1 files changed, 101 insertions, 0 deletions
diff --git a/snek.c b/snek.c
new file mode 100644
index 0000000..cbe8dd6
--- /dev/null
+++ b/snek.c
@@ -0,0 +1,101 @@
+#include <SDL2/SDL.h>
+#include <stdlib.h>
+
+#define UP 0
+#define DOWN 1
+#define LEFT 2
+#define RIGHT 3
+
+int pos(int x, int y, int width, int height) {
+	return (x % width) + (y % height) * width;
+}
+
+int main() {
+	SDL_Init(SDL_INIT_VIDEO);
+	SDL_Window *win = SDL_CreateWindow("Snek automata", 0, 0, 800, 600, 0);
+	SDL_Renderer *ren = SDL_CreateRenderer(win, -1, SDL_RENDERER_ACCELERATED);
+
+	int width = 40;
+	int height = 20;
+	int *grid = calloc(width * height, sizeof(int));
+	int direction = RIGHT;
+	int snake_length = 3;
+	grid[pos(10, 10, width, height)] = 1;
+	grid[pos(15, 15, width, height)] = 1 << 15;
+
+	SDL_Event e = {0};
+	int quit = 0;
+	while (e.type != SDL_QUIT && !quit) {
+		SDL_PollEvent(&e);
+		int state_len = -1;
+		const Uint8 *state = SDL_GetKeyboardState(&state_len);
+		if (state[SDL_SCANCODE_UP] && direction != DOWN) {
+			direction = UP;
+		}
+		if (state[SDL_SCANCODE_DOWN] && direction != UP) {
+			direction = DOWN;
+		}
+		if (state[SDL_SCANCODE_LEFT] && direction != RIGHT) {
+			direction = LEFT;
+		}
+		if (state[SDL_SCANCODE_RIGHT] && direction != LEFT) {
+			direction = RIGHT;
+		}
+		SDL_SetRenderDrawColor(ren, 20, 20, 20, 255);
+		SDL_RenderClear(ren);
+		for (int i = 0; i < width * height; i++) {
+			int cell = grid[i] & 0xffff;
+			if (cell == (1 << 15) || cell == 0) {
+				int x = 0;
+				int y = 0;
+				switch (direction) {
+					case UP: y++; break;
+					case DOWN: y+=height-1; break;
+					case LEFT: x++; break;
+					case RIGHT: x+=width-1; break;
+				}
+				int peek = grid[pos(i % width + x, i / width + y, width, height)] & 0xffff;
+				grid[i] = (cell << 16) | cell;
+				if (peek == 1) {
+					grid[i] = (1 << 16) | cell;
+					if (cell == (1 << 15)) {
+						snake_length++;
+						int new_pos = pos(rand(), rand(), width, height);
+						while (grid[new_pos] & 0xffff != 0) {
+							new_pos = pos(rand(), rand(), width, height);
+						}
+						grid[new_pos] |= ((1 << 15) << 16) | (1 << 15);
+					}
+				}
+			}
+			if (cell > 0 && cell < (1 << 15)) {
+				if (cell <= snake_length) {
+					grid[i] = ((cell + 1) << 16) | cell;
+				}
+			}
+		}
+		for (int i = 0; i < width * height; i++) {
+			grid[i] = grid[i] >> 16;
+
+			int cell = grid[i] & 0xffff;
+			if (cell == (1 << 15)) {
+				SDL_SetRenderDrawColor(ren, 200, 200, 0, 255);
+			} else if (cell < (1 << 15) && cell > 0) {
+				SDL_SetRenderDrawColor(ren, 255, 255, 255, 255);
+			} else {
+				SDL_SetRenderDrawColor(ren, 40, 40, 40, 255);
+			}
+			int y = (i / width) * 11;
+			int x = (i % width) * 11;
+			int w = 10;
+			int h = 10;
+			SDL_Rect r = { x, y, w, h };
+			SDL_RenderFillRect(ren, &r);
+		}
+
+		SDL_RenderPresent(ren);
+		SDL_Delay(50);
+	}
+	SDL_Quit();
+	return 0;
+}