HDRenderPipeline: Version that work but have a tiling bug. Push for julien

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

     // Change the number of samples per ray depending on the viewing angle for the surface. 
     // Oblique angles require  smaller step sizes to achieve more accurate precision for computing displacement.
     // int numSteps = (int)lerp(_PPPMaxSamples, _PPPMinSamples, viewDirTS.z);
-    int numSteps = (int)lerp(15, 15, viewDirTS.z);
+    int numSteps = (int)lerp(15, 15, viewDirTS.z); // TEMP
 
     ParallaxOcclusionMappingLayer(layerTexCoord, numSteps, viewDirTS);
 
 
     ApplyPerPixelDisplacement(input, V, layerTexCoord);
 
-    float height0 = SampleHeightmap0(LayerTexCoord layerTexCoord);
-    float height1 = SampleHeightmap1(LayerTexCoord layerTexCoord);
-    float height2 = SampleHeightmap2(LayerTexCoord layerTexCoord);
-    float height3 = SampleHeightmap3(LayerTexCoord layerTexCoord);
+    float height0 = SampleHeightmap0(layerTexCoord);
+    float height1 = SampleHeightmap1(layerTexCoord);
+    float height2 = SampleHeightmap2(layerTexCoord);
+    float height3 = SampleHeightmap3(layerTexCoord);
 
     float depthOffset = 0.0;
 #ifdef _DEPTHOFFSET_ON

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

 float ADD_IDX(SampleHeightmap)(LayerTexCoord layerTexCoord)
 {
 #ifdef _HEIGHTMAP
-    return (SAMPLE_TEXTURE2D(ADD_IDX(_HeightMap), ADD_IDX(sampler_HeightMap), ADD_IDX(layerTexCoord.base).uv).r - ADD_IDX(_HeightCenter)) * ADD_IDX(_HeightAmplitude);
+    return (SAMPLE_TEXTURE2D(ADD_IDX(_HeightMap), ADD_ZERO_IDX(sampler_HeightMap), ADD_IDX(layerTexCoord.base).uv).r - ADD_IDX(_HeightCenter)) * ADD_IDX(_HeightAmplitude);
 #else
     return 0.0;
 #endif
     float2 uv = ADD_IDX(layerTexCoord.base).uv;
 
     // Compute lod as we will sample inside a lop (so can't use regular sampling)
-    float lod = CALCULATE_TEXTURE2D_LOD(ADD_IDX(_HeightMap), ADD_IDX(sampler_HeightMap), uv);
+    float lod = CALCULATE_TEXTURE2D_LOD(ADD_IDX(_HeightMap), ADD_ZERO_IDX(sampler_HeightMap), uv);
-    float prevHeight = SAMPLE_TEXTURE2D_LOD(ADD_IDX(_HeightMap), ADD_IDX(sampler_HeightMap), ADD_IDX(layerTexCoord.base).uv + texOffsetCurrent, lod).r * ADD_IDX(_HeightAmplitude);
+    float prevHeight = SAMPLE_TEXTURE2D_LOD(ADD_IDX(_HeightMap), ADD_ZERO_IDX(sampler_HeightMap), uv + texOffsetCurrent, lod).r;
-    float currHeight = SAMPLE_TEXTURE2D_LOD(ADD_IDX(_HeightMap), ADD_IDX(sampler_HeightMap), ADD_IDX(layerTexCoord.base).uv + texOffsetCurrent, lod).r * ADD_IDX(_HeightAmplitude);
+    float currHeight = SAMPLE_TEXTURE2D_LOD(ADD_IDX(_HeightMap), ADD_ZERO_IDX(sampler_HeightMap), uv + texOffsetCurrent, lod).r;
     float rayHeight = 1.0 - stepSize; // Start at top less one sample
 
     // Linear search
         texOffsetCurrent += texOffsetPerStep;
 
         // Sample height map which in this case is stored in the alpha channel of the normal map:
-        currHeight = SAMPLE_TEXTURE2D_LOD(ADD_IDX(_HeightMap), ADD_IDX(sampler_HeightMap), ADD_IDX(layerTexCoord.base).uv + texOffsetCurrent, lod).r * ADD_IDX(_HeightAmplitude);
+        currHeight = SAMPLE_TEXTURE2D_LOD(ADD_IDX(_HeightMap), ADD_ZERO_IDX(sampler_HeightMap), uv + texOffsetCurrent, lod).r;
-    float t0 = rayHeight + stepSize;
-    float t1 = rayHeight; 
-    float delta0 = t0 - prevHeight;
-    float delta1 = t1 - currHeight;
+
+    /*
+    float t0 = rayHeight + stepSize;
+    float t1 = rayHeight; 
+    float delta0 = t0 - prevHeight;
+    float delta1 = t1 - currHeight;
+    */
+        
+    float delta0 = currHeight - rayHeight;
+    float delta1 = (rayHeight + stepSize) - prevHeight;
+    float ratio = delta0 / (delta0 + delta1);
+    float2 offset = (ratio) * (texOffsetCurrent - texOffsetPerStep) + (1.0 - ratio) * texOffsetCurrent; 
+
-    // Apply offset
+    // Apply offset only on base. Details could use another mapping and will not be consistant...
+    // Don't know if this will still ok.
+    // TODO: check with artists
-    ADD_IDX(layerTexCoord.details).uv += offset;    
 }
 
 // Return opacity