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diff --git a/apps/plugins/doom/p_sight.c b/apps/plugins/doom/p_sight.c
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+/* Emacs style mode select   -*- C++ -*-
+ *-----------------------------------------------------------------------------
+ *
+ *
+ *  PrBoom a Doom port merged with LxDoom and LSDLDoom
+ *  based on BOOM, a modified and improved DOOM engine
+ *  Copyright (C) 1999 by
+ *  id Software, Chi Hoang, Lee Killough, Jim Flynn, Rand Phares, Ty Halderman
+ *  Copyright (C) 1999-2000 by
+ *  Jess Haas, Nicolas Kalkhof, Colin Phipps, Florian Schulze
+ *
+ *  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 the Free Software
+ *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ *  02111-1307, USA.
+ *
+ * DESCRIPTION:
+ *      LineOfSight/Visibility checks, uses REJECT Lookup Table.
+ *
+ *-----------------------------------------------------------------------------*/
+
+#include "doomstat.h"
+#include "r_main.h"
+#include "p_maputl.h"
+#include "p_setup.h"
+#include "m_bbox.h"
+#include "rockmacros.h"
+//
+// P_CheckSight
+//
+// killough 4/19/98:
+// Convert LOS info to struct for reentrancy and efficiency of data locality
+
+typedef struct {
+   fixed_t sightzstart, t2x, t2y;   // eye z of looker
+   divline_t strace;                // from t1 to t2
+   fixed_t topslope, bottomslope;   // slopes to top and bottom of target
+   fixed_t bbox[4];
+   fixed_t maxz,minz;               // cph - z optimisations for 2sided lines
+} los_t;
+
+static los_t los; // cph - made static
+
+//
+// P_DivlineSide
+// Returns side 0 (front), 1 (back), or 2 (on).
+//
+// killough 4/19/98: made static, cleaned up
+
+inline static int P_DivlineSide(fixed_t x, fixed_t y, const divline_t *node)
+{
+   fixed_t left, right;
+   return
+   !node->dx ? x == node->x ? 2 : x <= node->x ? node->dy > 0 : node->dy < 0 :
+   !node->dy ? x == node->y ? 2 : y <= node->y ? node->dx < 0 : node->dx > 0 :
+      (right = ((y - node->y) >> FRACBITS) * (node->dx >> FRACBITS)) <
+      (left  = ((x - node->x) >> FRACBITS) * (node->dy >> FRACBITS)) ? 0 :
+      right == left ? 2 : 1;
+}
+
+//
+// P_InterceptVector2
+// Returns the fractional intercept point
+// along the first divline.
+//
+// killough 4/19/98: made static, cleaned up
+
+static fixed_t P_InterceptVector2(const divline_t *v2, const divline_t *v1)
+{
+   fixed_t den;
+   return (den = FixedMul(v1->dy>>8, v2->dx) - FixedMul(v1->dx>>8, v2->dy)) ?
+          FixedDiv(FixedMul((v1->x - v2->x)>>8, v1->dy) +
+                   FixedMul((v2->y - v1->y)>>8, v1->dx), den) : 0;
+}
+
+//
+// P_CrossSubsector
+// Returns true
+//  if strace crosses the given subsector successfully.
+//
+// killough 4/19/98: made static and cleaned up
+
+static boolean P_CrossSubsector(int num)
+{
+   seg_t *seg = segs + subsectors[num].firstline;
+   int count;
+   fixed_t opentop = 0, openbottom = 0;
+   const sector_t *front = NULL, *back = NULL;
+
+#ifdef RANGECHECK
+   if (num >= numsubsectors)
+      I_Error("P_CrossSubsector: ss %i with numss = %i", num, numsubsectors);
+#endif
+
+   for (count = subsectors[num].numlines; --count >= 0; seg++) { // check lines
+      line_t *line = seg->linedef;
+      divline_t divl;
+
+      if(!line) // figgi -- skip minisegs
+         continue;
+
+      // allready checked other side?
+      if (line->validcount == validcount)
+         continue;
+
+      line->validcount = validcount;
+
+      /* OPTIMIZE: killough 4/20/98: Added quick bounding-box rejection test
+       * cph - this is causing demo desyncs on original Doom demos.
+       *  Who knows why. Exclude test for those.
