) * (
 641            !is_undef(align_tip)? rot(from=RIGHT, to=point2d(align_tip)) :
 642            !is_undef(align_side)? rot(from=RIGHT, to=point2d(align_side)) * zrot(180/n) :
 643            1
 644        );
 645    inset = opp_ang_to_hyp(rounding, (180-360/n)/2);
 646    anchors = [
 647        for (i = [0:1:n-1]) let(
 648            a1 = 360 - i*360/n,
 649            a2 = a1 - 360/n,
 650            p1 = apply(mat, polar_to_xy(r,a1)),
 651            p2 = apply(mat, polar_to_xy(r,a2)),
 652            tipp = apply(mat, polar_to_xy(r-inset+rounding,a1)),
 653            pos = (p1+p2)/2
 654        ) each [
 655            named_anchor(str("tip",i), tipp, unit(tipp,BACK), 0),
 656            named_anchor(str("side",i), pos, unit(pos,BACK), 0),
 657        ]
 658    ];
 659    path = regular_ngon(n=n, r=r, rounding=rounding, _mat=mat, _anchs=anchors);
 660    attachable(anchor,spin, two_d=true, path=path, extent=false, anchors=anchors) {
 661        polygon(path);
 662        children();
 663    }
 664}
 665
 666
 667// Function&Module: pentagon()
 668// Synopsis: Creates a regular pentagon.
 669// SynTags: Geom, Path
 670// Topics: Shapes (2D), Paths (2D), Path Generators, Attachable
 671// See Also: circle(), regular_ngon(), hexagon(), octagon(), ellipse(), star()
 672// Usage:
 673//   pentagon(or|od=, [realign=], [align_tip=|align_side=]) [ATTACHMENTS];
 674//   pentagon(ir=|id=, [realign=], [align_tip=|align_side=]) [ATTACHMENTS];
 675//   pentagon(side=, [realign=], [align_tip=|align_side=]) [ATTACHMENTS];
 676// Usage: as function
 677//   path = pentagon(...);
 678// Description:
 679//   When called as a function, returns a 2D path for a regular pentagon.
 680//   When called as a module, creates a 2D regular pentagon.
 681// Arguments:
 682//   r/or = Outside radius, at points.
 683//   ---
 684//   d/od = Outside diameter, at points.
 685//   ir = Inside radius, at center of sides.
 686//   id = Inside diameter, at center of sides.
 687//   side = Length of each side.
 688//   rounding = Radius of rounding for the tips of the polygon.  Default: 0 (no rounding)
 689//   realign = If false, vertex 0 will lie on the X+ axis.  If true then the midpoint of the last edge will lie on the X+ axis, and vertex 0 will be below the X axis.    Default: false
 690//   align_tip = If given as a 2D vector, rotates the whole shape so that the first vertex points in that direction.  This occurs before spin.
 691//   align_side = If given as a 2D vector, rotates the whole shape so that the normal of side0 points in that direction.  This occurs before spin.
 692//   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
 693//   spin = Rotate this many degrees around the Z axis after anchor.  See [spin](attachments.scad#subsection-spin).  Default: `0`
 694// Named Anchors:
 695//   "tip0" ... "tip4" = Each tip has an anchor, pointing outwards.
 696//   "side0" ... "side4" = The center of each side has an anchor, pointing outwards.
 697// Example(2D): by Outer Size
 698//   pentagon(or=30);
 699//   pentagon(od=60);
 700// Example(2D): by Inner Size
 701//   pentagon(ir=30);
 702//   pentagon(id=60);
 703// Example(2D): by Side Length
 704//   pentagon(side=20);
 705// Example(2D): Realigned
 706//   pentagon(side=20, realign=true);
 707// Example(2D): Alignment by Tip
 708//   pentagon(r=30, align_tip=BACK+RIGHT)
 709//       attach("tip0", FWD) color("blue")
 710//           stroke([[0,0],[0,7]], endcap2="arrow2");
 711// Example(2D): Alignment by Side
 712//   pentagon(r=30, align_side=BACK+RIGHT)
 713//       attach("side0", FWD) color("blue")
 714//           stroke([[0,0],[0,7]], endcap2="arrow2");
 715// Example(2D): Rounded
 716//   pentagon(od=100, rounding=20, $fn=20);
 717// Example(2D): Called as Function
 718//   stroke(closed=true, pentagon(or=30));
 719function pentagon(r, d, or, od, ir, id, side, rounding=0, realign=false, align_tip, align_side, anchor=CENTER, spin=0) =
 720    regular_ngon(n=5, r=r, d=d, or=or, od=od, ir=ir, id=id, side=side, rounding=rounding, realign=realign, align_tip=align_tip, align_side=align_side, anchor=anchor, spin=spin);
 721
 722
 723module pentagon(r, d, or, od, ir, id, side, rounding=0, realign=false, align_tip, align_side, anchor=CENTER, spin=0)
 724    regular_ngon(n=5, r=r, d=d, or=or, od=od, ir=ir, id=id, side=side, rounding=rounding, realign=realign, align_tip=align_tip, align_side=align_side, anchor=anchor, spin=spin) children();
 725
 726
 727// Function&Module: hexagon()
 728// Synopsis: Creates a regular hexagon.
 729// SynTags: Geom, Path
 730// Topics: Shapes (2D), Paths (2D), Path Generators, Attachable
 731// See Also: circle(), regular_ngon(), pentagon(), octagon(), ellipse(), star()
 732// Usage: As Module
 733//   hexagon(r/or, [realign=], <align_tip=|align_side=>, [rounding=], ...) [ATTACHMENTS];
 734//   hexagon(d=/od=, ...) [ATTACHMENTS];
 735//   hexagon(ir=/id=, ...) [ATTACHMENTS];
 736//   hexagon(side=, ...) [ATTACHMENTS];
 737// Usage: As Function
 738//   path = hexagon(...);
 739// Description:
 740//   When called as a function, returns a 2D path for a regular hexagon.
 741//   When called as a module, creates a 2D regular hexagon.
 742// Arguments:
 743//   r/or = Outside radius, at points.
 744//   ---
 745//   d/od = Outside diameter, at points.
 746//   ir = Inside radius, at center of sides.
 747//   id = Inside diameter, at center of sides.
 748//   side = Length of each side.
 749//   rounding = Radius of rounding for the tips of the polygon.  Default: 0 (no rounding)
 750//   realign = If false, vertex 0 will lie on the X+ axis.  If true then the midpoint of the last edge will lie on the X+ axis, and vertex 0 will be below the X axis.    Default: false
 751//   align_tip = If given as a 2D vector, rotates the whole shape so that the first vertex points in that direction.  This occurs before spin.
 752//   align_side = If given as a 2D vector, rotates the whole shape so that the normal of side0 points in that direction.  This occurs before spin.
 753//   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
 754//   spin = Rotate this many degrees around the Z axis after anchor.  See [spin](attachments.scad#subsection-spin).  Default: `0`
 755// Named Anchors:
 756//   "tip0" ... "tip5" = Each tip has an anchor, pointing outwards.
 757//   "side0" ... "side5" = The center of each side has an anchor, pointing outwards.
 758// Example(2D): by Outer Size
 759//   hexagon(or=30);
 760//   hexagon(od=60);
 761// Example(2D): by Inner Size
 762//   hexagon(ir=30);
 763//   hexagon(id=60);
 764// Example(2D): by Side Length
 765//   hexagon(side=20);
 766// Example(2D): Realigned
 767//   hexagon(side=20, realign=true);
 768// Example(2D): Alignment by Tip
 769//   hexagon(r=30, align_tip=BACK+RIGHT)
 770//       attach("tip0", FWD) color("blue")
 771//           stroke([[0,0],[0,7]], endcap2="arrow2");
 772// Example(2D): Alignment by Side
 773//   hexagon(r=30, align_side=BACK+RIGHT)
 774//       attach("side0", FWD) color("blue")
 775//           stroke([[0,0],[0,7]], endcap2="arrow2");
 776// Example(2D): Rounded
 777//   hexagon(od=100, rounding=20, $fn=20);
 778// Example(2D): Called as Function
 779//   stroke(closed=true, hexagon(or=30));
 780function hexagon(r, d, or, od, ir, id, side, rounding=0, realign=false, align_tip, align_side, anchor=CENTER, spin=0) =
 781    regular_ngon(n=6, r=r, d=d, or=or, od=od, ir=ir, id=id, side=side, rounding=rounding, realign=realign, align_tip=align_tip, align_side=align_side, anchor=anchor, spin=spin);
 782
 783
 784module hexagon(r, d, or, od, ir, id, side, rounding=0, realign=false, align_tip, align_side, anchor=CENTER, spin=0)
 785    regular_ngon(n=6, r=r, d=d, or=or, od=od, ir=ir, id=id, side=side, rounding=rounding, realign=realign, align_tip=align_tip, align_side=align_side, anchor=anchor, spin=spin) children();
 786
 787
 788// Function&Module: octagon()
 789// Synopsis: Creates a regular octagon.
 790// SynTags: Geom, Path
 791// Topics: Shapes (2D), Paths (2D), Path Generators, Attachable
 792// See Also: circle(), regular_ngon(), pentagon(), hexagon(), ellipse(), star()
 793// Usage: As Module
 794//   octagon(r/or, [realign=], [align_tip=|align_side=], [rounding=], ...) [ATTACHMENTS];
 795//   octagon(d=/od=, ...) [ATTACHMENTS];
 796//   octagon(ir=/id=, ...) [ATTACHMENTS];
 797//   octagon(side=, ...) [ATTACHMENTS];
 798// Usage: As Function
 799//   path = octagon(...);
 800// Description:
 801//   When called as a function, returns a 2D path for a regular octagon.
 802//   When called as a module, creates a 2D regular octagon.
 803// Arguments:
 804//   r/or = Outside radius, at points.
 805//   d/od = Outside diameter, at points.
 806//   ir = Inside radius, at center of sides.
 807//   id = Inside diameter, at center of sides.
 808//   side = Length of each side.
 809//   rounding = Radius of rounding for the tips of the polygon.  Default: 0 (no rounding)
 810//   realign = If false, vertex 0 will lie on the X+ axis.  If true then the midpoint of the last edge will lie on the X+ axis, and vertex 0 will be below the X axis.    Default: false
 811//   align_tip = If given as a 2D vector, rotates the whole shape so that the first vertex points in that direction.  This occurs before spin.
 812//   align_side = If given as a 2D vector, rotates the whole shape so that the normal of side0 points in that direction.  This occurs before spin.
 813//   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
 814//   spin = Rotate this many degrees around the Z axis after anchor.  See [spin](attachments.scad#subsection-spin).  Default: `0`
 815// Named Anchors:
 816//   "tip0" ... "tip7" = Each tip has an anchor, pointing outwards.
 817//   "side0" ... "side7" = The center of each side has an anchor, pointing outwards.
 818// Example(2D): by Outer Size
 819//   octagon(or=30);
 820//   octagon(od=60);
 821// Example(2D): by Inner Size
 822//   octagon(ir=30);
 823//   octagon(id=60);
 824// Example(2D): by Side Length
 825//   octagon(side=20);
 826// Example(2D): Realigned
 827//   octagon(side=20, realign=true);
 828// Example(2D): Alignment by Tip
 829//   octagon(r=30, align_tip=BACK+RIGHT)
 830//       attach("tip0", FWD) color("blue")
 831//           stroke([[0,0],[0,7]], endcap2="arrow2");
 832// Example(2D): Alignment by Side
 833//   octagon(r=30, align_side=BACK+RIGHT)
 834//       attach("side0", FWD) color("blue")
 835//           stroke([[0,0],[0,7]], endcap2="arrow2");
 836// Example(2D): Rounded
 837//   octagon(od=100, rounding=20, $fn=20);
 838// Example(2D): Called as Function
 839//   stroke(closed=true, octagon(or=30));
 840function octagon(r, d, or, od, ir, id, side, rounding=0, realign=false, align_tip, align_side, anchor=CENTER, spin=0) =
 841    regular_ngon(n=8, r=r, d=d, or=or, od=od, ir=ir, id=id, side=side, rounding=rounding, realign=realign, align_tip=align_tip, align_side=align_side, anchor=anchor, spin=spin);
 842
 843
 844module octagon(r, d, or, od, ir, id, side, rounding=0, realign=false, align_tip, align_side, anchor=CENTER, spin=0)
 845    regular_ngon(n=8, r=r, d=d, or=or, od=od, ir=ir, id=id, side=side, rounding=rounding, realign=realign, align_tip=align_tip, align_side=align_side, anchor=anchor, spin=spin) children();
 846
 847
 848// Function&Module: right_triangle()
 849// Synopsis: Creates a right triangle.
