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Fixed in 5.5.0



Found in


Issue ID




[Collider] Convex Mesh Collider is twice bigger than rendered Quad



To reproduce the bug please follow the steps
1. Create new project
2. Create new "Quad" game object
3. Toggle convex mesh collider for "Quad" game object
Mesh collider is now twice as big as rendered object.
I have also attached sample screenshot of the result.

Comments (7)

  1. hwf

    Feb 22, 2016 20:20

    really disappointed that this issue still exists in 5.3.2f1

  2. alex_hajdu

    Aug 24, 2015 06:48

    ouch..pls fix...

  3. robin.theilade

    Aug 06, 2015 18:50

    I wasn't told the reason but I really hope you're right about it being due to performance considerations. Dropping the support for flat and concave meshes makes rapid prototyping much more difficult and the requirements for entry Unity users are higher.

  4. dkjunior

    Aug 03, 2015 23:04

    Thanks Robin. Did they tell you why it was deprecated? My guess would be due to performance reasons although it's not clear to me why.

    Yeah, I ended up implementing a method that would add volume to a flat polygon by "conifying" it. It basically adds one extra vertex non-coplanar to the polygon plane and then closes the volume by adding n triangles (where n is the number of sides in the original polygon). The vertex is added at a very small distance so for all practical reasons the resulting mesh remains "flat". Honestly I hate this solution but this is the best I could come up with.

  5. robin.theilade

    Aug 01, 2015 19:08

    I've been told by Unity support that flat meshes are no longer supported by mesh collider and hence the weird result.

    Use box collider or add just a small volume to your flat mesh the enable the mesh collider. The sides of the previously flat mesh are not required to have polygons. Don't know if you can skip the polygon at the bottom or vertices are enough to define the volume.

  6. dkjunior

    Jul 30, 2015 22:54

    +1 I can repro it in 5.1.2f1 as well. I also tried creating a quad procedurally and it still expands the mesh if convex is checked. Can this be the case for all flat meshes? Anyways, that's a pretty serious problem and I think it should be prioritized higher.

  7. robin.theilade

    Jul 17, 2015 17:42

    This issue still exists in 5.1.2f1

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