Help! Metal backend doesn't seem to be working

[Tinker]

Hey guys,

I recently started messing around with the standard SDL2 rendering calls now that a metal backend has been added to the macOS version. I set up a basic SDL2 app, load up an image using SDL_Image, and use SDL_RenderCopy() to put it on the screen.

So far so good. Now I enable the metal backend by calling:

SDL_SetHintWithPriority(SDL_HINT_RENDER_DRIVER, “metal”, SDL_HINT_OVERRIDE);

Before SDL_Init() (I’ve tried doing it before creating a renderer as well, no luck). Now the image doesn’t appear. The screen clears to whatever color I tell it via SDL_RenderClear(), but no mater what I’ve tried I can’t seem to get the image to render.

If I comment out “SDL_SetHintWithPriority()” SDL loads up the standard OpenGL backend and everything appears as expected.

Has anyone encountered this issue before? Am I missing something? Is there a good example somewhere of setting up metal rendering with SDL2 2.0.8?

[Tinker]

Ok after doing a bit more digging I came across this thread:

Is SDL2 with METAL on macOS/iOS/tvOS getting much testing?

I found that on macOS that after creating a window, and then creating a metal renderer, that GetRenderOutputSize returns zero for w and h, unless a call is made to SDL_SetWindowSize with the same window size as created. Doesn’t work: create window create renderer get renderer output size Does work: create window create renderer set renderer target to null set renderer draw colour to black render clear render present set window size to same as created get renderer output size I’ve not test…

I’m guessing this is a known bug. I wrote this little workaround that seems to get metal rendering up and running. Hope someone in the future finds it useful until it’s hopefully fixed in the next release:

// After creating window and renderer (i.e. gCurrentWindow, gCurrentRenderer), do this.
if(kUseMetal)
{
	// HACK: This is a work around for a bug in SDL2.
	int w, h;
	SDL_RenderClear(gCurrentRenderer);
	SDL_GetWindowSize(gCurrentWindow, &w, &h);
	SDL_SetWindowSize(gCurrentWindow, w, h);
}

[icculus]

I believe this is broken in 2.0.8, but fixed in revision control, and won’t need that workaround for 2.0.9.

–ryan.

[Tinker]

Awesome! Not a huge emergency for me, looking forward to 2.0.9