Source to src/p_map.c

// P_map.c

#include "DoomDef.h"
#include "P_local.h"
#include "soundst.h"

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

NOTES:


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

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

mobj_t NOTES

mobj_ts are used to tell the refresh where to draw an image, tell the world simulation when objects are contacted, and tell the sound driver how to position a sound.

The refresh uses the next and prev links to follow lists of things in sectors as they are being drawn.  The sprite, frame, and angle elements determine which patch_t is used to draw the sprite if it is visible.  The sprite and frame values are allmost allways set from state_t structures.  The statescr.exe utility generates the states.h and states.c files that contain the sprite/frame numbers from the statescr.txt source file.  The xyz origin point represents a point at the bottom middle of the sprite (between the feet of a biped).  This is the default origin position for patch_ts grabbed with lumpy.exe.  A walking creature will have its z equal to the floor it is standing on.
 
The sound code uses the x,y, and subsector fields to do stereo positioning of any sound effited by the mobj_t.

The play simulation uses the blocklinks, x,y,z, radius, height to determine when mobj_ts are touching each other, touching lines in the map, or hit by trace lines (gunshots, lines of sight, etc). The mobj_t->flags element has various bit flags used by the simulation.


Every mobj_t is linked into a single sector based on it's origin coordinates.
The subsector_t is found with R_PointInSubsector(x,y), and the sector_t can be found with subsector->sector.  The sector links are only used by the rendering code,  the play simulation does not care about them at all.

Any mobj_t that needs to be acted upon be something else in the play world (block movement, be shot, etc) will also need to be linked into the blockmap.  If the thing has the MF_NOBLOCK flag set, it will not use the block links. It can still interact with other things, but only as the instigator (missiles will run into other things, but nothing can run into a missile).   Each block in the grid is 128*128 units, and knows about every line_t that it contains a piece of, and every interactable mobj_t that has it's origin contained.  

A valid mobj_t is a mobj_t that has the proper subsector_t filled in for it's xy coordinates and is linked into the subsector's sector or has the MF_NOSECTOR flag set (the subsector_t needs to be valid even if MF_NOSECTOR is set), and is linked into a blockmap block or has the MF_NOBLOCKMAP flag set.  Links should only be modified by the P_[Un]SetThingPosition () functions.  Do not change the MF_NO? flags while a thing is valid.


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

fixed_t		tmbbox[4];
mobj_t		*tmthing;
int			tmflags;
fixed_t		tmx, tmy;

boolean		floatok;				// if true, move would be ok if
									// within tmfloorz - tmceilingz

fixed_t		tmfloorz, tmceilingz, tmdropoffz;

// keep track of the line that lowers the ceiling, so missiles don't explode
// against sky hack walls
line_t		*ceilingline;

// keep track of special lines as they are hit, but don't process them
// until the move is proven valid
#define	MAXSPECIALCROSS		8
line_t	*spechit[MAXSPECIALCROSS];
int			 numspechit;

mobj_t *onmobj; //generic global onmobj...used for landing on pods/players

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

					TELEPORT MOVE
 
===============================================================================
*/

/*
==================
=
= PIT_StompThing
=
==================
*/

boolean PIT_StompThing (mobj_t *thing)
{
	fixed_t		blockdist;
		
	if (!(thing->flags & MF_SHOOTABLE) )
		return true;
		
	blockdist = thing->radius + tmthing->radius;
	if ( abs(thing->x - tmx) >= blockdist || abs(thing->y - tmy) >= blockdist )
		return true;		// didn't hit it
		
	if (thing == tmthing)
		return true;		// don't clip against self

	if(!(tmthing->flags2&MF2_TELESTOMP))
	{ // Not allowed to stomp things
		return(false);
	}
		
	P_DamageMobj (thing, tmthing, tmthing, 10000);
	
	return true;
}


/*
===================
=
= P_TeleportMove
=
===================
*/

boolean P_TeleportMove (mobj_t *thing, fixed_t x, fixed_t y)
{
	int			xl,xh,yl,yh,bx,by;
	subsector_t		*newsubsec;