 850// SynTags: Geom, Path
 851// Topics: Shapes (2D), Paths (2D), Path Generators, Attachable
 852// See Also: square(), rect(), regular_ngon(), pentagon(), hexagon(), octagon(), star()
 853// Usage: As Module
 854//   right_triangle(size, [center], ...) [ATTACHMENTS];
 855// Usage: As Function
 856//   path = right_triangle(size, [center], ...);
 857// Description:
 858//   When called as a module, creates a right triangle with the Hypotenuse in the X+Y+ quadrant.
 859//   When called as a function, returns a 2D path for a right triangle with the Hypotenuse in the X+Y+ quadrant.
 860// Arguments:
 861//   size = The width and length of the right triangle, given as a scalar or an XY vector.
 862//   center = If true, forces `anchor=CENTER`.  If false, forces `anchor=[-1,-1]`.  Default: undef (use `anchor=`)
 863//   ---
 864//   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
 865//   spin = Rotate this many degrees around the Z axis after anchor.  See [spin](attachments.scad#subsection-spin).  Default: `0`
 866// Named Anchors:
 867//   "hypot" = Center of angled side, perpendicular to that side.
 868// Example(2D):
 869//   right_triangle([40,30]);
 870// Example(2D): With `center=true`
 871//   right_triangle([40,30], center=true);
 872// Example(2D): Standard Anchors
 873//   right_triangle([80,30], center=true)
 874//       show_anchors(custom=false);
 875//   color([0.5,0.5,0.5,0.1])
 876//       square([80,30], center=true);
 877// Example(2D): Named Anchors
 878//   right_triangle([80,30], center=true)
 879//       show_anchors(std=false);
 880function right_triangle(size=[1,1], center, anchor, spin=0) =
 881    let(
 882        size = is_num(size)? [size,size] : size,
 883        anchor = get_anchor(anchor, center, [-1,-1], [-1,-1])
 884    )
 885    assert(is_vector(size,2))
 886    assert(min(size)>0, "Must give positive size")
 887    let(
 888        path = [ [size.x/2,-size.y/2], [-size.x/2,-size.y/2], [-size.x/2,size.y/2] ],
 889        anchors = [
 890            named_anchor("hypot", CTR, unit([size.y,size.x])),
 891        ]
 892    ) reorient(anchor,spin, two_d=true, size=[size.x,size.y], anchors=anchors, p=path);
 893
 894module right_triangle(size=[1,1], center, anchor, spin=0) {
 895    size = is_num(size)? [size,size] : size;
 896    anchor = get_anchor(anchor, center, [-1,-1], [-1,-1]);
 897    check = assert(is_vector(size,2));
 898    path = right_triangle(size, anchor="origin");
 899    anchors = [
 900        named_anchor("hypot", CTR, unit([size.y,size.x])),
 901    ];
 902    attachable(anchor,spin, two_d=true, size=[size.x,size.y], anchors=anchors) {
 903        polygon(path);
 904        children();
 905    }
 906}
 907
 908
 909// Function&Module: trapezoid()
 910// Synopsis: Creates a trapezoid with parallel top and bottom sides.
 911// SynTags: Geom, Path
 912// Topics: Shapes (2D), Paths (2D), Path Generators, Attachable
 913// See Also: rect(), square()
 914// Usage: As Module
 915//   trapezoid(h, w1, w2, [shift=], [rounding=], [chamfer=], [flip=], ...) [ATTACHMENTS];
 916//   trapezoid(h, w1, ang=, [rounding=], [chamfer=], [flip=], ...) [ATTACHMENTS];
 917//   trapezoid(h, w2=, ang=, [rounding=], [chamfer=], [flip=], ...) [ATTACHMENTS];
 918//   trapezoid(w1=, w2=, ang=, [rounding=], [chamfer=], [flip=], ...) [ATTACHMENTS];
 919// Usage: As Function
 920//   path = trapezoid(...);
 921// Description:
 922//   When called as a function, returns a 2D path for a trapezoid with parallel front and back (top and bottom) sides. 
 923//   When called as a module, creates a 2D trapezoid.  You can specify the trapezoid by giving its height and the lengths
 924//   of its two bases.  Alternatively, you can omit one of those parameters and specify the lower angle(s).
 925//   The shift parameter, which cannot be combined with ang, shifts the back (top) of the trapezoid to the right.  
 926// Arguments:
 927//   h = The Y axis height of the trapezoid.
 928//   w1 = The X axis width of the front end of the trapezoid.
 929//   w2 = The X axis width of the back end of the trapezoid.
 930//   ---
 931//   ang = Specify the bottom angle(s) of the trapezoid.  Can give a scalar for an isosceles trapezoid or a list of two angles, the left angle and right angle.  You must omit one of `h`, `w1`, or `w2` to allow the freedom to control the angles. 
 932//   shift = Scalar value to shift the back of the trapezoid along the X axis by.  Cannot be combined with ang.  Default: 0
 933//   rounding = The rounding radius for the corners.  If given as a list of four numbers, gives individual radii for each corner, in the order [X+Y+,X-Y+,X-Y-,X+Y-]. Default: 0 (no rounding)
 934//   chamfer = The Length of the chamfer faces at the corners.  If given as a list of four numbers, gives individual chamfers for each corner, in the order [X+Y+,X-Y+,X-Y-,X+Y-].  Default: 0 (no chamfer)
 935//   flip = If true, negative roundings and chamfers will point forward and back instead of left and right.  Default: `false`.
 936//   atype = The type of anchoring to use with `anchor=`.  Valid opptions are "box" and "perim".  This lets you choose between putting anchors on the rounded or chamfered perimeter, or on the square bounding box of the shape. Default: "box"
 937//   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
 938//   spin = Rotate this many degrees around the Z axis after anchor.  See [spin](attachments.scad#subsection-spin).  Default: `0`
 939// Anchor Types:
 940//   box = Anchor is with respect to the rectangular bounding box of the shape.
 941//   perim = Anchors are placed along the rounded or chamfered perimeter of the shape.
 942// Examples(2D):
 943//   trapezoid(h=30, w1=40, w2=20);
 944//   trapezoid(h=25, w1=20, w2=35);
 945//   trapezoid(h=20, w1=40, w2=0);
 946//   trapezoid(h=20, w1=30, ang=60);
 947//   trapezoid(h=20, w1=20, ang=120);
 948//   trapezoid(h=20, w2=10, ang=60);
 949//   trapezoid(h=20, w1=50, ang=[40,60]);
 950//   trapezoid(w1=30, w2=10, ang=[30,90]);
 951// Example(2D): Chamfered Trapezoid
 952//   trapezoid(h=30, w1=60, w2=40, chamfer=5);
 953// Example(2D): Negative Chamfered Trapezoid
 954//   trapezoid(h=30, w1=60, w2=40, chamfer=-5);
 955// Example(2D): Flipped Negative Chamfered Trapezoid
 956//   trapezoid(h=30, w1=60, w2=40, chamfer=-5, flip=true);
 957// Example(2D): Rounded Trapezoid
 958//   trapezoid(h=30, w1=60, w2=40, rounding=5);
 959// Example(2D): Negative Rounded Trapezoid
 960//   trapezoid(h=30, w1=60, w2=40, rounding=-5);
 961// Example(2D): Flipped Negative Rounded Trapezoid
 962//   trapezoid(h=30, w1=60, w2=40, rounding=-5, flip=true);
 963// Example(2D): Mixed Chamfering and Rounding
 964//   trapezoid(h=30, w1=60, w2=40, rounding=[5,0,-10,0],chamfer=[0,8,0,-15],$fa=1,$fs=1);
 965// Example(2D): default anchors for roundings
 966//   trapezoid(h=30, w1=100, ang=[66,44],rounding=5) show_anchors();
 967// Example(2D): default anchors for negative roundings are still at the trapezoid corners
 968//   trapezoid(h=30, w1=100, ang=[66,44],rounding=-5) show_anchors();
 969// Example(2D): "perim" anchors are at the tips of negative roundings
 970//   trapezoid(h=30, w1=100, ang=[66,44],rounding=-5, atype="perim") show_anchors();
 971// Example(2D): They point the other direction if you flip them
 972//   trapezoid(h=30, w1=100, ang=[66,44],rounding=-5, atype="perim",flip=true) show_anchors();
 973// Example(2D): Called as Function
 974//   stroke(closed=true, trapezoid(h=30, w1=40, w2=20));
 975
 976function _trapezoid_dims(h,w1,w2,shift,ang) = 
 977    let(  
 978        h = is_def(h)? h
 979          : num_defined([w1,w2,each ang])==4 ? (w1-w2) * sin(ang[0]) * sin(ang[1]) / sin(ang[0]+ang[1])
 980          : undef
 981    )
 982    is_undef(h) ? [h]
 983  :
 984    let(
 985        x1 = is_undef(ang[0]) || ang[0]==90 ? 0 : h/tan(ang[0]),
 986        x2 = is_undef(ang[1]) || ang[1]==90 ? 0 : h/tan(ang[1]),
 987        w1 = is_def(w1)? w1
 988           : is_def(w2) && is_def(ang[0]) ? w2 + x1 + x2
 989           : undef,
 990        w2 = is_def(w2)? w2
 991           : is_def(w1) && is_def(ang[0]) ? w1 - x1 - x2
 992           : undef,
 993        shift = first_defined([shift,(x1-x2)/2])
 994    )
 995    [h,w1,w2,shift];
 996
 997
 998
 999function trapezoid(h, w1, w2, ang, shift, chamfer=0, rounding=0, flip=false, anchor=CENTER, spin=0,atype="box", _return_override, angle) =
1000    assert(is_undef(angle), "The angle parameter has been replaced by ang, which specifies trapezoid interior angle")
1001    assert(is_undef(h) || is_finite(h))
1002    assert(is_undef(w1) || is_finite(w1))
1003    assert(is_undef(w2) || is_finite(w2))
1004    assert(is_undef(ang) || is_finite(ang) || is_vector(ang,2))
1005    assert(num_defined([h, w1, w2, ang]) == 3, "Must give exactly 3 of the arguments h, w1, w2, and angle.")
1006    assert(is_undef(shift) || is_finite(shift))
1007    assert(num_defined([shift,ang])<2, "Cannot specify shift and ang together")
1008    assert(is_finite(chamfer)  || is_vector(chamfer,4))
1009    assert(is_finite(rounding) || is_vector(rounding,4))
1010    let(
1011        ang = force_list(ang,2),
1012        angOK = len(ang)==2 && (ang==[undef,undef] || (all_positive(ang) && ang[0]<180 && ang[1]<180))
1013    )
1014    assert(angOK, "trapezoid angles must be scalar or 2-vector, strictly between 0 and 180")
1015    let(
1016        h_w1_w2_shift = _trapezoid_dims(h,w1,w2,shift,ang),
1017        h = h_w1_w2_shift[0],
1018        w1 = h_w1_w2_shift[1],
1019        w2 = h_w1_w2_shift[2],
1020        shift = h_w1_w2_shift[3],
1021        chamfer = force_list(chamfer,4),
1022        rounding = force_list(rounding,4)
1023    )
1024    assert(all_zero(v_mul(chamfer,rounding),0), "Cannot specify chamfer and rounding at the same corner")
1025    let(
1026        srads = chamfer+rounding, 
1027        rads = v_abs(srads)
1028    )
1029    assert(w1>=0 && w2>=0 && h>0, "Degenerate trapezoid geometry.")
