How to handle collision detection & response in voxel engine with slopes?

Question

• Voxels are fairly small
• An object can span an area of 8x8x8 or more
• Vertices of Voxel Type are always snapped to the grid:

• Voxel types are convex (except the second type - which can be thought of as an OR between two rotated voxels of third type)

• Including all the configurations of the above, there are 77 distinct voxel types.

Seems like there could be a fairly simple algorithm for doing collision detection and response between AABB / Bounding-Box / sphere and a single Voxel - considering the simple and rigid geometry restrictions in place, but I can't come up with one at the moment.

Answer 1

There is a fairly simple way to do collision detection between a single "voxel shape" and an AABB.

It relies on the SAT (separating axis theorem) - finding a plane which separates both objects. As soon as we find one we know there's no collision.

First off checking all planes of AABB of the voxel and then again against all sloped planes of the voxel.

4th voxel type also has 3 potential sloped edges to check against.

Now this only handles the collision detection part. In order to resolve the collision after we find that objects intersect, we have to enumerate all the potential separating planes to see which one has the least amount of overlap - and then move the object away along the plane normal using the penetration depth.

The real tricky part is figuring out how to resolve collision vs multiple sloped voxels at the same time - there are multiple penetration vectors and distances.