Precompute '_InvPrimScale' and '_InvTilingScale'

SampleScenes/HDTest/GraphicTest/Parallax Occlusion Mapping/Material/POM - Wood.mat

     - _HorizonFade: 1
     - _IOR: 1
     - _InitialBend: 1
+    - _InvTilingScale: 1
     - _MaterialID: 1
     - _Metallic: 0
     - _Mode: 0
     - _DoubleSidedConstants: {r: 1, g: 1, b: -1, a: 0}
     - _EmissionColor: {r: 0, g: 0, b: 0, a: 1}
     - _EmissiveColor: {r: 0, g: 0, b: 0, a: 1}
+    - _InvPrimScale: {r: 0.1, g: 0.1, b: 0, a: 0}
     - _SpecularColor: {r: 1, g: 1, b: 1, a: 1}
     - _TransmittanceColor: {r: 1, g: 1, b: 1, a: 1}
     - _UVDetailsMappingMask: {r: 1, g: 0, b: 0, a: 0}

SampleScenes/HDTest/GraphicTest/Tessellation/Material/Tessellation - Wood.mat

     - _HorizonFade: 1
     - _IOR: 1
     - _InitialBend: 1
+    - _InvTilingScale: 0.4
     - _MaterialID: 1
     - _Metallic: 0
     - _Mode: 0
     - _DoubleSidedConstants: {r: 1, g: 1, b: -1, a: 0}
     - _EmissionColor: {r: 0, g: 0, b: 0, a: 1}
     - _EmissiveColor: {r: 0, g: 0, b: 0, a: 1}
+    - _InvPrimScale: {r: 1, g: 1, b: 0, a: 0}
     - _SpecularColor: {r: 1, g: 1, b: 1, a: 1}
     - _TransmittanceColor: {r: 1, g: 1, b: 1, a: 1}
     - _UVDetailsMappingMask: {r: 1, g: 0, b: 0, a: 0}

ScriptableRenderPipeline/HDRenderPipeline/Material/LayeredLit/LayeredLit.shader

         _PPDLodThreshold("Start lod to fade out the POM effect", Range(0.0, 16.0)) = 5
         _PPDPrimitiveLength("Primitive length for POM", Float) = 1
         _PPDPrimitiveWidth("Primitive width for POM", Float) = 1
+        [HideInInspector] _InvPrimScale("Inverse primitive scale for non-planar POM", Vector) = (1, 1, 0, 0)
         [ToggleOff] _PerPixelDisplacementObjectScale("Per pixel displacement object scale", Float) = 1.0
         [ToggleOff] _PerPixelDisplacementTilingScale("Per pixel displacement tiling scale", Float) = 1.0
 
         _TexWorldScale1("Tiling", Float) = 1.0
         _TexWorldScale2("Tiling", Float) = 1.0
         _TexWorldScale3("Tiling", Float) = 1.0
+
+        [HideInInspector] _InvTilingScale("Inverse tiling scale = 2 / (abs(_BaseColorMap_ST.x) + abs(_BaseColorMap_ST.y))", Vector) = (1, 1, 1, 1)
 
         [Enum(UV0, 0, UV1, 1, UV2, 2, UV3, 3, Planar, 4, Triplanar, 5)] _UVBase0("UV Set for base0", Float) = 0 // no UV1/2/3 for main layer (matching Lit.shader and for PPDisplacement restriction)
         [Enum(UV0, 0, UV1, 1, UV2, 2, UV3, 3, Planar, 4, Triplanar, 5)] _UVBase1("UV Set for base1", Float) = 0

ScriptableRenderPipeline/HDRenderPipeline/Material/LayeredLit/LayeredLitTessellation.shader

         _PPDLodThreshold("Start lod to fade out the POM effect", Range(0.0, 16.0)) = 5
         _PPDPrimitiveLength("Primitive length for POM", Float) = 1
         _PPDPrimitiveWidth("Primitive width for POM", Float) = 1
+        [HideInInspector] _InvPrimScale("Inverse primitive scale for non-planar POM", Vector) = (1, 1, 0, 0)
         [ToggleOff] _PerPixelDisplacementObjectScale("Per pixel displacement object scale", Float) = 1.0
         [ToggleOff] _PerPixelDisplacementTilingScale("Per pixel displacement tiling scale", Float) = 1.0
 
         _TexWorldScale1("Tiling", Float) = 1.0
         _TexWorldScale2("Tiling", Float) = 1.0
         _TexWorldScale3("Tiling", Float) = 1.0
+
+        [HideInInspector] _InvTilingScale("Inverse tiling scale = 2 / (abs(_BaseColorMap_ST.x) + abs(_BaseColorMap_ST.y))", Vector) = (1, 1, 1, 1)
 