1030    assert(w1+w2>0, "Degenerate trapezoid geometry.")
1031    let(
1032        base = [
1033            [ w2/2+shift, h/2],
1034            [-w2/2+shift, h/2],
1035            [-w1/2,-h/2],
1036            [ w1/2,-h/2],
1037        ],
1038        ang1 = v_theta(base[0]-base[3])-90,
1039        ang2 = v_theta(base[1]-base[2])-90,
1040        angs = [ang1, ang2, ang2, ang1],
1041        qdirs = [[1,1], [-1,1], [-1,-1], [1,-1]],
1042        hyps = [for (i=[0:3]) adj_ang_to_hyp(rads[i],angs[i])],
1043        offs = [
1044            for (i=[0:3]) let(
1045                xoff = adj_ang_to_opp(rads[i],angs[i]),
1046                a = [xoff, -rads[i]] * qdirs[i].y * (srads[i]<0 && flip? -1 : 1),
1047                b = a + [hyps[i] * qdirs[i].x * (srads[i]<0 && !flip? 1 : -1), 0]
1048            ) b
1049        ],
1050        corners = [
1051             (
1052                let(i = 0)
1053                rads[i] == 0? [base[i]]
1054              : srads[i] > 0? arc(n=rounding[i]?undef:2, cp=base[i]+offs[i], angle=[angs[i], 90], r=rads[i])
1055              : flip? arc(n=rounding[i]?undef:2, cp=base[i]+offs[i], angle=[angs[i],-90], r=rads[i])
1056              : arc(n=rounding[i]?undef:2, cp=base[i]+offs[i], angle=[180+angs[i],90], r=rads[i])
1057            ),
1058             (
1059                let(i = 1)
1060                rads[i] == 0? [base[i]] 
1061              : srads[i] > 0? arc(n=rounding[i]?undef:2, cp=base[i]+offs[i], angle=[90,180+angs[i]], r=rads[i]) 
1062              : flip? arc(n=rounding[i]?undef:2, cp=base[i]+offs[i], angle=[270,180+angs[i]], r=rads[i]) 
1063              : arc(n=rounding[i]?undef:2, cp=base[i]+offs[i], angle=[90,angs[i]], r=rads[i])
1064            ),
1065             (
1066                let(i = 2)
1067                rads[i] == 0? [base[i]] 
1068              : srads[i] > 0? arc(n=rounding[i]?undef:2, cp=base[i]+offs[i], angle=[180+angs[i],270], r=rads[i]) 
1069              : flip? arc(n=rounding[i]?undef:2, cp=base[i]+offs[i], angle=[180+angs[i],90], r=rads[i]) 
1070              : arc(n=rounding[i]?undef:2, cp=base[i]+offs[i], angle=[angs[i],-90], r=rads[i])
1071            ),
1072             (
1073                let(i = 3)
1074                rads[i] == 0? [base[i]] 
1075              : srads[i] > 0? arc(n=rounding[i]?undef:2, cp=base[i]+offs[i], angle=[-90,angs[i]], r=rads[i]) 
1076              : flip? arc(n=rounding[i]?undef:2, cp=base[i]+offs[i], angle=[90,angs[i]], r=rads[i]) 
1077              : arc(n=rounding[i]?undef:2, cp=base[i]+offs[i], angle=[270,180+angs[i]], r=rads[i])
1078            ),
1079        ],
1080        path = reverse(flatten(corners)),
1081        override = [for(i=[0:3])
1082                      if (atype!="box" && srads[i]!=0)
1083                         srads[i]>0?
1084                             let(dir = unit(base[i]-select(base,i-1)) + unit(base[i]-select(base,i+1)),
1085                                pt=[for(seg=pair(corners[i])) let(isect=line_intersection(seg, [base[i],base[i]+dir],SEGMENT,LINE))
1086                                                             if (is_def(isect) && isect!=seg[0]) isect]
1087                             )
1088                             [qdirs[i], [pt[0], undef]]
1089                        : flip?
1090                            let(  dir=unit(base[i] - select(base,i+(i%2==0?-1:1))))
1091                            [qdirs[i], [select(corners[i],i%2==0?0:-1), dir]]
1092                        : let( dir = [qdirs[i].x,0])
1093                            [qdirs[i], [select(corners[i],i%2==0?-1:0), dir]]]
1094    ) _return_override ? [reorient(anchor,spin, two_d=true, size=[w1,h], size2=w2, shift=shift, p=path, override=override),override]
1095                       : reorient(anchor,spin, two_d=true, size=[w1,h], size2=w2, shift=shift, p=path, override=override);
1096
1097
1098
1099
1100module trapezoid(h, w1, w2, ang, shift, chamfer=0, rounding=0, flip=false, anchor=CENTER, spin=0, atype="box", angle) {
1101    path_over = trapezoid(h=h, w1=w1, w2=w2, ang=ang, shift=shift, chamfer=chamfer, rounding=rounding,
1102                          flip=flip, angle=angle,atype=atype,anchor="origin",_return_override=true);
1103    path=path_over[0];
1104    override = path_over[1];
1105    ang = force_list(ang,2);
1106    h_w1_w2_shift = _trapezoid_dims(h,w1,w2,shift,ang);
1107    h = h_w1_w2_shift[0];
1108    w1 = h_w1_w2_shift[1];
1109    w2 = h_w1_w2_shift[2];
1110    shift = h_w1_w2_shift[3];
1111    attachable(anchor,spin, two_d=true, size=[w1,h], size2=w2, shift=shift, override=override) {
1112        polygon(path);
1113        children();
1114    }
1115}
1116
1117
1118
1119// Function&Module: star()
1120// Synopsis: Creates a star-shaped polygon or returns a star-shaped region.
1121// SynTags: Geom, Path
1122// Topics: Shapes (2D), Paths (2D), Path Generators, Attachable
1123// See Also: circle(), ellipse(), regular_ngon()
1124// Usage: As Module
1125//   star(n, r/or, ir, [realign=], [align_tip=], [align_pit=], ...) [ATTACHMENTS];
1126//   star(n, r/or, step=, ...) [ATTACHMENTS];
1127// Usage: As Function
1128//   path = star(n, r/or, ir, [realign=], [align_tip=], [align_pit=], ...);
1129//   path = star(n, r/or, step=, ...);
1130// Description:
1131//   When called as a function, returns the path needed to create a star polygon with N points.
1132//   When called as a module, creates a star polygon with N points.
1133// Arguments:
1134//   n = The number of stellate tips on the star.
1135//   r/or = The radius to the tips of the star.
1136//   ir = The radius to the inner corners of the star.
1137//   ---
1138//   d/od = The diameter to the tips of the star.
1139//   id = The diameter to the inner corners of the star.
1140//   step = Calculates the radius of the inner star corners by virtually drawing a straight line `step` tips around the star.  2 <= step < n/2
1141//   realign = If false, vertex 0 will lie on the X+ axis.  If true then the midpoint of the last edge will lie on the X+ axis, and vertex 0 will be below the X axis.    Default: false
1142//   align_tip = If given as a 2D vector, rotates the whole shape so that the first star tip points in that direction.  This occurs before spin.
1143//   align_pit = If given as a 2D vector, rotates the whole shape so that the first inner corner is pointed towards that direction.  This occurs before spin.
1144//   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
1145//   spin = Rotate this many degrees around the Z axis after anchor.  See [spin](attachments.scad#subsection-spin).  Default: `0`
1146//   atype = Choose "hull" or "intersect" anchor methods.  Default: "hull"
1147// Named Anchors:
1148//   "tip0" ... "tip4" = Each tip has an anchor, pointing outwards.
1149//   "pit0" ... "pit4" = The inside corner between each tip has an anchor, pointing outwards.
1150//   "midpt0" ... "midpt4" = The center-point between each pair of tips has an anchor, pointing outwards.
1151// Examples(2D):
1152//   star(n=5, r=50, ir=25);
1153//   star(n=5, r=50, step=2);
1154//   star(n=7, r=50, step=2);
1155//   star(n=7, r=50, step=3);
1156// Example(2D): Realigned
1157//   star(n=7, r=50, step=3, realign=true);
1158// Example(2D): Alignment by Tip
1159//   star(n=5, ir=15, or=30, align_tip=BACK+RIGHT)
1160//       attach("tip0", FWD) color("blue")
1161//           stroke([[0,0],[0,7]], endcap2="arrow2");
1162// Example(2D): Alignment by Pit
1163//   star(n=5, ir=15, or=30, align_pit=BACK+RIGHT)
1164//       attach("pit0", FWD) color("blue")
1165//           stroke([[0,0],[0,7]], endcap2="arrow2");
1166// Example(2D): Called as Function
1167//   stroke(closed=true, star(n=5, r=50, ir=25));
1168function star(n, r, ir, d, or, od, id, step, realign=false, align_tip, align_pit, anchor=CENTER, spin=0, atype="hull", _mat, _anchs) =
1169    assert(in_list(atype, _ANCHOR_TYPES), "Anchor type must be \"hull\" or \"intersect\"")  
1170    assert(is_undef(align_tip) || is_vector(align_tip))
1171    assert(is_undef(align_pit) || is_vector(align_pit))
1172    assert(is_undef(align_tip) || is_undef(align_pit), "Can only specify one of align_tip and align_pit")
1173    assert(is_def(n), "Must specify number of points, n")
1174    let(
1175        r = get_radius(r1=or, d1=od, r=r, d=d),
1176        count = num_defined([ir,id,step]),
1177        stepOK = is_undef(step) || (step>1 && step<n/2)
1178    )
1179    assert(count==1, "Must specify exactly one of ir, id, step")
1180    assert(stepOK,  n==4 ? "Parameter 'step' not allowed for 4 point stars"
1181                  : n==5 || n==6 ? str("Parameter 'step' must be 2 for ",n," point stars")
1182                  : str("Parameter 'step' must be between 2 and ",floor(n/2-1/2)," for ",n," point stars"))
1183    let(
1184        mat = !is_undef(_mat) ? _mat :
1185            ( realign? zrot(-180/n) : ident(4) ) * (
1186                !is_undef(align_tip)? rot(from=RIGHT, to=point2d(align_tip)) :
1187                !is_undef(align_pit)? rot(from=RIGHT, to=point2d(align_pit)) * zrot(180/n) :
1188                1
1189            ),
1190        stepr = is_undef(step)? r : r*cos(180*step/n)/cos(180*(step-1)/n),
1191        ir = get_radius(r=ir, d=id, dflt=stepr),
1192        offset = realign? 180/n : 0,
1193        path1 = [for(i=[2*n:-1:1]) let(theta=180*i/n, radius=(i%2)?ir:r) radius*[cos(theta), sin(theta)]],
1194        path = apply(mat, path1),
1195        anchors = !is_undef(_anchs) ? _anchs :
1196            !is_string(anchor)? [] : [
1197            for (i = [0:1:n-1]) let(
1198                a1 = 360 - i*360/n,
1199                a2 = a1 - 180/n,
1200                a3 = a1 - 360/n,
1201                p1 = apply(mat, polar_to_xy(r,a1)),
1202                p2 = apply(mat, polar_to_xy(ir,a2)),
1203                p3 = apply(mat, polar_to_xy(r,a3)),
1204                pos = (p1+p3)/2
1205            ) each [
1206                named_anchor(str("tip",i), p1, unit(p1,BACK), 0),
1207                named_anchor(str("pit",i), p2, unit(p2,BACK), 0),
1208                named_anchor(str("midpt",i), pos, unit(pos,BACK), 0),
1209            ]
1210        ]
1211    ) reorient(anchor,spin, two_d=true, path=path, p=path, extent=atype=="hull", anchors=anchors);
1212
1213
1214module star(n, r, ir, d, or, od, id, step, realign=false, align_tip, align_pit, anchor=CENTER, spin=0, atype="hull") {
1215    checks =
1216        assert(in_list(atype, _ANCHOR_TYPES), "Anchor type must be \"hull\" or \"intersect\"")
1217        assert(is_undef(align_tip) || is_vector(align_tip))
1218        assert(is_undef(align_pit) || is_vector(align_pit))
1219        assert(is_undef(align_tip) || is_undef(align_pit), "Can only specify one of align_tip and align_pit");
1220    r = get_radius(r1=or, d1=od, r=r, d=d, dflt=undef);
1221    stepr = is_undef(step)? r : r*cos(180*step/n)/cos(180*(step-1)/n);
1222    ir = get_radius(r=ir, d=id, dflt=stepr);
1223    mat = ( realign? zrot(-180/n) : ident(4) ) * (
1224            !is_undef(align_tip)? rot(from=RIGHT, to=point2d(align_tip)) :
1225            !is_undef(align_pit)? rot(from=RIGHT, to=point2d(align_pit)) * zrot(180/n) :
1226            1
1227        );
1228    anchors = [
1229        for (i = [0:1:n-1]) let(
1230            a1 = 360 - i*360/n - (realign? 180/n : 0),
1231            a2 = a1 - 180/n,
1232            a3 = a1 - 360/n,
1233            p1 = apply(mat, polar_to_xy(r,a1)),
1234            p2 = apply(mat, polar_to_xy(ir,a2)),
1235            p3 = apply(mat, polar_to_xy(r,a3)),
1236            pos = (p1+p3)/2
1237        ) each [
1238            named_anchor(str("tip",i), p1, unit(p1,BACK), 0),
1239            named_anchor(str("pit",i), p2, unit(p2,BACK), 0),
1240            named_anchor(str("midpt",i), pos, unit(pos,BACK), 0),
1241        ]
1242    ];
1243    path = star(n=n, r=r, ir=ir, realign=realign, _mat=mat, _anchs=anchors);
1244    attachable(anchor,spin, two_d=true, path=path, extent=atype=="hull", anchors=anchors) {
1245        polygon(path);
1246        children();
1247    }
1248}
1249
1250
1251
1252/// Internal Function: _path_add_jitter()
1253/// Topics: Paths
1254/// See Also: jittered_poly()
1255/// Usage:
1256///   jpath = _path_add_jitter(path, [dist], [closed=]);
1257/// Description:
1258///   Adds tiny jitter offsets to collinear points in the given path so that they
1259///   are no longer collinear.  This is useful for preserving subdivision on long
1260///   straight segments, when making geometry with `polygon()`, for use with
1261///   `linear_exrtrude()` with a `twist()`.
