Merge pull request #83 from Unity-Technologies/Fix-baked-lightmap-rgbm

Fixed baked lightmap so that they are read in RGBM in HDRenderPipeline.

Assets/ScriptableRenderLoop/HDRenderPipeline/Material/MaterialUtilities.hlsl

         #ifdef DIRLIGHTMAP_COMBINED
         bakeDiffuseLighting += SampleDirectionalLightmap(TEXTURE2D_PARAM(unity_Lightmap, samplerunity_Lightmap),
                                                         TEXTURE2D_PARAM(unity_LightmapInd, samplerunity_Lightmap),
-                                                        uvStaticLightmap, unity_LightmapST, normalWS);
+                                                        uvStaticLightmap, unity_LightmapST, normalWS, true);
-        bakeDiffuseLighting += SampleSingleLightmap(TEXTURE2D_PARAM(unity_Lightmap, samplerunity_Lightmap), uvStaticLightmap, unity_LightmapST);
+        bakeDiffuseLighting += SampleSingleLightmap(TEXTURE2D_PARAM(unity_Lightmap, samplerunity_Lightmap), uvStaticLightmap, unity_LightmapST, true);
         #endif
     #endif
 
                                                         TEXTURE2D_PARAM(unity_DynamicDirectionality, samplerunity_DynamicLightmap),
-                                                        uvDynamicLightmap, unity_DynamicLightmapST, normalWS);
+                                                        uvDynamicLightmap, unity_DynamicLightmapST, normalWS, false);
-        bakeDiffuseLighting += SampleSingleLightmap(TEXTURE2D_PARAM(unity_DynamicLightmap, samplerunity_DynamicLightmap), uvDynamicLightmap, unity_DynamicLightmapST);
+        bakeDiffuseLighting += SampleSingleLightmap(TEXTURE2D_PARAM(unity_DynamicLightmap, samplerunity_DynamicLightmap), uvDynamicLightmap, unity_DynamicLightmapST, false);
         #endif
     #endif
 

Assets/ScriptableRenderLoop/ShaderLibrary/EntityLighting.hlsl

 // It is required for other platform that aren't supporting this format to implement variant of these functions
 // (But these kind of platform should use regular render loop and not news shaders).
 
-float3 SampleSingleLightmap(TEXTURE2D_ARGS(lightmapTex, lightmapSampler), float2 uv, float4 transform)
+#define LIGHTMAP_RGBM_RANGE 5.0
+
+// This is temporary. For now baked lightmap are in RGBM and the RGBM range for lightmaps is specific so we can't use the generic method.
+// In the end baked lightmaps are going to be BC6H so the code will be the same as dynamic lightmaps.
+float3 UnpackLightmapRGBM(float4 rgbmInput)
+{
+    return rgbmInput.rgb * rgbmInput.a * LIGHTMAP_RGBM_RANGE;
+}
+
+float3 SampleSingleLightmap(TEXTURE2D_ARGS(lightmapTex, lightmapSampler), float2 uv, float4 transform, bool lightmapRGBM)
-	// Remark: Lightmap is RGB9E5
+    float3 illuminance = float3(0.0, 0.0, 0.0);
+    // Remark: baked lightmap is RGBM for now, dynamic lightmap is RGB9E5
+    if (lightmapRGBM)
+    {
+        illuminance = UnpackLightmapRGBM(SAMPLE_TEXTURE2D(lightmapTex, lightmapSampler, uv).rgba);
+    }
+    else
+    {
+        illuminance = SAMPLE_TEXTURE2D(lightmapTex, lightmapSampler, uv).rgb;
+    }
-float3 SampleDirectionalLightmap(TEXTURE2D_ARGS(lightmapTex, lightmapSampler), TEXTURE2D_ARGS(lightmapDirTex, lightmapDirSampler), float2 uv, float4 transform, float3 normalWS)
+float3 SampleDirectionalLightmap(TEXTURE2D_ARGS(lightmapTex, lightmapSampler), TEXTURE2D_ARGS(lightmapDirTex, lightmapDirSampler), float2 uv, float4 transform, float3 normalWS, bool lightmapRGBM)
 {
 	// In directional mode Enlighten bakes dominant light direction
 	// in a way, that using it for half Lambert and then dividing by a "rebalancing coefficient"
 	uv = uv * transform.xy + transform.zw;
 
 	float4 direction = SAMPLE_TEXTURE2D(lightmapDirTex, lightmapDirSampler, uv);
-	// Remark: Lightmap is RGB9E5
-	float3 illuminance = SAMPLE_TEXTURE2D(lightmapTex, lightmapSampler, uv).rgb;
+	// Remark: baked lightmap is RGBM for now, dynamic lightmap is RGB9E5
+    float3 illuminance = float3(0.0, 0.0, 0.0);
+    if (lightmapRGBM)
+    {
+        illuminance = UnpackLightmapRGBM(SAMPLE_TEXTURE2D(lightmapTex, lightmapSampler, uv).rgba);
+    }
+    else
+    {
+        illuminance = SAMPLE_TEXTURE2D(lightmapTex, lightmapSampler, uv).rgb;
+    }
-#endif // UNITY_ENTITY_LIGHTING_INCLUDED
+#endif // UNITY_ENTITY_LIGHTING_INCLUDED