Cycles: fully decouple triangle and curve primitive storage from BVH2

Previously the storage here was optimized to avoid indirections in BVH2
traversal. This helps improve performance a bit, but makes performance
and memory usage of Embree and OptiX BVHs a bit worse also. It also adds
code complexity in other parts of the code.

Now decouple triangle and curve primitive storage from BVH2.
* Reduced peak memory usage on all devices
* Bit better performance for OptiX and Embree
* Bit worse performance for CUDA
* Simplified code:
** Intersection.prim/object now matches ShaderData.prim/object
** No more offset manipulation for mesh displacement before a BVH is built
** Remove primitive packing code and flags for Embree and OptiX
** Curve segments are now stored in a KernelCurve struct
* Also happens to fix a bug in baking with incorrect prim/object

Fixes T91968, T91770, T91902

Differential Revision: https://developer.blender.org/D12766

1 files changed, 16 insertions, 1 deletions

diff --git a/intern/cycles/kernel/kernel_types.h b/intern/cycles/kernel/kernel_types.h
index 22dde3537eb..4a72f45f1a2 100644
--- a/intern/cycles/kernel/kernel_types.h
+++ b/intern/cycles/kernel/kernel_types.h
@@ -1270,10 +1270,25 @@ typedef struct KernelObject {
 
   float ao_distance;
 
-  float pad1, pad2;
+  uint visibility;
+  int primitive_type;
 } KernelObject;
 static_assert_align(KernelObject, 16);
 
+typedef struct KernelCurve {
+  int shader_id;
+  int first_key;
+  int num_keys;
+  int type;
+} KernelCurve;
+static_assert_align(KernelCurve, 16);
+
+typedef struct KernelCurveSegment {
+  int prim;
+  int type;
+} KernelCurveSegment;
+static_assert_align(KernelCurveSegment, 8);
+
 typedef struct KernelSpotLight {
   float radius;
   float invarea;