1262/// Arguments:
1263///   path = The path to add jitter to.
1264///   dist = The amount to jitter points by.  Default: 1/512 (0.00195)
1265///   ---
1266///   closed = If true, treat path like a closed polygon.  Default: true
1267/// Example(3D):
1268///   d = 100; h = 75; quadsize = 5;
1269///   path = pentagon(d=d);
1270///   spath = subdivide_path(path, maxlen=quadsize, closed=true);
1271///   jpath = _path_add_jitter(spath, closed=true);
1272///   linear_extrude(height=h, twist=72, slices=h/quadsize)
1273///      polygon(jpath);
1274function _path_add_jitter(path, dist=1/512, closed=true) =
1275    assert(is_path(path))
1276    assert(is_finite(dist))
1277    assert(is_bool(closed))
1278    [
1279        path[0],
1280        for (i=idx(path,s=1,e=closed?-1:-2)) let(
1281            n = line_normal([path[i-1],path[i]])
1282        ) path[i] + n * (is_collinear(select(path,i-1,i+1))? (dist * ((i%2)*2-1)) : 0),
1283        if (!closed) last(path)
1284    ];
1285
1286
1287
1288// Module: jittered_poly()
1289// Synopsis: Creates a polygon with extra points for smoother twisted extrusions.
1290// SynTags: Geom
1291// Topics: Extrusions
1292// See Also: subdivide_path()
1293// Usage:
1294//   jittered_poly(path, [dist]);
1295// Description:
1296//   Creates a 2D polygon shape from the given path in such a way that any extra
1297//   collinear points are not stripped out in the way that `polygon()` normally does.
1298//   This is useful for refining the mesh of a `linear_extrude()` with twist.
1299// Arguments:
1300//   path = The path to add jitter to.
1301//   dist = The amount to jitter points by.  Default: 1/512 (0.00195)
1302// Example:
1303//   d = 100; h = 75; quadsize = 5;
1304//   path = pentagon(d=d);
1305//   spath = subdivide_path(path, maxlen=quadsize, closed=true);
1306//   linear_extrude(height=h, twist=72, slices=h/quadsize)
1307//      jittered_poly(spath);
1308module jittered_poly(path, dist=1/512) {
1309    no_children($children);
1310    polygon(_path_add_jitter(path, dist, closed=true));
1311}
1312
1313
1314// Section: Curved 2D Shapes
1315
1316
1317// Function&Module: teardrop2d()
1318// Synopsis: Creates a 2D teardrop shape.
1319// SynTags: Geom, Path
1320// Topics: Shapes (2D), Paths (2D), Path Generators, Attachable
1321// See Also: teardrop(), onion(), keyhole()
1322// Description:
1323//   When called as a module, makes a 2D teardrop shape. Useful for extruding into 3D printable holes as it limits overhang to 45 degrees.  Uses "intersect" style anchoring.  
1324//   The cap_h parameter truncates the top of the teardrop.  If cap_h is taller than the untruncated form then
1325//   the result will be the full, untruncated shape.  The segments of the bottom section of the teardrop are
1326//   calculated to be the same as a circle or cylinder when rotated 90 degrees.  (Note that this agreement is poor when `$fn=6` or `$fn=7`.  
1327//   If `$fn` is a multiple of four then the teardrop will reach its extremes on all four axes.  The circum option
1328//   produces a teardrop that circumscribes the circle; in this case set `realign=true` to get a teardrop that meets its internal extremes
1329//   on the axes.  
1330//   When called as a function, returns a 2D path to for a teardrop shape.
1331//
1332// Usage: As Module
1333//   teardrop2d(r/d=, [ang], [cap_h]) [ATTACHMENTS];
1334// Usage: As Function
1335//   path = teardrop2d(r|d=, [ang], [cap_h]);
1336//
1337// Arguments:
1338//   r = radius of circular part of teardrop.  (Default: 1)
1339//   ang = angle of hat walls from the Y axis (half the angle of the peak).  (Default: 45 degrees)
1340//   cap_h = if given, height above center where the shape will be truncated.
1341//   ---
1342//   d = diameter of circular portion of bottom. (Use instead of r)
1343//   circum = if true, create a circumscribing teardrop.  Default: false
1344//   realign = if true, change whether bottom of teardrop is a point or a flat.  Default: false
1345//   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
1346//   spin = Rotate this many degrees around the Z axis after anchor.  See [spin](attachments.scad#subsection-spin).  Default: `0`
1347//
1348// Example(2D): Typical Shape
1349//   teardrop2d(r=30, ang=30);
1350// Example(2D): Crop Cap
1351//   teardrop2d(r=30, ang=30, cap_h=40);
1352// Example(2D): Close Crop
1353//   teardrop2d(r=30, ang=30, cap_h=20);
1354module teardrop2d(r, ang=45, cap_h, d, circum=false, realign=false, anchor=CENTER, spin=0)
1355{
1356    path = teardrop2d(r=r, d=d, ang=ang, circum=circum, realign=realign, cap_h=cap_h);
1357    attachable(anchor,spin, two_d=true, path=path, extent=false) {
1358        polygon(path);
1359        children();
1360    }
1361}
1362
1363// _extrapt = true causes the point to be duplicated so a teardrop with no cap
1364// has the same point count as one with a cap.  
1365
1366function teardrop2d(r, ang=45, cap_h, d, circum=false, realign=false, anchor=CENTER, spin=0, _extrapt=false) =
1367    let(
1368        r = get_radius(r=r, d=d, dflt=1),
1369        minheight = r*sin(ang),
1370        maxheight = r/sin(ang), //cos(90-ang),
1371        pointycap = is_undef(cap_h) || cap_h>=maxheight
1372    )
1373    assert(is_undef(cap_h) || cap_h>=minheight, str("cap_h cannot be less than ",minheight," but it is ",cap_h))
1374    let(
1375        cap = [
1376                pointycap? [0,maxheight] : [(maxheight-cap_h)*tan(ang), cap_h],
1377                r*[cos(ang),sin(ang)]
1378              ],
1379        fullcircle = ellipse(r=r, realign=realign, circum=circum,spin=90),        
1380        
1381        // Chose the point on the circle that is lower than the cap but also creates a segment bigger than
1382        // seglen/skipfactor so we don't have a teeny tiny segment at the end of the cap, except for the hexagoin
1383        // case which is treated specially
1384        skipfactor = len(fullcircle)==6 ? 15 : 3,
1385        path = !circum ?
1386                  let(seglen = norm(fullcircle[0]-fullcircle[1]))
1387                  [
1388                   each cap,
1389                   for (p=fullcircle)
1390                          if (
1391                               p.y<last(cap).y-EPSILON
1392                                 && norm([abs(p.x)-last(cap).x,p.y-last(cap.y)])>seglen/skipfactor
1393                             ) p,
1394                   xflip(cap[1]),
1395                   if (_extrapt || !pointycap) xflip(cap[0])
1396                  ]
1397             : let(
1398                   isect = [for(i=[0:1:len(fullcircle)/4])
1399                               let(p = line_intersection(cap, select(fullcircle,[i,i+1]), bounded1=RAY, bounded2=SEGMENT))
1400                               if (p) [i,p]
1401                           ],
1402                   i = last(isect)[0],
1403                   p = last(isect)[1]
1404               )
1405               [
1406                 cap[0],
1407                 p,
1408                 each select(fullcircle,i+1,-i-1-(realign?1:0)),
1409                 xflip(p),
1410                 if(_extrapt || !pointycap) xflip(cap[0])
1411               ]
1412    )
1413    reorient(anchor,spin, two_d=true, path=path, p=path, extent=false);
1414
1415
1416
1417// Function&Module: egg()
1418// Synopsis: Creates an egg-shaped 2d object.
1419// SynTags: Geom, Path
1420// Topics: Shapes (2D), Paths (2D), Path Generators, Attachable
1421// See Also: circle(), ellipse(), glued_circles(), keyhole()
1422// Usage: As Module
1423//   egg(length, r1|d1=, r2|d2=, R|D=) [ATTACHMENTS];
1424// Usage: As Function
1425//   path = egg(length, r1|d1=, r2|d2=, R|D=);
1426// Description:
1427//   When called as a module, constructs an egg-shaped object by connecting two circles with convex arcs that are tangent to the circles.
1428//   You specify the length of the egg, the radii of the two circles, and the desired arc radius.
1429//   Note that because the side radius, R, is often much larger than the end radii, you may get better
1430//   results using `$fs` and `$fa` to control the number of semgments rather than using `$fn`.
1431//   This shape may be useful for creating a cam. 
1432//   When called as a function, returns a 2D path for an egg-shaped object. 
1433// Arguments:
1434//   length = length of the egg
1435//   r1 = radius of the left-hand circle
1436//   r2 = radius of the right-hand circle
1437//   R = radius of the joining arcs
1438//   ---
1439//   d1 = diameter of the left-hand circle
1440//   d2 = diameter of the right-hand circle
1441//   D = diameter of the joining arcs
1442// Named Anchors:
1443//   "left" = center of the left circle
1444//   "right" = center of the right circle
1445// Example(2D,NoAxes): This first example shows how the egg is constructed from two circles and two joining arcs.
