Winding.cpp

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/*
===========================================================================
Copyright (C) 1999-2005 Id Software, Inc.

This file is part of Quake III Arena source code.

Quake III Arena source code 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.

Quake III Arena source code 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 Foobar; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
===========================================================================
*/


#include "stdafx.h"
#include <assert.h>
#include "qe3.h"
#include "winding.h"

#define BOGUS_RANGE 18000

/*
=============
Plane_Equal
=============
*/
#define NORMAL_EPSILON  0.0001
#define DIST_EPSILON    0.02

int Plane_Equal(plane_t *a, plane_t *b, int flip)
{
    vec3_t normal;
    float dist;

    if (flip) {
        normal[0] = - b->normal[0];
        normal[1] = - b->normal[1];
        normal[2] = - b->normal[2];
        dist = - b->dist;
    }
    else {
        normal[0] = b->normal[0];
        normal[1] = b->normal[1];
        normal[2] = b->normal[2];
        dist = b->dist;
    }
    if (
       fabs(a->normal[0] - normal[0]) < NORMAL_EPSILON
    && fabs(a->normal[1] - normal[1]) < NORMAL_EPSILON
    && fabs(a->normal[2] - normal[2]) < NORMAL_EPSILON
    && fabs(a->dist - dist) < DIST_EPSILON )
        return true;
    return false;
}

/*
============
Plane_FromPoints
============
*/
int Plane_FromPoints(vec3_t p1, vec3_t p2, vec3_t p3, plane_t *plane)
{
    vec3_t v1, v2;

    VectorSubtract(p2, p1, v1);
    VectorSubtract(p3, p1, v2);
    //CrossProduct(v2, v1, plane->normal);
    CrossProduct(v1, v2, plane->normal);
    if (VectorNormalize(plane->normal) < 0.1) return false;
    plane->dist = DotProduct(p1, plane->normal);
    return true;
}

/*
=================
Point_Equal
=================
*/
int Point_Equal(vec3_t p1, vec3_t p2, float epsilon)
{
    int i;

    for (i = 0; i < 3; i++)
    {
        if (fabs(p1[i] - p2[i]) > epsilon) return false;
    }
    return true;
}


/*
=================
Winding_BaseForPlane
=================
*/
winding_t *Winding_BaseForPlane (plane_t *p)
{
    int     i, x;
    vec_t   max, v;
    vec3_t  org, vright, vup;
    winding_t   *w;
    
    // find the major axis

    max = -BOGUS_RANGE;
    x = -1;
    for (i=0 ; i<3; i++)
    {
        v = fabs(p->normal[i]);
        if (v > max)
        {
            x = i;
            max = v;
        }
    }
    if (x==-1)
        Error ("Winding_BaseForPlane: no axis found");
        
    VectorCopy (vec3_origin, vup);  
    switch (x)
    {
    case 0:
    case 1:
        vup[2] = 1;
        break;      
    case 2:
        vup[0] = 1;
        break;      
    }


    v = DotProduct (vup, p->normal);
    VectorMA (vup, -v, p->normal, vup);
    VectorNormalize (vup);
        
    VectorScale (p->normal, p->dist, org);
    
    CrossProduct (vup, p->normal, vright);
    
    VectorScale (vup, BOGUS_RANGE, vup);
    VectorScale (vright, BOGUS_RANGE, vright);

    // project a really big axis aligned box onto the plane
    w = Winding_Alloc (4);
    
    VectorSubtract (org, vright, w->points[0]);
    VectorAdd (w->points[0], vup, w->points[0]);
    
    VectorAdd (org, vright, w->points[1]);
    VectorAdd (w->points[1], vup, w->points[1]);
    
    VectorAdd (org, vright, w->points[2]);
    VectorSubtract (w->points[2], vup, w->points[2]);
    
    VectorSubtract (org, vright, w->points[3]);
    VectorSubtract (w->points[3], vup, w->points[3]);
    
    w->numpoints = 4;
    
    return w;   
}

/*
==================
Winding_Alloc
==================
*/
winding_t *Winding_Alloc (int points)
{
    winding_t   *w;
    int         size;
    
    if (points > MAX_POINTS_ON_WINDING)
        Error ("Winding_Alloc: %i points", points);
    
    size = (int)((winding_t *)0)->points[points];
    w = (winding_t*) malloc (size);
    memset (w, 0, size);
    w->maxpoints = points;
    
    return w;
}


void Winding_Free (winding_t *w)
{
    free(w);
}


/*
==================
Winding_Clone
==================
*/
winding_t *Winding_Clone(winding_t *w)
{
    int         size;
    winding_t   *c;
    
    size = (int)((winding_t *)0)->points[w->numpoints];
    c = (winding_t*)qmalloc (size);
    memcpy (c, w, size);
    return c;
}

