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[iOS][Physics] Two MeshColliders pass through each other at certain angles on iOS only




Priority: 2Necessary for shipping a final release


Severity: 3Workaround is possible

With a specific mesh in the scene, when another mesh is moving towards it (standard Cube, Sphere or a custom mesh), instead of colliding, it passes through.

Steps to reproduce:
1) Open the latest attached project (
2) Build for iOS.
3) Run on a device.
- Notice the cube passing through the mesh
- The scene reloads every 3 seconds
4) As the cube is approaching the wall, touch the screen (this rotates the cube a bit)
- The cube doesn't pass through the mesh

The scene consists of a mesh (curved wall mesh) and a cube moving towards it with small velocity. Instead of colliding with the mesh, the cube goes right through it. This does not occur if the mesh or the cube is initially rotated slightly (the angle is not 0, 90, 180, etc.) or rotated in runtime.
This issue doesn't occur on the Editor and Android.

Note: the mesh has volume.

Workaround: uncheck "Enable PCM" in Physics settings.

Reproduced on:
5.6.0b6, 5.5.1p1

Did not reproduce:

Devices tested:
iPhone 7 iOS 10.3
iPad Mini 2 iOS 9.2.1
LG Nexus 5 Android 6.0

Comments (2)

  1. A73264327f318b860cb58d756040f930?d=mm


    Mar 13, 2017 19:00

  2. 4c8b9eafa639599c7c83303a902c5f51?d=mm


    Mar 05, 2017 09:45

    reproduce Unity 5.5.x and iOS build
    did not reproduce 5.4.x and iOS build

    We have the same issue if rb drag value of box collider gameobject is higher than the default value.

    Test scene:
    - ground gameobject with static mesh collider
    - moving gameobject with box collider and rb/continues dynamic collision detection (if rb drag value is 0.5 it is OK, if rb drag value is 12, gameobject very often goes through a ground/mesh collider

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