From fbf00dd54d787c6e22b0f1785a64dfb2fb1e300a Mon Sep 17 00:00:00 2001
From: "Nathan V. Morrical" <natemorrical@gmail.com>
Date: Tue, 25 May 2021 11:06:54 -0600
Subject: 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>
---
 source/slang/slang-type-layout.cpp | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

(limited to 'source/slang/slang-type-layout.cpp')

diff --git a/source/slang/slang-type-layout.cpp b/source/slang/slang-type-layout.cpp
index f21722bd7..f2869886e 100644
--- a/source/slang/slang-type-layout.cpp
+++ b/source/slang/slang-type-layout.cpp
@@ -686,6 +686,12 @@ struct HLSLRayTracingLayoutRulesImpl : DefaultVaryingLayoutRulesImpl
         : DefaultVaryingLayoutRulesImpl(kind)
     {}
 };
+struct CUDARayTracingLayoutRulesImpl : DefaultVaryingLayoutRulesImpl
+{
+    CUDARayTracingLayoutRulesImpl(LayoutResourceKind kind)
+        : DefaultVaryingLayoutRulesImpl(kind)
+    {}
+};
 
 DefaultLayoutRulesImpl kDefaultLayoutRulesImpl;
 Std140LayoutRulesImpl kStd140LayoutRulesImpl;
@@ -707,7 +713,13 @@ HLSLRayTracingLayoutRulesImpl kHLSLRayPayloadParameterLayoutRulesImpl(LayoutReso
 HLSLRayTracingLayoutRulesImpl kHLSLCallablePayloadParameterLayoutRulesImpl(LayoutResourceKind::CallablePayload);
 HLSLRayTracingLayoutRulesImpl kHLSLHitAttributesParameterLayoutRulesImpl(LayoutResourceKind::HitAttributes);
 
+// Just copying what was done above for now, but for CUDA...
+//CUDAVaryingLayoutRulesImpl kCUDAVaryingInputLayoutRulesImpl(LayoutResourceKind::VertexInput);
+//CUDAVaryingLayoutRulesImpl kCUDAVaryingOutputLayoutRulesImpl(LayoutResourceKind::FragmentOutput);
 //
+CUDARayTracingLayoutRulesImpl kCUDARayPayloadParameterLayoutRulesImpl(LayoutResourceKind::RayPayload);
+//CUDARayTracingLayoutRulesImpl kCUDACallablePayloadParameterLayoutRulesImpl(LayoutResourceKind::CallablePayload);
+//CUDARayTracingLayoutRulesImpl kCUDAHitAttributesParameterLayoutRulesImpl(LayoutResourceKind::HitAttributes);
 
 struct GLSLLayoutRulesFamilyImpl : LayoutRulesFamilyImpl
 {
@@ -929,6 +941,12 @@ LayoutRulesImpl kCUDAAnyValueLayoutRulesImpl_ = {
     &kCUDAObjectLayoutRulesImpl,
 };
 
+// We want a custom layout for ray payloads to handle the logic of
+// copying payload registers vs reading / writing to and from memory
+LayoutRulesImpl kCUDARayPayloadParameterLayoutRulesImpl_ = {
+    &kCUDALayoutRulesFamilyImpl, &kCUDARayPayloadParameterLayoutRulesImpl, &kCUDAObjectLayoutRulesImpl,
+};
+
 // GLSL cases
 
 LayoutRulesImpl kStd140LayoutRulesImpl_ = {
@@ -1276,7 +1294,8 @@ LayoutRulesImpl* CUDALayoutRulesFamilyImpl::getParameterBlockRules()
 }
 LayoutRulesImpl* CUDALayoutRulesFamilyImpl::getRayPayloadParameterRules()
 {
-    return nullptr;
+    // Mimicking HLSL 
+    return &kCUDARayPayloadParameterLayoutRulesImpl_;
 }
 LayoutRulesImpl* CUDALayoutRulesFamilyImpl::getCallablePayloadParameterRules()
 {
-- 
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