SDL_Metal Clear Screen Example

sdl2_metal_clearscreen.m

/* Requires >= SDL 2.0.11 (not yet released)
 * Also requires a patch that has not yet been merged:
 * https://bugzilla.libsdl.org/show_bug.cgi?id=4796
 */

#include <SDL.h>
#import <Metal/Metal.h>
#import <QuartzCore/CAMetalLayer.h>

int main(int argc, char **argv) {
	SDL_Init(SDL_INIT_VIDEO);
	SDL_Window* window = SDL_CreateWindow(
		"Metal Clear Screen Example",
		SDL_WINDOWPOS_CENTERED,
		SDL_WINDOWPOS_CENTERED,
		640,
		480,
		SDL_WINDOW_METAL | SDL_ALLOW_HIGHDPI
	);

	id<MTLDevice> device = MTLCreateSystemDefaultDevice();
	SDL_MetalView view = SDL_Metal_CreateView(window);
	CAMetalLayer *layer = SDL_Metal_GetLayer(view);
	layer.device = device;
	layer.pixelFormat = MTLPixelFormatBGRA8Unorm;

	id<MTLCommandQueue> commandQueue = [device newCommandQueue];
	SDL_Event e;
	int quit = 0;
	while (!quit) {
		while (SDL_PollEvent(&e)) {
			if (e.type == SDL_QUIT) {
				quit = 1;
			}
		}

		id<CAMetalDrawable> drawable = [layer nextDrawable];
		MTLRenderPassDescriptor *passDesc = [MTLRenderPassDescriptor renderPassDescriptor];
		passDesc.colorAttachments[0].texture = drawable.texture;
		passDesc.colorAttachments[0].loadAction = MTLLoadActionClear;
		passDesc.colorAttachments[0].storeAction = MTLStoreActionStore;
		passDesc.colorAttachments[0].clearColor = MTLClearColorMake(1.0, 0.0, 1.0, 1.0);
		id<MTLCommandBuffer> commandBuffer = [commandQueue commandBuffer];
		id<MTLRenderCommandEncoder> encoder = [commandBuffer renderCommandEncoderWithDescriptor:passDesc];
		[encoder endEncoding];
		[commandBuffer presentDrawable:drawable];
		[commandBuffer commit];

		SDL_Delay(16);
	}
	SDL_Metal_DestroyView(view);
	SDL_DestroyWindow(window);
	SDL_Quit();
}