Merge pull request #455 from Unity-Technologies/feature/transparency

Use LOAD_TEXTURE2D to get depth from depth pyramid, fixed roughness t…

ScriptableRenderPipeline/Core/ShaderLibrary/ImageBasedLighting.hlsl

 // approximating the cone of the specular lobe, and then computing the MIP map level
 // which (approximately) covers the footprint of the lobe with a single texel.
 // Improves the perceptual roughness distribution.
-float PerceptualRoughnessToMipmapLevel(float perceptualRoughness)
+float PerceptualRoughnessToMipmapLevel(float perceptualRoughness, uint mipMapCount)
-    return perceptualRoughness * UNITY_SPECCUBE_LOD_STEPS;
+    return perceptualRoughness * mipMapCount;
+}
+
+float PerceptualRoughnessToMipmapLevel(float perceptualRoughness)
+{
+    return PerceptualRoughnessToMipmapLevel(perceptualRoughness, UNITY_SPECCUBE_LOD_STEPS);
 }
 
 // The *accurate* version of the non-linear remapping. It works by

ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/Lit.hlsl

 // Color pyramid (width, height, lodcount, Unused)
 float4 _GaussianPyramidColorMipSize;
 TEXTURE2D(_GaussianPyramidColorTexture);
-SAMPLER2D(sampler_GaussianPyramidColorTexture);
-SAMPLER2D(sampler_PyramidDepthTexture);
+SamplerState ltc_trilinear_clamp_sampler;
 // TODO: This one should be set into a constant Buffer at pass frequency (with _Screensize)
 TEXTURE2D(_PreIntegratedFGD);
 TEXTURE2D_ARRAY(_LtcData); // We pack the 3 Ltc data inside a texture array
     float3 refractedBackPointWS = float3(0.0, 0.0, 0.0);
     float opticalDepth = 0.0;
 
+    uint2 depthSize = uint2(_PyramidDepthMipSize.xy);
+
     // For all refraction approximation, to calculate the refracted point in world space,
     //   we approximate the scene as a plane (back plane) with normal -V at the depth hit point.
     //   (We avoid to raymarch the depth texture to get the refracted point.)
     float3 R = refract(-V, bsdfData.normalWS, 1.0 / bsdfData.ior);
 
     // Get the depth of the approximated back plane
-    float pyramidDepth = SAMPLE_TEXTURE2D_LOD(_PyramidDepthTexture, sampler_PyramidDepthTexture, posInput.positionSS, 2.0).r;
+    float pyramidDepth = LOAD_TEXTURE2D_LOD(_PyramidDepthTexture, posInput.positionSS * (depthSize >> 2), 2).r;
     float depth = LinearEyeDepth(pyramidDepth, _ZBufferParams);
 
     // Distance from point to the back plane
     //  So the light is refracted twice: in and out of the tangent sphere
 
     // Get the depth of the approximated back plane
-    float pyramidDepth = SAMPLE_TEXTURE2D_LOD(_PyramidDepthTexture, sampler_PyramidDepthTexture, posInput.positionSS, 2.0).r;
+    float pyramidDepth = LOAD_TEXTURE2D_LOD(_PyramidDepthTexture, posInput.positionSS * (depthSize >> 2), 2).r;
     float depth = LinearEyeDepth(pyramidDepth, _ZBufferParams);
 
     // Distance from point to the back plane
     float3 R = refract(-V, bsdfData.normalWS, 1.0 / bsdfData.ior);
 
     // Get the depth of the approximated back plane
-    float pyramidDepth = SAMPLE_TEXTURE2D_LOD(_PyramidDepthTexture, sampler_PyramidDepthTexture, posInput.positionSS, 2.0).r;
+    float pyramidDepth = LOAD_TEXTURE2D_LOD(_PyramidDepthTexture, posInput.positionSS * (depthSize >> 2), 2).r;
     float depth = LinearEyeDepth(pyramidDepth, _ZBufferParams);
 
     // Distance from point to the back plane
     // Calculate screen space coordinates of refracted point in back plane
     float4 refractedBackPointCS = mul(_ViewProjMatrix, float4(refractedBackPointWS, 1.0));
     float2 refractedBackPointSS = ComputeScreenSpacePosition(refractedBackPointCS);
-    float refractedBackPointDepth = LinearEyeDepth(SAMPLE_TEXTURE2D_LOD(_PyramidDepthTexture, sampler_PyramidDepthTexture, refractedBackPointSS, 0.0).r, _ZBufferParams);
+    float refractedBackPointDepth = LinearEyeDepth(LOAD_TEXTURE2D_LOD(_PyramidDepthTexture, refractedBackPointSS * depthSize, 0).r, _ZBufferParams);
 
     // Exit if texel is out of color buffer
     // Or if the texel is from an object in front of the object
     {
-        diffuseLighting = SAMPLE_TEXTURE2D_LOD(_GaussianPyramidColorTexture, sampler_GaussianPyramidColorTexture, posInput.positionSS, 0.0).rgb;
+        diffuseLighting = SAMPLE_TEXTURE2D_LOD(_GaussianPyramidColorTexture, ltc_trilinear_clamp_sampler, posInput.positionSS, 0.0).rgb;
-    float mipLevel = PerceptualRoughnessToMipmapLevel(bsdfData.perceptualRoughness);
-    diffuseLighting = SAMPLE_TEXTURE2D_LOD(_GaussianPyramidColorTexture, sampler_GaussianPyramidColorTexture, refractedBackPointSS.xy, mipLevel).rgb;
+    float mipLevel = PerceptualRoughnessToMipmapLevel(bsdfData.perceptualRoughness, uint(_GaussianPyramidColorMipSize.z));
+    diffuseLighting = SAMPLE_TEXTURE2D_LOD(_GaussianPyramidColorTexture, ltc_trilinear_clamp_sampler, refractedBackPointSS, mipLevel).rgb;
 
     // Beer-Lamber law for absorption
     float3 transmittance = exp(-bsdfData.absorptionCoefficient * opticalDepth);
     // Use perfect flat transparency when we cannot fetch the correct pixel color for the refracted point
-    diffuseLighting = SAMPLE_TEXTURE2D_LOD(_GaussianPyramidColorTexture, sampler_GaussianPyramidColorTexture, posInput.positionSS, 0.0).rgb;
+    diffuseLighting = SAMPLE_TEXTURE2D_LOD(_GaussianPyramidColorTexture, ltc_trilinear_clamp_sampler, posInput.positionSS, 0.0).rgb;
 #endif
 }