Hello everyone!

I started learning Processing two days ago and I'm experimenting quite a bit. So far, I'm loving it. I've been trying to make a little program where the user can control a square (SquareA) and when he collides with SquareB, the screen goes all red.

I managed to program a very primitive form of collision, but it only takes in account SquareB's corner (I'm comparing the coordinates of both squares to generate a big, red rect() that would cover the whole screen.

I think the logic is kind of there, but I would need to find a way to take in account all the points in both squares and compare them. I don't know how to do this yet and there's where I would need some help. My idea, for the moment, is to find a way to calculate the squares areas to know which coordinates they're occupying and then comparing them. But this seems kind of complicated, I'm sure there's another way that I don't know yet.

Any pointers for syntax and those kind of things will be appreciated too.

Here's a screenshot, for visual reference.

Here's the code.

2. void setup(){
3.   size(500,500);
4.   frameRate(60);
5.   background(255);
6.   smooth();
7. }
8. 
   
9. //Positions
10. int posX = 250;
11. int posY = 250;
12. 
    
13. int posEx = 200;
14. int posEy = 100;
15. 
    
16. //Function to call "SquareB"
17. void enemy() {
18. fill(255,8,8);
19. rect(posEx,posEy,50,50);
20. }
21. 
    
22.   
23. //Moving SquareA
24. void keyPressed() {
25.   background(255);
26.   print("PosX:"); println(posX);
27. print("PosY:"); println(posY);
28. print("PosEx:"); println(posEx);
29. print("PosEy:"); println(posEy);
30. println("------------");
31.   if (key ==CODED){
32.     if (keyCode==DOWN)
33.     posY = posY+10;
34.     else if (keyCode==LEFT)
35.     posX = posX-10;
36.     else if (keyCode==RIGHT)
37.     posX = posX+10;
38.     else if (keyCode==UP)
39.     posY = posY-10;
40.       }
41. }
42. 
    
43. //Here is where my problem is, I think
44. void draw(){
45. noStroke();
46. fill(2);
47. rect(posX,posY,20,20);
48. enemy();
49. if ((posX==posEx) && (posY==posEy)){
50. fill(255,8,8);
51. rect(0,0,5000,1000);
52. }}