//
// kill anything occupying the position
//

	tmthing = thing;
	tmflags = thing->flags;
	
	tmx = x;
	tmy = y;
	
	tmbbox[BOXTOP] = y + tmthing->radius;
	tmbbox[BOXBOTTOM] = y - tmthing->radius;
	tmbbox[BOXRIGHT] = x + tmthing->radius;
	tmbbox[BOXLEFT] = x - tmthing->radius;

	newsubsec = R_PointInSubsector (x,y);
	ceilingline = NULL;
	
//
// the base floor / ceiling is from the subsector that contains the
// point.  Any contacted lines the step closer together will adjust them
//
	tmfloorz = tmdropoffz = newsubsec->sector->floorheight;
	tmceilingz = newsubsec->sector->ceilingheight;
			
	validcount++;
	numspechit = 0;

//
// stomp on any things contacted
//
	xl = (tmbbox[BOXLEFT] - bmaporgx - MAXRADIUS)>>MAPBLOCKSHIFT;
	xh = (tmbbox[BOXRIGHT] - bmaporgx + MAXRADIUS)>>MAPBLOCKSHIFT;
	yl = (tmbbox[BOXBOTTOM] - bmaporgy - MAXRADIUS)>>MAPBLOCKSHIFT;
	yh = (tmbbox[BOXTOP] - bmaporgy + MAXRADIUS)>>MAPBLOCKSHIFT;

	for (bx=xl ; bx<=xh ; bx++)
		for (by=yl ; by<=yh ; by++)
			if (!P_BlockThingsIterator(bx,by,PIT_StompThing))
				return false;
	
//
// the move is ok, so link the thing into its new position
//	
	P_UnsetThingPosition (thing);

	thing->floorz = tmfloorz;
	thing->ceilingz = tmceilingz;	
	thing->x = x;
	thing->y = y;

	P_SetThingPosition (thing);
	
	return true;
}

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

					MOVEMENT ITERATOR FUNCTIONS
 
===============================================================================
*/

/*
==================
=
= PIT_CheckLine
=
= Adjusts tmfloorz and tmceilingz as lines are contacted
==================
*/

boolean PIT_CheckLine(line_t *ld)
{
	if (tmbbox[BOXRIGHT] <= ld->bbox[BOXLEFT]
		||	tmbbox[BOXLEFT] >= ld->bbox[BOXRIGHT]
		||	tmbbox[BOXTOP] <= ld->bbox[BOXBOTTOM]
		||	tmbbox[BOXBOTTOM] >= ld->bbox[BOXTOP])
	{
		return(true);
	}
	if(P_BoxOnLineSide(tmbbox, ld) != -1)
	{
		return(true);
	}

// a line has been hit
/*
=
= The moving thing's destination position will cross the given line.
= If this should not be allowed, return false.
= If the line is special, keep track of it to process later if the move
= 	is proven ok.  NOTE: specials are NOT sorted by order, so two special lines
= 	that are only 8 pixels apart could be crossed in either order.
*/

	if(!ld->backsector)
	{ // One sided line
		if(tmthing->flags&MF_MISSILE)
		{ // Missiles can trigger impact specials
			if(ld->special)
			{
				spechit[numspechit] = ld;
				numspechit++;
			}
		}
		return false;
	}
	if(!(tmthing->flags&MF_MISSILE))
	{
		if(ld->flags&ML_BLOCKING)
		{ // Explicitly blocking everything
			return(false);
		}
		if(!tmthing->player && ld->flags&ML_BLOCKMONSTERS
			&& tmthing->type != MT_POD)
		{ // Block monsters only
			return(false);
		}
	}
	P_LineOpening(ld);		// set openrange, opentop, openbottom
	// adjust floor / ceiling heights
	if(opentop < tmceilingz)
	{
		tmceilingz = opentop;
		ceilingline = ld;
	}
	if(openbottom > tmfloorz)
	{
		tmfloorz = openbottom;
	}
	if(lowfloor < tmdropoffz)
	{
		tmdropoffz = lowfloor;
	}
	if(ld->special)
	{ // Contacted a special line, add it to the list
		spechit[numspechit] = ld;
		numspechit++;
	}
	return(true);
}

