p_maputl.c

游戏类程序源代码---WinDoom 3D源程序.zip

// 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 <stdlib.h>


#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;
    }

    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 )
{
#if 1
    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;
#else	// UNUSED, float debug.
    float	frac;
    float	num;
    float	den;
    float	v1x;
    float	v1y;
    float	v1dx;
    float	v1dy;
    float	v2x;
    float	v2y;
    float	v2dx;
    float	v2dy;

    v1x = (float)v1->x/FRACUNIT;
    v1y = (float)v1->y/FRACUNIT;
    v1dx = (float)v1->dx/FRACUNIT;
    v1dy = (float)v1->dy/FRACUNIT;
    v2x = (float)v2->x/FRACUNIT;
    v2y = (float)v2->y/FRACUNIT;
    v2dx = (float)v2->dx/FRACUNIT;
    v2dy = (float)v2->dy/FRACUNIT;
	
    den = v1dy*v2dx - v1dx*v2dy;

    if (den == 0)
	return 0;	// parallel
    
    num = (v1x - v2x)*v1dy + (v2y - v1y)*v1dx;
    frac = num / den;

    return frac*FRACUNIT;
#endif
}


//
// 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;