- some redesign of P_CheckSight to handle portals.

Portal stuff not tested yet.
This commit is contained in:
Christoph Oelckers 2016-03-07 21:58:34 +01:00
parent f82c217047
commit 3c25b2c066
11 changed files with 268 additions and 65 deletions

View file

@ -140,7 +140,7 @@ DEFINE_SPECIAL(Sector_ChangeSound, 140, 2, 2, 2)
DEFINE_SPECIAL(Teleport_NoStop, 154, 2, 3, 3)
// portal specials
DEFINE_SPECIAL(Line_SetPortal, 156, -1, -1, 3)
DEFINE_SPECIAL(Line_SetPortal, 156, -1, -1, 4)
// GZDoom/Vavoom specials
// Although ZDoom doesn't support them it's better to have them defined so that
// WADs using them somewhere can at least be started without aborting due

View file

@ -743,7 +743,7 @@ public:
inline bool IsNoClip2() const;
void CheckPortalTransition(bool islinked);
fixedvec3 GetPortalTransition(fixed_t byoffset);
fixedvec3 GetPortalTransition(fixed_t byoffset, sector_t **pSec = NULL);
// What species am I?
virtual FName GetSpecies();

View file

@ -121,7 +121,7 @@ struct maplinedef2_t
// LineDef attributes.
//
enum ELineFlags
enum ELineFlags : unsigned
{
ML_BLOCKING =0x00000001, // solid, is an obstacle
ML_BLOCKMONSTERS =0x00000002, // blocks monsters only
@ -163,6 +163,8 @@ enum ELineFlags
ML_BLOCKSIGHT = 0x04000000, // blocks monster line of sight
ML_BLOCKHITSCAN = 0x08000000, // blocks hitscan attacks
ML_3DMIDTEX_IMPASS = 0x10000000, // [TP] if 3D midtex, behaves like a height-restricted ML_BLOCKING
ML_PORTALCONNECT = 0x80000000, // for internal use only: This line connects to a sector with a linked portal (used to speed up sight checks.)
};

View file

@ -275,7 +275,7 @@ void P_PlayerStartStomp (AActor *actor, bool mononly=false); // [RH] Stomp on t
void P_SlideMove (AActor* mo, fixed_t tryx, fixed_t tryy, int numsteps);
bool P_BounceWall (AActor *mo);
bool P_BounceActor (AActor *mo, AActor *BlockingMobj, bool ontop);
bool P_CheckSight (const AActor *t1, const AActor *t2, int flags=0);
bool P_CheckSight (AActor *t1, AActor *t2, int flags=0);
enum ESightFlags
{

View file

@ -5575,7 +5575,6 @@ void P_FindBelowIntersectors(AActor *actor)
if (!(actor->flags & MF_SOLID))
return;
AActor *thing;
FPortalGroupArray check;
FMultiBlockThingsIterator it(check, actor);
FMultiBlockThingsIterator::CheckResult cres;

View file

@ -162,7 +162,7 @@ void P_LineOpening (FLineOpening &open, AActor *actor, const line_t *linedef,
front = linedef->frontsector;
back = linedef->backsector;
if (!(flags & FFCF_NOPORTALS))
if (!(flags & FFCF_NOPORTALS) && (linedef->flags & ML_PORTALCONNECT))
{
if (!linedef->frontsector->PortalBlocksMovement(sector_t::ceiling)) fc = FIXED_MAX;
if (!linedef->backsector->PortalBlocksMovement(sector_t::ceiling)) bc = FIXED_MAX;

View file

@ -3285,7 +3285,7 @@ void AActor::SetRoll(angle_t r, bool interpolate)
}
fixedvec3 AActor::GetPortalTransition(fixed_t byoffset)
fixedvec3 AActor::GetPortalTransition(fixed_t byoffset, sector_t **pSec)
{
bool moved = false;
sector_t *sec = Sector;
@ -3316,6 +3316,7 @@ fixedvec3 AActor::GetPortalTransition(fixed_t byoffset)
else break;
}
}
if (pSec) *pSec = sec;
return pos;
}

