HDRenderPipeline: Make distance based edge factor (WIP, lot of thing to change)

Assets/ScriptableRenderLoop/HDRenderPipeline/Material/LayeredLit/LayeredLitTessellation.shader

   
         // Tesselation specific
         [Enum(Phong, 0, Displacement, 1, DisplacementPhong, 2)] _TessellationMode("Tessellation mode", Float) = 1
-        _TessellationFactorFixed("Tessellation Factor", Float) = -1.0 // if != -1.0 force fixed factor
+        _TessellationFactorFixed("Tessellation Factor", Float) = 4.0 // if != -1.0 force fixed factor
         _TessellationFactorMaxDistance("Tessellation max distance factor", Float) = 12.0
         _TessellationFactorTriangleSize("Tessellation triangle size", Float) = 20.0
         _TessellationShapeFactor("Tessellation shape factor", Range(0.0, 1.0)) = 0.75 // Only use with Phong

Assets/ScriptableRenderLoop/HDRenderPipeline/Material/Lit/LitTessellation.hlsl

 
 float4 TessellationEdge(float3 p0, float3 p1, float3 p2, float3 n0, float3 n1, float3 n2)
 {
-    if (_TessellationFactorFixed >= 0.0f)
+  //  if (_TessellationFactorFixed >= 0.0f)
-        return  _TessellationFactorFixed.xxxx;
+    //    return  _TessellationFactorFixed.xxxx;
-    return  _TessellationFactorFixed.xxxx;
-
- //   return UnityDistanceBasedTess(input0.positionOS, input1.positionOS, input2.positionOS, minDist, maxDist, 0.5 /* _Tess */, unity_ObjectToWorld, _WorldSpaceCameraPos);
+    return DistanceBasedTess(p0, p1, p2, 0.0, _TessellationFactorMaxDistance, unity_ObjectToWorld, _WorldSpaceCameraPos) *  _TessellationFactorFixed.xxxx;
 }
 
 void Displacement(inout Attributes v)

Assets/ScriptableRenderLoop/HDRenderPipeline/Material/Lit/LitTessellation.shader

 
         // Tessellation specific
         [Enum(Phong, 0, Displacement, 1, DisplacementPhong, 2)] _TessellationMode("Tessellation mode", Float) = 0
-        _TessellationFactorFixed("Tessellation Factor", Float) = -1.0 // if != -1.0 force fixed factor
+        _TessellationFactorFixed("Tessellation Factor", Float) = 4.0 // if != -1.0 force fixed factor
         _TessellationFactorMaxDistance("Tessellation max distance factor", Float) = 12.0
         _TessellationFactorTriangleSize("Tessellation triangle size", Float) = 20.0        
         _TessellationShapeFactor("Tessellation shape factor", Range(0.0, 1.0)) = 0.75 // Only use with Phong

Assets/ScriptableRenderLoop/HDRenderPipeline/Material/Tessellation/TessellationShare.hlsl

     float3 p2 = TransformObjectToWorld(input[2].positionOS);
     float3 n2 = TransformObjectToWorldNormal(input[2].normalOS);
 
-
     float4 tf = TessellationEdge(p0, p1, p2, n0, n1, n2);
 #else
     float4 tf = float4(0.0, 0.0, 0.0, 0.0);

Assets/ScriptableRenderLoop/ShaderLibrary/Tessellation.hlsl

 }
 
 // ---- utility functions
-float UnityCalcDistanceTessFactor(float3 positionOS, float minDist, float maxDist, float tess, float4x4 objectToWorld, float3 cameraPosWS)
+float CalcDistanceTessFactor(float3 positionWS, float minDist, float maxDist, float4x4 objectToWorld, float3 cameraPosWS)
-    float3 positionWS = mul(objectToWorld, float4(positionOS, 1.0)).xyz;
-    float f = clamp(1.0 - (dist - minDist) / (maxDist - minDist), 0.01, 1.0) * tess;
+    float f = clamp(1.0 - (dist - minDist) / (maxDist - minDist), 0.01, 1.0);
     return f;
 }
 
 // Distance based tessellation:
 // Tessellation level is "tess" before "minDist" from camera, and linearly decreases to 1
 // up to "maxDist" from camera.
-float4 UnityDistanceBasedTess(float3 positionOS0, float3 positionOS1, float3 positionOS2, float minDist, float maxDist, float tess, float4x4 objectToWorld, float3 cameraPosWS)
+float4 DistanceBasedTess(float3 p0, float3 p1, float3 p2, float minDist, float maxDist, float4x4 objectToWorld, float3 cameraPosWS)
-    f.x = UnityCalcDistanceTessFactor(positionOS0, minDist, maxDist, tess, objectToWorld, cameraPosWS);
-    f.y = UnityCalcDistanceTessFactor(positionOS1, minDist, maxDist, tess, objectToWorld, cameraPosWS);
-    f.z = UnityCalcDistanceTessFactor(positionOS2, minDist, maxDist, tess, objectToWorld, cameraPosWS);
+    f.x = CalcDistanceTessFactor(p0, minDist, maxDist, objectToWorld, cameraPosWS);
+    f.y = CalcDistanceTessFactor(p1, minDist, maxDist, objectToWorld, cameraPosWS);
+    f.z = CalcDistanceTessFactor(p2, minDist, maxDist, objectToWorld, cameraPosWS);
     return UnityCalcTriEdgeTessFactors(f);
 }