From c7702913db03cf353e04131b04f7ffd95e9500c1 Mon Sep 17 00:00:00 2001
From: narzoul <narzoul@users.noreply.github.com>
Date: Sun, 14 May 2023 12:44:14 +0200
Subject: [PATCH] Updated gamma conversion formula for Intel GPUs

See issue #216.
---
 DDrawCompat/D3dDdi/ShaderBlitter.cpp | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/DDrawCompat/D3dDdi/ShaderBlitter.cpp b/DDrawCompat/D3dDdi/ShaderBlitter.cpp
index a1db838..6c7c662 100644
--- a/DDrawCompat/D3dDdi/ShaderBlitter.cpp
+++ b/DDrawCompat/D3dDdi/ShaderBlitter.cpp
@@ -62,7 +62,7 @@ namespace
 	{
 		for (UINT i = 0; i < 256; ++i)
 		{
-			ptr[i] = static_cast<BYTE>(ramp[i] * 0xFF / 0xFFFF);
+			ptr[i] = static_cast<BYTE>(ramp[i] / 256);
 		}
 	}
 }
@@ -693,8 +693,7 @@ namespace D3dDdi
 		g_isGammaRampDefault = true;
 		for (WORD i = 0; i < 256 && g_isGammaRampDefault; ++i)
 		{
-			const WORD defaultRamp = i * 0xFFFF / 0xFF;
-			g_isGammaRampDefault = defaultRamp == ramp.Red[i] && defaultRamp == ramp.Green[i] && defaultRamp == ramp.Blue[i];
+			g_isGammaRampDefault = i == ramp.Red[i] / 256 && i == ramp.Green[i] / 256 && i == ramp.Blue[i] / 256;
 		}
 		g_isGammaRampInvalidated = !g_isGammaRampDefault;
 	}