+       */
+      if (!demo_compatibility)
+         if (line->bbox[BOXLEFT  ] > los.bbox[BOXRIGHT ] ||
+               line->bbox[BOXRIGHT ] < los.bbox[BOXLEFT  ] ||
+               line->bbox[BOXBOTTOM] > los.bbox[BOXTOP   ] ||
+               line->bbox[BOXTOP]    < los.bbox[BOXBOTTOM])
+            continue;
+
+      // cph - do what we can before forced to check intersection
+      if (line->flags & ML_TWOSIDED) {
+
+         // no wall to block sight with?
+         if ((front = seg->frontsector)->floorheight ==
+               (back = seg->backsector)->floorheight   &&
+               front->ceilingheight == back->ceilingheight)
+            continue;
+
+         // possible occluder
+         // because of ceiling height differences
+         opentop = front->ceilingheight < back->ceilingheight ?
+                   front->ceilingheight : back->ceilingheight ;
+
+         // because of floor height differences
+         openbottom = front->floorheight > back->floorheight ?
+                      front->floorheight : back->floorheight ;
+
+         // cph - reject if does not intrude in the z-space of the possible LOS
+         if ((opentop >= los.maxz) && (openbottom <= los.minz))
+            continue;
+      }
+
+      { // Forget this line if it doesn't cross the line of sight
+         const vertex_t *v1,*v2;
+
+         v1 = line->v1;
+         v2 = line->v2;
+
+         if (P_DivlineSide(v1->x, v1->y, &los.strace) ==
+               P_DivlineSide(v2->x, v2->y, &los.strace))
+            continue;
+
+         divl.dx = v2->x - (divl.x = v1->x);
+         divl.dy = v2->y - (divl.y = v1->y);
+
+         // line isn't crossed?
+         if (P_DivlineSide(los.strace.x, los.strace.y, &divl) ==
+               P_DivlineSide(los.t2x, los.t2y, &divl))
+            continue;
+      }
+
+      // cph - if bottom >= top or top < minz or bottom > maxz then it must be
+      // solid wrt this LOS
+      if (!(line->flags & ML_TWOSIDED) || (openbottom >= opentop) ||
+            (opentop < los.minz) || (openbottom > los.maxz))
+         return false;
+
+      { // crosses a two sided line
+         fixed_t frac = P_InterceptVector2(&los.strace, &divl);
+
+         if (front->floorheight != back->floorheight)
+         {
+            fixed_t slope = FixedDiv(openbottom - los.sightzstart , frac);
+            if (slope > los.bottomslope)
+               los.bottomslope = slope;
+         }
+
+         if (front->ceilingheight != back->ceilingheight)
+         {
+            fixed_t slope = FixedDiv(opentop - los.sightzstart , frac);
+            if (slope < los.topslope)
+               los.topslope = slope;
+         }
+
+         if (los.topslope <= los.bottomslope)
+            return false;               // stop
+      }
+   }
+   // passed the subsector ok
+   return true;
+}
+
+//
+// P_CrossBSPNode
+// Returns true
+//  if strace crosses the given node successfully.
+//
+// killough 4/20/98: rewritten to remove tail recursion, clean up, and optimize
+// cph - Made to use R_PointOnSide instead of P_DivlineSide, since the latter
+//  could return 2 which was ambigous, and the former is
+//  better optimised; also removes two casts :-)
+
+static boolean P_CrossBSPNode_LxDoom(int bspnum)
+{
+   while (!(bspnum & NF_SUBSECTOR))
+   {
+      register const node_t *bsp = nodes + bspnum;
+      int side,side2;
+      side = R_PointOnSide(los.strace.x, los.strace.y, bsp);
+      side2 = R_PointOnSide(los.t2x, los.t2y, bsp);
+      if (side == side2)
+         bspnum = bsp->children[side]; // doesn't touch the other side
+      else         // the partition plane is crossed here
+         if (!P_CrossBSPNode_LxDoom(bsp->children[side]))
+            return 0;  // cross the starting side
+         else
+            bspnum = bsp->children[side^1];  // cross the ending side
+   }
+   return P_CrossSubsector(bspnum == -1 ? 0 : bspnum & ~NF_SUBSECTOR);
+}
+
+static boolean P_CrossBSPNode_PrBoom(int bspnum)
+{
+   while (!(bspnum & NF_SUBSECTOR))
+   {
+      register const node_t *bsp = nodes + bspnum;
+      int side,side2;
+      side = P_DivlineSide(los.strace.x,los.strace.y,(divline_t *)bsp)&1;
+      side2= P_DivlineSide(los.t2x, los.t2y, (divline_t *) bsp);
+      if (side == side2)
+         bspnum = bsp->children[side]; // doesn't touch the other side
+      else         // the partition plane is crossed here
+         if (!P_CrossBSPNode_PrBoom(bsp->children[side]))
+            return 0;  // cross the starting side
+         else
+            bspnum = bsp->children[side^1];  // cross the ending side
+   }
+   return P_CrossSubsector(bspnum == -1 ? 0 : bspnum & ~NF_SUBSECTOR);
+}
+
+/* proff - Moved the compatibility check outside the functions
+ * this gives a slight speedup
+ */
+static boolean P_CrossBSPNode(int bspnum)
+{
+   /* cph - LxDoom used some R_* funcs here */
+   if (compatibility_level == lxdoom_1_compatibility)
+      return P_CrossBSPNode_LxDoom(bspnum);
+   else
+      return P_CrossBSPNode_PrBoom(bspnum);
+}
+
+//
+// P_CheckSight
+// Returns true
+//  if a straight line between t1 and t2 is unobstructed.