1446//   $fn=100;
1447//   color("red") stroke(egg(78,25,12, 60),closed=true);
1448//   stroke([left(14,circle(25)),
1449//           right(27,circle(12))]);
1450// Example(2D,Anim,VPD=250,VPR=[0,0,0]): Varying length between circles
1451//   r1 = 25; r2 = 12; R = 65;
1452//   length = floor(lookup($t, [[0,55], [0.5,90], [1,55]]));
1453//   egg(length,r1,r2,R,$fn=180);
1454//   color("black") text(str("length=",length), size=8, halign="center", valign="center");
1455// Example(2D,Anim,VPD=250,VPR=[0,0,0]): Varying tangent arc radius R
1456//   length = 78; r1 = 25; r2 = 12;
1457//   R = floor(lookup($t, [[0,45], [0.5,150], [1,45]]));
1458//   egg(length,r1,r2,R,$fn=180);
1459//   color("black") text(str("R=",R), size=8, halign="center", valign="center");
1460// Example(2D,Anim,VPD=250,VPR=[0,0,0]): Varying circle radius r2
1461//   length = 78; r1 = 25; R = 65;
1462//   r2 = floor(lookup($t, [[0,5], [0.5,30], [1,5]]));
1463//   egg(length,r1,r2,R,$fn=180);
1464//   color("black") text(str("r2=",r2), size=8, halign="center", valign="center");
1465function egg(length, r1, r2, R, d1, d2, D, anchor=CENTER, spin=0) =
1466    let(
1467        r1 = get_radius(r1=r1,d1=d1),
1468        r2 = get_radius(r1=r2,d1=d2),
1469        D = get_radius(r1=R, d1=D)
1470    )
1471    assert(length>0)
1472    assert(R>length/2, "Side radius R must be larger than length/2")
1473    assert(length>r1+r2, "Length must be longer than 2*(r1+r2)")
1474    assert(length>2*r2, "Length must be longer than 2*r2")
1475    assert(length>2*r1, "Length must be longer than 2*r1")  
1476    let(
1477        c1 = [-length/2+r1,0],
1478        c2 = [length/2-r2,0],
1479        Rmin = (r1+r2+norm(c1-c2))/2,
1480        Mlist = circle_circle_intersection(R-r1, c1, R-r2, c2),
1481        arcparms = reverse([for(M=Mlist) [M, c1+r1*unit(c1-M), c2+r2*unit(c2-M)]]),
1482        path = concat(
1483                      arc(r=r2, cp=c2, points=[[length/2,0],arcparms[0][2]],endpoint=false),
1484                      arc(r=R, cp=arcparms[0][0], points=select(arcparms[0],[2,1]),endpoint=false),
1485                      arc(r=r1, points=[arcparms[0][1], [-length/2,0], arcparms[1][1]],endpoint=false),
1486                      arc(r=R, cp=arcparms[1][0], points=select(arcparms[1],[1,2]),endpoint=false),
1487                      arc(r=r2, cp=c2, points=[arcparms[1][2], [length/2,0]],endpoint=false)
1488        ),
1489        anchors = [named_anchor("left", c1, BACK, 0),
1490                   named_anchor("right", c2, BACK, 0)]
1491    )
1492    reorient(anchor, spin, two_d=true, path=path, extent=true, p=path, anchors=anchors);
1493
1494module egg(length,r1,r2,R,d1,d2,D,anchor=CENTER, spin=0)
1495{
1496  path = egg(length,r1,r2,R,d1,d2,D);
1497  anchors = [named_anchor("left", [-length/2+r1,0], BACK, 0),
1498             named_anchor("right", [length/2-r2,0], BACK, 0)];
1499  attachable(anchor, spin, two_d=true, path=path, extent=true, anchors=anchors){
1500    polygon(path);
1501    children();
1502  }
1503}
1504
1505
1506// Function&Module: ring()
1507// Synopsis: Draws a 2D ring or partial ring or returns a region or path
1508// SynTags: Geom, Region, Path
1509// Topics: Shapes (2D), Paths (2D), Path Generators, Regions, Attachable
1510// See Also: arc(), circle()
1511//
1512// Usage: ring or partial ring from radii/diameters
1513//   region=ring(n, r1=|d1=, r2=|d2=, [full=], [angle=], [start=]);
1514// Usage: ring or partial ring from radius and ring width
1515//   region=ring(n, ring_width, r=|d=, [full=], [angle=], [start=]);
1516// Usage: ring or partial ring passing through three points
1517//   region=ring(n, [ring_width], [r=,d=], points=[P0,P1,P2], [full=]);
1518// Usage: ring or partial ring from tangent point on segment `[P0,P1]` to the tangent point on segment `[P1,P2]`.
1519//   region=ring(n, [ring_width], corner=[P0,P1,P2], [r=,d=], [r1|d1=], [r2=|d2=], [full=]);
1520// Usage: ring or partial ring based on setting a width at the X axis and height above the X axis
1521//   region=ring(n, [ring_width], [r=|d=], width=, thickness=, [full=]);
1522// Usage: as a module
1523//   ring(...) [ATTACHMENTS];
1524// Description:
1525//   If called as a function returns a region or path for a ring or part of a ring.  If called as a module, creates the corresponding 2D ring or partial ring shape.
1526//   The geometry of the ring can be specified using any of the methods supported by {{arc()}}.  If `full` is true (the default) the ring will be complete and the
1527//   returned value a region.  If `full` is false then the return is a path describing a partial ring.  The returned path is always clockwise with the larger radius arc first.
1528//   A ring has two radii, the inner and outer.  When specifying geometry you must somehow specify one radius, which can be directly with `r=` or `r1=` or by giving a point list with 
1529//   or without a center point.  You specify the second radius by giving `r=` directly, or `r2=` if you used `r1=` for the first radius, or by giving `ring_width`.  If `ring_width`
1530//   the second radius will be larger than the first; if `ring_width` is negative the second radius will be smaller. 
1531// Arguments:
1532//   n = Number of vertices to use for the inner and outer portions of the ring
1533//   ring_width = width of the ring.  Can be positive or negative
1534//   ---
1535//   r1/d1 = inner radius or diameter of the ring
1536//   r2/d2 = outer radius or diameter of the ring
1537//   r/d = second radius or diameter of ring when r1 or d1 are not given
1538//   full = if true create a full ring, if false create a partial ring.  Default: true unless `angle` is given
1539//   cp = Centerpoint of ring.
1540//   points = Points on the ring boundary.
1541//   corner = A path of two segments to fit the ring tangent to.
1542//   long = if given with cp and points takes the long arc instead of the default short arc.  Default: false
1543//   cw = if given with cp and 2 points takes the arc in the clockwise direction.  Default: false
1544//   ccw = if given with cp and 2 points takes the arc in the counter-clockwise direction.  Default: false
1545//   width = If given with `thickness`, ring is defined based on an arc with ends on X axis.
1546//   thickness = If given with `width`, ring is defined based on an arc with ends on X axis, and this height above the X axis. 
1547//   start = Start angle of ring.  Default: 0
1548//   angle = If scalar, the end angle in degrees relative to start parameter.  If a vector specifies start and end angles of ring.  
1549//   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  (Module only) Default: `CENTER`
1550//   spin = Rotate this many degrees around the Z axis after anchor.  See [spin](attachments.scad#subsection-spin).  (Module only) Default: `0`
1551// Examples(2D):
1552//   ring(r1=5,r2=7, n=32);
1553//   ring(r=5,ring_width=-1, n=32);
1554//   ring(r=7, n=5, ring_width=-4);
1555//   ring(points=[[0,0],[3,3],[5,2]], ring_width=2, n=32);
1556//   ring(points=[[0,0],[3,3],[5,2]], r=1, n=32);
1557//   ring(cp=[3,3], points=[[4,4],[1,3]], ring_width=1);
1558//   ring(corner=[[0,0],[4,4],[7,3]], r2=2, r1=1.5,n=22,full=false);
1559//   ring(r1=5,r2=7, angle=[33,110], n=32);
1560//   ring(r1=5,r2=7, angle=[0,360], n=32);  // full circle
1561//   ring(r=5, points=[[0,0],[3,3],[5,2]], full=false, n=32);
1562//   ring(32,-2, cp=[1,1], points=[[4,4],[-3,6]], full=false);
1563//   ring(r=5,ring_width=-1, n=32);
1564//   ring(points=[[0,0],[3,3],[5,2]], ring_width=2, n=32);
1565//   ring(points=[[0,0],[3,3],[5,2]], r=1, n=32);
1566//   ring(cp=[3,3], points=[[4,4],[1,3]], ring_width=1);
1567// Example(2D): Using corner, the outer radius is the one tangent to the corner
1568//   corner = [[0,0],[4,4],[7,3]];
1569//   ring(corner=corner, r2=3, r1=2,n=22);
1570//   stroke(corner, width=.1,color="red");
1571// Example(2D): For inner radius tangent to a corner, specify `r=` and `ring_width`.
1572//   corner = [[0,0],[4,4],[7,3]];
1573//   ring(corner=corner, r=3, ring_width=1,n=22,full=false);
1574//   stroke(corner, width=.1,color="red");
1575// Example(2D):
1576//   $fn=128;
1577//   region = ring(width=5,thickness=1.5,ring_width=2);   
1578//   path = ring(width=5,thickness=1.5,ring_width=2,full=false);
1579//   stroke(region,width=.25);
1580//   color("red") dashed_stroke(path,dashpat=[1.5,1.5],closed=true,width=.25);
1581
1582module ring(n,ring_width,r,r1,r2,angle,d,d1,d2,cp,points,corner, width,thickness,start, long=false, full=true, cw=false,ccw=false, anchor=CENTER, spin=0)
1583{
1584  R = ring(n=n,r=r,ring_width=ring_width,r1=r1,r2=r2,angle=angle,d=d,d1=d1,d2=d2,cp=cp,points=points,corner=corner, width=width,thickness=thickness,start=start,
1585           long=long, full=full, cw=cw, ccw=ccw);
1586  attachable(anchor,spin,two_d=true,region=is_region(R)?R:undef,path=is_region(R)?undef:R,extent=false) {
1587     region(R);
1588     children();
1589  }
1590}  
1591
1592function ring(n,ring_width,r,r1,r2,angle,d,d1,d2,cp,points,corner, width,thickness,start, long=false, full=true, cw=false,ccw=false) =
1593    let(
1594        r1 = is_def(r1) ? assert(is_undef(d),"Cannot define r1 and d1")r1
1595           : is_def(d1) ? d1/2
1596           : undef,
1597        r2 = is_def(r2) ? assert(is_undef(d),"Cannot define r2 and d2")r2
1598           : is_def(d2) ? d2/2
1599           : undef,
1600        r = is_def(r) ? assert(is_undef(d),"Cannot define r and d")r
1601          : is_def(d) ? d/2
1602          : undef,
1603        full = is_def(angle) ? false : full
1604    )
1605    assert(is_undef(start) || is_def(angle), "start requires angle")
1606    assert(is_undef(angle) || !any_defined([thickness,width,points,corner]), "Cannot give angle with points, corner, width or thickness")
1607    assert(!is_vector(angle,2) || abs(angle[1]-angle[0]) <= 360, "angle gives more than 360 degrees")
1608    assert(is_undef(points) || is_path(points,2), str("Points must be a 2d vector",points))
1609    assert(!any_defined([points,thickness,width]) || num_defined([r1,r2])==0, "Cannot give r1, r2, d1, or d2 with points, width or thickness")
1610    is_def(width) && is_def(thickness)?
1611       assert(!any_defined([r,cp,points,angle,start]), "Conflicting or invalid parameters to ring")
1612       assert(all_positive([width,thickness]), "Width and thickness must be positive")
1613       ring(n=n,r=r,ring_width=ring_width,points=[[width/2,0], [0,thickness], [-width/2,0]],full=full)
1614  : full && is_undef(cp) && is_def(points) ?
