Add fallback support for graphics backend.

Will choose either GL/Vulkan depending on what the frontend allows.

Makefile

@@ -41,7 +41,7 @@ CORE_DEFINE := -DWANT_PSX_EMU
 TARGET_NAME := mednafen_psx
 
 ifeq ($(HAVE_VULKAN),1)
-   TARGET_NAME := mednafen_psx_vulkan
+   TARGET_NAME := mednafen_psx_hw
 else ifeq ($(HAVE_OPENGL),1)
    TARGET_NAME := mednafen_psx_hw
 endif

libretro.cpp

@@ -2484,13 +2484,14 @@ void retro_init(void)
 
 #ifdef HAVE_RUST
    rsx_intf_init(RSX_EXTERNAL_RUST);
-#elif defined(HAVE_VULKAN)
-   rsx_intf_init(RSX_VULKAN);
-#elif defined(HAVE_OPENGL) || defined(HAVE_OPENGLES)
-   rsx_intf_init(RSX_OPENGL);
-#else
-   rsx_intf_init(RSX_SOFTWARE);
 #endif
+#ifdef HAVE_VULKAN
+   rsx_intf_init(RSX_VULKAN);
+#endif
+#if defined(HAVE_OPENGL) || defined(HAVE_OPENGLES)
+   rsx_intf_init(RSX_OPENGL);
+#endif
+   rsx_intf_init(RSX_SOFTWARE);
 }
 
 void retro_reset(void)
@@ -2528,13 +2529,25 @@ static void check_variables(bool startup)
       if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)
       {
          if (!strcmp(var.value, "software"))
+         {
             rsx_intf_set_type(RSX_SOFTWARE);
+            rsx_intf_set_fallback_type(RSX_SOFTWARE);
+         }
          else if (!strcmp(var.value, "opengl"))
+         {
             rsx_intf_set_type(RSX_OPENGL);
+            rsx_intf_set_fallback_type(RSX_VULKAN);
+         }
          else if (!strcmp(var.value, "vulkan"))
+         {
             rsx_intf_set_type(RSX_VULKAN);
+            rsx_intf_set_fallback_type(RSX_OPENGL);
+         }
          else if (!strcmp(var.value, "opengl-rust"))
+         {
             rsx_intf_set_type(RSX_EXTERNAL_RUST);
+            rsx_intf_set_type(RSX_VULKAN);
+         }
       }
    }
 
@@ -3955,12 +3968,12 @@ void retro_set_controller_port_device(unsigned in_port, unsigned device)
 
 #if defined(HAVE_VULKAN)
 #define FIRST_RENDERER "vulkan"
-#if defined(HAVE_OPENGL)
+#if defined(HAVE_OPENGL) || defined(HAVE_OPENGLES)
 #define EXT_RENDERER "|opengl|software"
 #else
 #define EXT_RENDERER "|software"
 #endif
-#elif defined(HAVE_OPENGL)
+#elif defined(HAVE_OPENGL) || defined(HAVE_OPENGLES)
 #define FIRST_RENDERER "opengl"
 #define EXT_RENDERER "|software"
 #elif defined(HAVE_RUST)

rsx/rsx_intf.cpp

@@ -23,6 +23,8 @@
 static enum rsx_renderer_type rsx_type = 
 #ifdef HAVE_RUST
 RSX_EXTERNAL_RUST
+#elif defined(HAVE_VULKAN)
+RSX_VULKAN
 #elif defined(HAVE_OPENGL) || defined(HAVE_OPENGLES)
 RSX_OPENGL
 #else
@@ -30,6 +32,8 @@ RSX_SOFTWARE
 #endif
 ;
 
+static enum rsx_renderer_type rsx_fallback_type = RSX_SOFTWARE;
+
 void rsx_intf_set_environment(retro_environment_t cb)
 {
    switch (rsx_type)
@@ -141,34 +145,57 @@ void rsx_intf_set_type(enum rsx_renderer_type type)
    rsx_type = type;
 }
 
+void rsx_intf_set_fallback_type(enum rsx_renderer_type type)
+{
+   rsx_fallback_type = type;
+}
+
 bool rsx_intf_open(bool is_pal)
 {
+   bool ret = true;
    switch (rsx_type)
    {
       case RSX_SOFTWARE:
          if (!rsx_soft_open(is_pal))
-            return false;
+            ret = false;
          break;
       case RSX_OPENGL:
 #if defined(HAVE_OPENGL) || defined(HAVE_OPENGLES)
          if (!rsx_gl_open(is_pal))
-            return false;
+            ret = false;
+#else
+         ret = false;
 #endif
          break;
       case RSX_VULKAN:
 #if defined(HAVE_VULKAN)
          if (!rsx_vulkan_open(is_pal))
-            return false;
+            ret = false;
+#else
+         ret = false;
 #endif
          break;
       case RSX_EXTERNAL_RUST:
 #ifdef HAVE_RUST
          if (!rsx_open(is_pal))
-            return false;
+            ret = false;
+#else
+         ret = false;
 #endif
          break;
    }
 
+   if (!ret)
+   {
+      if (rsx_fallback_type == rsx_type) // We're screwed.
+         return false;
+
+      // Try the fallback type.
+      rsx_type = rsx_fallback_type;
+      rsx_fallback_type = RSX_SOFTWARE; // This shouldn't ever fail.
+      return rsx_intf_open(rsx_type);
+   }
+
 #if defined(RSX_DUMP)
    const char *env = getenv("RSX_DUMP");
    if (env)

rsx/rsx_intf.h

@@ -125,6 +125,7 @@ enum blending_modes
 		     uint16_t w, uint16_t h, bool mask_test, bool set_mask);
 
   void rsx_intf_set_type(enum rsx_renderer_type type);
+  void rsx_intf_set_fallback_type(enum rsx_renderer_type type);
 
   enum rsx_renderer_type rsx_intf_is_type(void);
 

rsx/rsx_lib_gl.cpp

@@ -37,8 +37,7 @@ bool rsx_gl_open(bool is_pal)
 {
    VideoClock clock = is_pal ? VideoClock_Pal : VideoClock_Ntsc;
    set_renderer( RetroGl::getInstance(clock) );
-
-   return true;
+   return static_renderer != NULL;
 }
 
 void rsx_gl_close(void)

rustation-libretro/src/retrogl/retrogl.cpp

@@ -3,6 +3,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h> // memcpy()
+#include <stdexcept>
 
 /*
 *
@@ -15,15 +16,19 @@ bool RetroGl::isCreated = false;
 
 RetroGl* RetroGl::getInstance(VideoClock video_clock)
 {
-    static RetroGl *single = NULL;
-    if (single && isCreated)
-    {
-        return single;
-    } else {
-        single = new RetroGl(video_clock);
-        isCreated = true;
-        return single;
-    }
+   static RetroGl *single = NULL;
+   if (single && isCreated)
+   {
+      return single;
+   } else {
+      try {
+         single = new RetroGl(video_clock);
+      } catch (const std::runtime_error &) {
+         return NULL;
+      }
+      isCreated = true;
+      return single;
+   }
 }
 
 RetroGl* RetroGl::getInstance()
@@ -52,7 +57,8 @@ RetroGl::RetroGl(VideoClock video_clock)
 
     if ( !glsm_ctl(GLSM_CTL_STATE_CONTEXT_INIT, &params) ) {
         puts("Failed to init hardware context\n");
-        exit(EXIT_FAILURE);
+        // TODO: Move this out to a init function to avoid exceptions?
+        throw std::runtime_error("Failed to init GLSM context.");
     }
 
     static DrawConfig config = {