Cycles: MetalRT support (kernel side)

This patch adds MetalRT support to Cycles kernel code. It is mostly additive in nature or confined to Metal-specific code, however there are a few areas where this interacts with other code:

- MetalRT closely follows the Optix implementation, and in some cases (notably handling of transforms) it makes sense to extend Optix special-casing to MetalRT. For these generalisations we now have `__KERNEL_GPU_RAYTRACING__` instead of `__KERNEL_OPTIX__`.
- MetalRT doesn't support primitive offsetting (as with `primitiveIndexOffset` in Optix), so we define and populate a new kernel texture, `__object_prim_offset`, containing per-object primitive / curve-segment offsets. This is referenced and applied in MetalRT intersection handlers.
- Two new BVH layout enum values have been added: `BVH_LAYOUT_METAL` and `BVH_LAYOUT_MULTI_METAL_EMBREE` for XPU mode). Some host-side enum case handling has been updated where it is trivial to do so.

Ref T92212

Reviewed By: brecht

Maniphest Tasks: T92212

Differential Revision: https://developer.blender.org/D13353

1 files changed, 6 insertions, 1 deletions

diff --git a/intern/cycles/device/multi/device.cpp b/intern/cycles/device/multi/device.cpp
index e319246d4f4..2513df63489 100644
--- a/intern/cycles/device/multi/device.cpp
+++ b/intern/cycles/device/multi/device.cpp
@@ -129,6 +129,10 @@ class MultiDevice : public Device {
     if ((bvh_layout_mask_all & BVH_LAYOUT_OPTIX_EMBREE) == BVH_LAYOUT_OPTIX_EMBREE) {
       return BVH_LAYOUT_MULTI_OPTIX_EMBREE;
     }
+    const BVHLayoutMask BVH_LAYOUT_METAL_EMBREE = (BVH_LAYOUT_METAL | BVH_LAYOUT_EMBREE);
+    if ((bvh_layout_mask_all & BVH_LAYOUT_METAL_EMBREE) == BVH_LAYOUT_METAL_EMBREE) {
+      return BVH_LAYOUT_MULTI_METAL_EMBREE;
+    }
 
     return bvh_layout_mask;
   }
@@ -151,7 +155,8 @@ class MultiDevice : public Device {
     }
 
     assert(bvh->params.bvh_layout == BVH_LAYOUT_MULTI_OPTIX ||
-           bvh->params.bvh_layout == BVH_LAYOUT_MULTI_OPTIX_EMBREE);
+           bvh->params.bvh_layout == BVH_LAYOUT_MULTI_OPTIX_EMBREE ||
+           bvh->params.bvh_layout == BVH_LAYOUT_MULTI_METAL_EMBREE);
 
     BVHMulti *const bvh_multi = static_cast<BVHMulti *>(bvh);
     bvh_multi->sub_bvhs.resize(devices.size());