Thread: Collision Detection Between Two Squares

Heya,

I have a program with predefined objects(squares) playerObject & stillObject; that have methods to get their x,y coordinates called getX() & getY().
playerObject: moves with the arrow keys of the keyboard via an already provided game engine.
stillObject: is set in a location on the screen.
Both objects have measurements of 100x100.

My problem is I'm having trouble defining a collision detection statement, which needs to account for the stillObject changing positions in debugging tests, so it can't be hard-coded.
So far what I have covers collisions between the top and left sides of the stillObject against playerObject by minusing the distance between them and if it's bigger than 0 than the objects have collided and the same for -200, which should be the other side of stillObject(which is what I thought), but it doesn't seem to be working that way for me.

if ((((stillObject.getX() + 100) - playerObject.getX()) > 0) && ((stillObject.getY() + 100) - playerObject.getY()) > 0) {
	    	collide = true;
	    } 
 
if ((((stillObject.getX() - 100) + playerObject.getX()) < -200) && ((stillObject.getY() - 100) + playerObject.getY()) < -200) {
                collide = true;
}

Any push in the right direction would be great, thank you.

Originally Posted by Norm

The way I debug these kinds of problems is by taking a piece of paper and drawing the shapes all the different ways that there can be a collision and then looking at the x,y & width,height of both shapes at each point of collision to come up with the tests needed to detect it.

The Rectangle class has methods that could be used.

Note on the posted code: You should NOT hard code the values 100 and 200 in the tests. Use variables that can be changed and whose names define what their values are.

I tried drawing it out, and this is the best thing I could come up with. I thought using those values wouldn't count as hard coding since I'm calculating them along with the current x,y values( getX() & getY() ), so even if the coordinates of the stillObject changes, it should still work. The measurements of the squares aren't going to change, just their location so in theory these values would still work, right?

The objects are drawn using a custom method, and it's not actually clear how they're drawn so I'm not sure whether it's drawn from the x,y being the top left corner like usual, or from the middle.

Thanks Norm, I'll find out how the rectangles are drawn then I'll try reworking my code

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Thanks for that, I didn't know there were cross posting rules. Usually I get arrogant posts just telling me I crossed posted and not mentioning any rules. I'll post up a link next time.