/*
	flow.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

static __attribute__ ((unused)) const char rcsid[] =
    "$Id$";

#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
CheckStack (cluster_t *cluster, threaddata_t *thread)
{
    pstack_t	*portal;
	
    for (portal = thread->pstack_head.next; portal; portal = portal->next)
		if (portal->cluster == cluster) {
			printf ("CheckStack: cluster recursion\n");
			return 1;
		}
	return 0;
}

/*
	ClipToSeparators

	Source, pass, and target are an ordering of portals.

	Generates seperating planes candidates by taking two points from source and
	one point from pass, and clips target by them.

	If target is totally clipped away, that portal can not be seen through.

	Normal clip keeps target on the same side as pass, which is correct if the
	order goes source, pass, target.  If the order goes pass, source, target
	then flipclip should be set.
*/
static winding_t	*
ClipToSeparators (winding_t *source, winding_t *pass, winding_t *target, 
				  qboolean flipclip)
{
    float		d;
    int			i, j, k, l;
    int			counts[3];
    qboolean	fliptest;
    plane_t		plane;
    vec3_t		v1, v2;
    vec_t		length;

	// check all combinations       
    for (i = 0; i < source->numpoints; i++) {
		l = (i + 1) % source->numpoints;
		VectorSubtract (source->points[l], source->points[i], v1);

		// find a vertex of pass that makes a plane that puts all of the
		// vertexes of pass on the front side and all of the vertexes of
		// source on the back side
		for (j = 0; j < pass->numpoints; j++) {
			VectorSubtract (pass->points[j], source->points[i], v2);

			plane.normal[0] = v1[1] * v2[2] - v1[2] * v2[1];
			plane.normal[1] = v1[2] * v2[0] - v1[0] * v2[2];
			plane.normal[2] = v1[0] * v2[1] - v1[1] * v2[0];

			length = DotProduct (plane.normal, plane.normal);

			// if points don't make a valid plane, skip it
			if (length < ON_EPSILON)
				continue;

			length = 1 / sqrt (length);
			VectorScale (plane.normal, length, plane.normal);

			plane.dist = DotProduct (pass->points[j], plane.normal);

			// find out which side of the generated seperating plane has the
			// source portal
			fliptest = false;
			for (k = 0; k < source->numpoints; k++) {
				if (k == i || k == l)
					continue;
				d = DotProduct (source->points[k], plane.normal) - plane.dist;
				if (d < -ON_EPSILON) {	
					// source is on the negative side, so we want all
					// pass and target on the positive side
					fliptest = false;
					break;
				} else if (d > ON_EPSILON) {	
					// source is on the positive side, so we want all
					// pass and target on the negative side
					fliptest = true;
					break;
				}
			}
			if (k == source->numpoints)
				continue;	// planar with source portal

			// flip the normal if the source portal is backwards
			if (fliptest) {
				VectorNegate (plane.normal, plane.normal);
				plane.dist = -plane.dist;
			}

			// if all of the pass portal points are now on the positive side,
			// this is the seperating plane
			counts[0] = counts[1] = counts[2] = 0;
			for (k = 0; k < pass->numpoints; k++) {
				if (k == j)
					continue;
				d = DotProduct (pass->points[k], plane.normal) - plane.dist;
				if (d < -ON_EPSILON)
					break;
				else if (d > ON_EPSILON)
					counts[0]++;
				else
					counts[2]++;
			}
			if (k != pass->numpoints)
				continue;	// points on negative side, not a seperating plane

			if (!counts[0]) {
				continue;	// planar with seperating plane
			}

			// flip the normal if we want the back side
			if (flipclip) {
				VectorNegate (plane.normal, plane.normal);
				plane.dist = -plane.dist;
			}

			// clip target by the seperating plane
			target = ClipWinding (target, &plane, false);
			if (!target)
				return NULL;	// target is not visible
			break;				//XXX is this correct? big speedup
		}
    }
    return target;
}

/*
	RecursiveClusterFlow

	Flood fill through the clusters
	If src_portal is NULL, this is the originating cluster
*/
static void
RecursiveClusterFlow (int clusternum, threaddata_t *thread, pstack_t *prevstack)
{
	int			i, j;
    cluster_t	*cluster;
    long		*test, *might, *vis;
    qboolean	more;
    pstack_t	stack;
    portal_t	*portal;
    plane_t		backplane;
    winding_t	*source, *target;

    c_chains++;

    cluster = &clusters[clusternum];
    if (CheckStack(cluster, thread))
		return;

