[GFXLIGHT-1755] Make LightBaker use standard radiometric units for its inputs/outputs

Author: yvain-raeymaekers

Packages/com.unity.render-pipelines.core/Editor/PathTracing/BakeInputToWorldConversion.cs

@@ -389,7 +389,7 @@ internal static void ConvertInstancesAndMeshes(
             sceneBounds = new Bounds();
 
             // Extract meshes
-            meshes = new Mesh[bakeInput.meshData.Length];
+            meshes = new Mesh[bakeInput.meshData.Length + bakeInput.terrainData.Length];
             int meshIndex = 0;
             for (int i = 0; i < bakeInput.meshData.Length; i++)
             {

Packages/com.unity.render-pipelines.high-definition/Runtime/Lighting/GlobalIlluminationUtils.cs

@@ -79,16 +79,6 @@ public static bool LightDataGIExtract(Light light, ref LightDataGI lightDataGI)
             lightDataGI.shadow = (byte)(light.shadows != LightShadows.None ? 1 : 0);
 
             LightType lightType = add.legacyLight.type;
-            if (!lightType.IsArea())
-            {
-                // For HDRP we need to divide the analytic light color by PI (HDRP do explicit PI division for Lambert, but built in Unity and the GI don't for punctual lights)
-                // We apply it on both direct and indirect are they are separated, seems that direct is no used if we used mixed mode with indirect or shadowmask bake.
-                lightDataGI.color.intensity /= Mathf.PI;
-                lightDataGI.indirectColor.intensity /= Mathf.PI;
-                directColor.intensity /= Mathf.PI;
-                indirectColor.intensity /= Mathf.PI;
-            }
-
             switch (lightType)
             {
                 case LightType.Directional:

Packages/com.unity.render-pipelines.universal/Runtime/UniversalRenderPipelineCore.cs

@@ -1096,7 +1096,7 @@ public static void InitializeShaderGlobalKeywords()
             ShaderGlobalKeywords._ENABLE_ALPHA_OUTPUT = GlobalKeyword.Create(ShaderKeywordStrings._ENABLE_ALPHA_OUTPUT);
             ShaderGlobalKeywords.ForwardPlus = GlobalKeyword.Create(ShaderKeywordStrings.ForwardPlus); // Backward compatibility. Deprecated in 6.1.
 #if (UNITY_META_QUEST)
-            ShaderGlobalKeywords.META_QUEST_ORTHO_PROJ = GlobalKeyword.Create(ShaderKeywordStrings.META_QUEST_ORTHO_PROJ); 
+            ShaderGlobalKeywords.META_QUEST_ORTHO_PROJ = GlobalKeyword.Create(ShaderKeywordStrings.META_QUEST_ORTHO_PROJ);
             ShaderGlobalKeywords.META_QUEST_LIGHTUNROLL = GlobalKeyword.Create(ShaderKeywordStrings.META_QUEST_LIGHTUNROLL);
 #endif
 
@@ -1434,7 +1434,7 @@ public static class ShaderKeywordStrings
 
 #if (UNITY_META_QUEST)
         /// <summary> Used to statically branch when checking for projection type on Meta Quest device . </summary>
-        internal const string META_QUEST_ORTHO_PROJ = "META_QUEST_ORTHO_PROJ"; 
+        internal const string META_QUEST_ORTHO_PROJ = "META_QUEST_ORTHO_PROJ";
 
         /// <summary> Unroll light loop if there is only one additional light on Meta Quest device . </summary>
         internal const string META_QUEST_LIGHTUNROLL = "META_QUEST_LIGHTUNROLL";
@@ -1607,6 +1607,12 @@ internal static RenderTextureDescriptor CreateRenderTextureDescriptor(Camera cam
         private static Lightmapping.RequestLightsDelegate lightsDelegate = (Light[] requests, NativeArray<LightDataGI> lightsOutput) =>
         {
             LightDataGI lightData = new LightDataGI();
+
+            // URP uses a game like lambertian response for punctual lights, they are off by a factor PI.
+            // Since LightBaker expects its punctual lights to be expressed in standard radiometric units, the intensity is pre-multiplied by PI here to counteract this.
+            // This ensures that the baked punctual light intensity matches realtime intensity. (See GFXLIGHT-1755)
+            const float piCorrection = Mathf.PI;
+
 #if UNITY_EDITOR
             // Always extract lights in the Editor.
             for (int i = 0; i < requests.Length; i++)
@@ -1621,6 +1627,8 @@ internal static RenderTextureDescriptor CreateRenderTextureDescriptor(Camera cam
                     case LightType.Directional:
                         DirectionalLight directionalLight = new DirectionalLight();
                         LightmapperUtils.Extract(light, ref directionalLight);
+                        directionalLight.color.intensity *= piCorrection;
+                        directionalLight.indirectColor.intensity *= piCorrection;
 
                         if (light.cookie != null)
                         {
@@ -1642,11 +1650,15 @@ internal static RenderTextureDescriptor CreateRenderTextureDescriptor(Camera cam
                     case LightType.Point:
                         PointLight pointLight = new PointLight();
                         LightmapperUtils.Extract(light, ref pointLight);
+                        pointLight.color.intensity *= piCorrection;
+                        pointLight.indirectColor.intensity *= piCorrection;
                         lightData.Init(ref pointLight, ref cookie);
                         break;
                     case LightType.Spot:
                         SpotLight spotLight = new SpotLight();
                         LightmapperUtils.Extract(light, ref spotLight);
+                        spotLight.color.intensity *= piCorrection;
+                        spotLight.indirectColor.intensity *= piCorrection;
                         spotLight.innerConeAngle = light.innerSpotAngle * Mathf.Deg2Rad;
                         spotLight.angularFalloff = AngularFalloffType.AnalyticAndInnerAngle;
                         lightData.Init(ref spotLight, ref cookie);
@@ -1692,16 +1704,22 @@ internal static RenderTextureDescriptor CreateRenderTextureDescriptor(Camera cam
                         case LightType.Directional:
                             DirectionalLight directionalLight = new DirectionalLight();
                             LightmapperUtils.Extract(light, ref directionalLight);
+                            directionalLight.color.intensity *= piCorrection;
+                            directionalLight.indirectColor.intensity *= piCorrection;
                             lightData.Init(ref directionalLight);
                             break;
                         case LightType.Point:
                             PointLight pointLight = new PointLight();
                             LightmapperUtils.Extract(light, ref pointLight);
+                            pointLight.color.intensity *= piCorrection;
+                            pointLight.indirectColor.intensity *= piCorrection;
                             lightData.Init(ref pointLight);
                             break;
                         case LightType.Spot:
                             SpotLight spotLight = new SpotLight();
                             LightmapperUtils.Extract(light, ref spotLight);
+                            spotLight.color.intensity *= piCorrection;
+                            spotLight.indirectColor.intensity *= piCorrection;
                             spotLight.innerConeAngle = light.innerSpotAngle * Mathf.Deg2Rad;
                             spotLight.angularFalloff = AngularFalloffType.AnalyticAndInnerAngle;
                             lightData.Init(ref spotLight);