[2.1 RC1] - Collider clips through box colliders

Unity Engine
1

Alright, fair warning: this is an extremely weird problem. And, before I even explain the problem and someone suggests it, collider damping is 0 and the models I’m using have perfectly straight faces.

Now, the problem is that FBX models I export from Blender and apply a 1 meter tall box collider to cause the Cinemachine FreeLook camera to sink into them at seemingly random points. Using a mesh collider (either convex or not; both work) seems to prevent the clipping, but the camera still makes weird bumpy movements as it slides across the surface.

There are no additional colliders on the object, and there are no additional colliders from other objects near the object. I have observed the same problem in a scene with only the camera, the target, and a single floor tile. I scale the object laterally to create larger floors. I have not been able to reproduce the problem with primitives included with Unity.

Examples
Here is an example image showing a grass plane (which uses a mesh collider) and a floor plane (which uses a box collider). Note that the character height does not change, proving that the ground is at the same height in both cases. Yet, the camera clips through the box collider.
https://gfycat.com/HeftySickHawaiianmonkseal

Here is an example demonstrating the same behavior on a contiguous face:
https://gfycat.com/AlienatedBowedGossamerwingedbutterfly

And, here is an example showing the camera moving up and down in the editor. The wireframe edge can be ignored; I have observed the same behavior far away from edges.
https://gfycat.com/AstonishingFavorableAmericanmarten

Settings
Finally, here are my collider settings:
Imgur

Setting the collider radius to a higher value significantly exacerbates the problem.

Files
Here’s one of the models I apply the collider to: Test Plane

Versions
Unity 2017.1.0p4
Cinemachine 2.1 RC1

2

@OhiraKyou Thanks for the detailed report. I was able to repro with your fbx. It looks like you’re tripping over a recently-reported issue in the Physics system, relating to collision resolution against scaled box colliders. CM is using that to implement the camera radius feature. The physics team is on it, and it will probably get cleared up in the next iteration of Unity.

3

Thanks for looking into it.

Weirdly, I was able to improve the collision by disabling the original box collider and adding a Unity cube to the planes as a sibling in a scaled container object with its mesh renderer and filter removed. Although it’s still being scaled via the same method, the camera no longer clips through it. The camera now twitches pretty hard as it passes over seams between floor chunks, but that’s more acceptable than seeing through the ground.