Rework SDL2 render driver selection.

The "direct3d" DX9 driver is no longer skipped by default.
There is a new --renderer=VALUE option to attempt to use the named
SDL2 render driver if present and compatible.

sc2/src/libs/graphics/gfx_common.h

@@ -63,7 +63,8 @@ extern int GfxFlags;
 
 // The following functions are driver-defined
 void TFB_PreInit (void);
-int TFB_InitGraphics (int driver, int flags, int width, int height);
+int TFB_InitGraphics (int driver, int flags, const char *renderer,
+		int width, int height);
 int TFB_ReInitGraphics (int driver, int flags, int width, int height);
 void TFB_UninitGraphics (void);
 void TFB_ProcessEvents (void);

sc2/src/libs/graphics/sdl/pure.c

@@ -237,7 +237,7 @@ TFB_Pure_ConfigureVideo (int driver, int flags, int width, int height, int toggl
 }
 
 int
-TFB_Pure_InitGraphics (int driver, int flags, int width, int height)
+TFB_Pure_InitGraphics (int driver, int flags, const char *renderer, int width, int height)
 {
 	char VideoName[256];
 
@@ -245,10 +245,12 @@ TFB_Pure_InitGraphics (int driver, int flags, int width, int height)
 
 	SDL_VideoDriverName (VideoName, sizeof (VideoName));
 	log_add (log_Info, "SDL driver used: %s", VideoName);
-			// Set the environment variable SDL_VIDEODRIVER to override
+	(void) renderer;
-			// For Linux: x11 (default), dga, fbcon, directfb, svgalib,
+	// The "renderer" argument is ignored by SDL1. To control how SDL1
-			//            ggi, aalib
+	// gets its pixmap, set the environment variable SDL_VIDEODRIVER.
-			// For Windows: directx (default), windib
+	// For Linux:   x11 (default), dga, fbcon, directfb, svgalib,
+	//              ggi, aalib
+	// For Windows: directx (default), windib
 
 	log_add (log_Info, "SDL initialized.");
 	log_add (log_Info, "Initializing Screen.");

sc2/src/libs/graphics/sdl/pure.h

@@ -21,7 +21,7 @@
 
 #include "libs/graphics/sdl/sdl_common.h"
 
-int TFB_Pure_InitGraphics (int driver, int flags, int width, int height);
+int TFB_Pure_InitGraphics (int driver, int flags, const char *renderer, int width, int height);
 void TFB_Pure_UninitGraphics (void);
 int TFB_Pure_ConfigureVideo (int driver, int flags, int width, int height, int togglefullscreen);
 void Scale_PerfTest (void);

sc2/src/libs/graphics/sdl/sdl2_pure.c

@@ -34,6 +34,7 @@ static TFB_SDL2_SCREENINFO SDL2_Screens[TFB_GFX_NUMSCREENS];
 
 static SDL_Window *window = NULL;
 static SDL_Renderer *renderer = NULL;
+static const char *rendererBackend = NULL;
 
 static int ScreenFilterMode;
 
@@ -99,26 +100,26 @@ static int
 FindBestRenderDriver (void)
 {
 	int i, n;
+	if (!rendererBackend) {
+		/* If the user has no preference, just let SDL2 choose */
+		return -1;
+	}
 	n = SDL_GetNumRenderDrivers ();
+	log_add (log_Info, "Searching for render driver \"%s\".", rendererBackend);
+
 	for (i = 0; i < n; i++) {
 		SDL_RendererInfo info;
 		if (SDL_GetRenderDriverInfo (i, &info) < 0) {
 			continue;
 		}
-		if (!strcmp(info.name, "direct3d")) {
+		if (!strcmp(info.name, rendererBackend)) {
-			/* The 32-bit Windows 8+ Intel Integrated Graphics
-			 * driver has a common bug that causes the D3D9
-			 * display to crash with a divide-by-zero error.
-			 * If we have any alternatives, we will ask for
-			 * them instead. */
-			continue;
-		}
-		if (info.flags & SDL_RENDERER_ACCELERATED) {
 			return i;
 		}
+		log_add (log_Info, "Skipping render driver \"%s\"", info.name);
 	}
 	/* We did not find any accelerated drivers that weren't D3D9.
 	 * Return -1 to ask SDL2 to do its best. */
+	log_add (log_Info, "Render driver \"%s\" not available, using system default", rendererBackend);
 	return -1;
 }
 
@@ -265,7 +266,7 @@ TFB_Pure_ConfigureVideo (int driver, int flags, int width, int height, int toggl
 }
 
 int
-TFB_Pure_InitGraphics (int driver, int flags, int width, int height)
+TFB_Pure_InitGraphics (int driver, int flags, const char *renderer, int width, int height)
 {
 	log_add (log_Info, "Initializing SDL.");
 	log_add (log_Info, "SDL initialized.");
@@ -273,6 +274,7 @@ TFB_Pure_InitGraphics (int driver, int flags, int width, int height)
 
