From a02057425ab4b40b0d14e8a9d542da5c4440e92d Mon Sep 17 00:00:00 2001
From: myT <>
Date: Tue, 1 Oct 2024 18:15:24 +0200
Subject: [PATCH] tweaked GRP fog curve to match the original better

---
 code/renderer/shaders/grp/fog.hlsli        | 10 ++++++++++
 code/renderer/shaders/grp/fog_inside.hlsl  |  3 ++-
 code/renderer/shaders/grp/fog_outside.hlsl |  3 ++-
 3 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/code/renderer/shaders/grp/fog.hlsli b/code/renderer/shaders/grp/fog.hlsli
index 6b9bb08..951d603 100644
--- a/code/renderer/shaders/grp/fog.hlsli
+++ b/code/renderer/shaders/grp/fog.hlsli
@@ -64,4 +64,14 @@ cbuffer RootConstants
 
 Texture2D depthTexture : register(t0);
 
+float FogOpacityFromDistance01(float x)
+{
+	if(x >= 1.0)
+	{
+		return 1.0;
+	}
+
+	return 1.0 - exp2(-10.0 * x);
+}
+
 #endif
diff --git a/code/renderer/shaders/grp/fog_inside.hlsl b/code/renderer/shaders/grp/fog_inside.hlsl
index cdc62cd..e6736fa 100644
--- a/code/renderer/shaders/grp/fog_inside.hlsl
+++ b/code/renderer/shaders/grp/fog_inside.hlsl
@@ -33,7 +33,8 @@ float4 ps(VOut input) : SV_Target
 	float depthBuff = LinearDepth(zwDepth, input.proj2232.x, input.proj2232.y);
 	float depthFrag = input.depthVS;
 	float depth = min(depthBuff, depthFrag);
-	float fogOpacity = saturate(depth / colorDepth.w);
+	float distance01 = saturate(depth / colorDepth.w);
+	float fogOpacity = FogOpacityFromDistance01(distance01);
 
 	return float4(colorDepth.rgb, fogOpacity);
 
diff --git a/code/renderer/shaders/grp/fog_outside.hlsl b/code/renderer/shaders/grp/fog_outside.hlsl
index b0c1222..f2e1476 100644
--- a/code/renderer/shaders/grp/fog_outside.hlsl
+++ b/code/renderer/shaders/grp/fog_outside.hlsl
@@ -37,7 +37,8 @@ float4 ps(VOut input) : SV_Target
 		discard;
 	}
 
-	float fogOpacity = saturate((depthBuff - depthFrag) / colorDepth.w);
+	float distance01 = saturate((depthBuff - depthFrag) / colorDepth.w);
+	float fogOpacity = FogOpacityFromDistance01(distance01);
 
 	return float4(colorDepth.rgb, fogOpacity);