Ready. Set. Go!

.gitignore

@@ -0,0 +1,2 @@
+*.o
+nothing

Makefile

@@ -0,0 +1,14 @@
+OBJS = src/main.o src/player.o
+LIBS=$(shell pkg-config gl sdl2 --libs)
+CFLAGS=-Wall -Werror -std=c11 $(shell pkg-config gl sdl2 --cflags)
+
+nothing: $(OBJS)
+	cc $(CFLAGS) $(OBJS) -o nothing $(LIBS)
+
+%.o: %.c
+	cc $(CFLAGS) -c $< -o $@
+
+.PHONY: clean
+
+clean:
+	rm -rf nothing $(OBJS)

default.nix

@@ -0,0 +1,12 @@
+with import <nixpkgs> {}; {
+    nothingEnv = stdenv.mkDerivation {
+        name = "nothing-env";
+        buildInputs = [ stdenv
+                        gcc
+                        SDL2
+                        mesa
+                        pkgconfig
+                      ];
+        LD_LIBRARY_PATH="${mesa}/lib";
+    };
+}

src/main.c

@@ -0,0 +1,88 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <SDL2/SDL.h>
+
+#include "./player.h"
+
+#define SCREEN_WIDTH 800
+#define SCREEN_HEIGHT 600
+#define GAME_FPS 60
+
+int main(int argc, char *argv[])
+{
+    int exit_code = 0;
+
+    if (SDL_Init(SDL_INIT_VIDEO) < 0) {
+        fprintf(stderr, "Could not initialize SDL: %s", SDL_GetError());
+        exit_code = -1;
+        goto sdl_init_fail;
+    }
+
+    SDL_Window *window = SDL_CreateWindow("Nothing",
+                                          100, 100,
+                                          SCREEN_WIDTH, SCREEN_HEIGHT,
+                                          SDL_WINDOW_SHOWN);
+    if (window == NULL) {
+        fprintf(stderr, "Could not create SDL window: %s", SDL_GetError());
+        exit_code = -1;
+        goto sdl_create_window_fail;
+    }
+
+    SDL_Renderer *renderer = SDL_CreateRenderer(window, -1,
+                                                SDL_RENDERER_ACCELERATED |
+                                                SDL_RENDERER_PRESENTVSYNC);
+    if (renderer == NULL) {
+        fprintf(stderr, "Could not create SDL renderer: %s", SDL_GetError());
+        exit_code = -1;
+        goto sdl_create_renderer_fail;
+    }
+
+    struct player *player = create_player(0.0f, 200.0f);
+    if (player == NULL) {
+        perror("Could not create player");
+        exit_code = -1;
+        goto create_player_fail;
+    }
+
+    int quit = 0;
+
+    const Uint8 *keyboard_state = SDL_GetKeyboardState(NULL);
+    const int delay_ms = roundf(1000.0 / GAME_FPS);
+    SDL_Event e;
+    while (!quit) {
+        while (SDL_PollEvent(&e)) {
+            switch (e.type) {
+            case SDL_QUIT:
+                quit = 1;
+                break;
+            }
+
+        }
+
+        if (keyboard_state[SDL_SCANCODE_A]) {
+            player_move_left(player);
+        } else if (keyboard_state[SDL_SCANCODE_D]) {
+            player_move_right(player);
+        } else {
+            player_stop(player);
+        }
+
+        update_player(player, delay_ms);
+
+        SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
+        SDL_RenderClear(renderer);
+        render_player(player, renderer);
+        SDL_RenderPresent(renderer);
+        SDL_Delay(delay_ms);
+    }
+
+    destroy_player(player);
+create_player_fail:
+    SDL_DestroyRenderer(renderer);
+sdl_create_renderer_fail:
+    SDL_DestroyWindow(window);
+sdl_create_window_fail:
+    SDL_Quit();
+sdl_init_fail:
+    return exit_code;
+}

src/player.c

@@ -0,0 +1,78 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <SDL2/SDL.h>
+
+#include "./player.h"
+
+#define PLAYER_WIDTH 50.0f
+#define PLAYER_HEIGHT 50.0f
+#define PLAYER_SPEED 500.0f
+
+struct player {
+    float x, y;
+    float dx, dy;
+};
+
+struct player *create_player(float x, float y)
+{
+    struct player *player = malloc(sizeof(struct player));
+
+    if (player == NULL) {
+        return NULL;
+    }
+
+    player->x = x;
+    player->y = y;
+    player->dx = 0.0f;
+    player->dy = 0.0f;
+
+    return player;
+}
+
+void destroy_player(struct player * player)
+{
+    free(player);
+}
+
+int render_player(const struct player * player,
+                  SDL_Renderer *renderer)
+{
+    if (SDL_SetRenderDrawColor(renderer, 255, 0, 0, 255) < 0) {
+        return -1;
+    }
+
+    SDL_Rect rect;
+    rect.x = roundf(player->x);
+    rect.y = roundf(player->y);
+    rect.w = roundf(PLAYER_WIDTH);
+    rect.h = roundf(PLAYER_HEIGHT);
+
+    if (SDL_RenderFillRect(renderer, &rect) < 0) {
+        return -1;
+    }
+
+    return 0;
+}
+
+void update_player(struct player * player, int delta_time)
+{
+    float d = delta_time / 1000.0;
+
+    player->x += player->dx * d;
+    player->y += player->dy * d;
+}
+
+void player_move_left(struct player *player)
+{
+    player->dx = -PLAYER_SPEED;
+}
+
+void player_move_right(struct player *player)
+{
+    player->dx = PLAYER_SPEED;
+}
+
+void player_stop(struct player *player)
+{
+    player->dx = 0.0f;
+}

src/player.h

@@ -0,0 +1,18 @@
+#ifndef PLAYER_H_
+#define PLAYER_H_
+
+struct player;
+struct SDL_Renderer;
+
+struct player *create_player(float x, float y);
+void destroy_player(struct player * player);
+
+int render_player(const struct player * player,
+                  SDL_Renderer *renderer);
+void update_player(struct player * player, int delta_time);
+
+void player_move_left(struct player *player);
+void player_move_right(struct player *player);
+void player_stop(struct player *player);
+
+#endif  // PLAYER_H_