Fix metal shader pipeline crashes for LuminanceHistogramGenerator and MorphTargetCS due to the use of atomic operations with typed buffers. Switching them to use Structured buffers. Plus misc cleanup

Gems/Atom/Feature/Common/Assets/Shaders/MorphTargets/MorphTargetCS.shader

@@ -10,7 +10,5 @@
           "type": "Compute"
         }
       ]
-    },
-    "DisabledRHIBackends": ["metal"]
-
+    }
 }

Gems/Atom/Feature/Common/Assets/Shaders/MorphTargets/MorphTargetSRG.azsli

@@ -16,7 +16,7 @@
 
 ShaderResourceGroup MorphTargetPassSrg : SRG_PerPass
 {
-    RWBuffer<int> m_accumulatedDeltas;    
+    RWStruturedBuffer<int> m_accumulatedDeltas;    
 }
 
 // This class represents the data that is passed to the morph target compute shader of an individual delta

Gems/Atom/Feature/Common/Assets/Shaders/PostProcessing/LuminanceHeatmap.azsl

@@ -1,4 +1,4 @@
-/*
+    /*
 * All or portions of this file Copyright (c) Amazon.com, Inc. or its affiliates or
 * its licensors.
 *
@@ -37,7 +37,7 @@ ShaderResourceGroup PassSrg : SRG_PerPass
     Texture2D<float4> m_sceneLuminance;    
     
     // This should be of size NUM_HISTOGRAM_BINS. 
-    Buffer<uint> m_histogram;    
+    StructuredBuffer<uint> m_histogram;
     
     Sampler LinearSampler 
     {

Gems/Atom/Feature/Common/Assets/Shaders/PostProcessing/LuminanceHistogramGenerator.azsl

@@ -20,7 +20,7 @@
 ShaderResourceGroup PassSrg : SRG_PerPass
 {
     Texture2D<float4> m_inputTexture;
-    RWBuffer<uint> m_outputTexture;
+    RWStructuredBuffer<uint> m_outputTexture;
 }
 
 groupshared uint shared_histogramBins[NUM_HISTOGRAM_BINS];

Gems/Atom/Feature/Common/Assets/Shaders/PostProcessing/LuminanceHistogramGenerator.shader

@@ -12,7 +12,5 @@
           "type": "Compute"
         }
       ]
-    },
-    "DisabledRHIBackends": ["metal"]
-
+    }
 }

Gems/Atom/Feature/Common/Assets/Shaders/SkinnedMesh/LinearSkinningPassSRG.azsli

@@ -16,7 +16,7 @@
 
 ShaderResourceGroup PassSrg : SRG_PerPass
 {
-    RWBuffer<float> m_skinnedMeshOutputStream;    
+    RWStructuredBuffer<float> m_skinnedMeshOutputStream;    
 }
 
 ShaderResourceGroup InstanceSrg : SRG_PerDraw

Gems/Atom/Feature/Common/Code/Source/PostProcessing/LuminanceHistogramGeneratorPass.cpp

@@ -72,7 +72,7 @@ namespace AZ
             desc.m_bufferName = AZStd::string::format("LuminanceHistogramBuffer_%s", uuidString.c_str());
             desc.m_elementSize = sizeof(uint32_t);
             desc.m_byteCount = NumHistogramBins * sizeof(uint32_t);
-            desc.m_elementFormat = RHI::Format::R32_UINT;
+            desc.m_elementFormat = RHI::Format::Unknown;
             m_histogram = RPI::BufferSystemInterface::Get()->CreateBufferFromCommonPool(desc);
             AZ_Assert(m_histogram != nullptr, "Unable to allocate buffer");
         }

Gems/Atom/Feature/Common/Code/Source/SkinnedMesh/SkinnedMeshOutputStreamManager.cpp

@@ -67,8 +67,8 @@ namespace AZ
             creator.SetBuffer(nullptr, 0, bufferDescriptor);
 
             RHI::BufferViewDescriptor viewDescriptor;
-            viewDescriptor.m_elementFormat = RHI::Format::R32_FLOAT;
-            viewDescriptor.m_elementSize = RHI::GetFormatSize(viewDescriptor.m_elementFormat);
+            viewDescriptor.m_elementFormat = RHI::Format::Unknown;
+            viewDescriptor.m_elementSize = sizeof(float);
             viewDescriptor.m_elementCount = aznumeric_cast<uint32_t>(m_sizeInBytes) / viewDescriptor.m_elementSize;
             viewDescriptor.m_elementOffset = 0;
             creator.SetBufferViewDescriptor(viewDescriptor);

Gems/Atom/RHI/Code/Include/Atom/RHI/ShaderResourceGroupData.h

@@ -410,7 +410,6 @@ namespace AZ
                 // For any other type the buffer view's element size should match the stride.
                 if (shaderInputBuffer.m_strideSize != bufferViewDescriptor.m_elementSize)
                 {
-                    // [GFX TODO][ATOM-5735][AZSL] ByteAddressBuffer shader input is setting a stride of 16 instead of 4
                     AZ_Error("ShaderResourceGroupData", false, "Buffer Input '%s[%d]': Does not match expected stride size %d",
                         shaderInputBuffer.m_name.GetCStr(), arrayIndex, bufferViewDescriptor.m_elementSize);
                     return false;

Gems/Atom/RHI/DX12/Code/Source/RHI/CommandList.h

@@ -271,6 +271,12 @@ namespace AZ
             ShaderResourceBindings& bindings = GetShaderResourceBindingsByPipelineType(pipelineType);
 
             const PipelineState* pipelineState = static_cast<const PipelineState*>(item.m_pipelineState);
+            if(!pipelineState)
+            {
+                AZ_Assert(false, "Pipeline state not provided");
+                return false;
+            }
+            
             bool updatePipelineState = m_state.m_pipelineState != pipelineState;
             // The pipeline state gets set first.
             if (updatePipelineState)