View file

@ -48,13 +48,48 @@ static int sightcounts[6];
static cycle_t SightCycles;
static cycle_t MaxSightCycles;
enum
{
SO_TOPFRONT = 1,
SO_TOPBACK = 2,
SO_BOTTOMFRONT = 4,
SO_BOTTOMBACK = 8,
};
struct SightOpening
{
fixed_t top;
fixed_t bottom;
int range;
int portalflags;
void SwapSides()
{
portalflags = ((portalflags & (SO_TOPFRONT | SO_BOTTOMFRONT)) << 1) | ((portalflags & (SO_TOPBACK | SO_BOTTOMBACK)) >> 1);
}
};
struct SightTask
{
fixed_t frac;
fixed_t topslope;
fixed_t bottomslope;
int direction;
int portalgroup;
};
static TArray<intercept_t> intercepts (128);
static TArray<SightTask> portals(32);
class SightCheck
{
fixed_t sightzstart; // eye z of looker
const AActor * sightthing;
const AActor * seeingthing;
fixedvec3 sightstart;
fixedvec2 sightend;
fixed_t startfrac;
AActor * seeingthing;
fixed_t lastztop; // z at last line
fixed_t lastzbottom; // z at last line
sector_t * lastsector; // last sector being entered by trace
@ -63,28 +98,95 @@ class SightCheck
divline_t trace;
unsigned int myseethrough;
void P_SightOpening(SightOpening &open, const line_t *linedef, fixed_t x, fixed_t y);
bool PTR_SightTraverse (intercept_t *in);
bool P_SightCheckLine (line_t *ld);
bool P_SightBlockLinesIterator (int x, int y);
int P_SightBlockLinesIterator (int x, int y);
bool P_SightTraverseIntercepts ();
public:
bool P_SightPathTraverse (fixed_t x1, fixed_t y1, fixed_t x2, fixed_t y2);
bool P_SightPathTraverse ();
SightCheck(const AActor * t1, const AActor * t2, int flags)
void init(AActor * t1, AActor * t2, sector_t *startsector, SightTask *task, int flags)
{
lastztop = lastzbottom = sightzstart = t1->Z() + t1->height - (t1->height>>2);
lastsector = t1->Sector;
sightthing=t1;
sightstart = t1->PosRelative(startsector);
sightend = t2->PosRelative(startsector);
sightstart.z += t1->height - (t1->height >> 2);
startfrac = task->frac;
trace = { sightstart.x, sightstart.y, sightend.x - sightstart.x, sightend.y - sightstart.y };
lastztop = lastzbottom = sightstart.z;
lastsector = startsector;
seeingthing=t2;
bottomslope = t2->Z() - sightzstart;
topslope = bottomslope + t2->height;
topslope = task->topslope;
bottomslope = task->bottomslope;
Flags = flags;
portaldir = task->direction;
myseethrough = FF_SEETHROUGH;
if (portaldir != sector_t::floor && !t1->Sector->PortalBlocksSight(sector_t::ceiling))
{
portals.Push({ 0, topslope, bottomslope, sector_t::ceiling, t1->Sector->SkyBoxes[sector_t::ceiling]->Sector->PortalGroup });
}
if (portaldir != sector_t::ceiling && !t1->Sector->PortalBlocksSight(sector_t::floor))
{
portals.Push({ 0, topslope, bottomslope, sector_t::floor, t1->Sector->SkyBoxes[sector_t::floor]->Sector->PortalGroup });
}
}
};
//==========================================================================
//
// P_SightOpening
//
// Simplified version that removes everything not needed for a sight check
//
//==========================================================================
void SightCheck::P_SightOpening(SightOpening &open, const line_t *linedef, fixed_t x, fixed_t y)
{
open.portalflags = 0;
sector_t *front = linedef->frontsector;
sector_t *back = linedef->backsector;
if (back == NULL)
{
// single sided line
if (linedef->flags & ML_PORTALCONNECT)
{
if (!front->PortalBlocksSight(sector_t::ceiling)) open.portalflags |= SO_TOPFRONT;
if (!front->PortalBlocksSight(sector_t::floor)) open.portalflags |= SO_BOTTOMFRONT;
}
