subdivision_curve.java

PVector[] subdivide(PVector[] curve) {
  //we add a midpoint for each segment, so we get twice as many points
  PVector newCurve[] = new PVector[curve.length*2];
  for(int i=0;i<curve.length;++i) {
    PVector currPt = curve[i];
    PVector prevPt = curve[(i-1+curve.length)%curve.length];
    PVector nextPt = curve[(i+1)%curve.length];
    newCurve[2*i] = new PVector();
    newCurve[2*i].add(PVector.mult(prevPt,.125));
    newCurve[2*i].add(PVector.mult(currPt,.75));
    newCurve[2*i].add(PVector.mult(nextPt,.125));
    newCurve[2*i+1] = new PVector();
    newCurve[2*i+1].add(currPt);
    newCurve[2*i+1].add(nextPt);
    newCurve[2*i+1].mult(.5);
  }
  return newCurve;
}