1//////////////////////////////////////////////////////////////////////
  2// LibFile: constants.scad
  3//   Constants for directions (used with anchoring), and for specifying line termination for
  4//   use with geometry.scad.  
  5// Includes:
  6//   include <BOSL2/std.scad>
  7// FileSummary: Constants provided by the library
  8
  9//////////////////////////////////////////////////////////////////////
 10
 11// a value that the user should never enter randomly;
 12// result of `dd if=/dev/random bs=32 count=1 |base64` :
 13_UNDEF="LRG+HX7dy89RyHvDlAKvb9Y04OTuaikpx205CTh8BSI";
 14
 15// Section: General Constants
 16
 17// Constant: $slop
 18// Description:
 19//   A number of printers, particularly FDM/FFF printers, tend to be a bit sloppy in their printing.
 20//   This has made it so that some parts won't fit together without adding a bit of extra slop space.
 21//   That is what the `$slop` value is for.  The value for this will vary from printer to printer.
 22//   By default, we use a value of 0.00 so that parts should fit exactly for resin and other precision
 23//   printers.  This value is measured in millimeters.  When making your own parts, you should add
 24//   `$slop` to both sides of a hole that another part is to fit snugly into. For a loose fit, add
 25//   `2*$slop` to each side.  This should be done for both X and Y axes.  The Z axis will require a
 26//   slop that depends on your layer height and bridging settings, and hole sizes.  We leave that as
 27//   a more complicated exercise for the user.
 28//   .
 29//   Note that the slop value is accessed using the {{get_slop()}} function.  This function provides
 30//   the default value of 0 if you have not set `$slop`. This approach makes it possible for you to
 31//   set `$slop` in your programs without experiencing peculiar OpenSCAD issues having to do with multiple
 32//   definitions of the variable.  If you write code that uses `$slop` be sure to reference it using {{get_slop()}}. 
 33// DefineHeader(NumList): Calibration
 34// Calibration: To calibrate the `$slop` value for your printer, follow this procedure:
 35//   Print the Slop Calibration part from the example below.
 36//   Take the long block and orient it so the numbers are upright, facing you.
 37//   Take the plug and orient it so that the arrow points down, facing you.
 38//   Starting with the hole with the largest number in front of it, insert the small end of the plug into the hole.
 39//   If you can insert and remove the small end of the plug from the hole without much force, then try again with the hole with the next smaller number.
 40//   Repeat step 5 until you have found the hole with the smallest number that the plug fits into without much force.
 41//   The correct hole should hold the plug when the long block is turned upside-down.
 42//   The number in front of that hole will indicate the `$slop` value that is ideal for your printer.
 43//   Remember to set that slop value in your scripts after you include the BOSL2 library:  ie: `$slop = 0.15;`
 44// Example(3D,Med): Slop Calibration Part.
 45//   min_slop = 0.00;
 46//   slop_step = 0.05;
 47//   holes = 8;
 48//   holesize = [15,15,15];
 49//   height = 20;
 50//   gap = 5;
 51//   l = holes * (holesize.x + gap) + gap;
 52//   w = holesize.y + 2*gap;
 53//   h = holesize.z + 5;
 54//   diff("holes")
 55//   cuboid([l, w, h], anchor=BOT) {
 56//     for (i=[0:holes-1]) {
 57//       right((i-holes/2+0.5)*(holesize.x+gap)) {
 58//         s = min_slop + slop_step * i;
 59//         tag("holes") {
 60//           cuboid([holesize.x + 2*s, holesize.y + 2*s, h+0.2]);
 61//           fwd(w/2-1) xrot(90) linear_extrude(1.1) {
 62//             text(
 63//               text=format_fixed(s,2),
 64//               size=0.4*holesize.x,
 65//               halign="center",
 66//               valign="center"
 67//             );
 68//           }
 69//         }
 70//       }
 71//     }
 72//   }
 73//   back(holesize.y*2.5) {
 74//     difference() {
 75//       union() {
 76//         cuboid([holesize.x+10, holesize.y+10, 15], anchor=BOT);
 77//         cuboid([holesize.x, holesize.y, 15+holesize.z], anchor=BOT);
 78//       }
 79//       up(3) fwd((holesize.y+10)/2) {
 80//         prismoid([holesize.x/2,1], [0,1], h=holesize.y-6);
 81//       }
 82//     }
 83//   }
 84// Example(2D): Where to add `$slop` gaps.
 85//   $slop = 0.2;
 86//   difference() {
 87//     square([20,12],center=true);
 88//     back(3) square([10+2*$slop,11],center=true);
 89//   }
 90//   back(8) {
 91//     rect([15,5],anchor=FWD);
 92//     rect([10,8],anchor=BACK);
 93//   }
 94//   color("#000") {
 95//     arrow_path = [[5.1,6.1], [6.0,7.1], [8,7.1], [10.5,10]];
 96//     xflip_copy()
 97//       stroke(arrow_path, width=0.3, endcap1="arrow2");
 98//     xcopies(21) back(10.5) {
 99//         back(1.8) text("$slop", size=1.5, halign="center");
100//         text("gap", size=1.5, halign="center");
101//     }
102//   }
103
104// Function: get_slop()
105// Usage:
106//    slop = get_slop();
107// Description:
108//    Returns the current $slop value, or the default value if the user did not set $slop.
