Merge pull request #27 from EvgeniiG/master

Improvements and fixes for the sky, IBL and area lights

Assets/ScriptableRenderLoop/HDRenderLoop/HDRenderLoop.cs

             //Shader.SetGlobalTexture("_CookieTextures", m_CookieTexArray.GetTexCache());
             //Shader.SetGlobalTexture("_CubeCookieTextures", m_CubeCookieTexArray.GetTexCache());
             Shader.SetGlobalTexture("_EnvTextures", m_CubeReflTexArray.GetTexCache());
-            m_SkyRenderer.SetGlobalSkyTexture();
+
+            if (m_SkyRenderer.IsSkyValid(m_SkyParameters))
+            {
+                m_SkyRenderer.SetGlobalSkyTexture();
+                Shader.SetGlobalInt("_EnvLightSkyEnabled", 1);
+            }
+            else
+            {
+                Shader.SetGlobalInt("_EnvLightSkyEnabled", 0);
+            }
 
             if (debugParameters.useSinglePassLightLoop)
             {

Assets/ScriptableRenderLoop/HDRenderLoop/Lighting/SinglePass/SinglePass.hlsl

     uint _PunctualLightCount;
     uint _AreaLightCount;
     uint _EnvLightCount;
+    int  _EnvLightSkyEnabled;         // TODO: make it a bool
-    float4 _DirShadowSplitSpheres[4]; // TODO share this max between C# and hlsl
+    float4 _DirShadowSplitSpheres[4]; // TODO: share this max between C# and hlsl
 CBUFFER_END
 
 struct LightLoopContext

Assets/ScriptableRenderLoop/HDRenderLoop/Lighting/SinglePass/SinglePassLoop.hlsl

         iblSpecularLighting = lerp(iblSpecularLighting, localSpecularLighting, weight.y);
     }
 
-    // Sky Ibl
+    // Only apply sky IBL if the sky texture is available.
+    if (_EnvLightSkyEnabled)
     {
         float3 localDiffuseLighting, localSpecularLighting;
         float2 weight;

Assets/ScriptableRenderLoop/HDRenderLoop/Material/Lit/Lit.hlsl

     // Aniso
     float TdotV;
     float BdotV;
-    
+
-    // image based lighting
-    // These variables aim to be use with EvaluateBSDF_Env 
-    float3 iblNormalWS; // Normal to be use with image based lighting
-    float3 iblR;        // Reflection vector, same as above.
+    float3 iblDirWS;    // Dominant specular direction, used for IBL in EvaluateBSDF_Env()
 
     float3 specularFGD; // Store preconvole BRDF for both specular and diffuse
     float diffuseFGD;
 
     preLightData.ggxLambdaV = GetSmithJointGGXLambdaV(preLightData.NdotV, bsdfData.roughness);
 
-    float iblNdotV = preLightData.NdotV;
+    float  iblNdotV    = preLightData.NdotV;
     float3 iblNormalWS = bsdfData.normalWS;
 
     // Check if we precompute anisotropy too
         preLightData.anisoGGXLambdaV = GetSmithJointGGXAnisoLambdaV(preLightData.TdotV, preLightData.BdotV, preLightData.NdotV, bsdfData.roughnessT, bsdfData.roughnessB);
         // Tangent = highlight stretch (anisotropy) direction. Bitangent = grain (brush) direction.
         iblNormalWS = GetAnisotropicModifiedNormal(bsdfData.bitangentWS, bsdfData.normalWS, V, bsdfData.anisotropy);
-        
+
         // NOTE: If we follow the theory we should use the modified normal for the different calculation implying a normal (like NDotV) and use iblNormalWS
         // into function like GetSpecularDominantDir(). However modified normal is just a hack. The goal is just to stretch a cubemap, no accuracy here.
         // With this in mind and for performance reasons we chose to only use modified normal to calculate R.
-    // We need to take into account the modified normal for faking anisotropic here.
-    preLightData.iblR = reflect(-V, iblNormalWS);
+
+    // We need to take into account the modified normal for faking anisotropic here.
+    float3 iblR = reflect(-V, iblNormalWS);
+    preLightData.iblDirWS = GetSpecularDominantDir(bsdfData.normalWS, iblR, bsdfData.roughness);
 
