From 5c4cf3d720f8cb2870b5b91baecea391435c6373 Mon Sep 17 00:00:00 2001
From: myT <>
Date: Mon, 15 Apr 2024 04:03:22 +0200
Subject: [PATCH] fixed some motion blur artifacts

fixed:
- sharp moving pixels at screen edges
- static foreground meshes leaving a trail
- static foreground meshes surrounded by sharp moving background pixels
the last 2 items were very noticeable with view weapons

the trade-off is that blurred silhouettes of foreground objects now look worse
---
 code/renderer/shaders/crp/mblur_blur.hlsl | 46 ++++++++++++++---------
 1 file changed, 29 insertions(+), 17 deletions(-)

diff --git a/code/renderer/shaders/crp/mblur_blur.hlsl b/code/renderer/shaders/crp/mblur_blur.hlsl
index 1a7c84a..33262f3 100644
--- a/code/renderer/shaders/crp/mblur_blur.hlsl
+++ b/code/renderer/shaders/crp/mblur_blur.hlsl
@@ -55,23 +55,34 @@ References:
 
 void ProcessSample(
 	inout float4 fgAccum, inout float4 bgAccum, inout float alpha, inout float center,
-	float Zs, float Zc, float Vsl, float Vcl, float distTC, float3 C0s, float3 C1s, float W0d)
+	float Z0s, float Z1s, float Zc, float Vsl, float Vcl, float distTC, float3 C0s, float3 C1s, float W0d)
 {
 	const float DepthThreshold = 0.28; // 10mm assuming 56u == 2m
 
-	if(Zs - DepthThreshold < Zc && Vsl >= distTC)
+	if(Z0s - DepthThreshold < Zc)
 	{
-		fgAccum += float4(C0s, 1) * W0d;
-		bgAccum += float4(C1s, 1);
-		alpha += 1.0;
+		if(Vsl >= distTC)
+		{
+			fgAccum += float4(C0s, 1) * W0d;
+			if(Z1s >= Zc)
+			{
+				bgAccum += float4(C1s, 1);
+			}
+			alpha += 1.0;
+		}
 	}
-	else if(Zs >= Zc && Vcl >= distTC)
+	else if(Z0s + DepthThreshold >= Zc)
 	{
-		bgAccum += float4(C0s, 1);
+		if(Vcl >= distTC)
+		{
+			bgAccum += float4(C0s, 1);
+		}
 	}
 	else
 	{
-		center += 1.0;
+		float bgness = saturate(0.5 * (Zc + DepthThreshold - Z0s) / DepthThreshold);
+		bgAccum += float4(C0s, 1) * bgness;
+		center += 1.0 - bgness;
 	}
 }
 
@@ -170,12 +181,6 @@ float4 ps(VOut input) : SV_Target
 		float2 TC0 = input.texCoords + i0 * tcStep;
 		float2 TC1 = input.texCoords + i1 * tcStep;
 
-		[branch]
-		if(!Is01(TC0) || !Is01(TC1))
-		{
-			continue;
-		}
-
 		uint2 packedSample0 = packedTexture.Load(uint3(TC0 * fullResSize, 0));
 		float2 V0s = UnpackHalf2(packedSample0.x);
 		float V0sl = length(V0s);
@@ -194,10 +199,17 @@ float4 ps(VOut input) : SV_Target
 		float distTC1 = distance(TC1, input.texCoords);
 		float W1d = max(dot(V1sn, dirn), 0.0);
 
-		ProcessSample(fgAccum, bgAccum, alpha, center, Z0s, Zc, V0sl, Vcl, distTC0, C0s, C1s, W0d);
-		ProcessSample(fgAccum, bgAccum, alpha, center, Z1s, Zc, V1sl, Vcl, distTC1, C1s, C0s, W1d);
+		if(Is01(TC0))
+		{
+			ProcessSample(fgAccum, bgAccum, alpha, center, Z0s, Z1s, Zc, V0sl, Vcl, distTC0, C0s, C1s, W0d);
+			realSampleCount++;
+		}
 
-		realSampleCount += 2;
+		if(Is01(TC1))
+		{
+			ProcessSample(fgAccum, bgAccum, alpha, center, Z1s, Z0s, Zc, V1sl, Vcl, distTC1, C1s, C0s, W1d);
+			realSampleCount++;
+		}
 	}
 
 	if(fgAccum.w <= 0.0 || bgAccum.w <= 0.0)