/* Copyright (c) 1992 AT&T - All rights reserved. */
#include <libc.h>
#include <libg.h>
#include "libgint.h"
#include <math.h>

#define rad2deg(x) 180*((x)/3.1415926535897932384626433832795028841971693993751)

void
arc(Bitmap *b, Point p0, Point p1, Point p2, int v, Fcode f)
{
	unsigned int d;
	int x, y, r, start, end, delta;
	GC g;

	p1.x -= p0.x;
	p1.y -= p0.y;
	p2.x -= p0.x;
	p2.y -= p0.y;
	r = (int)sqrt((double)(p1.x*p1.x + p1.y*p1.y));
	start = (int)(64*rad2deg(atan2(-p2.y, p2.x)));
	end = (int)(64*rad2deg(atan2(-p1.y, p1.x)));
	if(start < 0)
		start += 64*360;
	if(end < 0)
		end += 64*360;
	delta = end - start;
	if(delta < 0)
		delta += 64*360;
	x = p0.x - r;
	y = p0.y - r;
	if(b->flag&SHIFT){
		x -= b->r.min.x;
		y -= b->r.min.y;
	}
	d = 2*r;
	g = _getfillgc(f, b, v);
	/*
	 * delta is positive, so this draws counterclockwise arc
	 * from start to start+delta
	 */
	XDrawArc(_dpy, (Drawable)b->id, g, x, y, d, d, start, delta);
}