Add docs/NOTES_renderer_v3.md

docs/NOTES_renderer_v3.md

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+# GFX/Renderer v3
+
+- Build around draw indirect
+- Keep many meshlets together in one large buffer
+- Meshlet: 128 triangles
+- Mesh: List of meshlets
+- Do compute based culling per VIEW
+- Each View gets a list of mesh-refs (expanded to meshlet refs), and associated transforms
+- **Optional:**
+    - These are, by default, permanent, allowing us to build a efficient bvh.
+    - Mark nodes as deleted, only collapse once the entire subtree is deleted.
+
+Draw/Materials:
+- Culling outputs tri-idx, meshlet for every pixel (For hardware that supports it, this could use raytracing)
+- Meshlet refers to a (sub)material (via index)
+- Per tile, create a list of draw indirect commands and a read-back buffer containing the (sub-)material index for each draw (+ total nr of draws)
+- CPU loops over materials, issueing draw indirect calls upon material changes
+- The ref to a sub-material may be made via meshlet -> material and view type -> sub-material
+
+Some (most) sub-materials could draw into a gbuffer.
+
+SubMaterialData is baked into structs containing constants and/or bindless ids.
+Kept in one huge buffer
+SubMaterial:
+- Data
+- PSO 
+Material:
+- View Type -> SubMaterial
+
+Frame Graph - Each view is a pass. Can re-use existing?
+
+Renderer API:
+- CreateMesh(data) -> MeshRef
+- InstantiateMesh(MeshRef) -> MeshRef
+- CreateView(type) -> View
+- AddToView(MeshRef, Transform, Material) -> InstanceRef
+- RemoveFromView(InstanceRef)
+- UpdateInView(InstanceRef, Transform, Material)
+- SetViewCamera(View, Camera)
+- RenderView(View)
+- CreateMaterial(NumSubMaterials, SubMaterialInfo*) -> Material
+- CreateTexture(Format, W, H, NumMipLevels, Optional<InitialData*>) -> Texture
+- EnqueueTextureUpdate(Texture, MipLevel, NewData)