OpenSCAD and Bash source code: layered paper coaster generator

layers.sh

#!/bin/bash
# Layering paper cutouts
# Ed Nisley KE4ZNU - 2022-08-21

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

SVGFlags='--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='Marquetry Layers.gcmc'


[ -z "$1" ] && leaves="6" || leaves="$1"
[ -z "$2" ] && aspect="0.50" || aspect="$2"
[ -z "$3" ] && center="0.0mm" || center="$3"

numlayers=8
sashmin=2.0
sashstep=2.0
sashmax=$(echo "$sashmin+$sashstep*($numlayers-1)" | bc)

echo min: $sashmin step: $sashstep max: $sashmax

for sash in $(seq $sashmin $sashstep $sashmax) ; do

    fn=Marq-$leaves-$aspect-$center-S$sash.svg
    echo Output: $fn

    gcmc $Flags $SVGFlags --include "$LibPath" \
     -D "NumLeaves=$leaves" -D "LeafAspect=$aspect" -D "CenterDia=$center" \
     -D "Sash=${sash}mm" \
     "$ScriptPath"/"$Script" > "$fn"

done

Marquetry Layers.gcmc

// Marquetry Layers
// Ed Nisley KE4ZNU
// 2022-08-21 layered paper test piece

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

//-----
// Library routines

include("tracepath.inc.gcmc");
include("varcs.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 =  120.0mm;
}

if (!isdefined("CenterDia")) {
  CenterDia = 20.0mm;
}

if (!isdefined("NumLeaves")) {
  NumLeaves = 8;
}

if (!isdefined("Sash")) {
  Sash = 4.0mm;
}

if (!isdefined("LeafAspect")) {
  LeafAspect = 0.50;
}

// Leaf values

LeafStemAngle = 360.0deg/NumLeaves;                     // subtended by inner sides
LeafStemHA = LeafStemAngle/2;

LeafOAL = OuterDia/2 - Sash - (Sash/2)/sin(LeafStemHA);

LeafWidth = LeafAspect*LeafOAL;
L1 = (LeafWidth/2)/tan(LeafStemHA);
L2 = LeafOAL - L1;
// message("Len: ",LeafOAL," L1: ",L1," L2: ",L2);

LeafTipHA = to_deg(atan(LeafWidth/2,L2));      // subtended by outer sides
LeafTipAngle = 2*LeafTipHA;

// message("Width: ",LeafWidth);
// message("Tip HA: ",LeafTipHA);

LeafID = CenterDia + 2*Sash;
LeafOD = LeafID + LeafOAL;

// message("ID: ",LeafID," OD: ",LeafOD);

// Find leaf and rim vertices

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

m = tan(LeafStemHA);
y0 = -(Sash/2) / cos(LeafStemHA);

if (CenterDia) {    // one sash width around center spot
  a = 1 + pow(m,2);
  b = 2 * m * y0;
  c = pow(y0,2) - pow(LeafID/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*tan(LeafStemHA) - (Sash/2) / cos(LeafStemHA);
  P1 = [xp,y];
  if (FALSE) {
    message("a: ",a);
    message("b: ",b);
    message("c: ",c);
    message("p: ",xp," n: ",xn," y: ",y);
  }
}
else {              // force sharp point without center spot
  P1 = P0;
}

P2 = P0 + [L1,LeafWidth/2];
P3 = P0 + [LeafOAL,0mm];

P4 = P3 + [Sash/sin(LeafTipHA),0.0mm];
P5r = P4.x * sin(LeafTipHA) / sin(180deg - LeafStemHA - LeafTipHA);
P5 = rotate_xy([P5r,0.0mm],LeafStemHA);
P6 = rotate_xy(P4,LeafStemAngle);

t2 = pow(tan(-LeafTipHA),2);
a = 1 + t2;
b = -2 * t2 * P4.x;
c = t2 * pow(P4.x,2) - pow(P3.x,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 - P4.x)*tan(-LeafTipHA);
// message("p: ",xp," n: ",xn," y: ",y);

P4a = [xp,y];
P6a = rotate_xy(P4a,LeafStemAngle - 2*atan(P4a.y,P4a.x));

if (FALSE) {
  message("P0: ",P0);
  message("P1: ",P1);
  message("P2: ",P2);
  message("P3: ",P3);
  message("P4: ",P4);
  message("P4a: ",P4a);
  message("P5: ",P5);
  message("P6: ",P6);
  message("P6a: ",P6a);
}

// Construct paths

LeafPoints = {P1,P2,P3,[P2.x,-P2.y],[P1.x,-P1.y]};

if (P0 != P1) {
  StemArc = varc_ccw(P1 - [P1.x,-P1.y],LeafID/2);
  StemArc += [P1.x,-P1.y];
  LeafPoints += StemArc;
}

RimChord = length(P4a - P6a);
RimThick = OuterDia/2 - Sash - length(P5);

RimPoints = {P4a,P5,P6a};
RimArc = varc_cw(P4a - P6a,P4a.x);
RimArc += P6a;
RimPoints += RimArc;

//--- Lay out the frame

linecolor(0xff0000);

layer("Frame");

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

repeat(NumLeaves;i) {
  a = (i-1)*LeafStemAngle;
  tracepath(rotate_xy(LeafPoints,a));
}

repeat(NumLeaves;i) {
  a = (i-1)*LeafStemAngle;
  tracepath(rotate_xy(RimPoints,a));
}

linecolor(0xff0000);

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

More details on my blog at https://wp.me/poZKh-bdG