Motion blur and two-level BVH

[Marko_S]

I am following tutorial02 to write my own simple renderer on top of embree. I have two questions regarding motion blur: 1. How do you specify motion for user-defined primitives? 2. How do you enable motion blur for two-level BVH? It appears that bvh4mb accelerator for VirtualObject does not work. Thanks.

[SvenW_Intel]

1) As you control the intersection code of the user defined primitive, you have to implement motion blur by yourself using the time specified in the ray. 2) We never tested motion blur for two level scenes, however, it should work if you use a normal BVH over your moving objects (that use the bvh4mb). You only have to be carefull that the bounding boxes you use in your toplevel BVH are conservatively bounding the motion of each object.

[Marko_S]

Thanks for clarification.

If I understand correctly:

1. bvh4mb is only used for motion-blurred triangular meshes

2. If two-level structure is used for scene containing motion, ordinary

bvh4 should be used (and *not* bvh4mb)

[SvenW_Intel]

Exactly, for the toplevel you should use a normal bvh4 for now. One can do better, but that is not implemented yet.