NoMSAA supervariant support

Added a ShaderSystem supervariant to provide a system-wide supervariant name.
Changed ShaderAsset to append the system-wide supervariant name when searching for supervariants.
Added the NoMSAA supervariant to several shaders.

Gems/Atom/Feature/Common/Assets/Passes/MSAAResolveColor.pass

@@ -50,6 +50,13 @@
                         "Attachment": "ResolvedOutput"
                     }
                 }
+            ],
+            "FallbackConnections": [
+                // used in non-MSAA pipelines when the resolve is disabled
+                {
+                    "Input" : "Input",
+                    "Output" : "Output"
+                }
             ]
         }
     }

Gems/Atom/Feature/Common/Assets/Passes/MSAAResolveCustom.pass

@@ -48,6 +48,13 @@
                     }
                 }
             ],
+            "FallbackConnections": [
+                // used in non-MSAA pipelines when the resolve is disabled
+                {
+                    "Input" : "Input",
+                    "Output" : "Output"
+                }
+            ],
             "PassData": {
                 "$type": "FullscreenTrianglePassData",
                 "ShaderAsset": {

Gems/Atom/Feature/Common/Assets/Passes/MSAAResolveDepth.pass

@@ -54,6 +54,13 @@
                     }
                 }
             ],
+            "FallbackConnections": [
+                // used in non-MSAA pipelines when the resolve is disabled
+                {
+                    "Input" : "Input",
+                    "Output" : "Output"
+                }
+            ],
             "PassData": {
                 "$type": "FullscreenTrianglePassData",
                 "ShaderAsset": {

Gems/Atom/Feature/Common/Assets/Shaders/DiffuseGlobalIllumination/DiffuseComposite.shader

@@ -52,5 +52,14 @@
                 "type": "Fragment"
             }
         ]
-    } 
+    },
+
+    "Supervariants":
+    [
+        {
+            "Name": "NoMSAA",
+            "PlusArguments": "--no-ms",
+            "MinusArguments": ""
+        }
+    ]
 }

Gems/Atom/Feature/Common/Assets/Shaders/DiffuseGlobalIllumination/DiffuseGlobalFullscreen.shader

@@ -52,5 +52,14 @@
                 "type": "Fragment"
             }
         ]
-    }
+    },
+
+    "Supervariants":
+    [
+        {
+            "Name": "NoMSAA",
+            "PlusArguments": "--no-ms",
+            "MinusArguments": ""
+        }
+    ]
 }

Gems/Atom/Feature/Common/Assets/Shaders/DiffuseGlobalIllumination/DiffuseProbeGridDownsample.shader

@@ -30,5 +30,14 @@
                 "type": "Fragment"
             }
         ]
-    }
+    },
+
+    "Supervariants":
+    [
+        {
+            "Name": "NoMSAA",
+            "PlusArguments": "--no-ms",
+            "MinusArguments": ""
+        }
+    ]
 }

Gems/Atom/Feature/Common/Assets/Shaders/LightCulling/LightCullingTilePrepare.shader

@@ -15,5 +15,14 @@
                 "type" : "Compute"
             }
         ] 
-    }       
+    },
+
+    "Supervariants":
+    [
+        {
+            "Name": "NoMSAA",
+            "PlusArguments": "--no-ms",
+            "MinusArguments": ""
+        }
+    ]
 }

Gems/Atom/Feature/Common/Assets/Shaders/Reflections/ReflectionComposite.shader

@@ -49,5 +49,14 @@
                 "type": "Fragment"
             }
         ]
-    } 
+    },
+
+    "Supervariants":
+    [
+        {
+            "Name": "NoMSAA",
+            "PlusArguments": "--no-ms",
+            "MinusArguments": ""
+        }
+    ]
 }

Gems/Atom/Feature/Common/Assets/Shaders/Reflections/ReflectionGlobalFullscreen.shader

@@ -40,5 +40,14 @@
                 "type": "Fragment"
             }
         ]
-    }
+    },
+
+    "Supervariants":
+    [
+        {
+            "Name": "NoMSAA",
+            "PlusArguments": "--no-ms",
+            "MinusArguments": ""
+        }
+    ]  
 }