         [Enum(UV0, 0, UV1, 1, UV2, 2, UV3, 3, Planar, 4, Triplanar, 5)] _UVBase0("UV Set for base0", Float) = 0 // no UV1/2/3 for main layer (matching Lit.shader and for PPDisplacement restriction)
         [Enum(UV0, 0, UV1, 1, UV2, 2, UV3, 3, Planar, 4, Triplanar, 5)] _UVBase1("UV Set for base1", Float) = 0

ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/Editor/BaseLitUI.cs

         protected const string kPpdPrimitiveLength = "_PPDPrimitiveLength";
         protected MaterialProperty ppdPrimitiveWidth = null;
         protected const string kPpdPrimitiveWidth = "_PPDPrimitiveWidth";
+        protected MaterialProperty invPrimScale = null;
+        protected const string kInvPrimScale = "_InvPrimScale";
         protected MaterialProperty perPixelDisplacementObjectScale = null;
         protected const string kPerPixelDisplacementObjectScale = "_PerPixelDisplacementObjectScale";
         protected MaterialProperty perPixelDisplacementTilingScale = null;
             ppdLodThreshold = FindProperty(kPpdLodThreshold, props);
             ppdPrimitiveLength = FindProperty(kPpdPrimitiveLength, props);
             ppdPrimitiveWidth  = FindProperty(kPpdPrimitiveWidth, props);
+            invPrimScale = FindProperty(kInvPrimScale, props);
             perPixelDisplacementObjectScale = FindProperty(kPerPixelDisplacementObjectScale, props);            
             perPixelDisplacementTilingScale = FindProperty(kPerPixelDisplacementTilingScale, props);            
 
                 ppdPrimitiveLength.floatValue = Mathf.Max(0.01f, ppdPrimitiveLength.floatValue);
                 m_MaterialEditor.ShaderProperty(ppdPrimitiveWidth, StylesBaseLit.ppdPrimitiveWidth);
                 ppdPrimitiveWidth.floatValue = Mathf.Max(0.01f, ppdPrimitiveWidth.floatValue);
+                invPrimScale.vectorValue = new Vector4(1.0f / ppdPrimitiveLength.floatValue, 1.0f / ppdPrimitiveWidth.floatValue); // Precompute
                 m_MaterialEditor.ShaderProperty(perPixelDisplacementObjectScale, StylesBaseLit.lockWithObjectScaleText);
                 m_MaterialEditor.ShaderProperty(perPixelDisplacementTilingScale, StylesBaseLit.lockWithTilingRateText);
                 m_MaterialEditor.ShaderProperty(depthOffsetEnable, StylesBaseLit.depthOffsetEnableText);                

ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/Editor/LitUI.cs

         protected const string kUVBase = "_UVBase";
         protected MaterialProperty[] TexWorldScale = new MaterialProperty[kMaxLayerCount];
         protected const string kTexWorldScale = "_TexWorldScale";
+        protected MaterialProperty[] InvTilingScale = new MaterialProperty[kMaxLayerCount];
+        protected const string kInvTilingScale = "_InvTilingScale";
         protected MaterialProperty[] UVMappingMask = new MaterialProperty[kMaxLayerCount];
         protected const string kUVMappingMask = "_UVMappingMask";
 
             {
                 UVBase[i] = FindProperty(string.Format("{0}{1}", kUVBase, m_PropertySuffixes[i]), props);
                 TexWorldScale[i] = FindProperty(string.Format("{0}{1}", kTexWorldScale, m_PropertySuffixes[i]), props);
+                InvTilingScale[i] = FindProperty(string.Format("{0}{1}", kInvTilingScale, m_PropertySuffixes[i]), props);
                 UVMappingMask[i] = FindProperty(string.Format("{0}{1}", kUVMappingMask, m_PropertySuffixes[i]), props);
 
                 baseColor[i] = FindProperty(string.Format("{0}{1}", kBaseColor, m_PropertySuffixes[i]), props);
                 m_MaterialEditor.ShaderProperty(TexWorldScale[layerIndex], Styles.texWorldScaleText);
             }
             m_MaterialEditor.TextureScaleOffsetProperty(baseColorMap[layerIndex]);
+
+            // Precompute.
+            InvTilingScale[layerIndex].floatValue = 2 / (Mathf.Abs(baseColorMap[layerIndex].textureScaleAndOffset.x) + Mathf.Abs(baseColorMap[layerIndex].textureScaleAndOffset.y));
 
