Removed useless shader pass in TAA

First stone for the "keep alpha" mode (needed for AR)

Author: Chman

PostProcessing/Runtime/Effects/TemporalAntialiasing.cs

@@ -30,8 +30,7 @@ public sealed class TemporalAntialiasing
         enum Pass
         {
             SolverDilate,
-            SolverNoDilate,
-            AlphaClear
+            SolverNoDilate
         }
 
         readonly RenderTargetIdentifier[] m_Mrt = new RenderTargetIdentifier[2];
@@ -155,7 +154,7 @@ public void SetProjectionMatrix(Camera camera)
             jitter = new Vector2(jitter.x / camera.pixelWidth, jitter.y / camera.pixelHeight);
         }
 
-        RenderTexture CheckHistory(int id, PostProcessRenderContext context, PropertySheet sheet)
+        RenderTexture CheckHistory(int id, PostProcessRenderContext context)
         {
             var rt = m_HistoryTextures[id];
 
@@ -168,7 +167,7 @@ RenderTexture CheckHistory(int id, PostProcessRenderContext context, PropertyShe
                 rt.filterMode = FilterMode.Bilinear;
                 m_HistoryTextures[id] = rt;
 
-                context.command.BlitFullscreenTriangle(context.source, rt, sheet, (int)Pass.AlphaClear);
+                context.command.BlitFullscreenTriangle(context.source, rt);
             }
             else if (rt.width != context.width || rt.height != context.height)
             {
@@ -194,8 +193,8 @@ internal void Render(PostProcessRenderContext context)
             cmd.BeginSample("TemporalAntialiasing");
 
             int pp = m_HistoryPingPong;
-            var historyRead = CheckHistory(++pp % 2, context, sheet);
-            var historyWrite = CheckHistory(++pp % 2, context, sheet);
+            var historyRead = CheckHistory(++pp % 2, context);
+            var historyWrite = CheckHistory(++pp % 2, context);
             m_HistoryPingPong = ++pp % 2;
 
             const float kMotionAmplification = 100f * 60f;

PostProcessing/Shaders/Builtins/TemporalAntialiasing.shader

@@ -148,12 +148,6 @@ Shader "Hidden/PostProcessing/TemporalAntialiasing"
             return Solve(motion, i.texcoord);
         }
 
-        float4 FragAlphaClear(VaryingsDefault i) : SV_Target
-        {
-            float3 color = SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, i.texcoord).rgb;
-            return float4(color, 0.0);
-        }
-
     ENDHLSL
 
     SubShader
@@ -181,16 +175,5 @@ Shader "Hidden/PostProcessing/TemporalAntialiasing"
 
             ENDHLSL
         }
-
-        // 2: Alpha clear
-        Pass
-        {
-            HLSLPROGRAM
-
-                #pragma vertex VertDefault
-                #pragma fragment FragAlphaClear
-
-            ENDHLSL
-        }
     }
 }