# Body inside other body after collision

I'm using bullet to create a 2D topdown game. In my physics proof of concept, I can walk around and push a box. However, if I walk too fast the character goes through the box, instead of colliding with it. See gif:

This seems like a common thing to me. However, I cannot find other people having the same problem, so that's why I'm asking a question directly. I'm using a DiscreteDynamicsWorld with two rigid bodies which I step through at 60Hz.

• Why does this happen?
• Is there a way to tune bullet to support higher speeds and prevent this issue?

Help is very much appreciated.

Edit

Regarding the question about how I setup collision shapes:

btConvexHullShape shape;

• In ODE, this is tuned with the ERP and CFM parameters. I don't have Bullet setup, so I can only suggest you look for similar parameters in the contact joints. – Vaillancourt Dec 25 '18 at 19:06
• Can you show us how you've set up the collision representation for these shapes? This looks similar to issues I've seen when using polygon/edge-based colliders instead of a box primitive. – DMGregory Dec 29 '18 at 19:00
• @DMGregory see my edit. Is this what you are looking for? – Aart Stuurman Dec 30 '18 at 13:42
• Yes indeed. Have you considered using a btBoxShape for these square objects instead of a btConvexHull? The more primitive colliders are often both faster to process and also simplify the work of calculating & resolving penetration, making it easier for the physics engine to get the desired result. – DMGregory Dec 30 '18 at 13:47
• No have not, but I would like to have more complex shapes later on, so I think it would be good to make it works with a convex hull. However, I will see if there is an improvement by using a box shape. – Aart Stuurman Dec 30 '18 at 14:33