sdl2-hello-world/src/packages/game/main.c

#include <SDL.h>
#include <stdbool.h>
#include <stdio.h>

const char* APP_NAME = "SDL2";
const unsigned int SCREEN_WIDTH = 640;
const unsigned int SCREEN_HEIGHT = 480;

const unsigned char CONTROLS = 16;

const SDL_KeyCode KEYBOARD_CONTROLS[CONTROLS] = {
	SDLK_RIGHT,
	SDLK_DOWN,
	SDLK_LEFT,
	SDLK_UP,
	SDLK_RETURN, // yes
	SDLK_BACKSPACE, // no
	SDLK_a, // action0
	SDLK_s, // action1
	SDLK_d, // action2
	SDLK_f, // action3
	SDLK_z, // action4
	SDLK_x, // action5
	SDLK_c, // action6
	SDLK_v, // action7
	SDLK_w, // action8
	SDLK_e, // action9
};

int main(int argc, char* args[]) {
	SDL_Window* window = NULL;
	SDL_Surface* screenSurface = NULL;

	if (SDL_Init(
		SDL_INIT_VIDEO
		| SDL_INIT_GAMECONTROLLER
		| SDL_INIT_EVENTS
	) < 0) {
		printf("SDL could not initialize! SDL_Error: %s\n", SDL_GetError());
		return -1;
	}

	window = SDL_CreateWindow(
		APP_NAME,
		SDL_WINDOWPOS_UNDEFINED,
		SDL_WINDOWPOS_UNDEFINED,
		SCREEN_WIDTH,
		SCREEN_HEIGHT,
		SDL_WINDOW_SHOWN
	);

	if (window == NULL) {
		printf("Window could not be created! SDL_Error: %s\n", SDL_GetError());
		return -2;
	}

	bool quit = false;
	SDL_Event e;
	screenSurface = SDL_GetWindowSurface(window);

	unsigned short action = 0;
	while (!quit) {
		SDL_FillRect(screenSurface, NULL, SDL_MapRGB(screenSurface->format, 0x00, 0x00, 0x00));
		uint64_t ticks = SDL_GetTicks64();
		for (unsigned char i = 0; i < 64; i += 1) {
			const unsigned char column = (64 - i) % 32;
			const unsigned char row = i / 32;
			const uint64_t bitflag = (0x1lu << i);
			const unsigned char size = 4;
			if (ticks & bitflag) {
				SDL_FillRect(screenSurface, &(SDL_Rect) {
					column * size,
					SCREEN_HEIGHT - ((row + 1) * size),
					size,
					size
					}, SDL_MapRGB(screenSurface->format, 0x00, 0xff, 0xff));
			}
		}

		while (SDL_PollEvent(&e) != 0) {
			if (e.type == SDL_QUIT) {
				quit = true;
			}

			for (unsigned char i = 0; i < CONTROLS; i += 1) {
				// TODO do same for gamepad
				if (e.key.keysym.sym == KEYBOARD_CONTROLS[i]) {
					const unsigned short bitflag = (0x1 << i);
					if (e.type == SDL_KEYDOWN) {
						action |= bitflag;
					} else if (e.type == SDL_KEYUP) {
						action &= ~bitflag;
					}
				}
			}

			for (unsigned char i = 0; i < CONTROLS; i += 1) {
				const unsigned char column = i % 4;
				const unsigned char row = i / 4;
				const unsigned short bitflag = (0x1 << i);
				const unsigned char size = 4;
				if (action & bitflag) {
					SDL_FillRect(screenSurface, &(SDL_Rect) {
						column * size,
						row * size,
						size,
						size
					}, SDL_MapRGB(screenSurface->format, 0xff, 0xff, 0x00));
				}
			}

			SDL_UpdateWindowSurface(window);
		}
	}
	SDL_DestroyWindow(window);
	SDL_Quit();

	return 0;
}