p_maputl.c

使用Doom引擎开发的著名游戏《毁灭巫师》的源代码。

//**************************************************************************
//**
//** p_maputl.c : Heretic 2 : Raven Software, Corp.
//**
//** $RCSfile: p_maputl.c,v $
//** $Revision: 1.11 $
//** $Date: 95/10/04 02:39:28 $
//** $Author: paul $
//**
//**************************************************************************

#include "h2def.h"
#include "p_local.h"

static mobj_t *RoughBlockCheck(mobj_t *mo, int index);

/*
===================
=
= 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,dy;
	fixed_t left, 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, 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,dy;
	fixed_t left, 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, num, 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
float   frac, num, den, v1x,v1y,v1dx,v1dy,v2x,v2y,v2dx,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, openbottom, openrange;
fixed_t lowfloor;

void P_LineOpening (line_t *linedef)
{
	sector_t        *front, *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;
		tmfloorpic = front->floorpic;
	}
	else
	{
		openbottom = back->floorheight;
		lowfloor = front->floorheight;
		tmfloorpic = back->floorpic;
	}

	openrange = opentop - openbottom;
}

/*
===============================================================================

						THING POSITION SETTING

===============================================================================
*/

/*
===================
=
= P_UnsetThingPosition
=
= Unlinks a thing from block map and sectors
=
===================
*/

void P_UnsetThingPosition (mobj_t *thing)
{
	int                             blockx, 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, 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 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;

	int i;
	polyblock_t *polyLink;
	seg_t **tempSeg;
	extern polyblock_t **PolyBlockMap;

	if (x < 0 || y<0 || x>=bmapwidth || y>=bmapheight)
		return true;
	offset = y*bmapwidth+x;

	polyLink = PolyBlockMap[offset];
	while(polyLink)
	{
		if(polyLink->polyobj)
		{
			if(polyLink->polyobj->validcount != validcount)
			{
				polyLink->polyobj->validcount = validcount;
				tempSeg = polyLink->polyobj->segs;
				for(i = 0; i < polyLink->polyobj->numsegs; i++, tempSeg++)
				{
					if((*tempSeg)->linedef->validcount == validcount)
					{
						continue;
					}
					(*tempSeg)->linedef->validcount = validcount;
					if(!func((*tempSeg)->linedef))
					{
						return false;
					}
				}
			}
		}
		polyLink = polyLink->next;
	}

	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_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, s2;
	fixed_t         frac;
	divline_t       dl;

// avoid precision problems with two routines