linearGradient.osl

linearGradient.c

float scalarProj(vector a, vector b) {
  return dot(a, b) / dot(b, b);
}

float uquantize(float x, int levels) {
    return select(
        max(0.0, (ceil(x * levels) - 1.0) / (levels - 1.0)),
        x, levels < 2);
}

shader linearGradient(
  point Origin = point(-1.0, 0.0, 0.0),
  point Dest = point(1.0, 0.0, 0.0),
  point Point = P,
  int Quantize = 0,

  output float Fac = 0.0,
  output float Dot = 0.0,
  output point Vector = 0.0) {

  point a = Point - Origin;
  point b = Dest - Origin;
  Dot = scalarProj(a, b);
  Fac = uquantize(clamp(Dot, 0.0, 1.0), Quantize);
  Vector = Origin + b * Fac;
}