/* http://www.cyut.edu.tw/~ckhung/b/mi/ */
/* 1999-06 */
/* how to compile: gcc -Wall momentum.c -lncurses */

#include <ncurses/curses.h>
#include <stdio.h>

int main()
{
    int width, height;
    double u, v, x, y;
    int c, go_on;

    initscr();
    cbreak();
    noecho();
    nodelay(stdscr, 1);
    keypad(stdscr, 1);
    getmaxyx(stdscr, height, width);
    mvaddstr(0, 0, "press arrow keys to accelerate the cursor;");
    mvaddstr(1, 0, "press any other key to quit");
    u = v = 0;
    x = y = 0;
    go_on = 1;
    while (go_on) {
	while ((c = getch()) == ERR) {
	    move(y, x);
	    x += u / 1000;
	    y += v / 1000;
	    while (x < 0) x += width;
	    while (x >= width) x -= width;
	    while (y < 0) y += height;
	    while (y >= height) y -= height;
	}
	switch (c) {
	case KEY_LEFT:  --u; break;
	case KEY_RIGHT: ++u; break;
	case KEY_UP:    --v; break;
	case KEY_DOWN:  ++v; break;
	default:	go_on = 0;
	}
    }
    endwin();
    return 0;
}