Class for doing custom gradients / color wheels

theMetaPalette.pde

boolean captureFrames = false;
int nFrames = 120;
float phase = 0.0;
float phaseInc = 1 / (float) nFrames;
MetaPalette mp;
int nStrips = 40;
int ledsPerStrip = 32 * 5;

class MetaPalette {
  ArrayList<Integer> colors;

  MetaPalette() {
    colors = new ArrayList<Integer>();
  }

  void add(color c) {
    colors.add(c);
  }

  color get(float p) {
    int s = colors.size() - 1;
    p *= s;
    color c1 = colors.get(floor(p));
    color c2 = colors.get(ceil(p));
    float interp = (p - floor(p));
    return lerpColor(c1, c2, interp);
  }
}

void settings() {
  size(500, 500, P2D);
}

void setup() {
  mp = new MetaPalette();

  mp.add(color(255));    
  mp.add(color(255, 128, 0));
  mp.add(color(255, 0, 128));
  mp.add(color(0));
  mp.add(color(255, 0, 255));
  mp.add(color(255));    
  mp.add(color(255, 128, 0));
  mp.add(color(255, 0, 128));
  mp.add(color(0));
  mp.add(color(255, 0, 255));
  mp.add(color(255));

  noStroke();
  blendMode(ADD);
}

void draw() {
  background(0);

  float thisPhase = phase;
  float stripLength = 250;  // Units in screen pixels

  pushMatrix();
  translate(width / 2.0, height / 2.0);
  for (int i = 0; i < nStrips; i++) {
    float n = i / (float) nStrips;
    float angle = n * TAU;

    PVector p = PVector.fromAngle(angle);
    for (int j = 0; j < stripLength; j++) {
      PVector p2 = p.copy().mult(j);
      fill(mp.get(thisPhase));
      ellipse(p2.x, p2.y, 2, 2);
      thisPhase += phaseInc;
      thisPhase -= (int) thisPhase;
    }
  }
  popMatrix();

  phase += phaseInc;
  phase -= (int) phase;
  
  if (captureFrames) {
    saveFrame("./gif/f######.gif");
    if (frameCount == nFrames) {
      exit();
    }
  }
}