Merged final pass into uber when no FXAA is used and no custom "after stack" effects are enabled for the frame

Author: Chman

PostProcessing/Runtime/PostProcessLayer.cs

@@ -496,31 +496,31 @@ public void Render(PostProcessRenderContext context)
                 context.destination = finalDestination;
             }
 
+            bool hasBeforeStackEffects = HasActiveEffects(PostProcessEvent.BeforeStack, context);
+            bool hasAfterStackEffects = HasActiveEffects(PostProcessEvent.AfterStack, context) && !breakBeforeColorGrading;
+            bool needsFinalPass = (hasAfterStackEffects || antialiasingMode == Antialiasing.FastApproximateAntialiasing) && !breakBeforeColorGrading;
+
             // Right before the builtin stack
-            lastTarget = RenderInjectionPoint(PostProcessEvent.BeforeStack, context, "BeforeStack", lastTarget);
+            if (hasBeforeStackEffects)
+                lastTarget = RenderInjectionPoint(PostProcessEvent.BeforeStack, context, "BeforeStack", lastTarget);
 
             // Builtin stack
-            lastTarget = RenderBuiltins(context, lastTarget);
+            lastTarget = RenderBuiltins(context, !needsFinalPass, lastTarget);
 
             // After the builtin stack but before the final pass (before FXAA & Dithering)
-            if (!breakBeforeColorGrading)
+            if (hasAfterStackEffects)
                 lastTarget = RenderInjectionPoint(PostProcessEvent.AfterStack, context, "AfterStack", lastTarget);
 
             // And close with the final pass
-            RenderFinalPass(context, lastTarget);
+            if (needsFinalPass)
+                RenderFinalPass(context, lastTarget);
 
             TextureLerper.instance.EndFrame();
             m_SettingsUpdateNeeded = true;
         }
 
         int RenderInjectionPoint(PostProcessEvent evt, PostProcessRenderContext context, string marker, int releaseTargetAfterUse = -1)
         {
-            // Make sure we have active effects in this injection point, skip it otherwise
-            bool hasActiveEffects = HasActiveEffects(evt, context);
-
-            if (!hasActiveEffects)
-                return releaseTargetAfterUse;
-
             int tempTarget = m_TargetPool.Get();
             var finalDestination = context.destination;
 
@@ -595,7 +595,7 @@ void RenderList(List<SerializedBundleRef> list, PostProcessRenderContext context
             cmd.EndSample(marker);
         }
 
-        int RenderBuiltins(PostProcessRenderContext context, int releaseTargetAfterUse = -1)
+        int RenderBuiltins(PostProcessRenderContext context, bool isFinalPass, int releaseTargetAfterUse = -1)
         {
             var uberSheet = context.propertySheets.Get(context.resources.shaders.uber);
             uberSheet.ClearKeywords();
@@ -606,11 +606,16 @@ int RenderBuiltins(PostProcessRenderContext context, int releaseTargetAfterUse =
             var cmd = context.command;
             cmd.BeginSample("BuiltinStack");
 
-            // Render to an intermediate target as this won't be the final pass
-            int tempTarget = m_TargetPool.Get();
-            cmd.GetTemporaryRT(tempTarget, context.width, context.height, 24, FilterMode.Bilinear, context.sourceFormat);
+            int tempTarget = -1;
             var finalDestination = context.destination;
-            context.destination = tempTarget;
+
+            if (!isFinalPass)
+            {
+                // Render to an intermediate target as this won't be the final pass
+                tempTarget = m_TargetPool.Get();
+                cmd.GetTemporaryRT(tempTarget, context.width, context.height, 24, FilterMode.Bilinear, context.sourceFormat);
+                context.destination = tempTarget;
+            }
 
             // Depth of field final combination pass used to be done in Uber which led to artifacts
             // when used at the same time as Bloom (because both effects used the same source, so
@@ -636,7 +641,13 @@ int RenderBuiltins(PostProcessRenderContext context, int releaseTargetAfterUse =
 
             if (!breakBeforeColorGrading)
                 RenderEffect<ColorGrading>(context);
-            
+
+            if (isFinalPass)
+            {
+                uberSheet.EnableKeyword("FINALPASS");
+                dithering.Render(context);
+            }
+
             cmd.BlitFullscreenTriangle(context.source, context.destination, uberSheet, 0);
 
             context.source = context.destination;