109//    Always acess the `$slop` variable using this function.  
110function get_slop() = is_undef($slop) ? 0 : $slop;
111
112
113// Constant: INCH
114// Description:
115//   The number of millimeters in an inch.
116// Example(2D):
117//   square(2*INCH, center=true);
118// Example(3D):
119//   cube([4,3,2.5]*INCH, center=true);
120INCH = 25.4;
121
122
123
124// Section: Directional Vectors
125//   Vectors useful for `rotate()`, `mirror()`, and `anchor` arguments for `cuboid()`, `cyl()`, etc.
126
127// Constant: LEFT
128// Topics: Constants, Vectors
129// See Also: RIGHT, FRONT, BACK, UP, DOWN, CENTER
130// Description: Vector pointing left.  [-1,0,0]
131// Example(3D): Usage with `anchor`
132//   cuboid(20, anchor=LEFT);
133LEFT  = [-1,  0,  0];
134
135// Constant: RIGHT
136// Topics: Constants, Vectors
137// See Also: LEFT, FRONT, BACK, UP, DOWN, CENTER
138// Description: Vector pointing right.  [1,0,0]
139// Example(3D): Usage with `anchor`
140//   cuboid(20, anchor=RIGHT);
141RIGHT = [ 1,  0,  0];
142
143// Constant: FRONT
144// Aliases: FWD, FORWARD
145// Topics: Constants, Vectors
146// See Also: LEFT, RIGHT, BACK, UP, DOWN, CENTER
147// Description: Vector pointing forward.  [0,-1,0]
148// Example(3D): Usage with `anchor`
149//   cuboid(20, anchor=FRONT);
150FRONT = [ 0, -1,  0];
151FWD = FRONT;
152FORWARD = FRONT;
153
154// Constant: BACK
155// Topics: Constants, Vectors
156// See Also: LEFT, RIGHT, FRONT, UP, DOWN, CENTER
157// Description: Vector pointing back.  [0,1,0]
158// Example(3D): Usage with `anchor`
159//   cuboid(20, anchor=BACK);
160BACK  = [ 0,  1,  0];
161
162// Constant: BOTTOM
163// Aliases: BOT, DOWN
164// Topics: Constants, Vectors
165// See Also: LEFT, RIGHT, FRONT, BACK, UP, CENTER
166// Description: Vector pointing down.  [0,0,-1]
167// Example(3D): Usage with `anchor`
168//   cuboid(20, anchor=BOTTOM);
169BOTTOM  = [ 0,  0, -1];
170BOT = BOTTOM;
171DOWN = BOTTOM;
172
173// Constant: TOP
174// Aliases: UP
175// Topics: Constants, Vectors
176// See Also: LEFT, RIGHT, FRONT, BACK, DOWN, CENTER
177// Description: Vector pointing up.  [0,0,1]
178// Example(3D): Usage with `anchor`
179//   cuboid(20, anchor=TOP);
180TOP = [ 0,  0,  1];
181UP = TOP;
182
183// Constant: CENTER
184// Aliases: CTR, CENTRE
185// Topics: Constants, Vectors
186// See Also: LEFT, RIGHT, FRONT, BACK, UP, DOWN
187// Description: Zero vector.  Centered.  [0,0,0]
188// Example(3D): Usage with `anchor`
189//   cuboid(20, anchor=CENTER);
190CENTER = [ 0,  0,  0];  // Centered zero vector.
191CTR = CENTER;
192CENTRE = CENTER;
193
194
195// Section: Line specifiers
196//   Used by functions in geometry.scad for specifying whether two points
197//   are treated as an unbounded line, a ray with one endpoint, or a segment
198//   with two endpoints.  
199
200// Constant: SEGMENT
201// Topics: Constants, Lines
202// See Also: RAY, LINE
203// Description: Treat a line as a segment.  [true, true]
204// Example: Usage with line_intersection:
205//    line1 = 10*[[9, 4], [5, 7]];
206//    line2 = 10*[[2, 3], [6, 5]];
207//    isect = line_intersection(line1, line2, SEGMENT, SEGMENT);
208SEGMENT = [true,true];
209
210
211// Constant: RAY
212// Topics: Constants, Lines
213// See Also: SEGMENT, LINE
214// Description: Treat a line as a ray, based at the first point.  [true, false]
215// Example: Usage with line_intersection:
216//    line = [[-30,0],[30,30]];
217//    pt = [40,25];
218//    closest = line_closest_point(line,pt,RAY);
219RAY = [true, false];
220
221
222// Constant: LINE
223// Topics: Constants, Lines
224// See Also: RAY, SEGMENT
225// Description: Treat a line as an unbounded line.  [false, false]
226// Example: Usage with line_intersection:
227//    line1 = 10*[[9, 4], [5, 7]];
228//    line2 = 10*[[2, 3], [6, 5]];
229//    isect = line_intersection(line1, line2, LINE, SEGMENT);
230LINE = [false, false];
231
232
233// Constant: IDENT
234// Description: Identity transformation matrix for three-dimensional transforms.  Equal to `ident(4)`.  
235IDENT=ident(4);
236
237
238// vim: expandtab tabstop=4 shiftwidth=4 softtabstop=4 nowrap