[Bf-cycles] GSoC - Spectral Rendering

[storm]

Just FYI, accurate motion blur is most difficult task. Nobody solve it
optimal way yet in whole industry, only some workarounds that can look
better then other. The problem is mostly with BVH and composed motion
matrix, as any matrix with rotation will degrade any linear
interpolation picewise-based solutions, imagine rotating helicopter
rotor blades that move forward same time, it sweep along very many BVH
leafs during frame  and you get poor (slow) triangle intersection test
that make > 50% of overall render time. Same time, any "accurate" MB
significally increase memory required for BVH.