/*
 * p2d_copy.c - Copy a polygon, with or without reversing it
 *
 * Written 2012 by Werner Almesberger
 * Copyright 2012 Werner Almesberger
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */


#include <math.h>

#include "util.h"
#include "poly2d.h"


struct p2d *p2d_copy(const struct p2d *p)
{
	struct p2d *np;
	const struct v2d *v;
	struct v2d *nv, **last;

	np = alloc_type(struct p2d);
	np->v = NULL;
	np->last = NULL;
	np->next = NULL;

	last = &np->v;
	v = p->v;
	while (v) {
		nv = alloc_type(struct v2d);
		nv->x = v->x;
		nv->y = v->y;
		nv->next = NULL;
		*last = nv;
		last = &nv->next;

		np->last = nv;

		v = v->next;
		if (v == p->v)
			break;
	}
	if (v)
		*last = np->v;
	return np;
}


struct p2d *p2d_copy_all(const struct p2d *p)
{
	struct p2d *res = NULL, **last = &res;

	while (p) {
		*last = p2d_copy(p);
		last = &(*last)->next;
		p = p->next;
	}
	return res;
}


struct p2d *p2d_reverse(const struct p2d *p)
{
	struct p2d *np;
	const struct v2d *v;
	struct v2d *nv;

	np = alloc_type(struct p2d);
	np->v = NULL;
	np->last = NULL;
	np->next = NULL;

	v = p->v;
	while (v) {
		nv = alloc_type(struct v2d);
		nv->x = v->x;
		nv->y = v->y;
		nv->next = np->v;
		np->v = nv;

		if (!np->last)
			np->last= nv;

		v = v->next;
		if (v == p->v)
			break;
	}
	if (v && np->last)
		np->last->next = np->v;
	return np;
}