Gems/Atom/Feature/Common/Assets/Shaders/Reflections/ReflectionProbeBlendWeight.shader

@@ -49,5 +49,14 @@
                 "type": "Fragment"
             }
         ]
-    }
+    },
+
+    "Supervariants":
+    [
+        {
+            "Name": "NoMSAA",
+            "PlusArguments": "--no-ms",
+            "MinusArguments": ""
+        }
+    ]
 }

Gems/Atom/Feature/Common/Assets/Shaders/Reflections/ReflectionProbeRenderInner.shader

@@ -42,5 +42,14 @@
                 "type": "Fragment"
             }
         ]
-    }
+    },
+
+    "Supervariants":
+    [
+        {
+            "Name": "NoMSAA",
+            "PlusArguments": "--no-ms",
+            "MinusArguments": ""
+        }
+    ]
 }

Gems/Atom/Feature/Common/Assets/Shaders/Reflections/ReflectionProbeRenderOuter.shader

@@ -49,5 +49,14 @@
                 "type": "Fragment"
             }
         ]
-    }
+    },
+
+    "Supervariants":
+    [
+        {
+            "Name": "NoMSAA",
+            "PlusArguments": "--no-ms",
+            "MinusArguments": ""
+        }
+    ]
 }

Gems/Atom/Feature/Common/Assets/Shaders/Reflections/ReflectionProbeStencil.shader

@@ -47,5 +47,14 @@
                 "type": "Vertex"
             }
         ]
-    }
+    },
+
+    "Supervariants":
+    [
+        {
+            "Name": "NoMSAA",
+            "PlusArguments": "--no-ms",
+            "MinusArguments": ""
+        }
+    ]
 }

Gems/Atom/Feature/Common/Code/Source/Mesh/MeshFeatureProcessor.cpp

@@ -658,7 +658,7 @@ namespace AZ
                 if (!m_shaderResourceGroup)
                 {
                     auto& shaderAsset = material->GetAsset()->GetMaterialTypeAsset()->GetShaderAssetForObjectSrg();
-                    m_shaderResourceGroup = RPI::ShaderResourceGroup::Create(shaderAsset, RPI::DefaultSupervariantIndex, objectSrgLayout->GetName());
+                    m_shaderResourceGroup = RPI::ShaderResourceGroup::Create(shaderAsset, objectSrgLayout->GetName());
                     if (!m_shaderResourceGroup)
                     {
                         AZ_Warning("MeshFeatureProcessor", false, "Failed to create a new shader resource group, skipping.");

Gems/Atom/Feature/Common/Code/Source/RayTracing/RayTracingFeatureProcessor.cpp

@@ -74,12 +74,12 @@ namespace AZ
             }
 
             // create the RayTracingSceneSrg
-            m_rayTracingSceneSrg = RPI::ShaderResourceGroup::Create(m_rayTracingSrgAsset, RPI::DefaultSupervariantIndex, Name("RayTracingSceneSrg"));
+            m_rayTracingSceneSrg = RPI::ShaderResourceGroup::Create(m_rayTracingSrgAsset, Name("RayTracingSceneSrg"));
             AZ_Assert(m_rayTracingSceneSrg, "Failed to create RayTracingSceneSrg");
 
             // create the RayTracingMaterialSrg
             const AZ::Name rayTracingMaterialSrgName("RayTracingMaterialSrg");
-            m_rayTracingMaterialSrg = RPI::ShaderResourceGroup::Create(m_rayTracingSrgAsset, RPI::DefaultSupervariantIndex, Name("RayTracingMaterialSrg"));
+            m_rayTracingMaterialSrg = RPI::ShaderResourceGroup::Create(m_rayTracingSrgAsset, Name("RayTracingMaterialSrg"));
             AZ_Assert(m_rayTracingMaterialSrg, "Failed to create RayTracingMaterialSrg");
         }
 

