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/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)
-            {
-                if (supervariants[index].m_name == supervariantName)
-                {
-                    return SupervariantIndex{index};
-                }
-            }
-            return InvalidSupervariantIndex;
-        }
+            SupervariantIndex supervariantIndex = InvalidSupervariantIndex;
 
+            // check for an RPI ShaderSystem supervariant
+            RPI::ShaderSystemInterface* shaderSystemInterface = ShaderSystemInterface::Get();
+            if (shaderSystemInterface && !shaderSystemInterface->GetSupervariantName().IsEmpty())
+            {
+                // 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 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.