Update code to allow Macro matrix to work after PR feedback

com.unity.render-pipelines.core/CoreRP/ShaderLibrary/UnityInstancing.hlsl

         #endif
     UNITY_INSTANCING_BUFFER_END(unity_Builtins2)
 
+
-    #define UNITY_MATRIX_M     UNITY_ACCESS_INSTANCED_PROP(unity_Builtins0, unity_ObjectToWorldArray)
+    #ifdef OVERRIDE_PRE_CAMERA_TRANSLATION_TO_MATRIX
+    #define UNITY_MATRIX_M  ApplyPreCameraTranslationToMatrix(UNITY_ACCESS_INSTANCED_PROP(unity_Builtins0, unity_ObjectToWorldArray))
+    #else
+    #define UNITY_MATRIX_M  UNITY_ACCESS_INSTANCED_PROP(unity_Builtins0, unity_ObjectToWorldArray)
+    #endif
-    #define UNITY_MATRIX_I_M     UNITY_ACCESS_INSTANCED_PROP(MERGE_UNITY_BUILTINS_INDEX(UNITY_WORLDTOOBJECTARRAY_CB), unity_WorldToObjectArray)
+    #ifdef OVERRIDE_PRE_CAMERA_TRANSLATION_TO_MATRIX
+    #define UNITY_MATRIX_I_M    ApplyPreCameraTranslationToInverseMatrix(UNITY_ACCESS_INSTANCED_PROP(MERGE_UNITY_BUILTINS_INDEX(UNITY_WORLDTOOBJECTARRAY_CB), unity_WorldToObjectArray))
+    #else
+    #define UNITY_MATRIX_I_M    UNITY_ACCESS_INSTANCED_PROP(MERGE_UNITY_BUILTINS_INDEX(UNITY_WORLDTOOBJECTARRAY_CB), unity_WorldToObjectArray)
+    #endif
 
 #else // UNITY_INSTANCING_ENABLED
 

com.unity.render-pipelines.high-definition/HDRP/Material/Lit/LitDataMeshModification.hlsl

 
 #ifdef _VERTEX_WIND
     // current wind implementation is in absolute world space
-    float3 rootWP = GetObjectPositionWS();
+    float3 rootWP = GetObjectAbsolutePositionWS();
     float3 absolutePositionWS = GetAbsolutePositionWS(positionWS);
     ApplyWindDisplacement(absolutePositionWS, normalWS, rootWP, _Stiffness, _Drag, _ShiverDrag, _ShiverDirectionality, _InitialBend, input.color.a, time);
     positionWS = GetCameraRelativePositionWS(absolutePositionWS);

com.unity.render-pipelines.high-definition/HDRP/ShaderPass/ShaderPassVelocity.hlsl

 
 float3 TransformPreviousObjectToWorld(float3 positionOS)
 {
-    float4x4 modelMatrix = unity_MatrixPreviousM;
-    // To handle camera relative rendering we substract the camera position in the model matrix
-    // User must not use UNITY_MATRIX_M directly, unless they understand what they do
-#if (SHADEROPTIONS_CAMERA_RELATIVE_RENDERING != 0)
-    modelMatrix._m03_m13_m23 -= _WorldSpaceCameraPos;
-#endif
-
-    return mul(modelMatrix, float4(positionOS, 1.0)).xyz;
+    float4x4 previousModelMatrix = ApplyCameraTranslationToMatrix(unity_MatrixPreviousM);
+    return mul(previousModelMatrix, float4(positionOS, 1.0)).xyz;
 }
 
 void VelocityPositionZBias(VaryingsToPS input)

com.unity.render-pipelines.high-definition/HDRP/ShaderVariables.hlsl

     return M;
 }
 
+// Helper to handle camera relative space
+
+float4x4 ApplyCameraTranslationToMatrix(float4x4 modelMatrix)
+{
+    // To handle camera relative rendering we substract the camera position in the model matrix
+    // User must not use UNITY_MATRIX_M directly, unless they understand what they do
+#if (SHADEROPTIONS_CAMERA_RELATIVE_RENDERING != 0)
+    modelMatrix._m03_m13_m23 -= _WorldSpaceCameraPos;
+#endif
+    return modelMatrix;
+}
+
+float4x4 ApplyCameraTranslationToInverseMatrix(float4x4 inverseModelMatrix)
+{
+#if (SHADEROPTIONS_CAMERA_RELATIVE_RENDERING != 0)
+    // To handle camera relative rendering we need to apply translation before converting to object space
+    float4x4 translationMatrix = { { 1.0, 0.0, 0.0, _WorldSpaceCameraPos.x },{ 0.0, 1.0, 0.0, _WorldSpaceCameraPos.y },{ 0.0, 0.0, 1.0, _WorldSpaceCameraPos.z },{ 0.0, 0.0, 0.0, 1.0 } };
+    return mul(inverseModelMatrix, translationMatrix);
+#else
+    return inverseModelMatrix;
+#endif
+}
+
 #ifdef USE_LEGACY_UNITY_MATRIX_VARIABLES
     #include "ShaderVariablesMatrixDefsLegacyUnity.hlsl"
 #else
+
+// This define allow to tell to unity instancing that we will use our camera relative functions (ApplyCameraTranslationToMatrix and  ApplyCameraTranslationToInverseMatrix) for the model view matrix
+#define MODIFY_MATRIX_FOR_CAMERA_RELATIVE_RENDERING
 #include "CoreRP/ShaderLibrary/UnityInstancing.hlsl"
 #include "ShaderVariablesFunctions.hlsl"
 