Gems/Atom/RPI/Code/Include/Atom/RPI.Public/Shader/Shader.h

@@ -139,6 +139,11 @@ namespace AZ
             //! This tag corresponds to the ShaderAsset object's DrawListName.
             RHI::DrawListTag GetDrawListTag() const;
 
+            //! Changes the supervariant of the shader to the specified supervariantIndex.
+            //! [GFX TODO][ATOM-15813]: this can be removed when the shader InstanceDatabase can support multiple shader
+            //! instances with different supervariants.
+            void ChangeSupervariant(SupervariantIndex supervariantIndex);
+
         private:
             explicit Shader(const SupervariantIndex& supervariantIndex) : m_supervariantIndex(supervariantIndex){};
             Shader() = delete;

Gems/Atom/RPI/Code/Include/Atom/RPI.Public/Shader/ShaderResourceGroup.h

@@ -61,6 +61,12 @@ namespace AZ
             AZ_CLASS_ALLOCATOR(ShaderResourceGroup, AZ::SystemAllocator, 0);
 
             /// Instantiates a unique shader resource group instance using its paired asset but with a random InstanceId.
+            /// This version uses the appropriate default supervariant.
+            static Data::Instance<ShaderResourceGroup> Create(
+                const Data::Asset<ShaderAsset>& shaderAsset, const AZ::Name& srgName);
+
+            /// Instantiates a unique shader resource group instance using its paired asset but with a random InstanceId.
+            /// This version uses the supervariant specified by the caller.
             static Data::Instance<ShaderResourceGroup> Create(
                 const Data::Asset<ShaderAsset>& shaderAsset, const SupervariantIndex& supervariantIndex, const AZ::Name& srgName);
 

Gems/Atom/RPI/Code/Include/Atom/RPI.Public/Shader/ShaderSystem.h

@@ -45,15 +45,19 @@ namespace AZ
             ShaderOptionValue GetGlobalShaderOption(const AZ::Name& shaderOptionName) override;
             const GlobalShaderOptionMap& GetGlobalShaderOptions() const override;
             void Connect(GlobalShaderOptionUpdatedEvent::Handler& handler) override;
+            void SetSupervariantName(const AZ::Name& supervariantName) override;
+            const AZ::Name& GetSupervariantName() const override;
             ///////////////////////////////////////////////////////////////////
 
         private:
             AZStd::unordered_map<Name, ShaderOptionValue> m_globalShaderOptionValues;
             GlobalShaderOptionUpdatedEvent m_globalShaderOptionUpdatedEvent;
             ShaderVariantAsyncLoader m_shaderVariantAsyncLoader;
-        };
-
-
 
+            //! The ShaderSystem supervariantName is used by the ShaderAsset to search for an additional supervariant permutation.
+            //! This is done by appending the supervariantName set here to the user-specified supervariant name.
+            //! Currently this is used for NoMSAA supervariant support.
+            AZ::Name m_supervariantName;
+        };
     } // namespace RPI
 } // namespace AZ

Gems/Atom/RPI/Code/Include/Atom/RPI.Public/Shader/ShaderSystemInterface.h

@@ -47,6 +47,12 @@ namespace AZ
 
             //! Connect a handler for GlobalShaderOptionUpdatedEvent's
             virtual void Connect(GlobalShaderOptionUpdatedEvent::Handler& handler) = 0;
+
+            //! The ShaderSystem supervariantName is used by the ShaderAsset to search for an additional supervariant permutation.
+            //! This is done by appending the supervariantName set here to the user-specified supervariant name.
+            //! Currently this is used for NoMSAA supervariant support.
+            virtual void SetSupervariantName(const AZ::Name& supervariantName) = 0;
+            virtual const AZ::Name& GetSupervariantName() const = 0;
         };
 
     }   // namespace RPI

Gems/Atom/RPI/Code/Include/Atom/RPI.Reflect/Shader/ShaderAsset.h

@@ -103,6 +103,8 @@ namespace AZ
             //! Returns the shader option group layout.
             const ShaderOptionGroupLayout* GetShaderOptionGroupLayout() const;
 