PostProcessing/Shaders/Builtins/Dithering.hlsl

@@ -0,0 +1,23 @@
+#ifndef UNITY_POSTFX_DITHERING
+#define UNITY_POSTFX_DITHERING
+
+TEXTURE2D_SAMPLER2D(_DitheringTex, sampler_DitheringTex);
+float4 _Dithering_Coords;
+
+float3 Dither(float3 color, float2 uv)
+{
+    // Final pass dithering
+    // Symmetric triangular distribution on [-1,1] with maximal density at 0
+    float noise = SAMPLE_TEXTURE2D(_DitheringTex, sampler_DitheringTex, uv * _Dithering_Coords.xy + _Dithering_Coords.zw).a * 2.0 - 1.0;
+    noise = FastSign(noise) * (1.0 - sqrt(1.0 - abs(noise)));
+
+#if UNITY_COLORSPACE_GAMMA
+    color += noise / 255.0;
+#else
+    color = SRGBToLinear(LinearToSRGB(color) + noise / 255.0);
+#endif
+
+    return color;
+}
+
+#endif // UNITY_POSTFX_DITHERING

PostProcessing/Shaders/Builtins/Dithering.hlsl.meta

@@ -6,6 +6,7 @@ Shader "Hidden/PostProcessing/FinalPass"
         #pragma multi_compile __ FXAA FXAA_LOW
         #include "../StdLib.hlsl"
         #include "../Colors.hlsl"
+        #include "Dithering.hlsl"
 
         // PS3 and XBOX360 aren't supported in Unity anymore, only use the PC variant
         #define FXAA_PC 1
@@ -30,10 +31,6 @@ Shader "Hidden/PostProcessing/FinalPass"
         TEXTURE2D_SAMPLER2D(_MainTex, sampler_MainTex);
         float4 _MainTex_TexelSize;
 
-        // Dithering
-        TEXTURE2D_SAMPLER2D(_DitheringTex, sampler_DitheringTex);
-        float4 _Dithering_Coords;
-
         float4 Frag(VaryingsDefault i) : SV_Target
         {
             half4 color = 0.0;
@@ -75,19 +72,7 @@ Shader "Hidden/PostProcessing/FinalPass"
             }
             #endif
 
-            {
-                // Final dithering
-                // Symmetric triangular distribution on [-1,1] with maximal density at 0
-                float noise = SAMPLE_TEXTURE2D(_DitheringTex, sampler_DitheringTex, i.texcoord * _Dithering_Coords.xy + _Dithering_Coords.zw).a * 2.0 - 1.0;
-                noise = FastSign(noise) * (1.0 - sqrt(1.0 - abs(noise)));
-
-                #if UNITY_COLORSPACE_GAMMA
-                    color.rgb += noise / 255.0;
-                #else
-                    color.rgb = SRGBToLinear(LinearToSRGB(color.rgb) + noise / 255.0);
-                #endif
-            }
-
+            color.rgb = Dither(color.rgb, i.texcoord);
             return float4(color.rgb, 1.0);
         }
 

PostProcessing/Shaders/Builtins/FinalPass.shader

@@ -10,10 +10,12 @@ Shader "Hidden/PostProcessing/Uber"
         #pragma multi_compile __ COLOR_GRADING_LDR COLOR_GRADING_HDR
         #pragma multi_compile __ VIGNETTE
         #pragma multi_compile __ GRAIN
+        #pragma multi_compile __ FINALPASS
 
         #include "../StdLib.hlsl"
         #include "../Colors.hlsl"
         #include "../Sampling.hlsl"
+        #include "Dithering.hlsl"
 
         #define MAX_CHROMATIC_SAMPLES 16
 
@@ -191,10 +193,21 @@ Shader "Hidden/PostProcessing/Uber"
             }
             #endif
 
-            // Put saturated luma in alpha for FXAA - higher quality than "green as luma" and
-            // necessary as RGB values will potentially still be HDR for the FXAA pass
-            half luma = Luminance(saturate(color));
-            half4 output = half4(color, luma);
+            half4 output;
+
+            #if FINALPASS
+            {
+                color.rgb = Dither(color.rgb, i.texcoord);
+                output = half4(color, 1.0);
+            }
+            #else
+            {
+                // Put saturated luma in alpha for FXAA - higher quality than "green as luma" and
+                // necessary as RGB values will potentially still be HDR for the FXAA pass
+                half luma = Luminance(saturate(color));
+                output = half4(color, luma);
+            }
+            #endif
 
             #if UNITY_COLORSPACE_GAMMA
             {
@@ -203,7 +216,6 @@ Shader "Hidden/PostProcessing/Uber"
             #endif
 
             // Output RGB is still HDR at that point (unless range was crunched by a tonemapper)
-            // Alpha is luminance of saturate(rgb)
             return output;
         }