Comments on: Challenge #7: Why Collisions Do Not Work?

By: sakura games

sakura games — Fri, 24 Nov 2006 15:48:46 +0000

you forgot to turn your monitor on

By: Jake Birkett

Jake Birkett — Thu, 23 Nov 2006 14:50:07 +0000

doh! :-D

By: Juuso - Game Producer

Juuso - Game Producer — Thu, 23 Nov 2006 14:16:03 +0000

@Toni: That’s correct. :) I told you it was a memory issue… ;)

@JR: uh..

By: J.R.

J.R. — Thu, 23 Nov 2006 13:56:12 +0000

I once encountered a problem with collisions. It was funny because its one of those occasions where since the code does exactly what you wanted, it gives you an anomaly. Basically it was a tiled map game where you see the entities from above ( picture zelda for the snes if you’d like ). Now every entity had a bounding box to collide with the blockade type tiles, in which they also had bounding boxes. So its a basic rectangular BB collision scene. Now, what i used to do is that when an entity wanted to move, i moved its position, and the BB with it, along the tilemap and then checked to see if it collided with the blockade type tiles. If it did, i would then realign the entity with the tilemap, so that it would be touching the blockade, not overlapping it. The code in itself worked nicely. Now here’s the problem. Suppose you have a wall of blockade type tiles, like a whole line of it on the tilemap. Now suppose an entity, that has a rectangular BB is moving downards AND left. What would happen sometimes is that the BB would overlap 2 blockade types in the tilemap. I made the code recognize that and realign itself with the positions of the blockade tiles. So since its moving to the left, it would realign itself with the tilemap it overlapped. Like i said, this was done by moving the entity to back to the right in this case. Since it also overlapped the blockade tile directly below it, it would also realign it to go back up again. Now if you keep this scene going a few times you’ll notice whats goin on. The entity that should scroll along the wall isn’t moving! Took me a while to understand the why of it. I got it solved now, so it’s one of the many other bugs from the past heh.

By: Toni MÃ¤kinen

Toni MÃ¤kinen — Thu, 23 Nov 2006 13:15:58 +0000

Forgot to actually call the function? :)

By: Tim Fisher

Tim Fisher — Thu, 23 Nov 2006 11:01:44 +0000

Hint: Are you thinking too much about erroneous code rather than the root of the problem?

By: Juuso - Game Producer

Juuso - Game Producer — Thu, 23 Nov 2006 11:00:08 +0000

@soniCron: lol, no :)
@Jake: nope.

By: Jake Birkett

Jake Birkett — Thu, 23 Nov 2006 09:58:45 +0000

Failed to use BMax collision layers properly? Or was trying to collide with an empty image! Thus no collision.

By: soniCron

soniCron — Thu, 23 Nov 2006 09:43:01 +0000

He erroneously chose to use a non-managed programming language? ;)

By: Tim Fisher

Tim Fisher — Thu, 23 Nov 2006 08:44:56 +0000

I know the answer. We’ll it was me that made the stoopid mistake :)