/*
	base-vis.c

	PVS PHS generator tool

	Copyright (C) 1996-1997  Id Software, Inc.
	Copyright (C) 2002 Colin Thompson

	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.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

	See the GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program; if not, write to:

		Free Software Foundation, Inc.
		59 Temple Place - Suite 330
		Boston, MA  02111-1307, USA

*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include <getopt.h>
#include <stdlib.h>
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif
#ifdef HAVE_IO_H
# include <io.h>
#endif
#ifdef HAVE_STRING_H
# include <string.h>
#endif
#ifdef HAVE_STRINGS_H
# include <strings.h>
#endif
#include <getopt.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>

#include "QF/bspfile.h"
#include "QF/cmd.h"
#include "QF/mathlib.h"
#include "QF/quakefs.h"
#include "QF/sys.h"

#include "vis.h"
#include "options.h"

static int  clustersee;
static set_t *portalsee;

/*
	This is a rough first-order aproximation that is used to trivially reject
	some of the final calculations.
*/
static void
SimpleFlood (portal_t *srcportal, int clusternum)
{
    int			i;
    cluster_t  *cluster;
    portal_t   *portal;

	if (set_is_member (srcportal->mightsee, clusternum))
		return;
	set_add (srcportal->mightsee, clusternum);
    clustersee++;

    cluster = &clusters[clusternum];

    for (i = 0; i < cluster->numportals; i++) {
		portal = cluster->portals[i];
		if (!set_is_member (portalsee, portal - portals))
			continue;
		SimpleFlood (srcportal, portal->cluster);
    }
}

static inline int
test_sphere (sphere_t *sphere, plane_t *plane)
{
	float       d;
	int         front, back;

	d = DotProduct (sphere->center, plane->normal) - plane->dist;
	front = (d >= sphere->radius);
	back = (d <= -sphere->radius);
	return front - back;
}

void
BasePortalVis (void)
{
    int			i, j, k;
	float		d;
    portal_t   *tp, *portal;
    winding_t  *winding;
	int         base_mightsee = 0;
	int         tp_side, portal_side;
	double      start, end;

	start = Sys_DoubleTime ();
	portalsee = set_new_size (numportals * 2);
    for (i = 0, portal = portals; i < numportals * 2; i++, portal++) {
		portal->mightsee = set_new_size (portalclusters);

		set_empty (portalsee);

		for (j = 0, tp = portals; j < numportals * 2; j++, tp++) {
			if (j == i)
				continue;

			// If the target portal is behind the portals's plane, then it
			// can't possibly be seen by the portal.
			//
			// If the portal is in front of the target's plane, then the target
			// is of no interest as it is facing counter to the flow of
			// visibility.

			// First check using the bounding spheres of the two portals.
			tp_side = test_sphere (&tp->sphere, &portal->plane);
			if (tp_side < 0) {
				// The test portal definitely is entirely behind the portal's
				// plane.
				continue;	// entirely behind
			}
			portal_side = test_sphere (&portal->sphere, &tp->plane);
			if (portal_side > 0) {
				// The portal definitely is entirely in front of the test
				// portal's plane.
				continue;	// entirely in front
			}

			if (tp_side == 0) {
				// The test portal's sphere touches the portal's plane, so
				// do a more refined check.
				winding = tp->winding;
				for (k = 0; k < winding->numpoints; k++) {
					d = DotProduct (winding->points[k],
									portal->plane.normal) - portal->plane.dist;
					if (d > ON_EPSILON)
						break;
				}
				if (k == winding->numpoints)
					continue;	// no points on front
			}

			if (portal_side == 0) {
				// The portal's sphere touches the test portal's plane, so
				// do a more refined check.
				winding = portal->winding;
				for (k = 0; k < winding->numpoints; k++) {
					d = DotProduct (winding->points[k],
									tp->plane.normal) - tp->plane.dist;
					if (d < -ON_EPSILON)
						break;
				}
				if (k == winding->numpoints)
					continue;	// no points on front
			}

			set_add (portalsee, j);
		}

		clustersee = 0;
		SimpleFlood (portal, portal->cluster);
		portal->nummightsee = clustersee;
		base_mightsee += clustersee;
    }
	set_delete (portalsee);
	end = Sys_DoubleTime ();
	if (options.verbosity > 0)
		printf ("base_mightsee: %d %gs\n", base_mightsee, end - start);
}