# How to fix this problem with collisions

0 favourites
• 8 posts
• Hello,

I have a problem with collisions in C3, example in a gif:

http://gph.is/2u79Nfp

As you can see, the right ball is reacting correctly to the collision, but the left ball not. The left ball is 1 or 2 pixels away from the left wall, but when it collides with the top wall, it checks the left collision too without reason.

The balls are simply sprites with bullet behaviour that collide with solids, with -90 angle of motion, i tried with physics behaviour and it has the same problem.

There is some trick to make the balls work correctly?

• It looks to me like the left hand ball is colliding with the left wall before it reaches the top of the screen - have you checked in the debug to see what its angle and x value are as it moves up the screen? It might be that it's slightly off -90 degrees and so is incrementally edging to the left as it progresses.

• ## Try Construct 3

Develop games in your browser. Powerful, performant & highly capable.

Construct 3 users don't see these ads
• All objects are rectangles with 0 degrees. Balls have -90 degrees in angle of motion.

You can try it in 1 minute, in c3 or c2.

• Can confirm, here's a cp3:

https://www.dropbox.com/s/dia9gfn1hm68l ... n.c3p?dl=0

Also if you check in debug there is a minute rounding error on the angle: it adds an extra -3x10^-14 to the angle - not sure why this would be.

Weirdl,y even though it appears that the position of the left wall is affecting the trajectory of the ball, it seems that the ball isn't colliding with it, if my collision check is working correctly (run in debug and check the no. variable for the left and top wall).

• I don't know if this can be considered a bug, maybe Tom or Ashley can give us a hint about this

I tried to move the start position of the ball and I needed 6 pixels to the right to get a correct collision, and its a lot, I'm not sure if it's a rounding problem.

Thanks for your answers mekonbecon, right know i prefer to forget my arkanoid twist idea because this collision problem affects it too much.

• Well, I'm sad and it's hard to buy C3 when things like incorrect collisions are not fixed or even get a response.

• Yea confirmed in C2 also.

i tried with different collision boxes and origin points and snapping but no change

I'm surprised its not been raised before.

Make a small cp3 and put it on the construct 3 git hub issues section.