/*
==================
BuildSurfaces
Returns a chain of all the external surfaces with one or more visible
faces.
==================
*/
void BuildSurfaces( tree_t *tree )
{
int i;
face_t **f;
face_t *count;
surface_t *s;
surface_t *surfhead;
surfhead = NULL;
for( i = 0, f = tree->validfaces; i < nummapplanes; i++, f++ ) {
if( !*f )
continue; // nothing left on this plane
// create a new surface to hold the faces on this plane
s = AllocSurface ();
s->planenum = i;
s->next = surfhead;
surfhead = s;
s->faces = *f;
for( count = s->faces; count; count = count->next )
numcsgmergefaces++;
CalcSurfaceInfo( s ); // bounding box and flags
}
tree->surfaces = surfhead;
}
/*
==================
DivideSurface
==================
*/
void DivideSurface (surface_t *in, dplane_t *split, surface_t **front, surface_t **back)
{
face_t *facet, *next;
face_t *frontlist, *backlist;
face_t *frontfrag, *backfrag;
surface_t *news;
dplane_t *inplane;
inplane = &dplanes[in->planenum];
// parallel case is easy
if (inplane->normal[0] == split->normal[0]
&& inplane->normal[1] == split->normal[1]
&& inplane->normal[2] == split->normal[2])
{
if (inplane->dist > split->dist)
{
*front = in;
*back = NULL;
}
else if (inplane->dist < split->dist)
{
*front = NULL;
*back = in;
}
else
{ // split the surface into front and back
frontlist = NULL;
backlist = NULL;
for (facet = in->faces ; facet ; facet = next)
{
next = facet->next;
if (facet->planenum & 1)
{
facet->next = backlist;
backlist = facet;
}
else
{
facet->next = frontlist;
frontlist = facet;
}
}
goto makesurfs;
}
return;
}
// do a real split. may still end up entirely on one side
// OPTIMIZE: use bounding box for fast test
frontlist = NULL;
backlist = NULL;
for (facet = in->faces ; facet ; facet = next)
{
next = facet->next;
SplitFace (facet, split, &frontfrag, &backfrag);
if (frontfrag)
{
frontfrag->next = frontlist;
frontlist = frontfrag;
}
if (backfrag)
{
backfrag->next = backlist;
backlist = backfrag;
}
}
// if nothing actually got split, just move the in plane
makesurfs:
if (frontlist == NULL)
{
*front = NULL;
*back = in;
in->faces = backlist;
return;
}
if (backlist == NULL)
{
*front = in;
*back = NULL;
in->faces = frontlist;
return;
}
// stuff got split, so allocate one new surface and reuse in
news = AllocSurface ();
*news = *in;
news->faces = backlist;
*back = news;
in->faces = frontlist;
*front = in;
// recalc bboxes and flags
CalcSurfaceInfo (news);
CalcSurfaceInfo (in);
}
/*
==================
DividePlane
==================
*/
void DividePlane (surface_t *in, plane_t *split, surface_t **front, surface_t **back)
{
face_t *facet, *next;
face_t *frontlist, *backlist;
face_t *frontfrag, *backfrag;
surface_t *news;
plane_t *inplane;
inplane = &planes[in->planenum];
// parallel case is easy
if (VectorCompare (inplane->normal, split->normal))
{
// check for exactly on node
if (inplane->dist == split->dist)
{ // divide the facets to the front and back sides
news = AllocSurface ();
*news = *in;
facet=in->faces;
in->faces = NULL;
news->faces = NULL;
in->onnode = news->onnode = true;
for ( ; facet ; facet=next)
{
next = facet->next;
if (facet->planeside == 1)
{
facet->next = news->faces;
news->faces = facet;
}
else
{
facet->next = in->faces;
in->faces = facet;
}
}
if (in->faces)
*front = in;
else
*front = NULL;
if (news->faces)
*back = news;
else
*back = NULL;
return;
}
if (inplane->dist > split->dist)
{
*front = in;
*back = NULL;
}
else
{
*front = NULL;
*back = in;
}
return;
}
// do a real split. may still end up entirely on one side
// OPTIMIZE: use bounding box for fast test
frontlist = NULL;
backlist = NULL;
for (facet = in->faces ; facet ; facet = next)
{
next = facet->next;
SplitFace (facet, split, &frontfrag, &backfrag);
if (frontfrag)
{
frontfrag->next = frontlist;
frontlist = frontfrag;
}
if (backfrag)
{
backfrag->next = backlist;
backlist = backfrag;
}
}
// if nothing actually got split, just move the in plane
if (frontlist == NULL)
{
*front = NULL;
*back = in;
in->faces = backlist;
return;
}
if (backlist == NULL)
{
*front = in;
*back = NULL;
in->faces = frontlist;
return;
}
// stuff got split, so allocate one new plane and reuse in
news = AllocSurface ();
*news = *in;
news->faces = backlist;
*back = news;
in->faces = frontlist;
*front = in;
// recalc bboxes and flags
CalcSurfaceInfo (news);
CalcSurfaceInfo (in);
}