1615       assert(is_def(points) && len(points)==3, "Without cp given, must provide exactly three points")
1616       assert(num_defined([r,ring_width]), "Must give r or ring_width with point list")
1617       let(
1618            ctr_rad = circle_3points(points),
1619            dummy=assert(is_def(ctr_rad[0]), "Collinear points given to ring()"),
1620            part1 = move(ctr_rad[0],circle(r=ctr_rad[1], $fn=is_def(n) ? n : $fn)),
1621            first_r = norm(part1[0]-ctr_rad[0]),
1622            r = is_def(r) ? r : first_r+ring_width,
1623            part2 = move(ctr_rad[0],circle(r=r, $fn=is_def(n) ? n : $fn))
1624       )
1625       assert(first_r!=r, "Ring has zero width")
1626       (first_r>r ? [part1, reverse(part2)] : [part2, reverse(part1)])
1627  : full && is_def(corner) ?
1628       assert(is_path(corner,2) && len(corner)==3, "corner must be a list of 3 points")
1629       assert(!any_defined([thickness,width,points,cp,angle.start]), "Conflicting or invalid parameters to ring")
1630       let(parmok = (all_positive([r1,r2]) && num_defined([r,ring_width])==0) 
1631                      || (num_defined([r1,r2])==0 && all_positive([r]) && is_finite(ring_width)))
1632       assert(parmok, "With corner must give (r1 and r2) or (r and ring_width), but you gave some other combination")
1633       let(
1634           newr1 = is_def(r1) ? min(r1,r2) : min(r,r+ring_width),
1635           newr2 = is_def(r2) ? max(r2,r1) : max(r,r+ring_width),
1636           data = circle_2tangents(newr2,corner[0],corner[1],corner[2]),
1637           cp=data[0]
1638       )
1639       [move(cp,circle($fn=is_def(n) ? n : $fn, r=newr2)),move(cp, circle( $fn=is_def(n) ? n : $fn, r=newr1))]
1640  : full && is_def(cp) && is_def(points) ?
1641       assert(in_list(len(points),[1,2]), "With cp must give a list of one or two points.")
1642       assert(num_defined([r,ring_width]), "Must give r or ring_width with point list")
1643       let(
1644           first_r=norm(points[0]-cp),
1645           part1 = move(cp,circle(r=first_r, $fn=is_def(n) ? n : $fn)),
1646           r = is_def(r) ? r : first_r+ring_width,
1647           part2 = move(cp,circle(r=r, $fn=is_def(n) ? n : $fn))
1648       )
1649       assert(first_r!=r, "Ring has zero width")
1650       first_r>r ? [part1, reverse(part2)] : [part2, reverse(part1)]
1651  : full || angle==360 || (is_vector(angle,2) && abs(angle[1]-angle[0])==360) ?
1652      let(parmok = (all_positive([r1,r2]) && num_defined([r,ring_width])==0) 
1653                     || (num_defined([r1,r2])==0 && all_positive([r]) && is_finite(ring_width)))
1654      assert(parmok, "Must give (r1 and r2) or (r and ring_width), but you gave some other combination")
1655      let(
1656          newr1 = is_def(r1) ? min(r1,r2) : min(r,r+ring_width),
1657          newr2 = is_def(r2) ? max(r2,r1) : max(r,r+ring_width),
1658          cp = default(cp,[0,0])
1659      )
1660      [move(cp,circle($fn=is_def(n) ? n : $fn, r=newr2)),move(cp, circle( $fn=is_def(n) ? n : $fn, r=newr1))]
1661  :  let(
1662         parmRok = (all_positive([r1,r2]) && num_defined([r,ring_width])==0) 
1663                     || (num_defined([r1,r2])==0 && all_positive([r]) && is_finite(ring_width)),
1664         pass_r = any_defined([points,thickness]) ? assert(!any_defined([r1,r2]),"Cannot give r1, d1, r2, or d2 with a point list or width & thickness")
1665                                                    assert(num_defined([ring_width,r])==1, "Must defined exactly one of r and ring_width when using a pointlist or width & thickness")
1666                                                    undef 
1667                : assert(num_defined([r,r2])==1,"Cannot give r or d and r1 or d1") first_defined([r,r2]),
1668         base_arc = clockwise_polygon(arc(r=pass_r,n=n,angle=angle,cp=cp,points=points, corner=corner, width=width, thickness=thickness,start=start, long=long, cw=cw,ccw=ccw,wedge=true)),
1669         center = base_arc[0],
1670         arc1 = list_tail(base_arc,1),
1671         r_actual = norm(center-arc1[0]),
1672         new_r = is_def(ring_width) ? r_actual+ring_width
1673               : first_defined([r,r1]),
1674         pts = [center+new_r*unit(arc1[0]-center), center+new_r*unit(arc1[floor(len(arc1)/2)]-center), center+new_r*unit(last(arc1)-center)],
1675         second=arc(n=n,points=pts),
1676         arc2 = is_polygon_clockwise(second) ? second : reverse(second) 
1677     ) new_r>r_actual ? concat(arc2, reverse(arc1)) : concat(arc1,reverse(arc2));
1678
1679
1680// Function&Module: glued_circles()
1681// Synopsis: Creates a shape of two circles joined by a curved waist.
1682// SynTags: Geom, Path
1683// Topics: Shapes (2D), Paths (2D), Path Generators, Attachable
1684// See Also: circle(), ellipse(), egg(), keyhole()
1685// Usage: As Module
1686//   glued_circles(r/d=, [spread], [tangent], ...) [ATTACHMENTS];
1687// Usage: As Function
1688//   path = glued_circles(r/d=, [spread], [tangent], ...);
1689// Description:
1690//   When called as a function, returns a 2D path forming a shape of two circles joined by curved waist.
1691//   When called as a module, creates a 2D shape of two circles joined by curved waist.  Uses "hull" style anchoring.  
1692// Arguments:
1693//   r = The radius of the end circles.
1694//   spread = The distance between the centers of the end circles.  Default: 10
1695//   tangent = The angle in degrees of the tangent point for the joining arcs, measured away from the Y axis.  Default: 30
1696//   ---
1697//   d = The diameter of the end circles.
1698//   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
1699//   spin = Rotate this many degrees around the Z axis after anchor.  See [spin](attachments.scad#subsection-spin).  Default: `0`
1700// Examples(2D):
1701//   glued_circles(r=15, spread=40, tangent=45);
1702//   glued_circles(d=30, spread=30, tangent=30);
1703//   glued_circles(d=30, spread=30, tangent=15);
1704//   glued_circles(d=30, spread=30, tangent=-30);
1705// Example(2D): Called as Function
1706//   stroke(closed=true, glued_circles(r=15, spread=40, tangent=45));
1707function glued_circles(r, spread=10, tangent=30, d, anchor=CENTER, spin=0) =
1708    let(
1709        r = get_radius(r=r, d=d, dflt=10),
1710        r2 = (spread/2 / sin(tangent)) - r,
1711        cp1 = [spread/2, 0],
1712        cp2 = [0, (r+r2)*cos(tangent)],
1713        sa1 = 90-tangent,
1714        ea1 = 270+tangent,
1715        lobearc = ea1-sa1,
1716        lobesegs = ceil(segs(r)*lobearc/360),
1717        sa2 = 270-tangent,
1718        ea2 = 270+tangent,
1719        subarc = ea2-sa2,
1720        arcsegs = ceil(segs(r2)*abs(subarc)/360),
1721        // In the tangent zero case the inner curves are missing so we need to complete the two
1722        // outer curves.  In the other case the inner curves are present and endpoint=false
1723        // prevents point duplication.  
1724        path = tangent==0 ?
1725                    concat(arc(n=lobesegs+1, r=r, cp=-cp1, angle=[sa1,ea1]),
1726                           arc(n=lobesegs+1, r=r, cp=cp1, angle=[sa1+180,ea1+180]))
1727                :
1728                    concat(arc(n=lobesegs, r=r, cp=-cp1, angle=[sa1,ea1], endpoint=false),
1729                           [for(theta=lerpn(ea2+180,ea2-subarc+180,arcsegs,endpoint=false))  r2*[cos(theta),sin(theta)] - cp2],
1730                           arc(n=lobesegs, r=r, cp=cp1, angle=[sa1+180,ea1+180], endpoint=false),
1731                           [for(theta=lerpn(ea2,ea2-subarc,arcsegs,endpoint=false))  r2*[cos(theta),sin(theta)] + cp2]),
1732        maxx_idx = max_index(column(path,0)),
1733        path2 = reverse_polygon(list_rotate(path,maxx_idx))
1734    ) reorient(anchor,spin, two_d=true, path=path2, extent=true, p=path2);
1735
1736
1737module glued_circles(r, spread=10, tangent=30, d, anchor=CENTER, spin=0) {
1738    path = glued_circles(r=r, d=d, spread=spread, tangent=tangent);
1739    attachable(anchor,spin, two_d=true, path=path, extent=true) {
1740        polygon(path);
1741        children();
1742    }
1743}
1744
1745
1746// Function&Module: keyhole()
1747// Synopsis: Creates a 2D keyhole shape.
1748// SynTags: Geom, Path
1749// Topics: Shapes (2D), Paths (2D), Path Generators, Attachable
1750// See Also: circle(), ellipse(), egg(), glued_circles()
1751// Usage: As Module
1752//   keyhole(l/length=, r1/d1=, r2/d2=, [shoulder_r=], ...) [ATTACHMENTS];
1753// Usage: As Function
1754//   path = keyhole(l/length=, r1/d1=, r2/d2=, [shoulder_r=], ...);
1755// Description:
1756//   When called as a function, returns a 2D path forming a shape of two differently sized circles joined by a straight slot, making what looks like a keyhole.
1757//   When called as a module, creates a 2D shape of two differently sized circles joined by a straight slot, making what looks like a keyhole.  Uses "hull" style anchoring.  
1758// Arguments:
1759//   l = The distance between the centers of the two circles.  Default: `15`
1760//   r1= The radius of the back circle, centered on `[0,0]`.  Default: `2.5`
1761//   r2= The radius of the forward circle, centered on `[0,-length]`.  Default: `5`
1762//   ---
1763//   shoulder_r = The radius of the rounding of the shoulder between the larger circle, and the slot that leads to the smaller circle.  Default: `0`
1764//   d1= The diameter of the back circle, centered on `[0,0]`.
1765//   d2= The diameter of the forward circle, centered on `[0,-l]`.
1766//   length = An alternate name for the `l=` argument.
