OptiX ray payload read/write support in raytracing pipeline shaders (#1853)

* OptiX ray payload can now be read from and written to using the two payload register pointer method

* changing op to more descriptive name

* fixup: comment change to re-trigger CI

Co-authored-by: T. Foley <tfoleyNV@users.noreply.github.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/prelude/slang-cuda-prelude.h b/prelude/slang-cuda-prelude.h
index 4df60e965..a6c4f70dc 100644
--- a/prelude/slang-cuda-prelude.h
+++ b/prelude/slang-cuda-prelude.h
@@ -1612,3 +1612,29 @@ found via reflection or defined such that it matches the shader appropriately.
 */
 struct UniformEntryPointParams;
 struct UniformState;
+
+// ---------------------- OptiX Ray Payload --------------------------------------
+#ifdef SLANG_CUDA_ENABLE_OPTIX
+static __forceinline__ __device__
+void *unpackOptiXRayPayloadPointer(uint32_t i0, uint32_t i1)
+{
+	const uint64_t uptr = static_cast<uint64_t>(i0) << 32 | i1;
+	void*           ptr = reinterpret_cast<void*>(uptr);
+	return ptr;
+}
+
+static __forceinline__ __device__
+void  packOptiXRayPayloadPointer(void* ptr, uint32_t& i0, uint32_t& i1)
+{
+	const uint64_t uptr = reinterpret_cast<uint64_t>(ptr);
+	i0 = uptr >> 32;
+	i1 = uptr & 0x00000000ffffffff;
+}
+
+static __forceinline__ __device__ void *getOptiXRayPayloadPtr()
+{
+	const uint32_t u0 = optixGetPayload_0();
+	const uint32_t u1 = optixGetPayload_1();
+	return unpackOptiXRayPayloadPointer(u0, u1);
+}
+#endif