/*
==================
ReverseWinding
==================
*/
winding_t *Winding_Reverse(winding_t *w)
{
    int         i;
    winding_t   *c;

    c = Winding_Alloc(w->numpoints);
    for (i = 0; i < w->numpoints; i++)
    {
        VectorCopy (w->points[w->numpoints-1-i], c->points[i]);
    }
    c->numpoints = w->numpoints;
    return c;
}


/*
==============
Winding_RemovePoint
==============
*/
void Winding_RemovePoint(winding_t *w, int point)
{
    if (point < 0 || point >= w->numpoints)
        Error("Winding_RemovePoint: point out of range");

    if (point < w->numpoints-1)
    {
        memmove(&w->points[point], &w->points[point+1], (int)((winding_t *)0)->points[w->numpoints - point - 1]);
    }
    w->numpoints--;
}

/*
=============
Winding_InsertPoint
=============
*/
winding_t *Winding_InsertPoint(winding_t *w, vec3_t point, int spot)
{
    int i, j;
    winding_t *neww;

    if (spot > w->numpoints)
    {
        Error("Winding_InsertPoint: spot > w->numpoints");
    } //end if
    if (spot < 0)
    {
        Error("Winding_InsertPoint: spot < 0");
    } //end if
    neww = Winding_Alloc(w->numpoints + 1);
    neww->numpoints = w->numpoints + 1;
    for (i = 0, j = 0; i < neww->numpoints; i++)
    {
        if (i == spot)
        {
            VectorCopy(point, neww->points[i]);
        }
        else
        {
            VectorCopy(w->points[j], neww->points[i]);
            j++;
        }
    }
    return neww;
}

/*
==============
Winding_IsTiny
==============
*/
#define EDGE_LENGTH 0.2

int Winding_IsTiny (winding_t *w)
{
    int     i, j;
    vec_t   len;
    vec3_t  delta;
    int     edges;

    edges = 0;
    for (i=0 ; i<w->numpoints ; i++)
    {
        j = i == w->numpoints - 1 ? 0 : i+1;
        VectorSubtract (w->points[j], w->points[i], delta);
        len = VectorLength (delta);
        if (len > EDGE_LENGTH)
        {
            if (++edges == 3)
                return false;
        }
    }
    return true;
}

/*
==============
Winding_IsHuge
==============
*/
int Winding_IsHuge(winding_t *w)
{
    int     i, j;

    for (i=0 ; i<w->numpoints ; i++)
    {
        for (j=0 ; j<3 ; j++)
            if (w->points[i][j] < -BOGUS_RANGE+1 || w->points[i][j] > BOGUS_RANGE-1)
                return true;
    }
    return false;
}

/*
=============
Winding_PlanesConcave
=============
*/
#define WCONVEX_EPSILON     0.2

int Winding_PlanesConcave(winding_t *w1, winding_t *w2,
                             vec3_t normal1, vec3_t normal2,
                             float dist1, float dist2)
{
    int i;

    if (!w1 || !w2) return false;

    // check if one of the points of winding 1 is at the back of the plane of winding 2
    for (i = 0; i < w1->numpoints; i++)
    {
        if (DotProduct(normal2, w1->points[i]) - dist2 > WCONVEX_EPSILON) return true;
    }
    // check if one of the points of winding 2 is at the back of the plane of winding 1
    for (i = 0; i < w2->numpoints; i++)
    {
        if (DotProduct(normal1, w2->points[i]) - dist1 > WCONVEX_EPSILON) return true;
    }

    return false;
}

/*
==================
Winding_Clip

Clips the winding to the plane, returning the new winding on the positive side
Frees the input winding.
If keepon is true, an exactly on-plane winding will be saved, otherwise
it will be clipped away.
==================
*/
winding_t *Winding_Clip (winding_t *in, plane_t *split, qboolean keepon)
{
    vec_t   dists[MAX_POINTS_ON_WINDING];
    int     sides[MAX_POINTS_ON_WINDING];
    int     counts[3];
    vec_t   dot;
    int     i, j;
    vec_t   *p1, *p2;
    vec3_t  mid;
    winding_t   *neww;
    int     maxpts;
    
    counts[0] = counts[1] = counts[2] = 0;