1767//   anchor = Translate so anchor point is at origin (0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
1768//   spin = Rotate this many degrees around the Z axis after anchor.  See [spin](attachments.scad#subsection-spin).  Default: `0`
1769// Examples(2D):
1770//   keyhole(40, 10, 30);
1771//   keyhole(l=60, r1=20, r2=40);
1772// Example(2D): Making the forward circle larger than the back circle
1773//   keyhole(l=60, r1=40, r2=20);
1774// Example(2D): Centering on the larger hole:
1775//   keyhole(l=60, r1=40, r2=20, spin=180);
1776// Example(2D): Rounding the shoulders
1777//   keyhole(l=60, r1=20, r2=40, shoulder_r=20);
1778// Example(2D): Called as Function
1779//   stroke(closed=true, keyhole(l=60, r1=20, r2=40));
1780
1781function keyhole(l, r1, r2, shoulder_r=0, d1, d2, length, anchor=CTR, spin=0) =
1782    let(
1783        l = first_defined([l,length,15]),
1784        r1 = get_radius(r=r1, d=d1, dflt=5),
1785        r2 = get_radius(r=r2, d=d2, dflt=10)
1786    )
1787    assert(is_num(l) && l>0)
1788    assert(l>=max(r1,r2))
1789    assert(is_undef(shoulder_r) || (is_num(shoulder_r) && shoulder_r>=0))
1790    let(
1791        cp1 = [0,0],
1792        cp2 = cp1 + [0,-l],
1793        shoulder_r = is_num(shoulder_r)? shoulder_r : min(r1,r2) / 2,
1794        minr = min(r1, r2) + shoulder_r,
1795        maxr = max(r1, r2) + shoulder_r,
1796        dy = opp_hyp_to_adj(minr, maxr),
1797        spt1 = r1>r2? cp1+[minr,-dy] : cp2+[minr,dy],
1798        spt2 = [-spt1.x, spt1.y],
1799        ds = spt1 - (r1>r2? cp1 : cp2),
1800        ang = atan2(abs(ds.y), abs(ds.x)),
1801        path = r1>r2? [
1802                if (shoulder_r<=0) spt1
1803                  else each arc(r=shoulder_r, cp=spt1, start=180-ang, angle=ang, endpoint=false),
1804                each arc(r=r2, cp=cp2, start=0, angle=-180, endpoint=false),
1805                if (shoulder_r<=0) spt2
1806                  else each arc(r=shoulder_r, cp=spt2, start=0, angle=ang, endpoint=false),
1807                each arc(r=r1, cp=cp1, start=180+ang, angle=-180-2*ang, endpoint=false),
1808            ] : [
1809                if (shoulder_r<=0) spt1
1810                  else each arc(r=shoulder_r, cp=spt1, start=180, angle=ang, endpoint=false),
1811                each arc(r=r2, cp=cp2, start=ang, angle=-180-2*ang, endpoint=false),
1812                if (shoulder_r<=0) spt2
1813                  else each arc(r=shoulder_r, cp=spt2, start=360-ang, angle=ang, endpoint=false),
1814                each arc(r=r1, cp=cp1, start=180, angle=-180, endpoint=false),
1815            ]
1816    ) reorient(anchor,spin, two_d=true, path=path, extent=true, p=path);
1817
1818
1819module keyhole(l, r1, r2, shoulder_r=0, d1, d2, length, anchor=CTR, spin=0) {
1820    path = keyhole(l=l, r1=r1, r2=r2, shoulder_r=shoulder_r, d1=d1, d2=d2, length=length);
1821    attachable(anchor,spin, two_d=true, path=path, extent=true) {
1822        polygon(path);
1823        children();
1824    }
1825}
1826
1827
1828// Function&Module: supershape()
1829// Synopsis: Creates a 2D [Superformula](https://en.wikipedia.org/wiki/Superformula) shape.
1830// SynTags: Geom, Path
1831// Topics: Shapes (2D), Paths (2D), Path Generators, Attachable
1832// See Also: circle(), ellipse()
1833// Usage: As Module
1834//   supershape([step],[n=], [m1=], [m2=], [n1=], [n2=], [n3=], [a=], [b=], [r=/d=]) [ATTACHMENTS];
1835// Usage: As Function
1836//   path = supershape([step], [n=], [m1=], [m2=], [n1=], [n2=], [n3=], [a=], [b=], [r=/d=]);
1837// Description:
1838//   When called as a function, returns a 2D path for the outline of the [Superformula](https://en.wikipedia.org/wiki/Superformula) shape.
1839//   When called as a module, creates a 2D [Superformula](https://en.wikipedia.org/wiki/Superformula) shape.
1840//   Note that the "hull" type anchoring (the default) is more intuitive for concave star-like shapes, but the anchor points do not
1841//   necesarily lie on the line of the anchor vector, which can be confusing, especially for simpler, ellipse-like shapes.
1842//   Note that the default step angle of 0.5 is very fine and can be slow, but due to the complex curves of the supershape,
1843//   many points are often required to give a good result.  
1844// Arguments:
1845//   step = The angle step size for sampling the superformula shape.  Smaller steps are slower but more accurate.  Default: 0.5
1846//   ---
1847//   n = Produce n points as output.  Alternative to step.  Not to be confused with shape parameters n1 and n2.  
1848//   m1 = The m1 argument for the superformula. Default: 4.
1849//   m2 = The m2 argument for the superformula. Default: m1.
1850//   n1 = The n1 argument for the superformula. Default: 1.
1851//   n2 = The n2 argument for the superformula. Default: n1.
1852//   n3 = The n3 argument for the superformula. Default: n2.
1853//   a = The a argument for the superformula.  Default: 1.
1854//   b = The b argument for the superformula.  Default: a.
1855//   r = Radius of the shape.  Scale shape to fit in a circle of radius r.
1856//   d = Diameter of the shape.  Scale shape to fit in a circle of diameter d.
1857//   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
1858//   spin = Rotate this many degrees around the Z axis after anchor.  See [spin](attachments.scad#subsection-spin).  Default: `0`
1859//   atype = Select "hull" or "intersect" style anchoring.  Default: "hull". 
1860// Example(2D):
1861//   supershape(step=0.5,m1=16,m2=16,n1=0.5,n2=0.5,n3=16,r=50);
1862// Example(2D): Called as Function
1863//   stroke(closed=true, supershape(step=0.5,m1=16,m2=16,n1=0.5,n2=0.5,n3=16,d=100));
1864// Examples(2D,Med):
1865//   for(n=[2:5]) right(2.5*(n-2)) supershape(m1=4,m2=4,n1=n,a=1,b=2);  // Superellipses
1866//   m=[2,3,5,7]; for(i=[0:3]) right(2.5*i) supershape(.5,m1=m[i],n1=1);
1867//   m=[6,8,10,12]; for(i=[0:3]) right(2.7*i) supershape(.5,m1=m[i],n1=1,b=1.5);  // m should be even
1868//   m=[1,2,3,5]; for(i=[0:3]) fwd(1.5*i) supershape(m1=m[i],n1=0.4);
1869//   supershape(m1=5, n1=4, n2=1); right(2.5) supershape(m1=5, n1=40, n2=10);
1870//   m=[2,3,5,7]; for(i=[0:3]) right(2.5*i) supershape(m1=m[i], n1=60, n2=55, n3=30);
1871//   n=[0.5,0.2,0.1,0.02]; for(i=[0:3]) right(2.5*i) supershape(m1=5,n1=n[i], n2=1.7);
1872//   supershape(m1=2, n1=1, n2=4, n3=8);
1873//   supershape(m1=7, n1=2, n2=8, n3=4);
1874//   supershape(m1=7, n1=3, n2=4, n3=17);
1875//   supershape(m1=4, n1=1/2, n2=1/2, n3=4);
1876//   supershape(m1=4, n1=4.0,n2=16, n3=1.5, a=0.9, b=9);
1877//   for(i=[1:4]) right(3*i) supershape(m1=i, m2=3*i, n1=2);
1878//   m=[4,6,10]; for(i=[0:2]) right(i*5) supershape(m1=m[i], n1=12, n2=8, n3=5, a=2.7);
1879//   for(i=[-1.5:3:1.5]) right(i*1.5) supershape(m1=2,m2=10,n1=i,n2=1);
1880//   for(i=[1:3],j=[-1,1]) translate([3.5*i,1.5*j])supershape(m1=4,m2=6,n1=i*j,n2=1);
1881//   for(i=[1:3]) right(2.5*i)supershape(step=.5,m1=88, m2=64, n1=-i*i,n2=1,r=1);
1882// Examples:
1883//   linear_extrude(height=0.3, scale=0) supershape(step=1, m1=6, n1=0.4, n2=0, n3=6);
1884//   linear_extrude(height=5, scale=0) supershape(step=1, b=3, m1=6, n1=3.8, n2=16, n3=10);
1885function supershape(step=0.5, n, m1=4, m2, n1=1, n2, n3, a=1, b, r, d,anchor=CENTER, spin=0, atype="hull") =
1886    assert(in_list(atype, _ANCHOR_TYPES), "Anchor type must be \"hull\" or \"intersect\"")
1887    let(
1888        n = first_defined([n, ceil(360/step)]),
1889        angs = lerpn(360,0,n,endpoint=false),  
1890        r = get_radius(r=r, d=d, dflt=undef),
1891        m2 = is_def(m2) ? m2 : m1,
1892        n2 = is_def(n2) ? n2 : n1,
1893        n3 = is_def(n3) ? n3 : n2,
1894        b = is_def(b) ? b : a,
1895        // superformula returns r(theta), the point in polar coordinates
1896        rvals = [for (theta = angs) _superformula(theta=theta,m1=m1,m2=m2,n1=n1,n2=n2,n3=n3,a=a,b=b)],
1897        scale = is_def(r) ? r/max(rvals) : 1,
1898        path = [for (i=idx(angs)) scale*rvals[i]*[cos(angs[i]), sin(angs[i])]]
1899    ) reorient(anchor,spin, two_d=true, path=path, p=path, extent=atype=="hull");
1900
1901module supershape(step=0.5,n,m1=4,m2=undef,n1,n2=undef,n3=undef,a=1,b=undef, r=undef, d=undef, anchor=CENTER, spin=0, atype="hull") {
1902    check = assert(in_list(atype, _ANCHOR_TYPES), "Anchor type must be \"hull\" or \"intersect\"");
1903    path = supershape(step=step,n=n,m1=m1,m2=m2,n1=n1,n2=n2,n3=n3,a=a,b=b,r=r,d=d);
1904    attachable(anchor,spin,extent=atype=="hull", two_d=true, path=path) {
1905        polygon(path);
1906        children();
1907    }
1908}
1909
1910function _superformula(theta,m1,m2,n1,n2=1,n3=1,a=1,b=1) =
1911    pow(pow(abs(cos(m1*theta/4)/a),n2)+pow(abs(sin(m2*theta/4)/b),n3),-1/n1);
1912
1913
1914// Function&Module: reuleaux_polygon()
1915// Synopsis: Creates a constant-width shape that is not circular.
1916// SynTags: Geom, Path
1917// Topics: Shapes (2D), Paths (2D), Path Generators, Attachable
1918// See Also: regular_ngon(), pentagon(), hexagon(), octagon()
1919// Usage: As Module
1920//   reuleaux_polygon(n, r|d=, ...) [ATTACHMENTS];
1921// Usage: As Function
1922//   path = reuleaux_polygon(n, r|d=, ...);
1923// Description:
1924//   When called as a module, reates a 2D Reuleaux Polygon; a constant width shape that is not circular.  Uses "intersect" type anchoring.  
1925//   When called as a function, returns a 2D path for a Reulaux Polygon.
1926// Arguments:
1927//   n = Number of "sides" to the Reuleaux Polygon.  Must be an odd positive number.  Default: 3
1928//   r = Radius of the shape.  Scale shape to fit in a circle of radius r.
1929//   ---
1930//   d = Diameter of the shape.  Scale shape to fit in a circle of diameter d.
1931//   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `CENTER`
1932//   spin = Rotate this many degrees around the Z axis after anchor.  See [spin](attachments.scad#subsection-spin).  Default: `0`
1933// Named Anchors:
1934//   "tip0", "tip1", etc. = Each tip has an anchor, pointing outwards.