open.range = 0;
return;
}
fixed_t fc = 0, ff = 0, bc = 0, bf = 0;
if (linedef->flags & ML_PORTALCONNECT)
{
if (!front->PortalBlocksSight(sector_t::ceiling)) fc = FIXED_MAX, open.portalflags |= SO_TOPFRONT;
if (!back->PortalBlocksSight(sector_t::ceiling)) bc = FIXED_MAX, open.portalflags |= SO_TOPBACK;
if (!front->PortalBlocksSight(sector_t::floor)) ff = FIXED_MIN, open.portalflags |= SO_BOTTOMFRONT;
if (!back->PortalBlocksSight(sector_t::floor)) bf = FIXED_MIN, open.portalflags |= SO_BOTTOMBACK;
}
if (fc == 0) fc = front->ceilingplane.ZatPoint(x, y);
if (bc == 0) bc = back->ceilingplane.ZatPoint(x, y);
if (ff == 0) ff = front->floorplane.ZatPoint(x, y);
if (bf == 0) bf = back->floorplane.ZatPoint(x, y);
open.bottom = MAX(ff, bf);
open.top = MIN(fc, bc);
// we only want to know if there is an opening, not how large it is.
open.range = open.bottom >= open.top ? 0 : 1;
}
/*
==============
=
@ -93,14 +195,12 @@ public:
==============
*/
/*
static bool PTR_SightTraverse (intercept_t *in)
*/
bool SightCheck::PTR_SightTraverse (intercept_t *in)
{
line_t *li;
fixed_t slope;
FLineOpening open;
SightOpening open;
int frontflag = -1;
li = in->d.line;
@ -114,30 +214,68 @@ bool SightCheck::PTR_SightTraverse (intercept_t *in)
fixed_t trX=trace.x + FixedMul (trace.dx, in->frac);
fixed_t trY=trace.y + FixedMul (trace.dy, in->frac);
P_LineOpening (open, NULL, li, trX, trY);
P_SightOpening (open, li, trX, trY);
if (open.range <= 0) // quick test for totally closed doors
FLinePortal *lport = li->getPortal();
if (open.range == 0 && open.portalflags == 0 && (lport == NULL || lport->mType != PORTT_LINKED)) // quick test for totally closed doors (must be delayed if portal checks are needed, though)
return false; // stop
// check bottom
slope = FixedDiv (open.bottom - sightzstart, in->frac);
if (slope > bottomslope)
bottomslope = slope;
if (open.bottom > FIXED_MIN)
{
slope = FixedDiv(open.bottom - sightstart.z, in->frac);
if (slope > bottomslope)
bottomslope = slope;
}
// check top
slope = FixedDiv (open.top - sightzstart, in->frac);
if (slope < topslope)
topslope = slope;
if (open.top < FIXED_MAX)
{
slope = FixedDiv(open.top - sightstart.z, in->frac);
if (slope < topslope)
topslope = slope;
}
if (topslope <= bottomslope)
if (open.portalflags)
{
sector_t *frontsec, *backsec;
frontflag = P_PointOnLineSidePrecise(sightstart.x, sightstart.y, li);
if (!frontflag)
{
frontsec = li->frontsector;
backsec = li->backsector;
}
else
{
frontsec = li->backsector;
if (!frontsec) return false; // We are looking through the backside of a one-sided line. Just abort if that happens.
backsec = li->backsector;
open.SwapSides(); // swap flags to make the next checks simpler.
}
if (portaldir != sector_t::floor && (open.portalflags & SO_TOPBACK) && !(open.portalflags & SO_TOPFRONT))
{
portals.Push({ in->frac, topslope, bottomslope, sector_t::ceiling, backsec->SkyBoxes[sector_t::ceiling]->Sector->PortalGroup });
}
if (portaldir != sector_t::ceiling && (open.portalflags & SO_BOTTOMBACK) && !(open.portalflags & SO_BOTTOMFRONT))
{
portals.Push({ in->frac, topslope, bottomslope, sector_t::floor, backsec->SkyBoxes[sector_t::floor]->Sector->PortalGroup });
}
}
if (lport)
{
portals.Push({ in->frac, topslope, bottomslope, portaldir, lport->mDestination->frontsector->PortalGroup });
return false;
}
if (topslope <= bottomslope || open.range == 0)
return false; // stop