    // determine sides for each point
    for (i=0 ; i<in->numpoints ; i++)
    {
        dot = DotProduct (in->points[i], split->normal);
        dot -= split->dist;
        dists[i] = dot;
        if (dot > ON_EPSILON)
            sides[i] = SIDE_FRONT;
        else if (dot < -ON_EPSILON)
            sides[i] = SIDE_BACK;
        else
        {
            sides[i] = SIDE_ON;
        }
        counts[sides[i]]++;
    }
    sides[i] = sides[0];
    dists[i] = dists[0];
    
    if (keepon && !counts[0] && !counts[1])
        return in;
        
    if (!counts[0])
    {
        Winding_Free (in);
        return NULL;
    }
    if (!counts[1])
        return in;
    
    maxpts = in->numpoints+4;   // can't use counts[0]+2 because
                                // of fp grouping errors
    neww = Winding_Alloc (maxpts);
        
    for (i=0 ; i<in->numpoints ; i++)
    {
        p1 = in->points[i];
        
        if (sides[i] == SIDE_ON)
        {
            VectorCopy (p1, neww->points[neww->numpoints]);
            neww->numpoints++;
            continue;
        }
    
        if (sides[i] == SIDE_FRONT)
        {
            VectorCopy (p1, neww->points[neww->numpoints]);
            neww->numpoints++;
        }
        
        if (sides[i+1] == SIDE_ON || sides[i+1] == sides[i])
            continue;
            
        // generate a split point
        p2 = in->points[(i+1)%in->numpoints];
        
        dot = dists[i] / (dists[i]-dists[i+1]);
        for (j=0 ; j<3 ; j++)
        {   // avoid round off error when possible
            if (split->normal[j] == 1)
                mid[j] = split->dist;
            else if (split->normal[j] == -1)
                mid[j] = -split->dist;
            else
                mid[j] = p1[j] + dot*(p2[j]-p1[j]);
        }
            
        VectorCopy (mid, neww->points[neww->numpoints]);
        neww->numpoints++;
    }
    
    if (neww->numpoints > maxpts)
        Error ("Winding_Clip: points exceeded estimate");
        
    // free the original winding
    Winding_Free (in);
    
    return neww;
}

/*
=============
Winding_SplitEpsilon

  split the input winding with the plane
  the input winding stays untouched
=============
*/
void Winding_SplitEpsilon (winding_t *in, vec3_t normal, double dist, 
                vec_t epsilon, winding_t **front, winding_t **back)
{
    vec_t   dists[MAX_POINTS_ON_WINDING+4];
    int     sides[MAX_POINTS_ON_WINDING+4];
    int     counts[3];
    vec_t   dot;
    int     i, j;
    vec_t   *p1, *p2;
    vec3_t  mid;
    winding_t   *f, *b;
    int     maxpts;
    
    counts[0] = counts[1] = counts[2] = 0;

    // determine sides for each point
    for (i = 0; i < in->numpoints; i++)
    {
        dot = DotProduct (in->points[i], normal);
        dot -= dist;
        dists[i] = dot;
        if (dot > epsilon)
            sides[i] = SIDE_FRONT;
        else if (dot < -epsilon)
            sides[i] = SIDE_BACK;
        else
        {
            sides[i] = SIDE_ON;
        }
        counts[sides[i]]++;
    }
    sides[i] = sides[0];
    dists[i] = dists[0];
    
    *front = *back = NULL;

    if (!counts[0])
    {
        *back = Winding_Clone(in);
        return;
    }
    if (!counts[1])
    {
        *front = Winding_Clone(in);
        return;
    }

    maxpts = in->numpoints+4;   // cant use counts[0]+2 because
                                // of fp grouping errors

