From 35a151d2cd4a2af8c35d13d9fc581d659e32427c Mon Sep 17 00:00:00 2001
From: helixhorned <helixhorned@1a8010ca-5511-0410-912e-c29ae57300e0>
Date: Thu, 27 Oct 2011 13:14:22 +0000
Subject: [PATCH] Workaround (two, actually) for the hardware gamma bug in
 8-bit fullscreen with ATI cards. From the time of OpenGL initialization,
 gamma lookup in classic/fullscreen will be done in software. Before that,
 always do a setgamma() after setting the palette, since this is what resets
 the HW gamma. However, this may lead to unappealing artifacts with portions
 of the scene being sent to the screen with different gammas.

git-svn-id: https://svn.eduke32.com/eduke32@2085 1a8010ca-5511-0410-912e-c29ae57300e0
---
 polymer/eduke32/build/src/winlayer.c | 33 ++++++++++++++++++++--------
 1 file changed, 24 insertions(+), 9 deletions(-)

diff --git a/polymer/eduke32/build/src/winlayer.c b/polymer/eduke32/build/src/winlayer.c
index 86fbadf2e..29d6b9259 100644
--- a/polymer/eduke32/build/src/winlayer.c
+++ b/polymer/eduke32/build/src/winlayer.c
@@ -40,6 +40,8 @@
 #define ANY_WINDOWED_SIZE
 
 static mutex_t m_initprintf;
+static int32_t winlayer_uselastgamma = -1;
+static int32_t winlayer_have_ATI = 0;
 
 int32_t   _buildargc = 0;
 const char **_buildargv = NULL;
@@ -2160,6 +2162,13 @@ int32_t setpalette(int32_t start, int32_t num)
             return -1;
         }
 
+        if (winlayer_have_ATI)
+        {
+            winlayer_uselastgamma = (winlayer_uselastgamma!=-1);
+            setgamma();
+            winlayer_uselastgamma = 0;
+        }
+
         return 0;
     }
 
@@ -2242,13 +2251,14 @@ static int32_t setgammaramp(WORD gt[3][256])
         IDirectDrawGammaControl_Release(gam);
         return 0;
     }
-    else return 0;
+
+    return 0;
 }
 
 int32_t setgamma(void)
 {
     int32_t i;
-    WORD gammaTable[3][256];
+    static WORD gammaTable[3][256];
     float gamma = max(0.1f,min(4.f,vid_gamma));
     float contrast = max(0.1f,min(3.f,vid_contrast));
     float bright = max(-0.8f,min(0.8f,vid_brightness));
@@ -2258,16 +2268,20 @@ int32_t setgamma(void)
 
     if (!hWindow) return -1;
 
+    if (winlayer_have_ATI && bpp==8 && fullscreen)
+        return -1;
+
     // This formula is taken from Doomsday
 
-    for (i = 0; i < 256; i++)
-    {
-        double val = i * contrast - (contrast - 1) * 127;
-        if (gamma != 1) val = pow(val, invgamma) / norm;
-        val += bright * 128;
+    if (!winlayer_uselastgamma)
+        for (i = 0; i < 256; i++)
+        {
+            double val = i * contrast - (contrast - 1) * 127;
+            if (gamma != 1) val = pow(val, invgamma) / norm;
+            val += bright * 128;
 
-        gammaTable[0][i] = gammaTable[1][i] = gammaTable[2][i] = (WORD)max(0.f,(double)min(0xffff,val*256));
-    }
+            gammaTable[0][i] = gammaTable[1][i] = gammaTable[2][i] = (WORD)max(0.f,(double)min(0xffff,val*256));
+        }
     return setgammaramp(gammaTable);
 }
 
@@ -2886,6 +2900,7 @@ static int32_t SetupOpenGL(int32_t width, int32_t height, int32_t bitspp)
         {
             if (!Bstrcmp(glinfo.vendor,"ATI Technologies Inc."))
             {
+                winlayer_have_ATI = 1;
 #ifdef POLYMER
                 pr_ati_fboworkaround = 1;
                 initprintf("Enabling ATI FBO color attachment workaround.\n");