terminal snow

userspace/csnow.c

@@ -0,0 +1,174 @@
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#ifdef __toaru__
+#include <syscall.h>
+DEFN_SYSCALL2(nanosleep,  46, unsigned long, unsigned long);
+int usleep(useconds_t time) { syscall_nanosleep(0, time / 10000); }
+#else
+#include <sys/ioctl.h>
+#endif
+
+#define MAX_SPEED        2
+#define INITIAL_SNOW     40
+#define INCREMENTAL_SNOW 10
+#define BUFFER_SIZE      10
+#define BLANK_SPACE      " "
+
+#define NUM_FLAKE_TEXTURES 4
+char * flake_textures[] = {
+	"❄",
+	"❅",
+	"❆",
+	"*",
+};
+
+typedef struct {
+	int width;
+	int height;
+	char ** backingstore;
+} screen_t;
+
+typedef struct {
+	char * display;
+	signed short x;
+	signed short y;
+	signed char  speed;
+	char   gravity;
+} flake_t;
+
+screen_t * init_screen() {
+	char * term = getenv("TERM");
+
+	screen_t * screen = malloc(sizeof(screen_t));
+
+#ifdef __toaru__
+	if (strstr(term, "toaru")) {
+		printf("\033[1003z");
+		fflush(stdout);
+		scanf("%d,%d", &screen->width, &screen->height);
+	} else {
+		screen->width  = 80; /* better safe than sorry */
+		screen->height = 24;
+	}
+#else
+	struct winsize w;
+	ioctl(0, TIOCGWINSZ, &w);
+	screen->width  = w.ws_col;
+	screen->height = w.ws_row;
+#endif
+
+	screen->backingstore = malloc(sizeof(char *) * screen->width * screen->height);
+
+	return screen;
+}
+
+flake_t * make_some_flakes(screen_t * screen, int how_many) {
+	flake_t * out = malloc(sizeof(flake_t) * (how_many + 1));
+
+	for (int i = 0; i < how_many; ++i) {
+		out[i].display = flake_textures[rand() % NUM_FLAKE_TEXTURES];
+		out[i].x       = rand() % screen->width;
+		out[i].y       = -(rand() % BUFFER_SIZE);
+		out[i].speed   = rand() % MAX_SPEED - (MAX_SPEED / 2);
+		out[i].gravity = 1;
+	}
+
+	out[how_many].display = NULL;
+	return out;
+}
+
+flake_t * add_flakes(screen_t * screen, flake_t * flakes, int how_many) {
+	flake_t * more = make_some_flakes(screen, how_many);
+
+	int len = 0; for (; flakes[len].display; ++len);
+	flakes = realloc(flakes, sizeof(flake_t) * (how_many + len + 1));
+
+	memcpy(&flakes[len], more, sizeof(flake_t) * (how_many + 1));
+
+	free(more);
+
+	return flakes;
+}
+
+int detect_collisions(screen_t * screen, flake_t * flakes, int i) {
+	int x = flakes[i].x;
+	int y = flakes[i].y;
+
+	if (flakes[i].y >= screen->height - 1) {
+		flakes[i].gravity = 0;
+		return 1;
+	}
+
+	for (int j = 0; flakes[j].display; ++j) {
+		if (flakes[j].gravity) continue;
+		if (flakes[j].x == x && flakes[j].y == (y + 1)) {
+			flakes[i].gravity = 0;
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+void update_flakes(screen_t * screen, flake_t * flakes) {
+	for (int i = 0; flakes[i].display; ++i) {
+		if (flakes[i].gravity) {
+			flakes[i].x += flakes[i].speed;
+			if (flakes[i].x < 0) {
+				flakes[i].x = screen->width - 1;
+			} else if (flakes[i].x >= screen->width) {
+				flakes[i].x = 0;
+			}
+			if (!detect_collisions(screen, flakes, i)) {
+				flakes[i].y += flakes[i].gravity;
+			}
+		}
+	}
+}
+
+void write_screen(screen_t * screen, flake_t * flakes) {
+	for (int y = 0; y < screen->height; ++y) {
+		for (int x = 0; x < screen->width; ++x) {
+			screen->backingstore[x + y * screen->width] = BLANK_SPACE;
+		}
+	}
+	for (int i = 0; flakes[i].display; ++i) {
+		if (flakes[i].y >= 0 && flakes[i].y < screen->height && flakes[i].x >= 0 && flakes[i].x < screen->width) {
+			screen->backingstore[flakes[i].x + flakes[i].y * screen->width] = flakes[i].display;
+		}
+	}
+}
+
+void flip_screen(screen_t * screen) {
+	printf("\033[H");
+	for (int y = 0; y < screen->height; ++y) {
+		for (int x = 0; x < screen->width; ++x) {
+			if ((y == screen->height - 1) && (x == screen->width - 1)) {
+				fflush(stdout);
+				return;
+			}
+			printf("%s", screen->backingstore[x + y * screen->width]);
+		}
+		printf("\n");
+	}
+}
+
+int main(int argc, char * argv) {
+
+	screen_t * main_screen = init_screen();
+	flake_t *  flakes      = make_some_flakes(main_screen, INITIAL_SNOW);
+
+	for (;;) {
+		write_screen(main_screen, flakes);
+		flip_screen(main_screen);
+		update_flakes(main_screen, flakes);
+		flakes = add_flakes(main_screen, flakes, INCREMENTAL_SNOW);
+		usleep(90000);
+	}
+
+
+	return 0;
+}