rockbox/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);
}