Relocate and enable the reference line light code path

Author: EvgeniiG

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

@@ -801,6 +801,53 @@ void IntegrateGGXAreaRef(   float3 V, float3 positionWS, PreLightData preLightDa
     specularLighting /= float(sampleCount);
 }
 
+//-----------------------------------------------------------------------------
+// EvaluateBSDFLine - Reference
+//-----------------------------------------------------------------------------
+
+void IntegrateBSDFLineRef(float3 V, float3 positionWS, PreLightData preLightData,
+                          LightData lightData, BSDFData bsdfData,
+                          out float3 diffuseLighting, out float3 specularLighting,
+                          int sampleCount = 64)
+{
+    diffuseLighting  = float3(0.0, 0.0, 0.0);
+    specularLighting = float3(0.0, 0.0, 0.0);
+
+    const float  len = lightData.size.x;
+    const float3 p0  = lightData.positionWS - lightData.right * (0.5 * len);
+    const float3 dir = lightData.right;
+    const float  dt  = len * rcp(sampleCount);
+    const float  off = 0.5 * dt;
+
+    // Uniformly sample the line segment with the Pdf = 1 / len.
+    const float invPdf = len;
+
+    for (int i = 0; i < sampleCount; ++i)
+    {
+        // Place the sample in the middle of the interval.
+        float  t     = off + i * dt;
+        float3 sPos  = p0 + t * dir;
+        float3 unL   = sPos - positionWS;
+        float  dist2 = dot(unL, unL);
+        float3 L     = normalize(unL);
+        float  sinLD = length(cross(L, dir));
+        float  NdotL = saturate(dot(bsdfData.normalWS, L));
+
+        float3 lightDiff, lightSpec;
+
+        BSDF(V, L, positionWS, preLightData, bsdfData, lightDiff, lightSpec);
+
+        diffuseLighting  += lightDiff * (sinLD / dist2 * NdotL);
+        specularLighting += lightSpec * (sinLD / dist2 * NdotL);
+    }
+
+    // The factor of 2 is due to the fact: Integral{0, 2 PI}{max(0, cos(x))dx} = 2.
+    float normFactor = 2.0 * invPdf * rcp(sampleCount);
+
+    diffuseLighting  *= normFactor * lightData.diffuseScale  * lightData.color;
+    specularLighting *= normFactor * lightData.specularScale * lightData.color;
+}
+
 //-----------------------------------------------------------------------------
 // EvaluateBSDF_Area
 //-----------------------------------------------------------------------------
@@ -811,7 +858,14 @@ void EvaluateBSDF_Area( LightLoopContext lightLoopContext,
                         out float3 specularLighting)
 {
 #ifdef LIT_DISPLAY_REFERENCE_AREA
-    IntegrateGGXAreaRef(V, positionWS, preLightData, lightData, bsdfData, diffuseLighting, specularLighting);
+    if (lightData.lightType == GPULIGHTTYPE_LINE)
+    {
+        IntegrateBSDFLineRef(V, positionWS, preLightData, lightData, bsdfData, diffuseLighting, specularLighting);
+    }
+    else
+    {
+        IntegrateGGXAreaRef(V, positionWS, preLightData, lightData, bsdfData, diffuseLighting, specularLighting);
+    }
 #else
     // TODO: This could be precomputed
     float halfWidth  = lightData.size.x * 0.5;
@@ -906,53 +960,6 @@ void EvaluateBSDF_Area( LightLoopContext lightLoopContext,
 #endif
 }
 
-//-----------------------------------------------------------------------------
-// EvaluateBSDFLine - Reference
-//-----------------------------------------------------------------------------
-
-void IntegrateBSDFLineRef(float3 V, float3 positionWS, PreLightData preLightData,
-                          LightData lightData, BSDFData bsdfData,
-                          out float3 diffuseLighting, out float3 specularLighting,
-                          int sampleCount = 64)
-{
-    diffuseLighting  = float3(0.0, 0.0, 0.0);
-    specularLighting = float3(0.0, 0.0, 0.0);
-
-    const float  len = lightData.size.x;
-    const float3 p0  = lightData.positionWS - lightData.right * (0.5 * len);
-    const float3 dir = lightData.right;
-    const float  dt  = len * rcp(sampleCount);
-    const float  off = 0.5 * dt;
-
-    // Uniformly sample the line segment with the Pdf = 1 / len.
-    const float invPdf = len;
-
-    for (int i = 0; i < sampleCount; ++i)
-    {
-        // Place the sample in the middle of the interval.
-        float  t     = off + i * dt;
-        float3 sPos  = p0 + t * dir;
-        float3 unL   = sPos - positionWS;
-        float  dist2 = dot(unL, unL);
-        float3 L     = normalize(L);
-        float  sinLD = length(cross(L, dir));
-        float  NdotL = saturate(dot(bsdfData.normalWS, L));
-
-        float3 lightDiff, lightSpec;
-
-        BSDF(V, L, positionWS, preLightData, bsdfData, lightDiff, lightSpec);
-
-        diffuseLighting  += lightDiff * (sinLD / dist2 * NdotL);
-        specularLighting += lightSpec * (sinLD / dist2 * NdotL);
-    }
-
-    // The factor of 2 is due to the fact: Integral{0, 2 PI}{max(0, cos(x))dx} = 2.
-    float normFactor = 2.0 * invPdf * rcp(sampleCount);
-
-    diffuseLighting  *= normFactor * lightData.diffuseScale  * lightData.color;
-    specularLighting *= normFactor * lightData.specularScale * lightData.color;
-}
-
 //-----------------------------------------------------------------------------
 // EvaluateBSDF_Env - Reference
 // ----------------------------------------------------------------------------