Fixed see-through AO with fog in Forward

Author: Chman

PostProcessing/Runtime/Effects/MultiScaleVO.cs

@@ -281,6 +281,7 @@ void RebuildCommandBuffers(PostProcessRenderContext context)
                 context.height
             );
 
+            m_PropertySheet.ClearKeywords();
             m_PropertySheet.properties.SetVector(ShaderIDs.AOColor, Color.white - color);
 
 #if !UNITY_2017_1_OR_NEWER
@@ -526,9 +527,36 @@ public void RenderAfterOpaque(PostProcessRenderContext context)
             var cmd = context.command;
             cmd.BeginSample("Ambient Occlusion");
             DoLazyInitialization(context);
+
+            var sheet = m_PropertySheet;
+
+            // In forward fog is applied at the object level in the grometry pass so we need to
+            // apply it to AO as well or it'll drawn on top of the fog effect.
+            // Not needed in Deferred.
+            if (context.camera.actualRenderingPath == RenderingPath.Forward && RenderSettings.fog)
+            {
+                sheet.properties.SetVector(
+                    ShaderIDs.FogParams,
+                    new Vector3(RenderSettings.fogDensity, RenderSettings.fogStartDistance, RenderSettings.fogEndDistance)
+                );
+
+                switch (RenderSettings.fogMode)
+                {
+                    case FogMode.Linear:
+                        sheet.EnableKeyword("FOG_LINEAR");
+                        break;
+                    case FogMode.Exponential:
+                        sheet.EnableKeyword("FOG_EXP");
+                        break;
+                    case FogMode.ExponentialSquared:
+                        sheet.EnableKeyword("FOG_EXP2");
+                        break;
+                }
+            }
+
             RebuildCommandBuffers(context);
             cmd.SetGlobalTexture(ShaderIDs.MSVOcclusionTexture, m_Result.id);
-            cmd.BlitFullscreenTriangle(context.source, context.destination, m_PropertySheet, (int)Pass.CompositeForward);
+            cmd.BlitFullscreenTriangle(context.source, context.destination, sheet, (int)Pass.CompositeForward);
             cmd.EndSample("Ambient Occlusion");
         }
 

PostProcessing/Runtime/Effects/ScalableAO.cs

@@ -115,7 +115,10 @@ void Render(PostProcessRenderContext context, CommandBuffer cmd, int occlusionSo
             // Not needed in Deferred.
             if (context.camera.actualRenderingPath == RenderingPath.Forward && RenderSettings.fog)
             {
-                sheet.properties.SetVector(ShaderIDs.FogParams, new Vector3(RenderSettings.fogDensity, RenderSettings.fogStartDistance, RenderSettings.fogEndDistance));
+                sheet.properties.SetVector(
+                    ShaderIDs.FogParams,
+                    new Vector3(RenderSettings.fogDensity, RenderSettings.fogStartDistance, RenderSettings.fogEndDistance)
+                );
 
                 switch (RenderSettings.fogMode)
                 {

PostProcessing/Shaders/Builtins/MultiScaleVO.shader

@@ -3,6 +3,7 @@ Shader "Hidden/PostProcessing/MultiScaleVO"
     HLSLINCLUDE
 
         #include "../StdLib.hlsl"
+        #include "Fog.hlsl"
 
         TEXTURE2D_SAMPLER2D(_MSVOcclusionTexture, sampler_MSVOcclusionTexture);
         float3 _AOColor;
@@ -86,15 +87,25 @@ Shader "Hidden/PostProcessing/MultiScaleVO"
         {
             HLSLPROGRAM
 
+                #pragma multi_compile _ FOG_LINEAR FOG_EXP FOG_EXP2
                 #pragma vertex VertDefault
                 #pragma fragment Frag
 
                 TEXTURE2D_SAMPLER2D(_MainTex, sampler_MainTex);
+                TEXTURE2D_SAMPLER2D(_CameraDepthTexture, sampler_CameraDepthTexture);
 
                 float4 Frag(VaryingsDefault i) : SV_Target
                 {
                     float2 texcoord = TransformStereoScreenSpaceTex(i.texcoord, 1);
                     half ao = 1.0 - SAMPLE_TEXTURE2D(_MSVOcclusionTexture, sampler_MSVOcclusionTexture, texcoord).r;
+
+                    // Apply fog when enabled (forward-only)
+                #if (FOG_LINEAR || FOG_EXP || FOG_EXP2)
+                    float d = Linear01Depth(SAMPLE_DEPTH_TEXTURE(_CameraDepthTexture, sampler_CameraDepthTexture, texcoord));
+                    d = ComputeFogDistance(d);
+                    ao *= ComputeFog(d);
+                #endif
+
                     half4 color = SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, texcoord);
                     color.rgb *= 1.0 - ao * _AOColor;
                     return color;