1935// Examples(2D):
1936//   reuleaux_polygon(n=3, r=50);
1937//   reuleaux_polygon(n=5, d=100);
1938// Examples(2D): Standard vector anchors are based on extents
1939//   reuleaux_polygon(n=3, d=50) show_anchors(custom=false);
1940// Examples(2D): Named anchors exist for the tips
1941//   reuleaux_polygon(n=3, d=50) show_anchors(std=false);
1942module reuleaux_polygon(n=3, r, d, anchor=CENTER, spin=0) {
1943    check = assert(n>=3 && (n%2)==1);
1944    r = get_radius(r=r, d=d, dflt=1);
1945    path = reuleaux_polygon(n=n, r=r);
1946    anchors = [
1947        for (i = [0:1:n-1]) let(
1948            ca = 360 - i * 360/n,
1949            cp = polar_to_xy(r, ca)
1950        ) named_anchor(str("tip",i), cp, unit(cp,BACK), 0),
1951    ];
1952    attachable(anchor,spin, two_d=true, path=path, extent=false, anchors=anchors) {
1953        polygon(path);
1954        children();
1955    }
1956}
1957
1958
1959function reuleaux_polygon(n=3, r, d, anchor=CENTER, spin=0) =
1960    assert(n>=3 && (n%2)==1)
1961    let(
1962        r = get_radius(r=r, d=d, dflt=1),
1963        ssegs = max(3,ceil(segs(r)/n)),
1964        slen = norm(polar_to_xy(r,0)-polar_to_xy(r,180-180/n)),
1965        path = [
1966            for (i = [0:1:n-1]) let(
1967                ca = 180 - (i+0.5) * 360/n,
1968                sa = ca + 180 + (90/n),
1969                ea = ca + 180 - (90/n),
1970                cp = polar_to_xy(r, ca)
1971            ) each arc(n=ssegs-1, r=slen, cp=cp, angle=[sa,ea], endpoint=false)
1972        ],
1973        anchors = [
1974            for (i = [0:1:n-1]) let(
1975                ca = 360 - i * 360/n,
1976                cp = polar_to_xy(r, ca)
1977            ) named_anchor(str("tip",i), cp, unit(cp,BACK), 0),
1978        ]
1979    ) reorient(anchor,spin, two_d=true, path=path, extent=false, anchors=anchors, p=path);
1980
1981
1982
1983// Section: Text
1984
1985// Module: text()
1986// Synopsis: Creates an attachable block of text.
1987// SynTags: Geom
1988// Topics: Attachments, Text
1989// See Also: text3d(), attachable()
1990// Usage:
1991//   text(text, [size], [font], ...);
1992// Description:
1993//   Creates a 3D text block that can be attached to other attachable objects.
1994//   You cannot attach children to text.
1995//   .
1996//   Historically fonts were specified by their "body size", the height of the metal body
1997//   on which the glyphs were cast.  This means the size was an upper bound on the size
1998//   of the font glyphs, not a direct measurement of their size.  In digital typesetting,
1999//   the metal body is replaced by an invisible box, the em square, whose side length is
2000//   defined to be the font's size.  The glyphs can be contained in that square, or they
2001//   can extend beyond it, depending on the choices made by the font designer.  As a
2002//   result, the meaning of font size varies between fonts: two fonts at the "same" size
2003//   can differ significantly in the actual size of their characters.  Typographers
2004//   customarily specify the size in the units of "points".  A point is 1/72 inch.  In
2005//   OpenSCAD, you specify the size in OpenSCAD units (often treated as millimeters for 3d
2006//   printing), so if you want points you will need to perform a suitable unit conversion.
2007//   In addition, the OpenSCAD font system has a bug: if you specify size=s you will
2008//   instead get a font whose size is s/0.72.  For many fonts this means the size of
2009//   capital letters will be approximately equal to s, because it is common for fonts to
2010//   use about 70% of their height for the ascenders in the font.  To get the customary
2011//   font size, you should multiply your desired size by 0.72.
2012//   .
2013//   To find the fonts that you have available in your OpenSCAD installation,
2014//   go to the Help menu and select "Font List".  
2015// Arguments:
2016//   text = Text to create.
2017//   size = The font will be created at this size divided by 0.72.   Default: 10
2018//   font = Font to use.  Default: "Liberation Sans"
2019//   ---
2020//   halign = If given, specifies the horizontal alignment of the text.  `"left"`, `"center"`, or `"right"`.  Overrides `anchor=`.
2021//   valign = If given, specifies the vertical alignment of the text.  `"top"`, `"center"`, `"baseline"` or `"bottom"`.  Overrides `anchor=`.
2022//   spacing = The relative spacing multiplier between characters.  Default: `1.0`
2023//   direction = The text direction.  `"ltr"` for left to right.  `"rtl"` for right to left. `"ttb"` for top to bottom. `"btt"` for bottom to top.  Default: `"ltr"`
2024//   language = The language the text is in.  Default: `"en"`
2025//   script = The script the text is in.  Default: `"latin"`
2026//   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#subsection-anchor).  Default: `"baseline"`
2027//   spin = Rotate this many degrees around the Z axis.  See [spin](attachments.scad#subsection-spin).  Default: `0`
2028// Named Anchors:
2029//   "baseline" = Anchors at the baseline of the text, at the start of the string.
2030//   str("baseline",VECTOR) = Anchors at the baseline of the text, modified by the X and Z components of the appended vector.
2031// Examples(2D):
2032//   text("Foobar", size=10);
2033//   text("Foobar", size=12, font="Helvetica");
2034//   text("Foobar", anchor=CENTER);
2035//   text("Foobar", anchor=str("baseline",CENTER));
2036// Example: Using line_copies() distributor
2037//   txt = "This is the string.";
2038//   line_copies(spacing=[10,-5],n=len(txt))
2039//       text(txt[$idx], size=10, anchor=CENTER);
2040// Example: Using arc_copies() distributor
2041//   txt = "This is the string";
2042//   arc_copies(r=50, n=len(txt), sa=0, ea=180)
2043//       text(select(txt,-1-$idx), size=10, anchor=str("baseline",CENTER), spin=-90);
2044module text(text, size=10, font="Helvetica", halign, valign, spacing=1.0, direction="ltr", language="en", script="latin", anchor="baseline", spin=0) {
2045    no_children($children);
2046    dummy1 =
2047        assert(is_undef(anchor) || is_vector(anchor) || is_string(anchor), str("Got: ",anchor))
2048        assert(is_undef(spin)   || is_vector(spin,3) || is_num(spin), str("Got: ",spin));
2049    anchor = default(anchor, CENTER);
2050    spin =   default(spin,   0);
2051    geom = attach_geom(size=[size,size],two_d=true);
2052    anch = !any([for (c=anchor) c=="["])? anchor :
2053        let(
2054            parts = str_split(str_split(str_split(anchor,"]")[0],"[")[1],","),
2055            vec = [for (p=parts) parse_float(str_strip(p," ",start=true))]
2056        ) vec;
2057    ha = halign!=undef? halign :
2058        anchor=="baseline"? "left" :
2059        anchor==anch && is_string(anchor)? "center" :
2060        anch.x<0? "left" :
2061        anch.x>0? "right" :
2062        "center";
2063    va = valign != undef? valign :
2064        starts_with(anchor,"baseline")? "baseline" :
2065        anchor==anch && is_string(anchor)? "center" :
2066        anch.y<0? "bottom" :
2067        anch.y>0? "top" :
2068        "center";
2069    base = anchor=="baseline"? CENTER :
2070        anchor==anch && is_string(anchor)? CENTER :
2071        anch.z<0? BOTTOM :
2072        anch.z>0? TOP :
2073        CENTER;
2074    m = _attach_transform(base,spin,undef,geom);
2075    multmatrix(m) {
2076        $parent_anchor = anchor;
2077        $parent_spin   = spin;
2078        $parent_orient = undef;
2079        $parent_geom   = geom;
2080        $parent_size   = _attach_geom_size(geom);
2081        $attach_to   = undef;
2082        if (_is_shown()){
2083            _color($color) {
2084                _text(
2085                    text=text, size=size, font=font,
2086                    halign=ha, valign=va, spacing=spacing,
2087                    direction=direction, language=language,
2088                    script=script
2089                );
2090            }
2091        }
2092    }
2093}
2094
2095
2096// Section: Rounding 2D shapes
2097
2098// Module: round2d()
2099// Synopsis: Rounds the corners of 2d objects.
2100// SynTags: Geom
2101// Topics: Rounding
2102// See Also: shell2d(), round3d(), minkowski_difference()
2103// Usage:
2104//   round2d(r) [ATTACHMENTS];
2105//   round2d(or=) [ATTACHMENTS];
2106//   round2d(ir=) [ATTACHMENTS];
2107//   round2d(or=, ir=) [ATTACHMENTS];
2108// Description:
2109//   Rounds arbitrary 2D objects.  Giving `r` rounds all concave and convex corners.  Giving just `ir`
2110//   rounds just concave corners.  Giving just `or` rounds convex corners.  Giving both `ir` and `or`
2111//   can let you round to different radii for concave and convex corners.  The 2D object must not have
2112//   any parts narrower than twice the `or` radius.  Such parts will disappear.
2113// Arguments:
2114//   r = Radius to round all concave and convex corners to.
2115//   ---
2116//   or = Radius to round only outside (convex) corners to.  Use instead of `r`.
2117//   ir = Radius to round only inside (concave) corners to.  Use instead of `r`.
2118// Examples(2D):
2119//   round2d(r=10) {square([40,100], center=true); square([100,40], center=true);}
2120//   round2d(or=10) {square([40,100], center=true); square([100,40], center=true);}
2121//   round2d(ir=10) {square([40,100], center=true); square([100,40], center=true);}
2122//   round2d(or=16,ir=8) {square([40,100], center=true); square([100,40], center=true);}
2123module round2d(r, or, ir)
2124{
2125    or = get_radius(r1=or, r=r, dflt=0);
2126    ir = get_radius(r1=ir, r=r, dflt=0);
2127    offset(or) offset(-ir-or) offset(delta=ir,chamfer=true) children();
2128}
2129
2130
2131// Module: shell2d()
2132// Synopsis: Creates a shell from 2D children.
2133// SynTags: Geom
2134// Topics: Shell
2135// See Also: round2d(), round3d(), minkowski_difference()
2136// Usage:
2137//   shell2d(thickness, [or], [ir])
2138// Description:
2139//   Creates a hollow shell from 2D children, with optional rounding.
2140// Arguments:
2141//   thickness = Thickness of the shell.  Positive to expand outward, negative to shrink inward, or a two-element list to do both.
2142//   or = Radius to round corners on the outside of the shell.  If given a list of 2 radii, [CONVEX,CONCAVE], specifies the radii for convex and concave corners separately.  Default: 0 (no outside rounding)
2143//   ir = Radius to round corners on the inside of the shell.  If given a list of 2 radii, [CONVEX,CONCAVE], specifies the radii for convex and concave corners separately.  Default: 0 (no inside rounding)
2144// Examples(2D):
2145//   shell2d(10) {square([40,100], center=true); square([100,40], center=true);}
2146//   shell2d(-10) {square([40,100], center=true); square([100,40], center=true);}
2147//   shell2d([-10,10]) {square([40,100], center=true); square([100,40], center=true);}
2148//   shell2d(10,or=10) {square([40,100], center=true); square([100,40], center=true);}
2149//   shell2d(10,ir=10) {square([40,100], center=true); square([100,40], center=true);}
2150//   shell2d(10,or=[10,0]) {square([40,100], center=true); square([100,40], center=true);}
2151//   shell2d(10,or=[0,10]) {square([40,100], center=true); square([100,40], center=true);}
2152//   shell2d(10,ir=[10,0]) {square([40,100], center=true); square([100,40], center=true);}
2153//   shell2d(10,ir=[0,10]) {square([40,100], center=true); square([100,40], center=true);}
2154//   shell2d(8,or=[16,8],ir=[16,8]) {square([40,100], center=true); square([100,40], center=true);}
2155module shell2d(thickness, or=0, ir=0)
2156{
2157    thickness = is_num(thickness)? (
2158        thickness<0? [thickness,0] : [0,thickness]
2159    ) : (thickness[0]>thickness[1])? (
2160        [thickness[1],thickness[0]]
2161    ) : thickness;
2162    orad = is_finite(or)? [or,or] : or;
2163    irad = is_finite(ir)? [ir,ir] : ir;
2164    difference() {
2165        round2d(or=orad[0],ir=orad[1])
2166            offset(delta=thickness[1])
2167                children();
2168        round2d(or=irad[1],ir=irad[0])
2169            offset(delta=thickness[0])
2170                children();
2171    }
2172}
2173
2174
2175// vim: expandtab tabstop=4 shiftwidth=4 softtabstop=4 nowrap