processing_java_rainbow_cube.java

float x,y,z,w,h,rotationX,rotationY;
int step;

void setup() {
  size(800,800,P3D);
  
  x = width/2;
  y = height/2;
  
  z = -100;
  
  step = 15;
  
  w = width;
  h = height;
}

void draw() {
  translate(x,y,z);
  
  rotationY = (mouseX / w) * PI * -2;
  rotationX = (mouseY / h) * PI * -2;  
  
  if (mousePressed) {
    if(mouseButton == LEFT) {
      z+=10;
    } else if(mouseButton == RIGHT) {
      z-=10;
    }
  }
 
  rotateX(rotationX);
  rotateY(rotationY);
  
  background(255);
    
  rainbowBlock(0,0,0, step);
}

void rainbowBlock(float bx, float by, float bz, int step) {
  pushMatrix();
  translate(bx, by-7, bz);
    
  int translate = ((255 / step) + 1) * -step;
    
  for(int r = 0; r <= 255; r+=step) {
    for(int g = 0; g <= 255; g+=step) {
      for(int b = 0; b <= 255; b+=step) {
        fill(r,g,b);
        box(step, step, step);
        
        translate(0, step);
      }
      translate(step, translate);
    }
    translate(translate, 0, step);
  }

  popMatrix();
}