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I'm trying to make a simple animation: ice cubes falling into a glass. I modeled my glass, my cube and applied Rigid body behavior to them (Active/Passive). But for some reason (probably me being stupid), the cube is stopped in its fall by a non-existing face at the top of the glass. I tried to switch the collision shape (tried pretty mush all the possibilities) and it didn't solve the issue. Few screenshots explaining the issue What am I doing wrong here? Thanks in advance !

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This is probably the number one mistake made with rigid bodies.

I made this quick scene below:

enter image description here

And that is what it looks like on the first frame. But on the last frame it will look like this:

enter image description here

And the sphere will be on top of it. The reason is that the rigid body for the bottom shape is set to convex hull:

enter image description here

You need to change the shape to mesh:

enter image description here

And then also change the ice cube in your scene to mesh too. For a quick definition, a convex hull is basically the outside of a shape. So if you wanted to make a sphere roll on a plane, you would use convex hull as the rigid body shape because the ball is just rolling on a simple 1 face shape. But if you have a scene like this:

enter image description here

You would need to choose mesh as the rigid body shape.

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  • $\begingroup$ Oh, thank you for the explanation and for taking the time to make a scene to illustrate it! $\endgroup$
    – Lou
    May 17, 2021 at 8:30

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