Add hack hack_VIUpdateOnCIChange for Quake II.

Quake II uses single buffer mode when underwater, so additional check
gDP.colorImage.changed != 0 is necessary to detect frame change.
This check may cause dummy buffers swaps, so now it is used for Quake II only.

Fixed #592

src/Config.h

@@ -120,6 +120,7 @@ struct Config
 #define hack_legoRacers				(1<<7)  //LEGO racers course map
 #define hack_blastCorps				(1<<8)  //Blast Corps black polygons
 #define hack_ignoreVIHeightChange	(1<<9)  //Do not reset FBO when VI height is changed. Space Invaders need it.
+#define hack_VIUpdateOnCIChange		(1<<10) //Update frame if color buffer changed. Needed for Quake II underwater.
 
 extern Config config;
 

src/RSP.cpp

@@ -330,6 +330,8 @@ void RSP_Init()
 		config.generalEmulation.hacks |= hack_blastCorps;
 	else if (strstr(RSP.romname, (const char *)"SPACE INVADERS") != NULL)
 		config.generalEmulation.hacks |= hack_ignoreVIHeightChange;
+	else if (strstr(RSP.romname, (const char *)"QUAKE II") != NULL)
+		config.generalEmulation.hacks |= hack_VIUpdateOnCIChange;
 
 	api().FindPluginPath(RSP.pluginpath);
 

src/VI.cpp

@@ -110,7 +110,7 @@ void VI_UpdateScreen()
 
 	if (config.frameBufferEmulation.enable) {
 		const bool bCFB = (gDP.changed&CHANGED_CPU_FB_WRITE) == CHANGED_CPU_FB_WRITE;
-		const bool bNeedUpdate = gDP.colorImage.changed != 0 || (bCFB ? true : (*REG.VI_ORIGIN != VI.lastOrigin));
+		const bool bNeedUpdate = (bCFB ? true : (*REG.VI_ORIGIN != VI.lastOrigin)) || ((config.generalEmulation.hacks & hack_VIUpdateOnCIChange) != 0 && gDP.colorImage.changed != 0);
 
 		if (bNeedUpdate) {
 			if (bCFB) {