     // #if SHADERPASS == SHADERPASS_GBUFFER
     // preLightData.ambientOcclusion = LOAD_TEXTURE2D(_AmbientOcclusion, coord.unPositionSS).x;
 
     float3 unL = positionWS - lightData.positionWS;
 
-    // Pick the axis along which to expand the fade-out sphere into an ellipsoid.
+    // Pick the major axis of the ellipsoid.
-    // We define the ellipsoid s.t. r1 = r, r2 = (r + len / 2).
+    // We define the ellipsoid s.t. r1 = (r + len / 2), r2 = r3 = r.
     // TODO: This could be precomputed.
     float radius         = rsqrt(lightData.invSqrAttenuationRadius);
     float invAspectRatio = radius / (radius + (0.5 * len));
 // EvaluateBSDF_Area - Approximation with Linearly Transformed Cosines
 //-----------------------------------------------------------------------------
 
+// #define ELLIPSOIDAL_ATTENUATION
+
 void EvaluateBSDF_Area(LightLoopContext lightLoopContext,
                        float3 V, float3 positionWS,
                        PreLightData preLightData, LightData lightData, BSDFData bsdfData,
 
     float3 unL = positionWS - lightData.positionWS;
 
-    // Pick the axis along which to expand the fade-out sphere into an ellipsoid.
-    float3 axis = (halfWidth >= halfHeight) ? lightData.right : lightData.up;
+    // Rotate the light direction into the light space.
+    float3x3 lightToWorld = float3x3(lightData.right, lightData.up, lightData.forward);
+    unL = mul(unL, transpose(lightToWorld));
-    // We define the ellipsoid s.t. r1 = r, r2 = (r + |w - h| / 2).
+    // Define the dimensions of the attenuation volume.
-    float radius         = rsqrt(lightData.invSqrAttenuationRadius);
-    float invAspectRatio = radius / (radius + abs(halfWidth - halfHeight));
+    float  radius     = rsqrt(lightData.invSqrAttenuationRadius);
+    float3 invHalfDim = rcp(float3(radius + halfWidth,
+                                   radius + halfHeight,
+                                   radius));
-    float intensity = GetEllipsoidalDistanceAttenuation(unL,  lightData.invSqrAttenuationRadius,
-                                                        axis, invAspectRatio);
+#ifdef ELLIPSOIDAL_ATTENUATION
+    // The attenuation volume is an axis-aligned ellipsoid s.t.
+    // r1 = (r + w / 2), r2 = (r + h / 2), r3 = r.
+    float intensity = GetEllipsoidalDistanceAttenuation(unL, invHalfDim);
+#else
+    // The attenuation volume is an axis-aligned box s.t.
+    // hX = (r + w / 2), hY = (r + h / 2), hZ = r.
+    float intensity = GetBoxDistanceAttenuation(unL, invHalfDim);
+#endif
 
     // Terminate if the shaded point is too far away.
     if (intensity == 0.0) return;
 
