Add SDL 3 support to ref_gl4.

This is mostly a port of the same changes to ref_gl3:

* Add SDL 3 support to the Makefile.
* Port API changes.
* Bump renderer API to version 7.

Makefile

@@ -44,6 +44,9 @@ WITH_OPENAL:=yes
 # or libopenal.so. Not supported on Windows.
 WITH_RPATH:=yes
 
+# Builds with SDL 3 instead of SDL 2.
+WITH_SDL3:=no
+
 # Enable systemwide installation of game assets.
 WITH_SYSTEMWIDE:=no
 
@@ -262,7 +265,12 @@ endif
 # ----------
 
 # Extra CFLAGS for SDL.
+ifeq ($(WITH_SDL3),yes)
+SDLCFLAGS := $(shell pkgconf --cflags sdl3)
+SDLCFLAGS += -DUSE_SDL3
+else
 SDLCFLAGS := $(shell sdl2-config --cflags)
+endif
 
 # ----------
 
@@ -339,11 +347,19 @@ endif
 # ----------
 
 # Extra LDFLAGS for SDL
+ifeq ($(WITH_SDL3),yes)
+ifeq ($(YQ2_OSTYPE), Darwin)
+SDLLDFLAGS := -lSDL3
+else
+SDLLDFLAGS := $(shell pkgconf --libs sdl3)
+endif
+else
 ifeq ($(YQ2_OSTYPE), Darwin)
 SDLLDFLAGS := -lSDL2
-else # not Darwin
+else
 SDLLDFLAGS := $(shell sdl2-config --libs)
-endif # Darwin
+endif
+endif
 
 # The renderer libs don't need libSDL2main, libmingw32 or -mwindows.
 ifeq ($(YQ2_OSTYPE), Windows)

src/client/refresh/gl4/gl4_main.c

@@ -1981,6 +1981,7 @@ GetRefAPI(refimport_t imp)
 	ri = imp;
 
 	re.api_version = API_VERSION;
+	re.framework_version = GL4_GetSDLVersion();
 
 	re.Init = GL4_Init;
 	re.Shutdown = GL4_Shutdown;

src/client/refresh/gl4/gl4_sdl.c

@@ -29,7 +29,11 @@
 
 #include "header/local.h"
 
+#ifdef USE_SDL3
+#include <SDL3/SDL.h>
+#else
 #include <SDL2/SDL.h>
+#endif
 
 static SDL_Window* window = NULL;
 static SDL_GLContext context = NULL;
@@ -162,7 +166,20 @@ void GL4_SetVsync(void)
 		}
 	}
 
+#ifdef USE_SDL3
+	int vsyncState;
+       if (SDL_GL_GetSwapInterval(&vsyncState) != 0)
+       {
+               R_Printf(PRINT_ALL, "Failed to get vsync state, assuming vsync inactive.\n");
+               vsyncActive = false;
+       }
+       else
+       {
+               vsyncActive = vsyncState ? true : false;
+       }
+#else
 	vsyncActive = SDL_GL_GetSwapInterval() != 0;
+#endif
 }
 
 /*
@@ -345,9 +362,9 @@ int GL4_InitContext(void* win)
 
 	// Load GL pointrs through GLAD and check context.
 #ifdef YQ2_GL3_GLES
-	if( !gladLoadGLES2Loader(SDL_GL_GetProcAddress))
+	if( !gladLoadGLES2Loader((void *)SDL_GL_GetProcAddress))
 #else // Desktop GL
-	if( !gladLoadGLLoader(SDL_GL_GetProcAddress))
+	if( !gladLoadGLLoader((void *)SDL_GL_GetProcAddress))
 #endif
 	{
 		R_Printf(PRINT_ALL, "GL4_InitContext(): ERROR: loading OpenGL function pointers failed!\n");
@@ -406,7 +423,11 @@ int GL4_InitContext(void* win)
 #if SDL_VERSION_ATLEAST(2, 26, 0)
 	// Figure out if we are high dpi aware.
 	int flags = SDL_GetWindowFlags(win);
+#ifdef USE_SDL3
+	IsHighDPIaware = (flags & SDL_WINDOW_HIGH_PIXEL_DENSITY) ? true : false;
+#else
 	IsHighDPIaware = (flags & SDL_WINDOW_ALLOW_HIGHDPI) ? true : false;
+#endif
 #endif
 
 	return true;
@@ -417,7 +438,11 @@ int GL4_InitContext(void* win)
  */
 void GL4_GetDrawableSize(int* width, int* height)
 {
+#ifdef USE_SDL3
+	SDL_GetWindowSizeInPixels(window, width, height);
+#else
 	SDL_GL_GetDrawableSize(window, width, height);
+#endif
 }
 
 /*
@@ -434,3 +459,21 @@ void GL4_ShutdownContext()
 		}
 	}
 }
+
+/*
+ * Returns the SDL major version. Implemented
+ * here to not polute gl3_main.c with the SDL
+ * headers.
+ */
+int GL4_GetSDLVersion()
+{
+#ifdef USE_SDL3
+	SDL_Version ver;
+#else
+	SDL_version ver;
+#endif
+
+	SDL_VERSION(&ver);
+
+	return ver.major;
+}

src/client/refresh/gl4/header/local.h

@@ -395,6 +395,7 @@ extern qboolean GL4_IsVsyncActive(void);
 extern void GL4_EndFrame(void);
 extern void GL4_SetVsync(void);
 extern void GL4_ShutdownContext(void);
+extern int GL4_GetSDLVersion(void);
 
 // gl4_misc.c
 extern void GL4_InitParticleTexture(void);

src/client/vid/header/ref.h

@@ -125,7 +125,7 @@ typedef enum {
 } ref_restart_t;
 
 // FIXME: bump API_VERSION?
-#define	API_VERSION		6
+#define	API_VERSION		7
 #define EXPORT
 #define IMPORT
 
@@ -137,6 +137,11 @@ typedef struct
 	// if api_version is different, the dll cannot be used
 	int		api_version;
 
+	// if framework_version is different, the dll cannot be used
+	// necessary because differend SDL major version cannot be
+	// mixed.
+	int		framework_version;
+
 	// called when the library is loaded
 	qboolean (EXPORT *Init) (void);