com.unity.render-pipelines.high-definition/HDRP/ShaderVariablesFunctions.hlsl

 #ifndef UNITY_SHADER_VARIABLES_FUNCTIONS_INCLUDED
 #define UNITY_SHADER_VARIABLES_FUNCTIONS_INCLUDED
 
+// This function always return the absolute position in WS either the CameraRelative mode is enabled or not
+float3 GetAbsolutePositionWS(float3 positionWS)
+{
+#if (SHADEROPTIONS_CAMERA_RELATIVE_RENDERING != 0)
+    positionWS += _WorldSpaceCameraPos;
+#endif
+    return positionWS;
+}
+
+// This function always return the camera relative position in WS either the CameraRelative mode is enabled or not
+float3 GetCameraRelativePositionWS(float3 positionWS)
+{
+#if (SHADEROPTIONS_CAMERA_RELATIVE_RENDERING != 0)
+    positionWS -= _WorldSpaceCameraPos;
+#endif
+    return positionWS;
+}
+
-// Return world position of current object
-float3 GetObjectPositionWS()
+// Return absolute world position of current object
+float3 GetObjectAbsolutePositionWS()
-    return modelMatrix._m03_m13_m23; // Translation object to world
+    return GetAbsolutePositionWS(modelMatrix._m03_m13_m23); // Translation object to world
-    float4x4 modelMatrix = UNITY_MATRIX_M;
-    // To handle camera relative rendering we substract the camera position in the model matrix
-    // User must not use UNITY_MATRIX_M directly, unless they understand what they do
-#if (SHADEROPTIONS_CAMERA_RELATIVE_RENDERING != 0)
-    modelMatrix._m03_m13_m23 -= _WorldSpaceCameraPos;
-#endif
-    return modelMatrix;
+    return UNITY_MATRIX_M;
-#if (SHADEROPTIONS_CAMERA_RELATIVE_RENDERING != 0)
-    // To handle camera relative rendering we need to apply translation before converting to object space
-    float4x4 modelMatrix = { {1.0, 0.0, 0.0, _WorldSpaceCameraPos.x}, { 0.0, 1.0, 0.0, _WorldSpaceCameraPos.y }, { 0.0, 0.0, 1.0, _WorldSpaceCameraPos.z }, { 0.0, 0.0, 0.0, 1.0 } };
-    return mul(UNITY_MATRIX_I_M, modelMatrix);
-#else
-#endif
 }
 
 // Transform to homogenous clip space
 float3 TransformViewToHClipDir(float3 directionVS)
 {
     return mul((float3x3)GetViewToHClipMatrix(), directionVS);
-}
-
-// This function always return the absolute position in WS either the CameraRelative mode is enabled or not
-float3 GetAbsolutePositionWS(float3 positionWS)
-{
-#if (SHADEROPTIONS_CAMERA_RELATIVE_RENDERING != 0)
-    positionWS += _WorldSpaceCameraPos;
-#endif
-    return positionWS;
-}
-
-// This function always return the camera relative position in WS either the CameraRelative mode is enabled or not
-float3 GetCameraRelativePositionWS(float3 positionWS)
-{
-#if (SHADEROPTIONS_CAMERA_RELATIVE_RENDERING != 0)
-    positionWS -= _WorldSpaceCameraPos;
-#endif
-    return positionWS;
 }
 
 float3 GetPrimaryCameraPosition()

com.unity.render-pipelines.high-definition/HDRP/ShaderVariablesMatrixDefsHDCamera.hlsl

 #ifndef UNITY_SHADER_VARIABLES_MATRIX_DEFS_HDCAMERA_INCLUDED
 #define UNITY_SHADER_VARIABLES_MATRIX_DEFS_HDCAMERA_INCLUDED
 
+#define UNITY_MATRIX_M     ApplyCameraTranslationToMatrix(unity_ObjectToWorld)
+#define UNITY_MATRIX_I_M   ApplyCameraTranslationToInverseMatrix(unity_WorldToObject)
+
-#define UNITY_MATRIX_M     unity_ObjectToWorld
-#define UNITY_MATRIX_I_M   unity_WorldToObject
 #define UNITY_MATRIX_V     _ViewMatrixStereo[unity_StereoEyeIndex]
 #define UNITY_MATRIX_I_V   _InvViewMatrixStereo[unity_StereoEyeIndex]
 #define UNITY_MATRIX_P     OptimizeProjectionMatrix(unity_StereoMatrixP[unity_StereoEyeIndex])
 
 #else
 
-#define UNITY_MATRIX_M     unity_ObjectToWorld
-#define UNITY_MATRIX_I_M   unity_WorldToObject
 #define UNITY_MATRIX_V     _ViewMatrix
 #define UNITY_MATRIX_I_V   _InvViewMatrix
 #define UNITY_MATRIX_P     OptimizeProjectionMatrix(_ProjMatrix)

com.unity.render-pipelines.high-definition/HDRP/ShaderVariablesMatrixDefsLegacyUnity.hlsl

 #ifndef UNITY_SHADER_VARIABLES_MATRIX_DEFS_LEGACY_UNITY_INCLUDED
 #define UNITY_SHADER_VARIABLES_MATRIX_DEFS_LEGACY_UNITY_INCLUDED
 
-#define UNITY_MATRIX_M     unity_ObjectToWorld
-#define UNITY_MATRIX_I_M   unity_WorldToObject
+#define UNITY_MATRIX_M     ApplyCameraTranslationToMatrix(unity_ObjectToWorld)
+#define UNITY_MATRIX_I_M   ApplyCameraTranslationToInverseMatrix(unity_WorldToObject)
 #define UNITY_MATRIX_V     unity_MatrixV
 #define UNITY_MATRIX_I_V   unity_MatrixInvV
 #define UNITY_MATRIX_P     OptimizeProjectionMatrix(glstate_matrix_projection)