why haven't i made one of these already

pattern2.pde

/*
rect moving
 */

float theta;
int side;

void setup() {
  size(300, 300);
  background(255);
  side = 20;
}

void draw() {
  background(255);
  for (int h = 0; h < height/side; h++) {
    for (int w = 0; w < width/side; w++) {
      makeT(w, h);
    }
  }
  theta += 0.1;
}

void makeT(int w, int h) {
  pushMatrix();
  translate(w*(side+5), h*(side+5));
  rotate(theta);
  float delta = dist(mouseX, mouseY, w, h);
  color c = getColor(mouseX+delta);
  fill(c);
  rect(-side/2, -side/2, side, side);
  popMatrix();
}

/*
resources:
http://krazydad.com/tutorials/makecolors.php
*/
color getColor(float i) {
  int center = 205; //pastelly
  int widthh = 55;
  double frequency = .3;
  int red   = (int)Math.ceil(Math.sin(frequency*i+0) * widthh + center);
  int green = (int)Math.ceil(Math.sin(frequency*i+2) * widthh + center);
  int blue  = (int)Math.ceil(Math.sin(frequency*i+4) * widthh + center);
  return color(red,green,blue);
}