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by berkut 4574 days ago
Working in the VFX industry, I'm well aware of what a production renderer needs :)

I wouldn't say adding features increases complexity exponentially - I guess it depends on the design of the system, but that hasn't been my experience with my stuff...

I assume by "different sampling types..." you mean BSDF importance sampling for outgoing direction and sampling the Solid Angle or pdf of taking that direction? If so, I'm not sure I'd call that especially difficult...

Building up ready-to-go materials (certainly as many as Vray ships with) undoubtedly takes time, but in the VFX industry, generally everyone writes their own shaders anyway...

Anyway, my focus is on VFX so I can concentrate on those type of issues, whereas I guess Vray needs to work well across different domains as well (product design, archviz, etc) - that'd be where things start getting difficult to balance out the different requirements I'd assume:

e.g. you can save quite a bit of memory by not storing vertex normals as vec3 floats, but as two 16-bit ushort numbers which can then be mapped via a LUT to the spherical coords of the normal. This is acceptable for VFX, and even in worst-case situations (very zoomed in on a very dense mesh with lots of crinkly displacement), it's barely noticeable, but for archviz people rendering at 10k x 10k, they might spot the issues at that size...