Allow hardware gamma, in theory

code/sdl/sdl_glimp.c

@@ -765,18 +765,12 @@ void GLimp_Init( void )
 	ri.Error( ERR_FATAL, "GLimp_Init() - could not load OpenGL subsystem" );
 
 success:
-	// This values force the UI to disable driver selection
+	// These values force the UI to disable driver selection
 	glConfig.driverType = GLDRV_ICD;
 	glConfig.hardwareType = GLHW_GENERIC;
 
-	// FIXME No SDL_SetGamma in SDL2?
-	/*glConfig.deviceSupportsGamma = SDL_SetGamma( 1.0f, 1.0f, 1.0f ) >= 0;*/
-
-	// Mysteriously, if you use an NVidia graphics card and multiple monitors,
-	// SDL_SetGamma will incorrectly return false... the first time; ask
-	// again and you get the correct answer. This is a suspected driver bug, see
-	// http://bugzilla.icculus.org/show_bug.cgi?id=4316
-	/*glConfig.deviceSupportsGamma = SDL_SetGamma( 1.0f, 1.0f, 1.0f ) >= 0;*/
+	// Only using SDL_SetWindowBrightness to determine if hardware gamma is supported
+	glConfig.deviceSupportsGamma = SDL_SetWindowBrightness( SDL_window, 1.0f ) >= 0;
 
 	if ( -1 == r_ignorehwgamma->integer)
 		glConfig.deviceSupportsGamma = 1;