Fixed subtractive mode

ScriptableRenderPipeline/LightweightPipeline/LWRP/ShaderLibrary/Lighting.hlsl

 
 
     // 1) Gives good estimate of illumination as if light would've been shadowed during the bake.
-    //    Preserves bounce and other baked lights
-    //    No shadows on the geometry facing away from the light
+    // We only subtract the main direction light. This is accounted in the contribution term below.
-    half NdotL = saturate(dot(mainLight.direction, normalWS));
-    half3 lambert = mainLight.color * NdotL;
+    half contributionTerm = saturate(dot(mainLight.direction, normalWS)) * (1.0 - _MainLightPosition.w);
+    half3 lambert = mainLight.color * contributionTerm;
     half3 estimatedLightContributionMaskedByInverseOfShadow = lambert * (1.0 - mainLight.attenuation);
     half3 subtractedLightmap = bakedGI - estimatedLightContributionMaskedByInverseOfShadow;
 
 
 void MixRealtimeAndBakedGI(inout Light light, half3 normalWS, inout half3 bakedGI, half4 shadowMask)
 {
-#if defined(_MIXED_LIGHTING_SUBTRACTIVE) && defined(LIGHTMAP_ON) && defined(_SHADOWS_ENABLED)
-    bakedGI = lerp(SubtractDirectMainLightFromLightmap(light, normalWS, bakedGI), bakedGI, _MainLightPosition.w);
+#if defined(_MIXED_LIGHTING_SUBTRACTIVE) && defined(LIGHTMAP_ON)
+    bakedGI = SubtractDirectMainLightFromLightmap(light, normalWS, bakedGI);
 #endif
 
 #if defined(LIGHTMAP_ON)