Added supervariantIndex check in Shader::OnShaderVariantAssetReady

Signed-off-by: dmcdiarmid-ly <63674186+dmcdiarmid-ly@users.noreply.github.com>

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

@@ -50,6 +50,7 @@ namespace AZ
             RPI::ShaderVariantStableId GetStableId() const { return m_stableId;  }
 
             const ShaderVariantId& GetShaderVariantId() const { return m_shaderVariantId; }
+            uint32_t GetSupervariantIndex() const;
 
             //! Returns the shader stage function associated with the provided stage enum value.
             const RHI::ShaderStageFunction* GetShaderStageFunction(RHI::ShaderStage shaderStage) const;

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

@@ -253,6 +253,12 @@ namespace AZ
             AZ_Assert(shaderVariantAsset, "Reloaded ShaderVariantAsset is null");
             const ShaderVariantStableId stableId = shaderVariantAsset->GetStableId();
 
+            // check the supervariantIndex of the ShaderVariantAsset to make sure it matches the supervariantIndex of this shader instance
+            if (shaderVariantAsset->GetSupervariantIndex() != m_supervariantIndex.GetIndex())
+            {
+                return;
+            }
+
             // We make a copy of the updated variant because OnShaderVariantReinitialized must not be called inside
             // m_variantCacheMutex or deadlocks may occur.
             // Or if there is an error, we leave this object in its default state to indicate there was an error.

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

@@ -65,6 +65,11 @@ namespace AZ
             return m_buildTimestamp;
         }
 
+        uint32_t ShaderVariantAsset::GetSupervariantIndex() const
+        {
+            return (m_assetId.m_subId >> SupervariantIndexBitPosition) & SupervariantIndexMaxValue;
+        }
+
         const RHI::ShaderStageFunction* ShaderVariantAsset::GetShaderStageFunction(RHI::ShaderStage shaderStage) const
         {
             return m_functionsByStage[static_cast<size_t>(shaderStage)].get();