// NOTE: This is identical to ClipWindingEpsilon, but it does a pre/post translation to improve precision
void ClipWindingEpsilon_Offset( winding_t *in, const Vector &normal, vec_t dist, vec_t epsilon, winding_t **front, winding_t **back, const Vector &offset )
{
TranslateWinding( in, offset );
ClipWindingEpsilon( in, normal, dist+DotProduct(offset,normal), epsilon, front, back );
TranslateWinding( in, -offset );
if ( front && *front )
{
TranslateWinding( *front, -offset );
}
if ( back && *back )
{
TranslateWinding( *back, -offset );
}
}
/*
==================
CreateBrushWindings
==================
*/
void CreateBrushWindings (bspbrush_t *brush)
{
int i, j;
winding_t *w;
side_t *side;
plane_t *plane;
// translate the CSG problem to improve precision
Vector insidePoint = PointInsideBrush( brush );
Vector offset = -insidePoint;
for (i=0 ; i<brush->numsides ; i++)
{
side = &brush->sides[i];
plane = &g_MainMap->mapplanes[side->planenum];
w = BaseWindingForPlane (plane->normal, plane->dist + DotProduct(plane->normal, offset));
for (j=0 ; j<brush->numsides && w; j++)
{
if (i == j)
continue;
if (brush->sides[j].bevel)
continue;
plane = &g_MainMap->mapplanes[brush->sides[j].planenum^1];
ChopWindingInPlace (&w, plane->normal, plane->dist + DotProduct(plane->normal, offset), 0); //CLIP_EPSILON);
}
TranslateWinding( w, -offset );
side->winding = w;
}
BoundBrush (brush);
}
void SplitBrush( bspbrush_t *brush, int planenum, bspbrush_t **front, bspbrush_t **back )
{
bspbrush_t *b[2];
int i, j;
winding_t *w, *cw[2], *midwinding;
plane_t *plane, *plane2;
side_t *s, *cs;
float d, d_front, d_back;
*front = *back = NULL;
plane = &g_MainMap->mapplanes[planenum];
// check all points
d_front = d_back = 0;
for (i=0 ; i<brush->numsides ; i++)
{
w = brush->sides[i].winding;
if (!w)
continue;
for (j=0 ; j<w->numpoints ; j++)
{
d = DotProduct (w->p[j], plane->normal) - plane->dist;
if (d > 0 && d > d_front)
d_front = d;
if (d < 0 && d < d_back)
d_back = d;
}
}
if (d_front < 0.1) // PLANESIDE_EPSILON)
{ // only on back
*back = CopyBrush (brush);
return;
}
if (d_back > -0.1) // PLANESIDE_EPSILON)
{ // only on front
*front = CopyBrush (brush);
return;
}
// Move the CSG problem so that offset is at the origin
// This gives us much better floating point precision in the clipping operations
Vector offset = -0.5f * (brush->mins + brush->maxs);
// create a new winding from the split plane
w = BaseWindingForPlane (plane->normal, plane->dist + DotProduct(plane->normal,offset));
for (i=0 ; i<brush->numsides && w ; i++)
{
plane2 = &g_MainMap->mapplanes[brush->sides[i].planenum ^ 1];
ChopWindingInPlace (&w, plane2->normal, plane2->dist+DotProduct(plane2->normal,offset), 0); // PLANESIDE_EPSILON);
}
if (!w || WindingIsTiny (w) )
{ // the brush isn't really split
int side;
side = BrushMostlyOnSide (brush, plane);
if (side == PSIDE_FRONT)
*front = CopyBrush (brush);
if (side == PSIDE_BACK)
*back = CopyBrush (brush);
return;
}
if (WindingIsHuge (w))
{
qprintf ("WARNING: huge winding\n");
}
TranslateWinding( w, -offset );
midwinding = w;
//
//
// split it for real
//
//
//
// allocate two new brushes referencing the original
//
for( i = 0; i < 2; i++ )
{
b[i] = AllocBrush( brush->numsides + 1 );
b[i]->original = brush->original;
}
//
// split all the current windings
//
for( i = 0; i < brush->numsides; i++ )
{
// get the current side
s = &brush->sides[i];
// get the sides winding
w = s->winding;
if( !w )
continue;
// clip the winding
ClipWindingEpsilon_Offset( w, plane->normal, plane->dist, 0 /*PLANESIDE_EPSILON*/, &cw[0], &cw[1], offset );
for( j = 0; j < 2; j++ )
{
// does winding exist?
if( !cw[j] )
continue;
#if 0
if (WindingIsTiny (cw[j]))
{
FreeWinding (cw[j]);
continue;
}
#endif
//
// create a clipped "side" with the new winding
//
cs = &b[j]->sides[b[j]->numsides];
b[j]->numsides++;
*cs = *s;
cs->winding = cw[j];
cs->tested = false;
// save the original side information
//cs->original = s->original;
}
}
// see if we have valid polygons on both sides
for (i=0 ; i<2 ; i++)
{
BoundBrush (b[i]);
for (j=0 ; j<3 ; j++)
{
if (b[i]->mins[j] < MIN_COORD_INTEGER || b[i]->maxs[j] > MAX_COORD_INTEGER)
{
qprintf ("bogus brush after clip\n");
break;
}
}
if (b[i]->numsides < 3 || j < 3)
{
FreeBrush (b[i]);
b[i] = NULL;
}
}
if ( !(b[0] && b[1]) )
{
if (!b[0] && !b[1])
qprintf ("split removed brush\n");
else
qprintf ("split not on both sides\n");
if (b[0])
{
FreeBrush (b[0]);
*front = CopyBrush (brush);
}
if (b[1])
{
FreeBrush (b[1]);
*back = CopyBrush (brush);
}
return;
}
// add the midwinding to both sides
for (i=0 ; i<2 ; i++)
{
cs = &b[i]->sides[b[i]->numsides];
b[i]->numsides++;
cs->planenum = planenum^i^1;
cs->texinfo = TEXINFO_NODE;
// initialize the displacement map index
cs->pMapDisp = NULL;
cs->visible = false;
cs->tested = false;
if (i==0)
cs->winding = CopyWinding (midwinding);
else
cs->winding = midwinding;
}
{
vec_t v1;
int i;
for (i=0 ; i<2 ; i++)
{
v1 = BrushVolume (b[i]);
if (v1 < 1.0)
{
FreeBrush (b[i]);
b[i] = NULL;
// qprintf ("tiny volume after clip\n");
}
}
}
*front = b[0];
*back = b[1];
}