	// mark the cluster as visible
    if (!(thread->clustervis[clusternum >> 3] & (1 << (clusternum & 7)))) {
		thread->clustervis[clusternum >> 3] |= 1 << (clusternum & 7);
		thread->base->numcansee++;
    }

    prevstack->next = &stack;
    stack.next = NULL;
    stack.cluster = cluster;
    stack.portal = NULL;
    stack.mightsee = malloc(bitbytes);
    might = (long *) stack.mightsee;
    vis = (long *) thread->clustervis;

	// check all portals for flowing into other clusters       
    for (i = 0; i < cluster->numportals; i++) {
		portal = cluster->portals[i];

		if (!(prevstack->mightsee[portal->cluster >> 3]
			  & (1 << (portal->cluster & 7))))
			continue;		// can't possibly see it
		// if the portal can't see anything we haven't already seen, skip it
		if (portal->status == stat_done) {
			c_vistest++;
			test = (long *) portal->visbits;
		} else {
			c_mighttest++;
			test = (long *) portal->mightsee;
		}
		more = false;
		for (j = 0; j < bitlongs; j++) {
			might[j] = ((long *) prevstack->mightsee)[j] & test[j];
			if (might[j] & ~vis[j])
				more = true;
		}

		if (!more)			// can't see anything new
			continue;

		// get plane of portal, point normal into the neighbor cluster
		stack.portalplane = portal->plane;
		VectorNegate (portal->plane.normal, backplane.normal);
		backplane.dist = -portal->plane.dist;

		if (_VectorCompare (prevstack->portalplane.normal, backplane.normal))
			continue;		// can't go out a coplanar face

		c_portalcheck++;

		stack.portal = portal;
		stack.next = NULL;

		target = ClipWinding(portal->winding, &thread->pstack_head.portalplane,
							 false);
		if (!target)
			continue;

		if (!prevstack->pass) {
			// the second cluster can only be blocked if coplanar

			stack.source = prevstack->source;
			stack.pass = target;
			RecursiveClusterFlow (portal->cluster, thread, &stack);
			FreeWinding (target);
			continue;
		}

		target = ClipWinding (target, &prevstack->portalplane, false);
		if (!target)
			continue;

		source = CopyWinding (prevstack->source);

		source = ClipWinding (source, &backplane, false);
		if (!source) {
			FreeWinding (target);
			continue;
		}

		c_portaltest++;

		if (options.level > 0) {
			// clip target to the image that would be formed by a laser
			// pointing from the edges of source passing though the corners of
			// pass
			target = ClipToSeparators (source, prevstack->pass, target, false);
			if (!target) {
				FreeWinding (source);
				continue;
			}
		}

		if (options.level > 1) {
			// now pass the laser along the edges of pass from the corners of
			// source. the resulting image will have a smaller aree. The
			// resulting shape will be the light image produced by a backlit
			// source shining past pass. eg, if source and pass are equilateral
			// triangles rotated 60 (or 180) degrees relative to each other,
			// parallel and in line, target will wind up being a hexagon.
			target = ClipToSeparators (prevstack->pass, source, target, true);
			if (!target) {
				FreeWinding (source);
				continue;
			}
		}

		// now do the same as for levels 1 and 2, but trimming source using 
		// the trimmed target
		if (options.level > 2) {
			source = ClipToSeparators (target, prevstack->pass, source, false);
			if (!source) {
				FreeWinding (target);
				continue;
			}
		}

		if (options.level > 3) {
			source = ClipToSeparators (prevstack->pass, target, source, true);
			if (!source) {
				FreeWinding (target);
				continue;
			}
		}

		stack.source = source;
		stack.pass = target;

		c_portalpass++;

		// flow through it for real
		RecursiveClusterFlow (portal->cluster, thread, &stack);

		FreeWinding (source);
		FreeWinding (target);
    }

    free (stack.mightsee);
}

void
PortalFlow (portal_t *portal)
{
    threaddata_t	data;

	LOCK;
    if (portal->status != stat_selected)
		Sys_Error ("PortalFlow: reflowed");
    portal->status = stat_working;
	UNLOCK;

    portal->visbits = calloc (1, bitbytes);

    memset (&data, 0, sizeof (data));
    data.clustervis = portal->visbits;
    data.base = portal;

    data.pstack_head.portal = portal;
    data.pstack_head.source = portal->winding;
    data.pstack_head.portalplane = portal->plane;
    data.pstack_head.mightsee = portal->mightsee;

    RecursiveClusterFlow (portal->cluster, &data, &data.pstack_head);

    portal->status = stat_done;
}