             EditorGUI.indentLevel--;
             EditorGUILayout.Space();

ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/Lit.shader

 
         [Enum(UV0, 0, Planar, 4, TriPlanar, 5)] _UVBase("UV Set for base", Float) = 0
         _TexWorldScale("Scale to apply on world coordinate", Float) = 1.0
+        [HideInInspector] _InvTilingScale("Inverse tiling scale = 2 / (abs(_BaseColorMap_ST.x) + abs(_BaseColorMap_ST.y))", Float) = 1
         [HideInInspector] _UVMappingMask("_UVMappingMask", Color) = (1, 0, 0, 0)
         [Enum(TangentSpace, 0, ObjectSpace, 1)] _NormalMapSpace("NormalMap space", Float) = 0
 
         _PPDLodThreshold("Start lod to fade out the POM effect", Range(0.0, 16.0)) = 5
         _PPDPrimitiveLength("Primitive length for POM", Float) = 1
         _PPDPrimitiveWidth("Primitive width for POM", Float) = 1
+        [HideInInspector] _InvPrimScale("Inverse primitive scale for non-planar POM", Vector) = (1, 1, 0, 0)
         [ToggleOff] _PerPixelDisplacementObjectScale("Per pixel displacement object scale", Float) = 1.0
         [ToggleOff] _PerPixelDisplacementTilingScale("Per pixel displacement tiling scale", Float) = 1.0
 

ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/LitData.hlsl

 float GetInverseTilingScale()
 {
 #ifdef _PER_PIXEL_DISPLACEMENT_TILING_SCALE
-    return rcp(0.5 * abs(_BaseColorMap_ST.x) + 0.5 * abs(_BaseColorMap_ST.y));                  // TODO: precompute
+    return _InvTilingScale;
 #else
     return 1;
 #endif
         NdotV = viewDirTS.z;
 
         // Transform the view vector into the UV space.
-        float2 invPrimScale = isPlanar ? 1 : rcp(float2(_PPDPrimitiveLength, _PPDPrimitiveWidth));  // TODO: precompute
+        float2 invPrimScale = isPlanar ? 1 : _InvPrimScale.xy;
         float  worldScale   = isPlanar ? _TexWorldScale : 1;
         float2 uvSpaceScale = invPrimScale * _BaseColorMap_ST.xy * (worldScale * maxHeight);
         float3 viewDirUV    = normalize(float3(viewDirTS.xy * uvSpaceScale, viewDirTS.z));

ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/LitProperties.hlsl

 // TODO: Fix the code in legacy unity so we can customize the beahvior for GI
 float3 _EmissionColor;
 
-float _PPDPrimitiveLength;
-float _PPDPrimitiveWidth;
+float4 _InvPrimScale; // Only XY are used
 
 // Wind
 float _InitialBend;
 float4 _SpecularColor;
 
 float _TexWorldScale;
+float _InvTilingScale;
 float4 _UVMappingMask;
 float4 _UVDetailsMappingMask;
 
 
 float _TexWorldScaleBlendMask;
 PROP_DECL(float, _TexWorldScale);
+PROP_DECL(float, _InvTilingScale);
 float4 _UVMappingMaskBlendMask;
 PROP_DECL(float4, _UVMappingMask);
 PROP_DECL(float4, _UVDetailsMappingMask);

ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/LitTessellation.shader

 
         [Enum(UV0, 0, Planar, 4, TriPlanar, 5)] _UVBase("UV Set for base", Float) = 0
         _TexWorldScale("Scale to apply on world coordinate", Float) = 1.0
+        [HideInInspector] _InvTilingScale("Inverse tiling scale = 2 / (abs(_BaseColorMap_ST.x) + abs(_BaseColorMap_ST.y))", Float) = 1
         [HideInInspector] _UVMappingMask("_UVMappingMask", Color) = (1, 0, 0, 0)
         [Enum(TangentSpace, 0, ObjectSpace, 1)] _NormalMapSpace("NormalMap space", Float) = 0
 
         _PPDLodThreshold("Start lod to fade out the POM effect", Range(0.0, 16.0)) = 5
         _PPDPrimitiveLength("Primitive length for POM", Float) = 1
         _PPDPrimitiveWidth("Primitive width for POM", Float) = 1
+        [HideInInspector] _InvPrimScale("Inverse primitive scale for non-planar POM", Vector) = (1, 1, 0, 0)
         [ToggleOff] _PerPixelDisplacementObjectScale("Per pixel displacement object scale", Float) = 1.0
         [ToggleOff] _PerPixelDisplacementTilingScale("Per pixel displacement tiling scale", Float) = 1.0