Bash and GCMC source code: SVG coaster generator with simple petals

petals.sh

#!/bin/bash
# Simple petals test piece
# Ed Nisley KE4ZNU - 2022-07-01

Flags='-P 4 --pedantic'       # quote to avoid leading hyphen gotcha

SVGFlags='-P 4 --pedantic --svg --svg-no-movelayer --svg-opacity=1.0 --svg-toolwidth=0.2'

# Set these to match your file layout

ProjPath='/mnt/bulkdata/Project Files/Laser Cutter/Coasters/Source Code'

LibPath='/opt/gcmc/library'

ScriptPath=$ProjPath
Script='Simple Petals.gcmc'

[ -z "$1" ] && petals="6" || petals="$1"

fn=Petals-$petals.svg
echo Output: $fn

gcmc $SVGFlags \
 -D "NumPetals=$petals" \
 --include "$LibPath" \
 "$ScriptPath"/"$Script" > "$fn"

Simple Petals.gcmc

// Simple Petals Test Piece
// Ed Nisley KE4ZNU
// 2022-07-12 Simplest possible petals

layerstack("Frame","Petals","Rim","Base","Center","Tool1");  // SVG layers map to LightBurn colors

//-----
// Library routines

include("tracepath.inc.gcmc");
include("tracepath_comp.inc.gcmc");
include("varcs.inc.gcmc");
include("engrave.inc.gcmc");

FALSE = 0;
TRUE = !FALSE;

//-----
// Command line parameters

// -D various useful tidbits
// add unit to speeds and depths: 2000mm / -3.00mm / etc

if (!isdefined("OuterDia")) {
  OuterDia =  100.0mm;
}

if (!isdefined("CenterDia")) {
  CenterDia = 25.0mm;
}

if (!isdefined("NumPetals")) {
  NumPetals = 6;
}

if (!isdefined("Sash")) {
  Sash = 5.0mm;
}

// Petal values

PetalAngle = 360.0deg/NumPetals;                     // subtended by inner sides
PetalHA = PetalAngle/2;

PetalOD = OuterDia - 2*Sash;
PetalID = CenterDia + 2*Sash;

PetalOAL = OuterDia/2 - Sash - (Sash/2)/sin(PetalHA);
//message("petalOAL: ",PetalOAL);

// Find petal vertices

P0 = [(Sash/2) / sin(PetalHA),0.0mm];

t1 = tan(PetalHA);
sc = (Sash/2) / cos(PetalHA);

if (P0.x < PetalID/2) {
  a = 1 + pow(t1,2);
  b = -2 * t1 * sc;
  c = pow(sc,2) - pow(PetalID/2,2);
  xp = (-b + sqrt(pow(b,2) - 4*a*c))/(2*a);
  xn = (-b - sqrt(pow(b,2) - 4*a*c))/(2*a);
  y = xp*t1 - sc;
  if (FALSE) {
    message("a: ",a);
    message("b: ",b);
    message("c: ",c);
    message("p: ",xp," n: ",xn," y: ",y);
  }
  P1 = [xp,y];
}
else {
  P1 = P0;
}

a = 1 + pow(t1,2);
b = -2 * t1 * sc;
c = pow(sc,2) - pow(PetalOD/2,2);

if (FALSE) {
  message("a: ",a);
  message("b: ",b);
  message("c: ",c);
}

xp = (-b + sqrt(pow(b,2) - 4*a*c))/(2*a);
xn = (-b - sqrt(pow(b,2) - 4*a*c))/(2*a);
y = to_mm(sqrt(pow(PetalOD/2,2) - pow(xp,2)));
//message("p: ",xp," n: ",xn," y: ",y);

P2 = [xp,y];

PetalWidth = 2*P2.y;

P3 = [PetalOD/2,0.0mm];

if (FALSE) {
  message("P0: ",P0);
  message("P1: ",P1);
  message("P2: ",P2);
  message("P3: ",P3);
}

// Construct paths

PetalPoints = {P1,P2};

OutArc = varc_cw([P2.x,-P2.y] - P2,PetalOD/2);
OutArc += P2;
PetalPoints += OutArc;

if (P0 != P1) {
  PetalPoints += {[P1.x,-P1.y]};
  InArc = varc_ccw(P1 - [P1.x,-P1.y],PetalID/2);
  InArc += [P1.x,-P1.y];
  PetalPoints += InArc;
}
else {
  PetalPoints += {P0};
}

//--- Lay out the frame

linecolor(0xff0000);

layer("Frame");

if (CenterDia) {
  goto([CenterDia/2,0mm]);
  circle_cw([0mm,0mm]);
}

repeat(NumPetals;i) {
  a = (i-1)*PetalAngle;
  tracepath(rotate_xy(PetalPoints,a));
}

goto([OuterDia/2,0]);
circle_cw([0mm,0mm]);

//--- Lay out internal pieces for oriented cutting

// baseplate

layer("Base");

relocate([OuterDia + 2*Sash,0]);
goto([OuterDia/2,0]);
circle_cw([0mm,0mm]);

// central circle

if (CenterDia) {
  layer("Center");

  relocate([OuterDia/2 + Sash,-(OuterDia - CenterDia)/2]);
  goto([CenterDia/2,0mm]);
  circle_cw([0mm,0mm]);
}

// petals

layer("Petals");

repeat(NumPetals;i) {
  org = [PetalWidth/2 - OuterDia/2,-(OuterDia + Sash)];
  relocate([(i-1)*(PetalWidth + Sash) + org.x,org.y]);
  tracepath(rotate_xy(PetalPoints,90deg));
}

// Debugging by printf()

if (FALSE) {
  layer("Tool1");
  linecolor(0xff1f00);

  goto([Sash/2,0mm]);
  circle_cw([0mm,0mm]);

  goto(P0);
  circle_cw([0mm,0mm]);

  goto([0,0]);
  move([OuterDia/2,0]);

  goto([0,0]);
  move(OuterDia/2 * [cos(PetalHA),sin(PetalHA)]);

  goto(P2);
  move_r([0,-PetalWidth/2]);

}