I am trying to setup a OpenGL-based project in my Macbook Pro 14 (M2 Pro CPU, Macos Sonoma 14.5). I have basically managed to get everything working, BUT no matter what I do I cannot make the program use OpenGL 4.1, and 2.1 loads instead.
I am using SDL3, Glad and Zig for this, but I am just loading the same libraries as if I were to use C or C++. Here is my initialization code:
pub fn initialize_sdl() !SDLComponents {
c.SDL_Log("Initializing SDL");
// Very important to set these before initializing SDL
_ = c.SDL_GL_LoadLibrary(null);
_ = c.SDL_GL_SetAttribute(c.SDL_GL_ACCELERATED_VISUAL, 1);
_ = c.SDL_GL_SetAttribute(c.SDL_GL_CONTEXT_FORWARD_COMPATIBLE_FLAG, c.GL_TRUE);
_ = c.SDL_GL_SetAttribute(c.SDL_GL_CONTEXT_PROFILE_MASK, c.SDL_GL_CONTEXT_PROFILE_CORE);
_ = c.SDL_GL_SetAttribute(c.SDL_GL_CONTEXT_MAJOR_VERSION, 4);
_ = c.SDL_GL_SetAttribute(c.SDL_GL_CONTEXT_MINOR_VERSION, 1);
_ = c.SDL_GL_SetAttribute(c.SDL_GL_DOUBLEBUFFER, 1);
_ = c.SDL_GL_SetAttribute(c.SDL_GL_DEPTH_SIZE, 24);
if (c.SDL_Init(c.SDL_INIT_VIDEO) != 0) {
c.SDL_LogError(c.SDL_LOG_CATEGORY_RENDER, "Unable to initialize SDL: %s", c.SDL_GetError());
return error.SDLInitializationFailed;
}
const window: *c.SDL_Window = c.SDL_CreateWindow("Powder3D", 400, 400, c.SDL_WINDOW_OPENGL | c.SDL_WINDOW_RESIZABLE) orelse {
c.SDL_LogError(c.SDL_LOG_CATEGORY_RENDER, "Unable to create window: %s", c.SDL_GetError());
return error.SDLInitializationFailed;
};
const open_gl_context: c.SDL_GLContext = c.SDL_GL_CreateContext(window) orelse {
c.SDL_LogError(c.SDL_LOG_CATEGORY_RENDER, "Unable to create OpenGL context: %s", c.SDL_GetError());
return error.SDLInitializationFailed;
};
if (c.gladLoadGLLoader(sdlGLGetProcAddress) == 0) {
c.SDL_LogError(c.SDL_LOG_CATEGORY_RENDER, "Unable to load OpenGL functions with glad");
return error.GLADInitializationFailed;
}
const versionStringPtr = c.glGetString(c.GL_VERSION) orelse {
c.SDL_LogError(c.SDL_LOG_CATEGORY_RENDER, "Could not get GL version");
return error.OPENGLInitializationFailed;
};
const versionString = std.mem.span(versionStringPtr);
std.debug.print("OpenGL version: {s}\n", .{versionString});
return .{ .window = window, .context = open_gl_context };
}
The reported open gl version (the code prints it at the bottom) outputs "2.1 Metal - 88.1". After skimming through the web, most people have fixed this by settings the SDL_GL_CONTEXT_PROFILE_MASK
, SDL_GL_CONTEXT_PROFILE_CORE
values, but this doesn't really work for me.
SDL_GL_SetAttribute()
calls need to occur after SDL_Init(SDL_INIT_VIDEO)
/SDL_VideoInit()
but before SDL_CreateWindow()
to be effective:
/**
* Set an OpenGL window attribute before window creation.
*
* This function sets the OpenGL attribute `attr` to `value`. The requested
* attributes should be set before creating an OpenGL window. You should use
* SDL_GL_GetAttribute() to check the values after creating the OpenGL
* context, since the values obtained can differ from the requested ones.
*
* \param attr an SDL_GLattr enum value specifying the OpenGL attribute to set
* \param value the desired value for the attribute
* \returns 0 on success or a negative error code on failure; call
* SDL_GetError() for more information.
*
* \since This function is available since SDL 3.0.0.
*
* \sa SDL_GL_GetAttribute
* \sa SDL_GL_ResetAttributes
*/
extern DECLSPEC int SDLCALL SDL_GL_SetAttribute(SDL_GLattr attr, int value);