I'm doing an animation in Blender where a bunch of cans are falling in an enclosed space. I give the cans a rigid body and enable collision on the bottom plane that they land on.

What I'm trying to do is make it so after the cans land on the platform there's a trapdoor that animates open causing them to fall through the floor. When I tried to do this by detaching part of the plane and animating it the cans don't fall through.

Can you guys help me figure out how to achieve this effect? Thanks. I feel like i'm missing a key element in these physics.

  • 1
    $\begingroup$ Check your Collision Bounds in the Physics properties - you need to be using Mesh rather than any of the others. This way the collision is based on the actual mesh rather than a simplified box or convex hull wrapped around it. $\endgroup$ Oct 30, 2016 at 6:57
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    $\begingroup$ I think u have used the convex hull type property use the mesh type property to get the required effect $\endgroup$ Oct 30, 2016 at 7:01

1 Answer 1


For completeness, far fetched problem sources are included.

  1. The cans should be set to active and dynamik. Since they are cylinder-shaped, I will set the shape to cylinder.
    enter image description here

  2. The enclosing platform should be set to passive. The shape property is set to mesh.
    passive rigid body

  3. The trap door should be set to passive and animated.
    passive animated rigid body

cans falling

  • $\begingroup$ This is amazing! Thank you so much Leander, exactly what I was looking for AND you added a blendfile to mess around with. I can't express how much I appreciate your answer. $\endgroup$
    – Kevin Doan
    Oct 31, 2016 at 5:38

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