     // TODO: test the strech from Tomasz
     // float shrinkedRoughness = AnisotropicStrechAtGrazingAngle(bsdfData.roughness, bsdfData.perceptualRoughness, NdotV);
-    
-    // Note: As explain in GetPreLightData we use normalWS and not iblNormalWS here (in case of anisotropy)
-    float3 rayWS = GetSpecularDominantDir(bsdfData.normalWS, preLightData.iblR, bsdfData.roughness);
-
-    float3 R = rayWS;
-    weight = float2(1.0, 1.0);
-    
-    // In Unity the cubemaps are capture with the localToWorld transform of the component. 
+
+    // In Unity the cubemaps are capture with the localToWorld transform of the component.
-    
+
+    float3 R = preLightData.iblDirWS;
     float3x3 worldToLocal = transpose(float3x3(lightData.right, lightData.up, lightData.forward)); // worldToLocal assume no scaling
     float3 positionLS = positionWS - lightData.positionWS;
     positionLS = mul(positionLS, worldToLocal).xyz - lightData.offsetLS; // We want to calculate the intersection from the center of the bounding box.
-        float3 rayLS = mul(rayWS, worldToLocal);
+        float3 dirLS = mul(preLightData.iblDirWS, worldToLocal);
-        float dist = BoxRayIntersectSimple(positionLS, rayLS, -boxOuterDistance, boxOuterDistance);
+        float dist = BoxRayIntersectSimple(positionLS, dirLS, -boxOuterDistance, boxOuterDistance);
-        R = (positionWS + dist * rayWS) - lightData.positionWS;
-        
+        R = (positionWS + dist * preLightData.iblDirWS) - lightData.positionWS;
+
-    } 
+    }
-        float3 rayLS = mul(rayWS, worldToLocal);
+        float3 dirLS = mul(preLightData.iblDirWS, worldToLocal);
-        float dist = SphereRayIntersectSimple(positionLS, rayLS, sphereOuterDistance);
+        float dist = SphereRayIntersectSimple(positionLS, dirLS, sphereOuterDistance);
-        R = (positionWS + dist * rayWS) - lightData.positionWS;
+        R = (positionWS + dist * preLightData.iblDirWS) - lightData.positionWS;
+    weight.y = 1.0;
+
     if (lightData.envShapeType == ENVSHAPETYPE_SPHERE)
     {
         float distFade = max(length(positionLS) - lightData.innerDistance.x, 0.0);

Assets/ScriptableRenderLoop/HDRenderLoop/Material/Material.hlsl

 #include "GeometricTools.hlsl"
 #include "CommonMaterial.hlsl"
 #include "EntityLighting.hlsl"
+#include "ImageBasedLighting.hlsl"
 
 //-----------------------------------------------------------------------------
 // BuiltinData

Assets/ScriptableRenderLoop/HDRenderLoop/Sky/SkyRenderer.cs

 
         }
 
-        bool IsSkyValid(SkyParameters parameters)
+        public bool IsSkyValid(SkyParameters parameters)
         {
             // Later we will also test shader for procedural skies.
             return parameters.skyHDRI != null;

Assets/ScriptableRenderLoop/ShaderLibrary/CommonLighting.hlsl

 // Light direction is oriented backward (-Z). i.e in shader code, light direction is -lightData.forward
 
 //-----------------------------------------------------------------------------
+// Helper functions
+//-----------------------------------------------------------------------------
+
+// Performs the mapping of the vector 'v' centered within the axis-aligned cube
+// of dimensions [-1, 1]^3 to a vector centered within the sphere of radius 1.
+// The function expects 'v' to be within the cube (possibly unexpected results otherwise).
+// Ref: http://mathproofs.blogspot.com/2005/07/mapping-cube-to-sphere.html
+float3 MapCubeToSphere(float3 v)
+{
+    float3 v2 = v * v;
+    float2 vr3 = v2.xy * rcp(3.0);
+    return v * sqrt((float3)1.0 - 0.5 * v2.yzx - 0.5 * v2.zxy + vr3.yxx * v2.zzy);
+}
+
+// Computes the squared magnitude of the vector computed by MapCubeToSphere().
+float ComputeCubeToSphereMapSqMagnitude(float3 v)
+{
+    float3 v2 = v * v;
+    // Note: dot(v, v) is often computed before this function is called,
+    // so the compiler should optimize and use the precomputed result here.
+    return dot(v, v) - v2.x * v2.y - v2.y * v2.z - v2.z * v2.x + v2.x * v2.y * v2.z;
+}
+
+//-----------------------------------------------------------------------------
 // Attenuation functions
 //-----------------------------------------------------------------------------
 
