/*
 * area-poly2d.c - Area fill (using libpoly2d)
 *
 * 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 <poly2d.h>

#include "path.h"
#include "area.h"


static void fill_path(const struct path *paths, double z, double overlap,
    struct path ***res)
{
	const struct path *path;
	const struct point *p;
	double r_tool;
	struct p2d *polys = NULL, *poly, *last = NULL;
	struct p2d *fill;
	const struct v2d *v;

	for (path = paths; path; path = path->next) {
		if (path->first->z != z)
			continue;
		if (!path->first || !path->first->next)
			continue;
		r_tool = path->r_tool;

		poly = p2d_new();
		if (last)
			last->next = poly;
		else
			polys = poly;
		last = poly;
		for (p = path->first; p && p->next; p = p->next)
			p2d_append(poly, v2d_new(p->x, p->y));
		p2d_close(poly);
	}

	fill = p2d_area(polys, r_tool, 2*r_tool-overlap);
	p2d_free_all(polys);

	for (poly = fill; poly; poly = poly->next) {
		**res = path_new(r_tool, "");
		v = poly->v;
		while (v) {
			path_add(**res, v->x, v->y, z);
			v = v->next;
			if (v == poly->v)
				break;
		}
		if (v)
			path_add(**res, v->x, v->y, z);
		*res = &(**res)->next;
	}
	p2d_free_all(fill);
}


struct path *area(const struct path *paths, double overlap)
{
	double z = HUGE_VAL, best_z;
	const struct path *path;
	struct path *res = NULL, **last = &res;

	while (1) {
		best_z = -HUGE_VAL;
		for (path = paths; path; path = path->next) {
			if (path->first->z >= z)
				continue;
			if (best_z >= path->first->z)
				continue;
			best_z = path->first->z;
		}
		if (best_z == -HUGE_VAL)
			break;
		fill_path(paths, best_z, overlap, &last);
		z = best_z;
	}
	return res;
}