ref: dc593372bfc4224c6cf91d2031d0ad0aeadaddfe
dir: /sys/src/games/doom/p_maputl.c/
// Emacs style mode select -*- C++ -*-
//-----------------------------------------------------------------------------
//
// $Id:$
//
// Copyright (C) 1993-1996 by id Software, Inc.
//
// This source is available for distribution and/or modification
// only under the terms of the DOOM Source Code License as
// published by id Software. All rights reserved.
//
// The source is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// FITNESS FOR A PARTICULAR PURPOSE. See the DOOM Source Code License
// for more details.
//
// $Log:$
//
// DESCRIPTION:
// Movement/collision utility functions,
// as used by function in p_map.c.
// BLOCKMAP Iterator functions,
// and some PIT_* functions to use for iteration.
//
//-----------------------------------------------------------------------------
static const char
rcsid[] = "$Id: p_maputl.c,v 1.5 1997/02/03 22:45:11 b1 Exp $";
#include "m_bbox.h"
#include "doomdef.h"
#include "p_local.h"
// State.
#include "r_state.h"
//
// P_AproxDistance
// Gives an estimation of distance (not exact)
//
fixed_t
P_AproxDistance
( fixed_t dx,
fixed_t dy )
{
dx = abs(dx);
dy = abs(dy);
if (dx < dy)
return dx+dy-(dx>>1);
return dx+dy-(dy>>1);
}
//
// P_PointOnLineSide
// Returns 0 or 1
//
int
P_PointOnLineSide
( fixed_t x,
fixed_t y,
line_t* line )
{
fixed_t dx;
fixed_t dy;
fixed_t left;
fixed_t right;
if (!line->dx)
{
if (x <= line->v1->x)
return line->dy > 0;
return line->dy < 0;
}
if (!line->dy)
{
if (y <= line->v1->y)
return line->dx < 0;
return line->dx > 0;
}
dx = (x - line->v1->x);
dy = (y - line->v1->y);
left = FixedMul ( line->dy>>FRACBITS , dx );
right = FixedMul ( dy , line->dx>>FRACBITS );
if (right < left)
return 0; // front side
return 1; // back side
}
//
// P_BoxOnLineSide
// Considers the line to be infinite
// Returns side 0 or 1, -1 if box crosses the line.
//
int
P_BoxOnLineSide
( fixed_t* tmbox,
line_t* ld )
{
int p1;
int p2;
switch (ld->slopetype)
{
case ST_HORIZONTAL:
p1 = tmbox[BOXTOP] > ld->v1->y;
p2 = tmbox[BOXBOTTOM] > ld->v1->y;
if (ld->dx < 0)
{
p1 ^= 1;
p2 ^= 1;
}
break;
case ST_VERTICAL:
p1 = tmbox[BOXRIGHT] < ld->v1->x;
p2 = tmbox[BOXLEFT] < ld->v1->x;
if (ld->dy < 0)
{
p1 ^= 1;
p2 ^= 1;
}
break;
case ST_POSITIVE:
p1 = P_PointOnLineSide (tmbox[BOXLEFT], tmbox[BOXTOP], ld);
p2 = P_PointOnLineSide (tmbox[BOXRIGHT], tmbox[BOXBOTTOM], ld);
break;
case ST_NEGATIVE:
p1 = P_PointOnLineSide (tmbox[BOXRIGHT], tmbox[BOXTOP], ld);
p2 = P_PointOnLineSide (tmbox[BOXLEFT], tmbox[BOXBOTTOM], ld);
break;
default:
return -1;
}
if (p1 == p2)
return p1;
return -1;
}
//
// P_PointOnDivlineSide
// Returns 0 or 1.
//
int
P_PointOnDivlineSide
( fixed_t x,
fixed_t y,
divline_t* line )
{
fixed_t dx;
fixed_t dy;
fixed_t left;
fixed_t right;
if (!line->dx)
{
if (x <= line->x)
return line->dy > 0;
return line->dy < 0;
}
if (!line->dy)
{
if (y <= line->y)
return line->dx < 0;
return line->dx > 0;
}
dx = (x - line->x);
dy = (y - line->y);
// try to quickly decide by looking at sign bits
if ( (line->dy ^ line->dx ^ dx ^ dy)&0x80000000 )
{
if ( (line->dy ^ dx) & 0x80000000 )
return 1; // (left is negative)
return 0;
}
left = FixedMul ( line->dy>>8, dx>>8 );
right = FixedMul ( dy>>8 , line->dx>>8 );
if (right < left)
return 0; // front side
return 1; // back side
}
//
// P_MakeDivline
//
void
P_MakeDivline
( line_t* li,
divline_t* dl )
{
dl->x = li->v1->x;
dl->y = li->v1->y;
dl->dx = li->dx;
dl->dy = li->dy;
}
//
// P_InterceptVector
// Returns the fractional intercept point
// along the first divline.