+// Uses REJECT.
+//
+// killough 4/20/98: cleaned up, made to use new LOS struct
+
+boolean P_CheckSight(mobj_t *t1, mobj_t *t2)
+{
+   const sector_t *s1 = t1->subsector->sector;
+   const sector_t *s2 = t2->subsector->sector;
+   int pnum = (s1-sectors)*numsectors + (s2-sectors);
+
+   // First check for trivial rejection.
+   // Determine subsector entries in REJECT table.
+   //
+   // Check in REJECT table.
+
+   if (rejectmatrix[pnum>>3] & (1 << (pnum&7)))   // can't possibly be connected
+      return false;
+
+   // killough 4/19/98: make fake floors and ceilings block monster view
+
+   if ((s1->heightsec != -1 &&
+         ((t1->z + t1->height <= sectors[s1->heightsec].floorheight &&
+           t2->z >= sectors[s1->heightsec].floorheight) ||
+          (t1->z >= sectors[s1->heightsec].ceilingheight &&
+           t2->z + t1->height <= sectors[s1->heightsec].ceilingheight)))
+         ||
+         (s2->heightsec != -1 &&
+          ((t2->z + t2->height <= sectors[s2->heightsec].floorheight &&
+            t1->z >= sectors[s2->heightsec].floorheight) ||
+           (t2->z >= sectors[s2->heightsec].ceilingheight &&
+            t1->z + t2->height <= sectors[s2->heightsec].ceilingheight))))
+      return false;
+
+   /* killough 11/98: shortcut for melee situations
+    * same subsector? obviously visible
+    * cph - compatibility optioned for demo sync, cf HR06-UV.LMP */
+   if ((t1->subsector == t2->subsector) &&
+         (compatibility_level >= mbf_compatibility))
+      return true;
+
+   // An unobstructed LOS is possible.
+   // Now look from eyes of t1 to any part of t2.
+
+   validcount++;
+
+   los.topslope = (los.bottomslope = t2->z - (los.sightzstart =
+                                        t1->z + t1->height -
+                                        (t1->height>>2))) + t2->height;
+   los.strace.dx = (los.t2x = t2->x) - (los.strace.x = t1->x);
+   los.strace.dy = (los.t2y = t2->y) - (los.strace.y = t1->y);
+
+   if (t1->x > t2->x)
+      los.bbox[BOXRIGHT] = t1->x, los.bbox[BOXLEFT] = t2->x;
+   else
+      los.bbox[BOXRIGHT] = t2->x, los.bbox[BOXLEFT] = t1->x;
+
+   if (t1->y > t2->y)
+      los.bbox[BOXTOP] = t1->y, los.bbox[BOXBOTTOM] = t2->y;
+   else
+      los.bbox[BOXTOP] = t2->y, los.bbox[BOXBOTTOM] = t1->y;
+
+   /* cph - calculate min and max z of the potential line of sight
+    * For old demos, we disable this optimisation by setting them to
+    * the extremes */
+   switch (compatibility_level) {
+   case lxdoom_1_compatibility:
+      if (los.sightzstart < t2->z) {
+         los.maxz = t2->z + t2->height; los.minz = los.sightzstart;
+      } else if (los.sightzstart > t2->z + t2->height) {
+         los.maxz = los.sightzstart; los.minz = t2->z;
+      } else {
+         los.maxz = t2->z + t2->height; los.minz = t2->z;
+      }
+      break;
+   default:
+      los.maxz = INT_MAX; los.minz = INT_MIN;
+   }
+
+   // the head node is the last node output
+   return P_CrossBSPNode(numnodes-1);
+}