Merge pull request #730 from Unity-Technologies/Add-GetHDAdditionalData-method

Add GetHDAdditionalLightData method

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Lighting/LightLoop/LightLoop.cs

             directionalLightData.up         = light.light.transform.up    * 2 / Mathf.Max(additionalData.shapeHeight, 0.001f);
             directionalLightData.positionWS = light.light.transform.position;
             directionalLightData.color = GetLightColor(light);
+
+            // Caution: This is bad but if additionalData == defaultHDAdditionalLightData it mean we are trying to promote legacy lights, which is the case for the preview for example, so we need to multiply by PI as legacy Unity do implicit divide by PI for direct intensity.
+            // So we expect that all light with additionalData == defaultHDAdditionalLightData are currently the one from the preview, light in scene MUST have additionalData
+            directionalLightData.color *= (defaultHDAdditionalLightData == additionalData) ? Mathf.PI : 1.0f;
+
             directionalLightData.diffuseScale = additionalData.affectDiffuse ? diffuseDimmer : 0.0f;
             directionalLightData.specularScale = additionalData.affectSpecular ? specularDimmer : 0.0f;
             directionalLightData.shadowIndex = directionalLightData.cookieIndex = -1;
                         var light = cullResults.visibleLights[lightIndex];
 
                         // Light should always have additional data, however preview light right don't have, so we must handle the case by assigning defaultHDAdditionalLightData
-                        var additionalData = light.light.GetComponent<HDAdditionalLightData>();
-                        if (additionalData == null)
-                            additionalData = defaultHDAdditionalLightData;
+                        var additionalData = GetHDAdditionalLightData(light);
 
                         LightCategory lightCategory = LightCategory.Count;
                         GPULightType gpuLightType = GPULightType.Point;
                         m_enableBakeShadowMask = m_enableBakeShadowMask || IsBakedShadowMaskLight(light.light);
 
                         // Light should always have additional data, however preview light right don't have, so we must handle the case by assigning defaultHDAdditionalLightData
-                        var additionalLightData = light.light.GetComponent<HDAdditionalLightData>();
-                        if (additionalLightData == null)
-                            additionalLightData = defaultHDAdditionalLightData;
-
+                        var additionalLightData = GetHDAdditionalLightData(light);
                         var additionalShadowData = light.light.GetComponent<AdditionalShadowData>(); // Can be null
 
                         // Directional rendering side, it is separated as it is always visible so no volume to handle here
                 add.blendDistancePositive = Vector3.one * probe.blendDistance;
                 add.blendDistanceNegative = add.blendDistancePositive;
                 add.influenceShape = ReflectionInfluenceShape.Box;
+            }
+            return add;
+        }
+
+        HDAdditionalLightData GetHDAdditionalLightData(VisibleLight light)
+        {
+            var add = light.light.GetComponent<HDAdditionalLightData>();
+            if (add == null)
+            {
+                add = defaultHDAdditionalLightData;
             }
             return add;
         }