Having some fun with the bash escape sequences

bash_fun.c

/*
 * bash_fun.c
 *
 * Dimitar T. Dimitrov
 * 15.06.2016
 *
 */
#include <sys/ioctl.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>

static const double PI = 3.1415926535;

int kbhit() {
	struct timeval tv = { 0L, 0L };
	fd_set fds;
	FD_ZERO(&fds);
	FD_SET(0, &fds);

	return select(1, &fds, NULL, NULL, &tv);
}

void clearScreen() {
	printf("\ec");
}

void putCursor(int x, int y) {
	printf("\e[%d;%dH", x, y);
}

void putPixel(int x, int y, int color)
{
	putCursor(x, y);
	printf("\e[%dm*", color);
}

void circle(int x, int y, int r, int color) {
	int i, angle, x1, y1;

	for(i = 0; i < 360; i++) {
		angle = i;
		x1 = r * cos(angle * PI / 180);
		y1 = r * sin(angle * PI / 180);

		putPixel(x + x1, y + y1, color);
	}
}


int main(int ac, char **av, char **ev) {
	struct winsize w;
	ioctl(STDOUT_FILENO, TIOCGWINSZ, &w); // Get terminal size

	printf("lines %d\n", w.ws_row);
	printf("columns %d\n", w.ws_col);

	while (!kbhit()) {
		clearScreen();

		circle(20, w.ws_col * 0.5f, 10, 34);
		circle(10, w.ws_col * 0.5f, 5, 33);
		circle(30, w.ws_col * 0.5f, 5, 35);
		circle(20, w.ws_col * 0.5f - 10, 5, 36);
		circle(20, w.ws_col * 0.5f + 10, 5, 37);

		usleep(16670); // ~ 60 fps
	}

	putCursor(w.ws_row, 0);
	printf("\e[0m"); // Reset color

	return EXIT_SUCCESS;
}