/*
 * p2d_make.c - Polygon creation
 *
 * Written 2012 by Werner Almesberger
 * Copyright 2012 Werner Almesberger
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 */


#include <assert.h>

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


struct p2d *p2d_new(void)
{
	struct p2d *np;

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


struct v2d *v2d_new(double x, double y)
{
	struct v2d *nv;

	nv = alloc_type(struct v2d);
	nv->x = x;
	nv->y = y;
	nv->next = NULL;
	return nv;
}


void p2d_append(struct p2d *p, struct v2d *v)
{
	if (p->last && p->last->next)
		v->next = p->v;
	if (p->last)
		p->last->next = v;
	else
		p->v = v;
	p->last = v;
}


void p2d_prepend(struct p2d *p, struct v2d *v)
{
	v->next = p->v;
	p->v = v;
	if (p->last) {
		if (p->last->next)
			p->last->next = v;
	} else {
		p->last = v;
	}
}


void p2d_close(struct p2d *p)
{
	assert(!p->v || !p->last->next);
	p->last->next = p->v;
}