Realtime Dynamic GI + Reflections + AO + Emissive - AHR

[RyanTorant]

@krstefan42;317481

You have a good point. I always assumed the reason that sparse voxel octrees gave bad performance was because the data structure itself is so non-contiguous, not because of the octree traversal algorithm itself. Like you said, the only to know for sure is to implement it and see. But I can say for sure that using distance fields will not have the same problem as it avoids the octree traversal altogether.

Another way to accelerate the raymarching would be to use a cascaded voxel representation and read from lower-resolution cascades as the rays get further apart, like I mentioned above (obviously, it would be for diffuse and blurry specular only). That way you could increase the ray step size as the rays get further away, but you avoid the octree traversal altogether. I’m quite certain that would give a speedup. If you aren’t sold, though, then I’d be willing take a crack at it, after you implement cascades. It should just be a matter of changing the shader code, which I’m quite good at (messing with the internals of UE4, not so much ;)).

Voxel cascades will have the stack problem though. Oh, wait, unless you mean using a lower res as you get away from the starting point. I’m in the middle of a change on the way I store the voxels, will use 3d textures, and that will surely make it easier to implement cascades. Will keep you updated. I do do trace against a packed binary voxels grid, so I need to sample less, but that have some implementation issues. Now ill move that binary grid to a r8_uint 3d Tex where I pack 8 voxels, so that it’s effectively at half res for the trace, but full res when sampling.