// This is only called by the addthings
// and addlines traversers.
//
fixed_t
P_InterceptVector
( divline_t* v2,
divline_t* v1 )
{
fixed_t frac;
fixed_t num;
fixed_t den;
den = FixedMul (v1->dy>>8,v2->dx) - FixedMul(v1->dx>>8,v2->dy);
if (den == 0)
return 0;
// I_Error ("P_InterceptVector: parallel");
num =
FixedMul ( (v1->x - v2->x)>>8 ,v1->dy )
+FixedMul ( (v2->y - v1->y)>>8, v1->dx );
frac = FixedDiv (num , den);
return frac;
}
//
// P_LineOpening
// Sets opentop and openbottom to the window
// through a two sided line.
// OPTIMIZE: keep this precalculated
//
fixed_t opentop;
fixed_t openbottom;
fixed_t openrange;
fixed_t lowfloor;
void P_LineOpening (line_t* linedef)
{
sector_t* front;
sector_t* back;
if (linedef->sidenum[1] == -1)
{
// single sided line
openrange = 0;
return;
}
front = linedef->frontsector;
back = linedef->backsector;
if (front->ceilingheight < back->ceilingheight)
opentop = front->ceilingheight;
else
opentop = back->ceilingheight;
if (front->floorheight > back->floorheight)
{
openbottom = front->floorheight;
lowfloor = back->floorheight;
}
else
{
openbottom = back->floorheight;
lowfloor = front->floorheight;
}
openrange = opentop - openbottom;
}
//
// THING POSITION SETTING
//
//
// P_UnsetThingPosition
// Unlinks a thing from block map and sectors.
// On each position change, BLOCKMAP and other
// lookups maintaining lists ot things inside
// these structures need to be updated.
//
void P_UnsetThingPosition (mobj_t* thing)
{
int blockx;
int blocky;
if ( ! (thing->flags & MF_NOSECTOR) )
{
// inert things don't need to be in blockmap?
// unlink from subsector
if (thing->snext)
thing->snext->sprev = thing->sprev;
if (thing->sprev)
thing->sprev->snext = thing->snext;
else
thing->subsector->sector->thinglist = thing->snext;
}
if ( ! (thing->flags & MF_NOBLOCKMAP) )
{
// inert things don't need to be in blockmap
// unlink from block map
if (thing->bnext)
thing->bnext->bprev = thing->bprev;
if (thing->bprev)
thing->bprev->bnext = thing->bnext;
else
{
blockx = (thing->x - bmaporgx)>>MAPBLOCKSHIFT;
blocky = (thing->y - bmaporgy)>>MAPBLOCKSHIFT;
if (blockx>=0 && blockx < bmapwidth
&& blocky>=0 && blocky <bmapheight)
{
blocklinks[blocky*bmapwidth+blockx] = thing->bnext;
}
}
}
}
//
// P_SetThingPosition
// Links a thing into both a block and a subsector
// based on it's x y.
// Sets thing->subsector properly
//
void
P_SetThingPosition (mobj_t* thing)
{
subsector_t* ss;
sector_t* sec;
int blockx;
int blocky;
mobj_t** link;
// link into subsector
ss = R_PointInSubsector (thing->x,thing->y);
thing->subsector = ss;
if ( ! (thing->flags & MF_NOSECTOR) )
{
// invisible things don't go into the sector links
sec = ss->sector;
thing->sprev = NULL;
thing->snext = sec->thinglist;
if (sec->thinglist)
sec->thinglist->sprev = thing;
sec->thinglist = thing;
}
// link into blockmap
if ( ! (thing->flags & MF_NOBLOCKMAP) )
{
// inert things don't need to be in blockmap
blockx = (thing->x - bmaporgx)>>MAPBLOCKSHIFT;
blocky = (thing->y - bmaporgy)>>MAPBLOCKSHIFT;
if (blockx>=0
&& blockx < bmapwidth
&& blocky>=0
&& blocky < bmapheight)
{
link = &blocklinks[blocky*bmapwidth+blockx];
thing->bprev = NULL;
thing->bnext = *link;
if (*link)
(*link)->bprev = thing;
*link = thing;
}
else
{
// thing is off the map
thing->bnext = thing->bprev = NULL;
}
}
}
//
// BLOCK MAP ITERATORS
// For each line/thing in the given mapblock,
// call the passed PIT_* function.