// now handle 3D-floors
if(li->frontsector->e->XFloor.ffloors.Size() || li->backsector->e->XFloor.ffloors.Size())
{
int frontflag;
frontflag = P_PointOnLineSidePrecise(sightthing->X(), sightthing->Y(), li);
if (frontflag == -1) frontflag = P_PointOnLineSidePrecise(sightstart.x, sightstart.y, li);
//Check 3D FLOORS!
for(int i=1;i<=2;i++)
@ -145,8 +283,8 @@ bool SightCheck::PTR_SightTraverse (intercept_t *in)
sector_t * s=i==1? li->frontsector:li->backsector;
fixed_t highslope, lowslope;
fixed_t topz= FixedMul (topslope, in->frac) + sightzstart;
fixed_t bottomz= FixedMul (bottomslope, in->frac) + sightzstart;
fixed_t topz= FixedMul (topslope, in->frac) + sightstart.z;
fixed_t bottomz= FixedMul (bottomslope, in->frac) + sightstart.z;
for(unsigned int j=0;j<s->e->XFloor.ffloors.Size();j++)
{
@ -158,8 +296,8 @@ bool SightCheck::PTR_SightTraverse (intercept_t *in)
fixed_t ff_bottom=rover->bottom.plane->ZatPoint(trX, trY);
fixed_t ff_top=rover->top.plane->ZatPoint(trX, trY);
highslope = FixedDiv (ff_top - sightzstart, in->frac);
lowslope = FixedDiv (ff_bottom - sightzstart, in->frac);
highslope = FixedDiv (ff_top - sightstart.z, in->frac);
lowslope = FixedDiv (ff_bottom - sightstart.z, in->frac);
if (highslope>=topslope)
{
@ -221,8 +359,8 @@ bool SightCheck::PTR_SightTraverse (intercept_t *in)
}
else lastsector=NULL; // don't need it if there are no 3D-floors
lastztop= FixedMul (topslope, in->frac) + sightzstart;
lastzbottom= FixedMul (bottomslope, in->frac) + sightzstart;
lastztop= FixedMul (topslope, in->frac) + sightstart.z;
lastzbottom= FixedMul (bottomslope, in->frac) + sightstart.z;
return true; // keep going
}
@ -308,18 +446,22 @@ bool SightCheck::P_SightCheckLine (line_t *ld)
===================
*/
bool SightCheck::P_SightBlockLinesIterator (int x, int y)
int SightCheck::P_SightBlockLinesIterator (int x, int y)
{
int offset;
int *list;
int res = 1;
bool portals;
polyblock_t *polyLink;
unsigned int i;
extern polyblock_t **PolyBlockMap;
offset = y*bmapwidth+x;
portals = PortalBlockmap(x, y).containsLinkedPortals;
polyLink = PolyBlockMap[offset];
portals |= (polyLink && PortalBlockmap.hasLinkedPolyPortals);
while (polyLink)
{
if (polyLink->polyobj)
@ -329,8 +471,11 @@ bool SightCheck::P_SightBlockLinesIterator (int x, int y)
polyLink->polyobj->validcount = validcount;
for (i = 0; i < polyLink->polyobj->Linedefs.Size(); i++)
{
if (!P_SightCheckLine (polyLink->polyobj->Linedefs[i]))
return false;
if (!P_SightCheckLine(polyLink->polyobj->Linedefs[i]))
{
if (!portals) return 0;
else res = -1;
}
}
}
}
@ -342,10 +487,13 @@ bool SightCheck::P_SightBlockLinesIterator (int x, int y)
for (list = blockmaplump + offset + 1; *list != -1; list++)
{
if (!P_SightCheckLine (&lines[*list]))
return false;
{
if (!portals) return 0;
else res = -1;
}
}
return true; // everything was checked
return res; // everything was checked
}
/*
@ -378,8 +526,7 @@ bool SightCheck::P_SightTraverseIntercepts ()
//
// go through in order
// [RH] Is it really necessary to go through in order? All we care about is if
// the trace is obstructed, not what specifically obstructed it.
// proper order is needed to handle 3D floors and portals.
//
in = NULL;
@ -408,8 +555,8 @@ bool SightCheck::P_SightTraverseIntercepts ()
{
// we must do one last check whether the trace has crossed a 3D floor in the last sector
fixed_t topz= topslope + sightzstart;
fixed_t bottomz= bottomslope + sightzstart;
