Ganja.js extrude cheat sheet

ganja.js

window.d = 2;

Algebra(d,0,1,()=>{
  
  
  
  var point = (x,y)=>!(1e0 + x*1e1 + y*1e2),
      // return functions instead of values, so they update when you drag the points
      linesFromPoints = ps => ps.map((p,i,a) => ()=>p & (a[(i+1)%a.length]||a[0])),
      pointsFromLines = e => e.map((ev,i,a) => ()=> ev * (a[(i+1)%a.length]||a[0])),
      vectorToTranslationRotor = (v, amount)=> ()=> 1+amount*v.Normalized*1e0,
      applyRotor=(obj,rotor)=> ()=>rotor>>>obj;
      
  var graphF = (arr,labelPrefix) => arr.map((x,i)=>[x,labelPrefix+(i+1)]).flat();
  
    // Extrude edges by given amount - by enkimute
  var extrude = (poly,amount=0.1)=>
        poly.map((x,i,a)=>x&(a[i+1]||a[0]))                  // to edges
            .map(x=>window.d==2?x : (plane|x))               // in 3D we want planes 
            .map((x,i)=>(1+amount*x.Normalized*1e0)>>>x)     // extrude edges
            .map((x,i,a)=>x^(a[i+1]||a[0]))                  // intersect edges.
            .map(x=>window.d==2?x: x^plane);                 // in 3D intersect with poly plane again.
  
  

  const amount = 0.2;
  
  var a = point(-0.5,0.5),
      b = point(0.5,0.5),
      c = point(0,1),
      d = point(-0.5,1),
      points = [a,b,c,d],
      edges = linesFromPoints(points),
      rotors = edges.map(e=>vectorToTranslationRotor(e,0.2)),
      outsetEdges = edges.map((E,i)=>()=>applyRotor(E,rotors[i])),
      newPoints = pointsFromLines(outsetEdges)

  document.body.appendChild(this.graph([
    "Outset experiment with PGA2D - twitter: @ToJans - Drag the blue points",
    newPoints,
    0xaaaaaa,
    points,
    0x0000088,
    ...graphF(points,"P"),
    ...graphF(edges,"E"),
    0x0880000,
    ...graphF(rotors,"R"),
    0x0008800,
    ...graphF(outsetEdges,"O"),
    ...graphF(newPoints,"NP"),
    1e0,"1E0"
    
  ],{lineWidth:3, grid:true, labels:true, pointradius:4}));
  
});