 	ScreenWidth = 320;
 	ScreenHeight = 240;
+	rendererBackend = renderer;
 
 	if (TFB_Pure_ConfigureVideo (driver, flags, width, height, 0))
 	{

sc2/src/libs/graphics/sdl/sdl_common.c

@@ -51,7 +51,7 @@ volatile int QuitPosted = 0;
 volatile int GameActive = 1; // Track the SDL_ACTIVEEVENT state SDL_APPACTIVE
 
 int
-TFB_InitGraphics (int driver, int flags, int width, int height)
+TFB_InitGraphics (int driver, int flags, const char *renderer, int width, int height)
 {
 	int result, i;
 	char caption[200];
@@ -72,12 +72,12 @@ TFB_InitGraphics (int driver, int flags, int width, int height)
 		driver = TFB_GFXDRIVER_SDL_PURE;
 		log_add (log_Warning, "OpenGL support not compiled in,"
 				" so using pure SDL driver");
-		result = TFB_Pure_InitGraphics (driver, flags, width, height);
+		result = TFB_Pure_InitGraphics (driver, flags, renderer, width, height);
 #endif
 	}
 	else
 	{
-		result = TFB_Pure_InitGraphics (driver, flags, width, height);
+		result = TFB_Pure_InitGraphics (driver, flags, renderer, width, height);
 	}
 
 #if SDL_MAJOR_VERSION == 1

sc2/src/uqm.c

@@ -102,6 +102,8 @@ struct options_struct
 	const char **addons;
 	int numAddons;
 
+	const char *graphicsBackend;
+	
 	// Commandline and user config options
 	DECL_CONFIG_OPTION(bool, opengl);
 	DECL_CONFIG_OPTION2(int, resolution, width, height);
@@ -236,6 +238,7 @@ main (int argc, char *argv[])
 		/* .addonDir = */           NULL,
 		/* .addons = */             NULL,
 		/* .numAddons = */          0,
+		/* .graphicsBackend = */     NULL,
 
 		INIT_CONFIG_OPTION(  opengl,            false ),
 		INIT_CONFIG_OPTION2( resolution,        640, 480 ),
@@ -419,8 +422,8 @@ main (int argc, char *argv[])
 		gfxFlags |= TFB_GFXFLAGS_SCANLINES;
 	if (options.showFps.value)
 		gfxFlags |= TFB_GFXFLAGS_SHOWFPS;
-	TFB_InitGraphics (gfxDriver, gfxFlags, options.resolution.width,
+	TFB_InitGraphics (gfxDriver, gfxFlags, options.graphicsBackend,
-			options.resolution.height);
+			options.resolution.width, options.resolution.height);
 	if (options.gamma.set && setGammaCorrection (options.gamma.value))
 		optGamma = options.gamma.value;
 	else
@@ -709,6 +712,7 @@ enum
 	ADDONDIR_OPT,
 	ACCEL_OPT,
 	SAFEMODE_OPT,
+	RENDERER_OPT,
 #ifdef NETPLAY
 	NETHOST1_OPT,
 	NETPORT1_OPT,
@@ -756,6 +760,7 @@ static struct option longOptions[] =
 	{"addondir", 1, NULL, ADDONDIR_OPT},
 	{"accel", 1, NULL, ACCEL_OPT},
 	{"safe", 0, NULL, SAFEMODE_OPT},
+	{"renderer", 1, NULL, RENDERER_OPT},
 #ifdef NETPLAY
 	{"nethost1", 1, NULL, NETHOST1_OPT},
 	{"netport1", 1, NULL, NETPORT1_OPT},
@@ -1050,6 +1055,9 @@ parseOptions (int argc, char *argv[], struct options_struct *options)
 			case SAFEMODE_OPT:
 				setBoolOption (&options->safeMode, true);
 				break;
+			case RENDERER_OPT:
+				options->graphicsBackend = optarg;
+				break;
 #ifdef NETPLAY
 			case NETHOST1_OPT:
 				netplayOptions.peer[0].isServer = false;
@@ -1208,6 +1216,8 @@ usage (FILE *out, const struct options_struct *defaults)
 			"may be specified multiple times)");
 	log_add (log_User, "  --addondir=ADDONDIR (directory where addons "
 			"reside)");
+	log_add (log_User, "  --renderer=name (Select named rendering engine "
+			"if possible)");
 	log_add (log_User, "  --sound=DRIVER (openal, mixsdl, none; default "
 			"mixsdl)");
 	log_add (log_User, "  --stereosfx (enables positional sound effects, "