fixed_t topz= topslope + sightstart.z;
fixed_t bottomz= bottomslope + sightstart.z;
for(unsigned int i=0;i<lastsector->e->XFloor.ffloors.Size();i++)
{
@ -441,8 +588,9 @@ bool SightCheck::P_SightTraverseIntercepts ()
==================
*/
bool SightCheck::P_SightPathTraverse (fixed_t x1, fixed_t y1, fixed_t x2, fixed_t y2)
bool SightCheck::P_SightPathTraverse ()
{
fixed_t x1, x2, y1, y2;
fixed_t xt1,yt1,xt2,yt2;
long long _x1,_y1,_x2,_y2;
fixed_t xstep,ystep;
@ -453,6 +601,11 @@ bool SightCheck::P_SightPathTraverse (fixed_t x1, fixed_t y1, fixed_t x2, fixed_
validcount++;
intercepts.Clear ();
x1 = sightstart.x + FixedMul(startfrac, trace.dx);
y1 = sightstart.y + FixedMul(startfrac, trace.dy);
x2 = sightend.x;
y2 = sightend.y;
if (lastsector == NULL) lastsector = P_PointInSector(x1, y1);
// for FF_SEETHROUGH the following rule applies:
// If the viewer is in an area without FF_SEETHROUGH he can only see into areas without this flag
@ -463,10 +616,10 @@ bool SightCheck::P_SightPathTraverse (fixed_t x1, fixed_t y1, fixed_t x2, fixed_
if(!(rover->flags & FF_EXISTS)) continue;
fixed_t ff_bottom=rover->bottom.plane->ZatPoint(sightthing);
fixed_t ff_top=rover->top.plane->ZatPoint(sightthing);
fixed_t ff_bottom=rover->bottom.plane->ZatPoint(sightstart);
fixed_t ff_top=rover->top.plane->ZatPoint(sightstart);
if (sightzstart < ff_top && sightzstart >= ff_bottom)
if (sightstart.z < ff_top && sightstart.z >= ff_bottom)
{
myseethrough = rover->flags & FF_SEETHROUGH;
break;
@ -477,10 +630,6 @@ bool SightCheck::P_SightPathTraverse (fixed_t x1, fixed_t y1, fixed_t x2, fixed_
x1 += FRACUNIT; // don't side exactly on a line
if ( ((y1-bmaporgy)&(MAPBLOCKSIZE-1)) == 0)
y1 += FRACUNIT; // don't side exactly on a line
trace.x = x1;
trace.y = y1;
trace.dx = x2 - x1;
trace.dy = y2 - y1;
_x1 = (long long)x1 - bmaporgx;
_y1 = (long long)y1 - bmaporgy;
@ -572,13 +721,15 @@ bool SightCheck::P_SightPathTraverse (fixed_t x1, fixed_t y1, fixed_t x2, fixed_
for (count = 0 ; count < 100 ; count++)
{
if (!P_SightBlockLinesIterator (mapx, mapy))
int res = P_SightBlockLinesIterator(mapx, mapy);
if (res == 0)
{
sightcounts[1]++;
return false; // early out
}
if ((mapxstep | mapystep) == 0)
// either reached the end or had an early-out condition with portals left to check,
if (res == -1 || (mapxstep | mapystep) == 0)
break;
switch ((((yintercept >> FRACBITS) == mapy) << 1) | ((xintercept >> FRACBITS) == mapx))
@ -649,7 +800,7 @@ sightcounts[2]++;
=====================
*/
bool P_CheckSight (const AActor *t1, const AActor *t2, int flags)
bool P_CheckSight (AActor *t1, AActor *t2, int flags)
{
SightCycles.Clock();
@ -717,8 +868,28 @@ sightcounts[0]++;
validcount++;
{
SightCheck s(t1, t2, flags);
res = s.P_SightPathTraverse (t1->X(), t1->Y(), t2->X(), t2->Y());
sector_t *sec;
fixed_t lookheight = t1->height - (t1->height >> 2);
t1->GetPortalTransition(lookheight, &sec);
fixed_t bottomslope = t2->Z() - (t1->Z() + lookheight);
fixed_t topslope = bottomslope + t2->height;
SightTask task = { 0, topslope, bottomslope, -1, sec->PortalGroup };
SightCheck s;
s.init(t1, t2, sec, &task, flags);
res = s.P_SightPathTraverse ();
if (!res)
{
fixed_t dist = t1->AproxDistance(t2);
for (unsigned i = 0; i < portals.Size(); i++)
{
portals[i].frac += FixedDiv(FRACUNIT, dist);
s.init(t1, t2, NULL, &portals[i], flags);
if (s.P_SightPathTraverse()) break;
}
}
}
done:

