Run a compute job that packs most commonly used instance data (LocalToWorld matrix and some other bits - 80 bytes) into per-instance vertex buffer. Vertex shader does not have access to GPUScene and instead loads instance data from a per-instance vertex buffer. If it needs more primitive/instance data than available then it will load it from Primitive UB, binding unique uniform buffer and breaking auto-instancing. Pixel shader has a full access to a GPUScene
There are 3 ways how FSceneDataIntermediates gets populated
1. PrimitiveId + GPUScene (Desktop)
2. Per-Instance data + Primitive UB (Mobile)
3. Primitive UB (auto-instancing disabled)
Details for GPUScene specific vertex inputs and access to FSceneDataIntermediates are hidden behind a macro:
VF_GPUSCENE_DECLARE_INPUT_BLOCK
VF_GPUSCENE_GET_INTERMEDIATES
FSceneDataIntermediates is now stored in FVertexFactoryIntermediates, FMaterialVertexParameters. Added a few GetPrimitiveData() overloads that allows you to access PrimitiveData depending on current context. Removed most of the cases where GetPrimitiveData() gets used with PrimitiveId.
#rb Ola.Ollson
[CL 17093848 by Dmitriy Dyomin in ue5-main branch]
