How to get the normal of the line I collide with?

[ronkorving]

Hi,

Thanks for this library, we're looking forward to using it. After reading the documentation, we have one question however. How would one go about calculating the rebound vector / direction when a collision occurs? For example, when bouncing a ball against a wall, how do I make it bounce in the right direction?

Thank you

[ShimShamSam]

The normal of the line you collide with is given via the Result object's overlap_x and overlap_y properties. Determining the resulting bounce angle is a matter of flipping the incoming angle across the axis that those two properties describe.

A more in-depth explanation can be found here. You might be able to find some better tutorials out there, but the concept is the same.

[ronkorving]

Thanks for your answer, that should get me on my way.

I may be wrong, but could it be that many users of Collisions would find themselves with this requirement?

Perhaps variables like bounciness, etc. make this too complex a problem to add to the Result object and have it work for everybody. Perhaps instead of a solution in code, an example could be added to the docs?

[ShimShamSam]

Rigid bodies make up only a small subset of use-cases for collision detection, so adding code specifically for it would be outside of the scope of this library. Collisions is meant to be a low-level library. If your project requires friction, bounciness, momentum, etc, you're better off using a physics engine (or writing your own that wraps around Collisions).

[ronkorving]

Agreed 👍