Unbounded memory&frame generation time growth in rasterization pipeline

[Hyiker]

Falcor 7 & 8's memory and cpu frame time grow fast and infinitely as time goes on. The immediate cause is that GraphicsStateGraph.mGraph(In GraphicsState.h) having unbounded growing nodes, such that scanForMatchingNode takes longer time and failed to find the desired node every single search in each frame. The root cause is in GraphicsState::getGSO, where some of the properties(in my case, GraphicsStateObjectDesc::pBlendState is alway null) of mDesc are not properly set but mpDevice->createGraphicsStateObject updates the descriptor passed by value afterwards. This leads to cmpFunc returns false all the time.

Luckily, a short fix, appending mDesc = pGso->getDesc(); after line 112 in GraphicsState.cpp could save the day.

[tomas-davidovic]

Thank you for pointing this out.
We've updated this in the internal version, if you open a PR here, we will merge it into the public one as well.