     return attenuation;
 }
 
-// Applies SmoothDistanceAttenuation() after stretching the fade-out sphere of the given radius
-// into an ellipsoid with the specified aspect ratio and the longest axis.
+// Applies SmoothDistanceAttenuation() after transforming the attenuation ellipsoid into a sphere
+// of the given radius. The process is performed along the major axis of the ellipsoid, and
+// the magnitude of the transformation is controlled by the aspect ratio (the inverse is given).
+// Both the ellipsoid (e.i. 'axis') and 'unL' should be in the same coordinate system.
+// 'unL' should be computed from the center of the ellipsoid.
-    // Project the unnormalized light vector onto the expansion axis.
+    // Project the unnormalized light vector onto the axis.
-    // We want 'unL' to shrink along 'axis' by the aspect ratio. Therefore, we compute
-    // the difference between the length of the original projection and the shrunk one.
-    // It is equivalent to the expansion of the fade-out sphere into an ellipsoid.
-    float scale = projL - projL * invAspectRatio;
-    unL -= scale * axis;
+    // Transform the light vector instead of transforming the ellipsoid.
+    float diff = projL - projL * invAspectRatio;
+    unL -= diff * axis;
+
+    float sqDist = dot(unL, unL);
+    return SmoothDistanceAttenuation(sqDist, invSqrAttenuationRadius);
+}
+
+// Applies SmoothDistanceAttenuation() using the axis-aligned ellipsoid of the given dimensions.
+// Both the ellipsoid and 'unL' should be in the same coordinate system.
+// 'unL' should be computed from the center of the ellipsoid.
+float GetEllipsoidalDistanceAttenuation(float3 unL, float3 invHalfDim)
+{
+    // Transform the light vector so that we can work with
+    // with the ellipsoid as if it was a unit sphere.
+    unL *= invHalfDim;
+
+    float sqDist = dot(unL, unL);
+    return SmoothDistanceAttenuation(sqDist, 1.0);
+}
+
+// Applies SmoothDistanceAttenuation() after mapping the axis-aligned box to a sphere.
+// If the diagonal of the box is 'd', invHalfDim = rcp(0.5 * d).
+// Both the box and 'unL' should be in the same coordinate system.
+// 'unL' should be computed from the center of the box.
+float GetBoxDistanceAttenuation(float3 unL, float3 invHalfDim)
+{
+    // Transform the light vector so that we can work with
+    // with the box as if it was a [-1, 1]^2 cube.
+    unL *= invHalfDim;
-    return SmoothDistanceAttenuation(dot(unL, unL), invSqrAttenuationRadius);
+    // Our algorithm expects the input vector to be within the cube.
+    if (Max3(abs(unL.x), abs(unL.y), abs(unL.z)) > 1.0) return 0.0;
+
+    float sqDist = ComputeCubeToSphereMapSqMagnitude(unL);
+    return SmoothDistanceAttenuation(sqDist, 1.0);
 }
 
 //-----------------------------------------------------------------------------
     tangentY    = float3(b, 1.0f - N.y * N.y * a, -N.y);
 }
 */
-
-//-----------------------------------------------------------------------------
-// various helper
-//-----------------------------------------------------------------------------
-
-// Performs the mapping of the vector 'v' located within the cube of dimensions [-r, r]^3
-// to a vector within the sphere of radius 'r', where r = sqrt(r2).
-// Modified version of http://mathproofs.blogspot.com/2005/07/mapping-cube-to-sphere.html
-float3 MapCubeToSphere(float3 v, float r2)
-{
-    float3 v2 = v * v;
-    float2 vr3 = v2.xy * rcp(3.0 * r2);
-    return v * sqrt((float3)r2 - 0.5 * v2.yzx - 0.5 * v2.zxy + vr3.yxx * v2.zzy);
-}
-
-// Computes the squared magnitude of the vector computed by MapCubeToSphere().
-float ComputeCubeToSphereMapSqMagnitude(float3 v, float r2)
-{
-    float3 v2 = v * v;
-    // Note: dot(v, v) is often computed before this function is called,
-    // so the compiler should optimize and use the precomputed result here.
-    return r2 * dot(v, v) - v2.x * v2.y - v2.y * v2.z - v2.z * v2.x + v2.x * v2.y * v2.z * rcp(r2);
-}
 
 #endif // UNITY_COMMON_LIGHTING_INCLUDED