// If the function returns false,
// exit with false without checking anything else.
//
//
// P_BlockLinesIterator
// The validcount flags are used to avoid checking lines
// that are marked in multiple mapblocks,
// so increment validcount before the first call
// to P_BlockLinesIterator, then make one or more calls
// to it.
//
boolean
P_BlockLinesIterator
( int x,
int y,
boolean(*func)(line_t*) )
{
int offset;
short* list;
line_t* ld;
if (x<0
|| y<0
|| x>=bmapwidth
|| y>=bmapheight)
{
return true;
}
offset = y*bmapwidth+x;
offset = *(blockmap+offset);
for ( list = blockmaplump+offset ; *list != -1 ; list++)
{
ld = &lines[*list];
if (ld->validcount == validcount)
continue; // line has already been checked
ld->validcount = validcount;
if ( !func(ld) )
return false;
}
return true; // everything was checked
}
//
// P_BlockThingsIterator
//
boolean
P_BlockThingsIterator
( int x,
int y,
boolean(*func)(mobj_t*) )
{
mobj_t* mobj;
if ( x<0
|| y<0
|| x>=bmapwidth
|| y>=bmapheight)
{
return true;
}
for (mobj = blocklinks[y*bmapwidth+x] ;
mobj ;
mobj = mobj->bnext)
{
if (!func( mobj ) )
return false;
}
return true;
}
//
// INTERCEPT ROUTINES
//
intercept_t intercepts[MAXINTERCEPTS];
intercept_t* intercept_p;
divline_t trace;
boolean earlyout;
int ptflags;
//
// PIT_AddLineIntercepts.
// Looks for lines in the given block
// that intercept the given trace
// to add to the intercepts list.
//
// A line is crossed if its endpoints
// are on opposite sides of the trace.
// Returns true if earlyout and a solid line hit.
//
boolean
PIT_AddLineIntercepts (line_t* ld)
{
int s1;
int s2;
fixed_t frac;
divline_t dl;
// avoid precision problems with two routines
if ( trace.dx > FRACUNIT*16
|| trace.dy > FRACUNIT*16
|| trace.dx < -FRACUNIT*16
|| trace.dy < -FRACUNIT*16)
{
s1 = P_PointOnDivlineSide (ld->v1->x, ld->v1->y, &trace);
s2 = P_PointOnDivlineSide (ld->v2->x, ld->v2->y, &trace);
}
else
{
s1 = P_PointOnLineSide (trace.x, trace.y, ld);
s2 = P_PointOnLineSide (trace.x+trace.dx, trace.y+trace.dy, ld);
}
if (s1 == s2)
return true; // line isn't crossed
// hit the line
P_MakeDivline (ld, &dl);
frac = P_InterceptVector (&trace, &dl);
if (frac < 0)
return true; // behind source
// try to early out the check
if (earlyout
&& frac < FRACUNIT
&& !ld->backsector)
{
return false; // stop checking
}
intercept_p->frac = frac;
intercept_p->isaline = true;
intercept_p->d.line = ld;
intercept_p++;
return true; // continue
}
//
// PIT_AddThingIntercepts
//
boolean PIT_AddThingIntercepts (mobj_t* thing)
{
fixed_t x1;
fixed_t y1;
fixed_t x2;
fixed_t y2;
int s1;
int s2;
boolean tracepositive;
divline_t dl;
fixed_t frac;
tracepositive = (trace.dx ^ trace.dy)>0;
// check a corner to corner crossection for hit
if (tracepositive)
{
x1 = thing->x - thing->radius;
y1 = thing->y + thing->radius;
x2 = thing->x + thing->radius;
y2 = thing->y - thing->radius;
}
else
{
x1 = thing->x - thing->radius;
y1 = thing->y - thing->radius;
x2 = thing->x + thing->radius;
y2 = thing->y + thing->radius;
}
s1 = P_PointOnDivlineSide (x1, y1, &trace);
s2 = P_PointOnDivlineSide (x2, y2, &trace);
if (s1 == s2)
return true; // line isn't crossed
dl.x = x1;
dl.y = y1;
dl.dx = x2-x1;
dl.dy = y2-y1;
frac = P_InterceptVector (&trace, &dl);
if (frac < 0)
return true; // behind source
intercept_p->frac = frac;
intercept_p->isaline = false;
intercept_p->d.thing = thing;
intercept_p++;
return true; // keep going
}
//
// P_TraverseIntercepts
// Returns true if the traverser function returns true
// for all lines.