    *front = f = Winding_Alloc (maxpts);
    *back = b = Winding_Alloc (maxpts);
        
    for (i = 0; i < in->numpoints; i++)
    {
        p1 = in->points[i];
        
        if (sides[i] == SIDE_ON)
        {
            VectorCopy (p1, f->points[f->numpoints]);
            f->numpoints++;
            VectorCopy (p1, b->points[b->numpoints]);
            b->numpoints++;
            continue;
        }
    
        if (sides[i] == SIDE_FRONT)
        {
            VectorCopy (p1, f->points[f->numpoints]);
            f->numpoints++;
        }
        if (sides[i] == SIDE_BACK)
        {
            VectorCopy (p1, b->points[b->numpoints]);
            b->numpoints++;
        }

        if (sides[i+1] == SIDE_ON || sides[i+1] == sides[i])
            continue;
            
        // generate a split point
        p2 = in->points[(i+1)%in->numpoints];
        
        dot = dists[i] / (dists[i]-dists[i+1]);
        for (j = 0; j < 3; j++)
        {
            // avoid round off error when possible
            if (normal[j] == 1)
                mid[j] = dist;
            else if (normal[j] == -1)
                mid[j] = -dist;
            else
                mid[j] = p1[j] + dot*(p2[j]-p1[j]);
        }
            
        VectorCopy (mid, f->points[f->numpoints]);
        f->numpoints++;
        VectorCopy (mid, b->points[b->numpoints]);
        b->numpoints++;
    }
    
    if (f->numpoints > maxpts || b->numpoints > maxpts)
        Error ("Winding_Clip: points exceeded estimate");
    if (f->numpoints > MAX_POINTS_ON_WINDING || b->numpoints > MAX_POINTS_ON_WINDING)
        Error ("Winding_Clip: MAX_POINTS_ON_WINDING");
}

/*
=============
Winding_TryMerge

If two windings share a common edge and the edges that meet at the
common points are both inside the other polygons, merge them

Returns NULL if the windings couldn't be merged, or the new winding.
The originals will NOT be freed.

if keep is true no points are ever removed
=============
*/
#define CONTINUOUS_EPSILON  0.005

winding_t *Winding_TryMerge(winding_t *f1, winding_t *f2, vec3_t planenormal, int keep)
{
    vec_t       *p1, *p2, *p3, *p4, *back;
    winding_t   *newf;
    int         i, j, k, l;
    vec3_t      normal, delta;
    vec_t       dot;
    qboolean    keep1, keep2;
    

    //
    // find a common edge
    //  
    p1 = p2 = NULL; // stop compiler warning
    j = 0;          // 
    
    for (i = 0; i < f1->numpoints; i++)
    {
        p1 = f1->points[i];
        p2 = f1->points[(i+1) % f1->numpoints];
        for (j = 0; j < f2->numpoints; j++)
        {
            p3 = f2->points[j];
            p4 = f2->points[(j+1) % f2->numpoints];
            for (k = 0; k < 3; k++)
            {
                if (fabs(p1[k] - p4[k]) > 0.1)//EQUAL_EPSILON) //ME
                    break;
                if (fabs(p2[k] - p3[k]) > 0.1)//EQUAL_EPSILON) //ME
                    break;
            } //end for
            if (k==3)
                break;
        } //end for
        if (j < f2->numpoints)
            break;
    } //end for
    
    if (i == f1->numpoints)
        return NULL;            // no matching edges

    //
    // check slope of connected lines
    // if the slopes are colinear, the point can be removed
    //
    back = f1->points[(i+f1->numpoints-1)%f1->numpoints];
    VectorSubtract (p1, back, delta);
    CrossProduct (planenormal, delta, normal);
    VectorNormalize (normal);
    
    back = f2->points[(j+2)%f2->numpoints];
    VectorSubtract (back, p1, delta);
    dot = DotProduct (delta, normal);
    if (dot > CONTINUOUS_EPSILON)
        return NULL;            // not a convex polygon
    keep1 = (qboolean)(dot < -CONTINUOUS_EPSILON);
    
    back = f1->points[(i+2)%f1->numpoints];
    VectorSubtract (back, p2, delta);
    CrossProduct (planenormal, delta, normal);
    VectorNormalize (normal);

    back = f2->points[(j+f2->numpoints-1)%f2->numpoints];
    VectorSubtract (back, p2, delta);
    dot = DotProduct (delta, normal);
    if (dot > CONTINUOUS_EPSILON)
        return NULL;            // not a convex polygon
    keep2 = (qboolean)(dot < -CONTINUOUS_EPSILON);