+            //! Returns the supervariant index from the specified name.
+            //! Note that this will append the system supervariant name from RPI::ShaderSystem when searching.
             SupervariantIndex GetSupervariantIndex(const AZ::Name& supervariantName) const;
 
             //! This function should be your one stop shop to get a ShaderVariantAsset.
@@ -139,22 +141,15 @@ namespace AZ
             Data::Asset<ShaderVariantAsset> GetRootVariant() const { return GetRootVariant(DefaultSupervariantIndex); }
 
 
-            //! Finds and returns the shader resource group asset with the requested name. Returns an empty handle if no matching group was
-            //! found.
+            //! Finds and returns the shader resource group asset with the requested name. Returns an empty handle if no matching group was found.
             const RHI::Ptr<RHI::ShaderResourceGroupLayout>& FindShaderResourceGroupLayout(
                 const Name& shaderResourceGroupName, SupervariantIndex supervariantIndex) const;
-            const RHI::Ptr<RHI::ShaderResourceGroupLayout>& FindShaderResourceGroupLayout(const Name& shaderResourceGroupName) const
-            {
-                return FindShaderResourceGroupLayout(shaderResourceGroupName, DefaultSupervariantIndex);
-            }
+            const RHI::Ptr<RHI::ShaderResourceGroupLayout>& FindShaderResourceGroupLayout(const Name& shaderResourceGroupName) const;
 
             //! Finds and returns the shader resource group layout associated with the requested binding slot. Returns an empty handle if no matching srg was found.
             const RHI::Ptr<RHI::ShaderResourceGroupLayout>& FindShaderResourceGroupLayout(
                 uint32_t bindingSlot, SupervariantIndex supervariantIndex) const;
-            const RHI::Ptr<RHI::ShaderResourceGroupLayout>& FindShaderResourceGroupLayout(uint32_t bindingSlot) const
-            {
-                return FindShaderResourceGroupLayout(bindingSlot, DefaultSupervariantIndex);
-            }
+            const RHI::Ptr<RHI::ShaderResourceGroupLayout>& FindShaderResourceGroupLayout(uint32_t bindingSlot) const;
 
             //! Finds and returns the shader resource group layout designated as a ShaderVariantKey fallback.
             const RHI::Ptr<RHI::ShaderResourceGroupLayout>& FindFallbackShaderResourceGroupLayout( SupervariantIndex supervariantIndex) const;
@@ -277,6 +272,8 @@ namespace AZ
             Supervariant* GetSupervariant(SupervariantIndex supervariantIndex);
             const Supervariant* GetSupervariant(SupervariantIndex supervariantIndex) const;
 
+            //! Search for a supervariant index by name.
+            SupervariantIndex GetSupervariantIndexInternal(AZ::Name supervariantName) const;
 
             //! The name is the stem of the source <name>.shader file.
             Name m_name;

Gems/Atom/RPI/Code/Include/Atom/RPI.Reflect/Shader/ShaderCommonTypes.h

@@ -37,6 +37,9 @@ namespace AZ
         //! in the list of supervariants owned by the ShaderAsset.
         static const SupervariantIndex DefaultSupervariantIndex(0);
 
+        //! The NoMSAA supervariant is auto-generated by AZSLc.
+        static const char* NoMsaaSupervariantName = "NoMSAA";
+
         static const SupervariantIndex InvalidSupervariantIndex;
 
         enum class ShaderStageType : uint32_t

Gems/Atom/RPI/Code/Source/RPI.Public/Material/Material.cpp

@@ -69,7 +69,7 @@ namespace AZ
             if (srgLayout)
             {
                 auto shaderAsset = m_materialAsset->GetMaterialTypeAsset()->GetShaderAssetForMaterialSrg();
-                m_shaderResourceGroup = ShaderResourceGroup::Create(shaderAsset, DefaultSupervariantIndex, srgLayout->GetName());
+                m_shaderResourceGroup = ShaderResourceGroup::Create(shaderAsset, srgLayout->GetName());
 