View file

@ -122,15 +122,27 @@ static void BuildBlockmap()
PortalBlockmap.containsLines = true;
block.portallines.Push(ld);
block.neighborContainsLines = true;
if (ld->getPortal()->mType == PORTT_LINKED) block.containsLinkedPortals = true;
if (x > 0) PortalBlockmap(x - 1, y).neighborContainsLines = true;
if (y > 0) PortalBlockmap(x, y - 1).neighborContainsLines = true;
if (x < PortalBlockmap.dx - 1) PortalBlockmap(x + 1, y).neighborContainsLines = true;
if (y < PortalBlockmap.dy - 1) PortalBlockmap(x, y + 1).neighborContainsLines = true;
}
else
{
bool yes = ld->frontsector->PortalIsLinked(sector_t::ceiling) || ld->frontsector->PortalIsLinked(sector_t::floor);
if (ld->backsector)
{
yes |= ld->backsector->PortalIsLinked(sector_t::ceiling) || ld->backsector->PortalIsLinked(sector_t::floor);
}
block.containsLinkedPortals |= yes;
PortalBlockmap.hasLinkedSectorPortals |= yes;
}
}
}
}
if (!PortalBlockmap.containsLines) PortalBlockmap.Clear();
}
//===========================================================================
@ -1066,6 +1078,14 @@ void P_CreateLinkedPortals()
{
sectors[i].CheckPortalPlane(sector_t::floor);
sectors[i].CheckPortalPlane(sector_t::ceiling);
// set a flag on each line connecting to a plane portal sector. This is used to reduce the amount of checks in P_CheckSight.
if (sectors[i].PortalIsLinked(sector_t::floor) || sectors[i].PortalIsLinked(sector_t::ceiling))
{
for (int j = 0; j < sectors[j].linecount; j++)
{
sectors[i].lines[j]->flags |= ML_PORTALCONNECT;
}
}
}
//BuildBlockmap();
}

View file

@ -78,11 +78,13 @@ extern FDisplacementTable Displacements;
struct FPortalBlock
{
bool neighborContainsLines; // this is for skipping the traverser and exiting early if we can quickly decide that there's no portals nearby.
bool containsLinkedPortals; // this is for sight check optimization. We can't early-out on an impenetrable line if there may be portals being found in the same block later on.
TArray<line_t*> portallines;
FPortalBlock()
{
neighborContainsLines = false;
containsLinkedPortals = false;
}
};
@ -91,6 +93,8 @@ struct FPortalBlockmap
TArray<FPortalBlock> data;
int dx, dy;
bool containsLines;
bool hasLinkedSectorPortals; // global flag to shortcut portal checks if the map has none.
bool hasLinkedPolyPortals; // this means that any early-outs in P_CheckSight need to be disabled if a block contains polyobjects.
void Create(int blockx, int blocky)
{
@ -105,6 +109,8 @@ struct FPortalBlockmap
data.ShrinkToFit();
dx = dy = 0;
containsLines = false;
hasLinkedPolyPortals = false;
hasLinkedSectorPortals = false;
}
FPortalBlock &operator()(int x, int y)

View file

@ -185,7 +185,6 @@ public:
//
class DSectorEffect;
struct sector_t;
struct line_t;
struct FRemapTable;
enum
@ -769,7 +768,7 @@ struct sector_t
bool PortalBlocksSight(int plane)
{
if (SkyBoxes[plane] == NULL || SkyBoxes[plane]->special1 != SKYBOX_LINKEDPORTAL) return true;
return !!(planes[plane].Flags & (PLANEF_NORENDER | PLANEF_DISABLED | PLANEF_OBSTRUCTED));
return !!(planes[plane].Flags & (PLANEF_NORENDER | PLANEF_NOPASS | PLANEF_DISABLED | PLANEF_OBSTRUCTED));
}
bool PortalBlocksMovement(int plane)
@ -784,6 +783,11 @@ struct sector_t
return !!(planes[plane].Flags & (PLANEF_BLOCKSOUND | PLANEF_DISABLED | PLANEF_OBSTRUCTED));
}
bool PortalIsLinked(int plane)
{
return (SkyBoxes[plane] != NULL && SkyBoxes[plane]->special1 == SKYBOX_LINKEDPORTAL);
}
// These may only be called if the portal has been validated
fixedvec2 FloorDisplacement()
{