HDRenderPipeline: Add worldViewFrustrum cull to tesselation

Assets/ScriptableRenderLoop/HDRenderPipeline/Material/Lit/Editor/LitUI.cs

             {
                 EditorGUI.indentLevel++;
                 m_MaterialEditor.ShaderProperty(heightAmplitude, Styles.heightMapAmplitudeText);
+                heightAmplitude.floatValue = Math.Max(0.0f, heightAmplitude.floatValue); // Must be positive
                 m_MaterialEditor.ShaderProperty(heightCenter, Styles.heightMapCenterText);
                 EditorGUI.showMixedValue = false;
                 EditorGUI.indentLevel--;

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

 float4 TessellationEdge(float3 p0, float3 p1, float3 p2, float3 n0, float3 n1, float3 n2)
 {
+    float maxDisplacement = ADD_ZERO_IDX(_HeightAmplitude);
+#ifdef _LAYER_COUNT
+    maxDisplacement = max(maxDisplacement, _HeightAmplitude1);
+    #if _LAYER_COUNT >= 3
+    maxDisplacement = max(maxDisplacement, _HeightAmplitude2);
+    #endif
+    #if _LAYER_COUNT >= 4
+    maxDisplacement = max(maxDisplacement, _HeightAmplitude3);
+#endif
+#endif
+
+    bool frustumCulled = WorldViewFrustumCull(p0, p1, p2, maxDisplacement, (float4[4])unity_CameraWorldClipPlanes);
+        
+    bool faceCull = false;
-        if (BackFaceCullTriangle(p0, p1, p2, _TessellationBackFaceCullEpsilon, _WorldSpaceCameraPos))
-        {
-            return float4(0.0, 0.0, 0.0, 0.0);
-        }
+        faceCull = BackFaceCullTriangle(p0, p1, p2, _TessellationBackFaceCullEpsilon, _WorldSpaceCameraPos);
+    }
+
+    if (frustumCulled || faceCull)
+    {
+        // Settings factor to 0 will kill the triangle
+        return float4(0.0, 0.0, 0.0, 0.0);
-    // Aaptive tessellation
+    // Aaptive screen space tessellation
     if (_TessellationFactorTriangleSize > 0.0)
     {
         // return a value between 0 and 1
+    // Distance based tessellation
     if (_TessellationFactorMaxDistance > 0.0)
     {
         tessFactor *= GetDistanceBasedTessFactor(p0, p1, p2, _WorldSpaceCameraPos, _TessellationFactorMinDistance, _TessellationFactorMaxDistance);

Assets/ScriptableRenderLoop/ShaderLibrary/Tessellation.hlsl

 #define TESSELLATION_INTERPOLATE_BARY(name, bary) ouput.name = input0.name * bary.x +  input1.name * bary.y +  input2.name * bary.z
 
+// TODO: Move in geomtry.hlsl
 float3 ProjectPointOnPlane(float3 position, float3 planePosition, float3 planeNormal)
 {
     return position - (dot(position - planePosition, planeNormal) * planeNormal);
     return tess;
 }
 
-/*
-float UnityDistanceFromPlane(float3 pos, float4 plane)
+// TODO: Move in geomtry.hlsl
+float DistanceFromPlane(float3 pos, float4 plane)
 {
     float d = dot(float4(pos, 1.0f), plane);
     return d;
 // cullEps is distance outside of frustum that is still considered to be inside (i.e. max displacement)
-bool UnityWorldViewFrustumCull(float3 wpos0, float3 wpos1, float3 wpos2, float cullEps)
+bool WorldViewFrustumCull(float3 p0, float3 p1, float3 p2, float cullEps, float4 cameraWorldClipPlanes[4])
-    planeTest.x = ((UnityDistanceFromPlane(wpos0, unity_CameraWorldClipPlanes[0]) > -cullEps) ? 1.0f : 0.0f) +
-        ((UnityDistanceFromPlane(wpos1, unity_CameraWorldClipPlanes[0]) > -cullEps) ? 1.0f : 0.0f) +
-        ((UnityDistanceFromPlane(wpos2, unity_CameraWorldClipPlanes[0]) > -cullEps) ? 1.0f : 0.0f);
-    // right
-    planeTest.y = ((UnityDistanceFromPlane(wpos0, unity_CameraWorldClipPlanes[1]) > -cullEps) ? 1.0f : 0.0f) +
-        ((UnityDistanceFromPlane(wpos1, unity_CameraWorldClipPlanes[1]) > -cullEps) ? 1.0f : 0.0f) +
-        ((UnityDistanceFromPlane(wpos2, unity_CameraWorldClipPlanes[1]) > -cullEps) ? 1.0f : 0.0f);
-    // top
-    planeTest.z = ((UnityDistanceFromPlane(wpos0, unity_CameraWorldClipPlanes[2]) > -cullEps) ? 1.0f : 0.0f) +
-        ((UnityDistanceFromPlane(wpos1, unity_CameraWorldClipPlanes[2]) > -cullEps) ? 1.0f : 0.0f) +
-        ((UnityDistanceFromPlane(wpos2, unity_CameraWorldClipPlanes[2]) > -cullEps) ? 1.0f : 0.0f);
-    // bottom
-    planeTest.w = ((UnityDistanceFromPlane(wpos0, unity_CameraWorldClipPlanes[3]) > -cullEps) ? 1.0f : 0.0f) +
-        ((UnityDistanceFromPlane(wpos1, unity_CameraWorldClipPlanes[3]) > -cullEps) ? 1.0f : 0.0f) +
-        ((UnityDistanceFromPlane(wpos2, unity_CameraWorldClipPlanes[3]) > -cullEps) ? 1.0f : 0.0f);
+    planeTest.x =   ((DistanceFromPlane(p0, cameraWorldClipPlanes[0]) > -cullEps) ? 1.0f : 0.0f) +
+                    ((DistanceFromPlane(p1, cameraWorldClipPlanes[0]) > -cullEps) ? 1.0f : 0.0f) +
+                    ((DistanceFromPlane(p2, cameraWorldClipPlanes[0]) > -cullEps) ? 1.0f : 0.0f);
+    // right                                   
+    planeTest.y =   ((DistanceFromPlane(p0, cameraWorldClipPlanes[1]) > -cullEps) ? 1.0f : 0.0f) +
+                    ((DistanceFromPlane(p1, cameraWorldClipPlanes[1]) > -cullEps) ? 1.0f : 0.0f) +
+                    ((DistanceFromPlane(p2, cameraWorldClipPlanes[1]) > -cullEps) ? 1.0f : 0.0f);
+    // top                                     
+    planeTest.z =   ((DistanceFromPlane(p0, cameraWorldClipPlanes[2]) > -cullEps) ? 1.0f : 0.0f) +
+                    ((DistanceFromPlane(p1, cameraWorldClipPlanes[2]) > -cullEps) ? 1.0f : 0.0f) +
+                    ((DistanceFromPlane(p2, cameraWorldClipPlanes[2]) > -cullEps) ? 1.0f : 0.0f);
+    // bottom                                  
+    planeTest.w =   ((DistanceFromPlane(p0, cameraWorldClipPlanes[3]) > -cullEps) ? 1.0f : 0.0f) +
+                    ((DistanceFromPlane(p1, cameraWorldClipPlanes[3]) > -cullEps) ? 1.0f : 0.0f) +
+                    ((DistanceFromPlane(p2, cameraWorldClipPlanes[3]) > -cullEps) ? 1.0f : 0.0f);
-*/