                 if (m_shaderResourceGroup)
                 {

Gems/Atom/RPI/Code/Source/RPI.Public/Pass/RasterPass.cpp

@@ -64,11 +64,10 @@ namespace AZ
 
             if (shaderAsset)
             {
-                auto supervariantIndex = DefaultSupervariantIndex;
-                const auto srgLayout = shaderAsset->FindShaderResourceGroupLayout(SrgBindingSlot::Pass, supervariantIndex);
+                const auto srgLayout = shaderAsset->FindShaderResourceGroupLayout(SrgBindingSlot::Pass);
                 if (srgLayout)
                 {
-                    m_shaderResourceGroup = ShaderResourceGroup::Create(shaderAsset, supervariantIndex, srgLayout->GetName());
+                    m_shaderResourceGroup = ShaderResourceGroup::Create(shaderAsset, srgLayout->GetName());
 
                     AZ_Assert(
                         m_shaderResourceGroup, "[RasterPass '%s']: Failed to create SRG from shader asset '%s'", GetPathName().GetCStr(),

Gems/Atom/RPI/Code/Source/RPI.Public/Scene.cpp

@@ -46,7 +46,7 @@ namespace AZ
             if (sceneSrgLayout)
             {
                 auto shaderAsset = RPISystemInterface::Get()->GetCommonShaderAssetForSrgs();
-                scene->m_srg = ShaderResourceGroup::Create(shaderAsset, DefaultSupervariantIndex, sceneSrgLayout->GetName());
+                scene->m_srg = ShaderResourceGroup::Create(shaderAsset, sceneSrgLayout->GetName());
             }
             
             return ScenePtr(scene);

Gems/Atom/RPI/Code/Source/RPI.Public/Shader/Shader.cpp

@@ -21,6 +21,7 @@
 #include <AtomCore/Instance/InstanceDatabase.h>
 
 #include <AzCore/Interface/Interface.h>
+#include <Atom/RPI.Public/Shader/ShaderSystemInterface.h>
 #include <Atom/RPI.Public/Shader/ShaderReloadNotificationBus.h>
 #include <Atom/RPI.Public/Shader/ShaderReloadDebugTracker.h>
 
@@ -33,6 +34,19 @@ namespace AZ
             auto anySupervariantName = AZStd::any(supervariantName);
             Data::Instance<Shader> shaderInstance = Data::InstanceDatabase<Shader>::Instance().FindOrCreate(
                 Data::InstanceId::CreateFromAssetId(shaderAsset.GetId()), shaderAsset, &anySupervariantName);
+
+            if (shaderInstance)
+            {
+                // [GFX TODO][ATOM-15813] Change InstanceDatabase<Shader> to support multiple instances with different supervariants.
+                // At this time we do not support multiple supervariants loaded for a shader asset simultaneously, so if this shader
+                // is referring to the wrong supervariant we need to change it to the correct one.
+                SupervariantIndex supervariantIndex = shaderAsset->GetSupervariantIndex(supervariantName);
+                if (supervariantIndex.IsValid() && shaderInstance->GetSupervariantIndex() != supervariantIndex)
+                {
+                    shaderInstance->ChangeSupervariant(supervariantIndex);
+                }
+            }
+
             return shaderInstance;
         }
 
@@ -68,8 +82,6 @@ namespace AZ
 
         RHI::ResultCode Shader::Init(ShaderAsset& shaderAsset)
         {
-            AZ_Assert(m_supervariantIndex != InvalidSupervariantIndex, "Invalid supervariant index");
-
             ShaderVariantFinderNotificationBus::Handler::BusDisconnect();
             ShaderVariantFinderNotificationBus::Handler::BusConnect(shaderAsset.GetId());
 
@@ -395,5 +407,15 @@ namespace AZ
         {
             return m_drawListTag;
         }
+
+        void Shader::ChangeSupervariant(SupervariantIndex supervariantIndex)
+        {
+            if (supervariantIndex != m_supervariantIndex)
+            {
+                m_supervariantIndex = supervariantIndex;
+                Init(*m_asset);
+            }
+        }
+
     } // namespace RPI
 } // namespace AZ

