float pX[], pY[];
float dirX[], dirY[];

void setup() {
  size(200,200);
  int numPs = 3;
  pX = new float[numPs];
  pY = new float[numPs];
  dirX = new float[numPs];
  dirY = new float[numPs];
  for (int i=0; i<pX.length; i++) {
    pX[i] = random(0f,1f);
    pY[i] = random(0f,1f);
    dirX[i] = random(-0.02f,0.02f);
    dirY[i] = random(-0.02f,0.02f);
  }
}

void loop() {
  for (int i=0; i<pX.length; i++) {
    pX[i] += dirX[i];
    pY[i] += dirY[i];
    if (pX[i] < 0) {pX[i]=0; dirX[i] = abs(dirX[i]);}
    if (pY[i] < 0) {pY[i]=0; dirY[i] = abs(dirY[i]);}
    if (pX[i] > 1) {pX[i]=1; dirX[i] = -abs(dirX[i]);}
    if (pY[i] > 1) {pY[i]=1; dirY[i] = -abs(dirY[i]);}
  }
  
  float w = (float) width;
  float h = (float) height;
  float cX, cY, dist2;
  float energy;
  for (float y=0; y<h; y++) {
    for (float x=0; x<w; x++) {
      cX = x/w;
      cY = y/w;
      energy = 0;
      for (int i=0; i<pX.length; i++) {
        dist2 = sqrt((float) ((Math.pow(cX-pX[i], 2) + Math.pow(cY-pY[i], 2))));
//        if (abs(dist2-0.2)<0.1) {
          energy += dist2;
//        }
      }
//      if (abs(energy-0.9)<0.05) {pixels[(int) y*width+(int) x] = 0xff000000;} else {pixels[(int) y*width+(int) x] = 0xffffffff;}
//      if (energy <= 2.5) {
        int bright = 255-(int)((energy/4.7)*255f);
        if (abs(bright) % 13 < 5) bright = 0;
        int red = bright/2;
        if (abs(bright) % 12 < 5) red = 255;
        int green = bright;
//        if (abs(bright) % 17 < 5) green = 128;
        int col = color(red, green, bright);
        pixels[(int) y*width+(int) x] = col;
//      } else {pixels[(int) y*width+(int) x] = 0xffffffff;}
    }  
  }
  for (int i=0; i<pX.length; i++) {
    if (mousePressed) {
      float mX = (float) (mouseX) / w;
      float mY = (float) (mouseY) / h;
      float dX = mX-pX[i];
      float dY = mY-pY[i];
      float l = sqrt(dX*dX+dY*dY);
      if (l>0) {
        dX /= l*200;
        dY /= l*200;
      }
      dirX[i] += dX;
      dirY[i] += dY;
    }
    float l = sqrt(dirX[i]*dirX[i]+dirY[i]*dirY[i]);
    if (l>0.02) {
      dirX[i] *= 0.95;
      dirY[i] *= 0.95;
    }
    set((int) (pX[i]*width), (int) (pY[i]*height), 0xFFFF0000);
  }
}