//
boolean
P_TraverseIntercepts
( traverser_t func,
fixed_t maxfrac )
{
int count;
fixed_t dist;
intercept_t* scan;
intercept_t* in;
count = intercept_p - intercepts;
for (in=(intercept_t*)0 ; count-- ; )
{
dist = MAXINT;
for (scan = intercepts ; scan<intercept_p ; scan++)
{
if (scan->frac < dist)
{
dist = scan->frac;
in = scan;
}
}
if (dist > maxfrac)
return true; // checked everything in range
if ( !func (in) )
return false; // don't bother going farther
in->frac = MAXINT;
}
return true; // everything was traversed
}
//
// P_PathTraverse
// Traces a line from x1,y1 to x2,y2,
// calling the traverser function for each.
// Returns true if the traverser function returns true
// for all lines.
//
boolean
P_PathTraverse
( fixed_t x1,
fixed_t y1,
fixed_t x2,
fixed_t y2,
int flags,
boolean (*trav) (intercept_t *))
{
fixed_t xt1;
fixed_t yt1;
fixed_t xt2;
fixed_t yt2;
fixed_t xstep;
fixed_t ystep;
fixed_t partial;
fixed_t xintercept;
fixed_t yintercept;
int mapx;
int mapy;
int mapxstep;
int mapystep;
int count;
earlyout = flags & PT_EARLYOUT;
validcount++;
intercept_p = intercepts;
if ( ((x1-bmaporgx)&(MAPBLOCKSIZE-1)) == 0)
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 -= bmaporgx;
y1 -= bmaporgy;
xt1 = x1>>MAPBLOCKSHIFT;
yt1 = y1>>MAPBLOCKSHIFT;
x2 -= bmaporgx;
y2 -= bmaporgy;
xt2 = x2>>MAPBLOCKSHIFT;
yt2 = y2>>MAPBLOCKSHIFT;
if (xt2 > xt1)
{
mapxstep = 1;
partial = FRACUNIT - ((x1>>MAPBTOFRAC)&(FRACUNIT-1));
ystep = FixedDiv (y2-y1,abs(x2-x1));
}
else if (xt2 < xt1)
{
mapxstep = -1;
partial = (x1>>MAPBTOFRAC)&(FRACUNIT-1);
ystep = FixedDiv (y2-y1,abs(x2-x1));
}
else
{
mapxstep = 0;
partial = FRACUNIT;
ystep = 256*FRACUNIT;
}
yintercept = (y1>>MAPBTOFRAC) + FixedMul (partial, ystep);
if (yt2 > yt1)
{
mapystep = 1;
partial = FRACUNIT - ((y1>>MAPBTOFRAC)&(FRACUNIT-1));
xstep = FixedDiv (x2-x1,abs(y2-y1));
}
else if (yt2 < yt1)
{
mapystep = -1;
partial = (y1>>MAPBTOFRAC)&(FRACUNIT-1);
xstep = FixedDiv (x2-x1,abs(y2-y1));
}
else
{
mapystep = 0;
partial = FRACUNIT;
xstep = 256*FRACUNIT;
}
xintercept = (x1>>MAPBTOFRAC) + FixedMul (partial, xstep);
// Step through map blocks.
// Count is present to prevent a round off error
// from skipping the break.
mapx = xt1;
mapy = yt1;
for (count = 0 ; count < 64 ; count++)
{
if (flags & PT_ADDLINES)
{
if (!P_BlockLinesIterator (mapx, mapy,PIT_AddLineIntercepts))
return false; // early out
}
if (flags & PT_ADDTHINGS)
{
if (!P_BlockThingsIterator (mapx, mapy,PIT_AddThingIntercepts))
return false; // early out
}
if (mapx == xt2
&& mapy == yt2)
{
break;
}
if ( (yintercept >> FRACBITS) == mapy)
{
yintercept += ystep;
mapx += mapxstep;
}
else if ( (xintercept >> FRACBITS) == mapx)
{
xintercept += xstep;
mapy += mapystep;
}
}
// go through the sorted list
return P_TraverseIntercepts ( trav, FRACUNIT );
}