Gems/Atom/RPI/Code/Source/RPI.Public/Shader/ShaderResourceGroup.cpp

@@ -40,6 +40,19 @@ namespace AZ
             return Data::InstanceId::CreateData(idString.data(), idString.size());
         }
 
+        Data::Instance<ShaderResourceGroup> ShaderResourceGroup::Create(
+            const Data::Asset<ShaderAsset>& shaderAsset, const AZ::Name& srgName)
+        {
+            // retrieve the supervariantIndex by searching for the default supervariant name, this will
+            // allow the shader asset to properly handle the RPI::ShaderSystem supervariant
+            SupervariantIndex supervariantIndex = shaderAsset->GetSupervariantIndex(AZ::Name(""));
+
+            SrgInitParams initParams{ supervariantIndex, srgName };
+            auto anyInitParams = AZStd::any(initParams);
+            return Data::InstanceDatabase<ShaderResourceGroup>::Instance().FindOrCreate(
+                Data::InstanceId::CreateRandom(), shaderAsset, &anyInitParams);
+        }
+
         Data::Instance<ShaderResourceGroup> ShaderResourceGroup::Create(
             const Data::Asset<ShaderAsset>& shaderAsset, const SupervariantIndex& supervariantIndex, const AZ::Name& srgName)
         {

Gems/Atom/RPI/Code/Source/RPI.Public/Shader/ShaderSystem.cpp

@@ -148,6 +148,16 @@ namespace AZ
         {
             handler.Connect(m_globalShaderOptionUpdatedEvent);
         }
+
+        void ShaderSystem::SetSupervariantName(const AZ::Name& supervariantName)
+        {
+            m_supervariantName = supervariantName;
+        }
+
+        const AZ::Name& ShaderSystem::GetSupervariantName() const
+        {
+            return m_supervariantName;
+        }
         ///////////////////////////////////////////////////////////////////
 
     } // namespace RPI

Gems/Atom/RPI/Code/Source/RPI.Public/View.cpp

@@ -59,7 +59,7 @@ namespace AZ
 
             if (viewSrgShaderAsset.IsReady())
             {
-                m_shaderResourceGroup = ShaderResourceGroup::Create(viewSrgShaderAsset, DefaultSupervariantIndex, RPISystemInterface::Get()->GetViewSrgLayout()->GetName());
+                m_shaderResourceGroup = ShaderResourceGroup::Create(viewSrgShaderAsset, RPISystemInterface::Get()->GetViewSrgLayout()->GetName());
             }
 #if AZ_TRAIT_MASKED_OCCLUSION_CULLING_SUPPORTED
             m_maskedOcclusionCulling = MaskedOcclusionCulling::Create();

Gems/Atom/RPI/Code/Source/RPI.Reflect/Shader/ShaderAsset.cpp

@@ -20,6 +20,7 @@
 
 #include <AzCore/Interface/Interface.h>
 #include <Atom/RPI.Reflect/Shader/IShaderVariantFinder.h>
+#include <Atom/RPI.Public/Shader/ShaderSystem.h>
 #include <Atom/RPI.Public/Shader/ShaderReloadDebugTracker.h>
 #include <Atom/RPI.Public/Shader/ShaderReloadNotificationBus.h>
 
@@ -148,18 +149,28 @@ namespace AZ
 
         SupervariantIndex ShaderAsset::GetSupervariantIndex(const AZ::Name& supervariantName) const
         {
-            const auto& supervariants = GetCurrentShaderApiData().m_supervariants;
-            const uint32_t supervariantCount = supervariants.size();
-            for (uint32_t index = 0; index < supervariantCount; ++index)
+            SupervariantIndex supervariantIndex = InvalidSupervariantIndex;
+
+            // check for an RPI ShaderSystem supervariant
+            RPI::ShaderSystemInterface* shaderSystemInterface = ShaderSystemInterface::Get();
+            if (shaderSystemInterface && !shaderSystemInterface->GetSupervariantName().IsEmpty())
             {
-                if (supervariants[index].m_name == supervariantName)
-                {
-                    return SupervariantIndex{index};
-                }
+                // search for the combined requested name and system supervariant name
+                // Note: the shader may not support this supervariant, if it doesn't we will
+                // fallback to the requested name below
+                AZStd::string combinedName = supervariantName.GetCStr();
+                combinedName.append(shaderSystemInterface->GetSupervariantName().GetCStr());
+                supervariantIndex = GetSupervariantIndexInternal(AZ::Name(combinedName));
+            }
+
+            if (supervariantIndex == InvalidSupervariantIndex)
+            {
+                // search for the requested name
+                supervariantIndex = GetSupervariantIndexInternal(supervariantName);
             }
-            return InvalidSupervariantIndex;
-        }
 
