sketch.js

var fixedRect, movingRect


function setup() {
  createCanvas(800,400);
  fixedRect = createSprite(400,200,100,100);
  fixedRect.shapeColor = "green";
  fixedRect.debug = true;
  movingRect = createSprite(600,300,100,100);
  movingRect.shapeColor = "green";
  movingRect.debug = true;
}

function draw() {
  background(0,0,0);
  movingRect.y = World.mouseY;
  movingRect.x = World.mouseX;  

  if(movingRect.x - fixedRect.x < fixedRect.width/2 + movingRect.width/2 
    && fixedRect.x - movingRect.x < fixedRect.width/2 + movingRect.width/2
    && fixedRect.y - movingRect.y < fixedRect.height/2 + movingRect.height/2
    && movingRect.y - fixedRect.y < movingRect.height/2 + fixedRect.height/2){
    movingRect.shapeColor = "red";
    fixedRect.shapeColor = "red";
  }
  else {
    movingRect.shapeColor = "green";
    fixedRect.shapeColor = "green";
  }

  drawSprites(); 
}