    //
    // build the new polygon
    //
    newf = Winding_Alloc (f1->numpoints + f2->numpoints);
    
    // copy first polygon
    for (k=(i+1)%f1->numpoints ; k != i ; k=(k+1)%f1->numpoints)
    {
        if (!keep && k==(i+1)%f1->numpoints && !keep2)
            continue;
        
        VectorCopy (f1->points[k], newf->points[newf->numpoints]);
        newf->numpoints++;
    }
    
    // copy second polygon
    for (l= (j+1)%f2->numpoints ; l != j ; l=(l+1)%f2->numpoints)
    {
        if (!keep && l==(j+1)%f2->numpoints && !keep1)
            continue;
        VectorCopy (f2->points[l], newf->points[newf->numpoints]);
        newf->numpoints++;
    }

    return newf;
}

/*
============
Winding_Plane
============
*/
void Winding_Plane (winding_t *w, vec3_t normal, double *dist)
{
    vec3_t v1, v2;
    int i;

    //find two vectors each longer than 0.5 units
    for (i = 0; i < w->numpoints; i++)
    {
        VectorSubtract(w->points[(i+1) % w->numpoints], w->points[i], v1);
        VectorSubtract(w->points[(i+2) % w->numpoints], w->points[i], v2);
        if (VectorLength(v1) > 0.5 && VectorLength(v2) > 0.5) break;
    }
    CrossProduct(v2, v1, normal);
    VectorNormalize(normal);
    *dist = DotProduct(w->points[0], normal);
}

/*
=============
Winding_Area
=============
*/
float Winding_Area (winding_t *w)
{
    int     i;
    vec3_t  d1, d2, cross;
    float   total;

    total = 0;
    for (i=2 ; i<w->numpoints ; i++)
    {
        VectorSubtract (w->points[i-1], w->points[0], d1);
        VectorSubtract (w->points[i], w->points[0], d2);
        CrossProduct (d1, d2, cross);
        total += 0.5 * VectorLength ( cross );
    }
    return total;
}

/*
=============
Winding_Bounds
=============
*/
void Winding_Bounds (winding_t *w, vec3_t mins, vec3_t maxs)
{
    vec_t   v;
    int     i,j;

    mins[0] = mins[1] = mins[2] = 99999;
    maxs[0] = maxs[1] = maxs[2] = -99999;

    for (i=0 ; i<w->numpoints ; i++)
    {
        for (j=0 ; j<3 ; j++)
        {
            v = w->points[i][j];
            if (v < mins[j])
                mins[j] = v;
            if (v > maxs[j])
                maxs[j] = v;
        }
    }
}


/*
=================
Winding_PointInside
=================
*/
int Winding_PointInside(winding_t *w, plane_t *plane, vec3_t point, float epsilon)
{
    int i;
    vec3_t dir, normal, pointvec;

    for (i = 0; i < w->numpoints; i++)
    {
        VectorSubtract(w->points[(i+1) % w->numpoints], w->points[i], dir);
        VectorSubtract(point, w->points[i], pointvec);
        //
        CrossProduct(dir, plane->normal, normal);
        //
        if (DotProduct(pointvec, normal) < -epsilon) return false;
    }
    return true;
}

/*
=================
Winding_VectorIntersect
=================
*/
int Winding_VectorIntersect(winding_t *w, plane_t *plane, vec3_t p1, vec3_t p2, float epsilon)
{
    float front, back, frac;
    vec3_t mid;

    front = DotProduct(p1, plane->normal) - plane->dist;
    back = DotProduct(p2, plane->normal) - plane->dist;
    //if both points at the same side of the plane
    if (front < -epsilon && back < -epsilon) return false;
    if (front > epsilon && back > epsilon) return false;
    //get point of intersection with winding plane
    if (fabs(front-back) < 0.001)
    {
        VectorCopy(p2, mid);
    }
    else
    {
        frac = front/(front-back);
        mid[0] = p1[0] + (p2[0] - p1[0]) * frac;
        mid[1] = p1[1] + (p2[1] - p1[1]) * frac;
        mid[2] = p1[2] + (p2[2] - p1[2]) * frac;
    }
    return Winding_PointInside(w, plane, mid, epsilon);
}

---