+            return supervariantIndex;
+        }
 
         Data::Asset<ShaderVariantAsset> ShaderAsset::GetVariant(
             const ShaderVariantId& shaderVariantId, SupervariantIndex supervariantIndex)
@@ -296,6 +307,24 @@ namespace AZ
             return RHI::NullSrgLayout;
         }
 
+        const RHI::Ptr<RHI::ShaderResourceGroupLayout>& ShaderAsset::FindShaderResourceGroupLayout(const Name& shaderResourceGroupName) const
+        {
+            SupervariantIndex supervariantIndex = DefaultSupervariantIndex;
+
+            // check for an RPI ShaderSystem specified supervariant
+            RPI::ShaderSystemInterface* shaderSystemInterface = ShaderSystemInterface::Get();
+            if (shaderSystemInterface && !shaderSystemInterface->GetSupervariantName().IsEmpty())
+            {
+                SupervariantIndex systemSupervariantIndex = GetSupervariantIndexInternal(shaderSystemInterface->GetSupervariantName());
+                if (systemSupervariantIndex.IsValid())
+                {
+                    supervariantIndex = systemSupervariantIndex;
+                }
+            }
+
+            return FindShaderResourceGroupLayout(shaderResourceGroupName, supervariantIndex);
+        }
+
         const RHI::Ptr<RHI::ShaderResourceGroupLayout>& ShaderAsset::FindShaderResourceGroupLayout(
             uint32_t bindingSlot, SupervariantIndex supervariantIndex) const
         {
@@ -319,6 +348,24 @@ namespace AZ
             return RHI::NullSrgLayout;
         }
 
+        const RHI::Ptr<RHI::ShaderResourceGroupLayout>& ShaderAsset::FindShaderResourceGroupLayout(uint32_t bindingSlot) const
+        {
+            SupervariantIndex supervariantIndex = DefaultSupervariantIndex;
+
+            // check for an RPI ShaderSystem specified supervariant
+            RPI::ShaderSystemInterface* shaderSystemInterface = ShaderSystemInterface::Get();
+            if (shaderSystemInterface && !shaderSystemInterface->GetSupervariantName().IsEmpty())
+            {
+                SupervariantIndex systemSupervariantIndex = GetSupervariantIndexInternal(shaderSystemInterface->GetSupervariantName());
+                if (systemSupervariantIndex.IsValid())
+                {
+                    supervariantIndex = systemSupervariantIndex;
+                }
+            }
+
+            return FindShaderResourceGroupLayout(bindingSlot, supervariantIndex);
+        }
+
         const RHI::Ptr<RHI::ShaderResourceGroupLayout>& ShaderAsset::FindFallbackShaderResourceGroupLayout(
             SupervariantIndex supervariantIndex) const
         {
@@ -467,6 +514,20 @@ namespace AZ
             return &supervariants[index];
         }
 
+        SupervariantIndex ShaderAsset::GetSupervariantIndexInternal(AZ::Name supervariantName) const
+        {
+            const auto& supervariants = GetCurrentShaderApiData().m_supervariants;
+            const uint32_t supervariantCount = supervariants.size();
+            for (uint32_t index = 0; index < supervariantCount; ++index)
+            {
+                if (supervariants[index].m_name == supervariantName)
+                {
+                    return SupervariantIndex{ index };
+                }
+            }
+            return InvalidSupervariantIndex;
+        }
+
         bool ShaderAsset::FinalizeAfterLoad()
         {
             // Use the current RHI that is active to select which shader data to use.