//---------------------------------------------------------------------------
//
// FUNC PIT_CheckThing
//
//---------------------------------------------------------------------------

boolean PIT_CheckThing(mobj_t *thing)
{
	fixed_t blockdist;
	boolean solid;
	int damage;

	if(!(thing->flags&(MF_SOLID|MF_SPECIAL|MF_SHOOTABLE)))
	{ // Can't hit thing
		return(true);
	}
	blockdist = thing->radius+tmthing->radius;
	if(abs(thing->x-tmx) >= blockdist || abs(thing->y-tmy) >= blockdist)
	{ // Didn't hit thing
		return(true);
	}
	if(thing == tmthing)
	{ // Don't clip against self
		return(true);
	}
	if(tmthing->flags2&MF2_PASSMOBJ)
	{ // check if a mobj passed over/under another object
		if((tmthing->type == MT_IMP || tmthing->type == MT_WIZARD)
			&& (thing->type == MT_IMP || thing->type == MT_WIZARD))
		{ // don't let imps/wizards fly over other imps/wizards
			return false;
		}
		if(tmthing->z > thing->z+thing->height 
			&& !(thing->flags&MF_SPECIAL))
		{	
			return(true);
		}
		else if(tmthing->z+tmthing->height < thing->z 
			&& !(thing->flags&MF_SPECIAL))
		{ // under thing
			return(true);
		}
	}
	// Check for skulls slamming into things
	if(tmthing->flags&MF_SKULLFLY)
	{
		damage = ((P_Random()%8)+1)*tmthing->damage;
		P_DamageMobj(thing, tmthing, tmthing, damage);
		tmthing->flags &= ~MF_SKULLFLY;
		tmthing->momx = tmthing->momy = tmthing->momz = 0;
		P_SetMobjState(tmthing, tmthing->info->seestate);
		return(false);
	}
	// Check for missile
	if(tmthing->flags&MF_MISSILE)
	{
		// Check for passing through a ghost
		if((thing->flags&MF_SHADOW) && (tmthing->flags2&MF2_THRUGHOST))
		{
			return(true);
		}
		// Check if it went over / under
		if(tmthing->z > thing->z+thing->height)
		{ // Over thing
			return(true);
		}
		if(tmthing->z+tmthing->height < thing->z)
		{ // Under thing
			return(true);
		}
		if(tmthing->target && tmthing->target->type == thing->type)
		{ // Don't hit same species as originator
			if(thing == tmthing->target)
			{ // Don't missile self
				return(true);
			}
			if(thing->type != MT_PLAYER)
			{ // Hit same species as originator, explode, no damage
				return(false);
			}
		}
		if(!(thing->flags&MF_SHOOTABLE))
		{ // Didn't do any damage
			return!(thing->flags&MF_SOLID);
		}
		if(tmthing->flags2&MF2_RIP)
		{
			if(!(thing->flags&MF_NOBLOOD))
			{ // Ok to spawn some blood
				P_RipperBlood(tmthing);
			}
			S_StartSound(tmthing, sfx_ripslop);
			damage = ((P_Random()&3)+2)*tmthing->damage;
			P_DamageMobj(thing, tmthing, tmthing->target, damage);
			if(thing->flags2&MF2_PUSHABLE
				&& !(tmthing->flags2&MF2_CANNOTPUSH))
			{ // Push thing
				thing->momx += tmthing->momx>>2;
				thing->momy += tmthing->momy>>2;
			}
			numspechit = 0;
			return(true);
		}
		// Do damage
		damage = ((P_Random()%8)+1)*tmthing->damage;
		if(damage)
		{
			if(!(thing->flags&MF_NOBLOOD) && P_Random() < 192)
			{
				P_BloodSplatter(tmthing->x, tmthing->y, tmthing->z, thing);
			}
			P_DamageMobj(thing, tmthing, tmthing->target, damage);
		}
		return(false);
	}
	if(thing->flags2&MF2_PUSHABLE && !(tmthing->flags2&MF2_CANNOTPUSH))
	{ // Push thing
		thing->momx += tmthing->momx>>2;
		thing->momy += tmthing->momy>>2;
	}
	// Check for special thing
	if(thing->flags&MF_SPECIAL)
	{
		solid = thing->flags&MF_SOLID;
		if(tmflags&MF_PICKUP)
		{ // Can be picked up by tmthing
			P_TouchSpecialThing(thing, tmthing); // Can remove thing
		}
		return(!solid);
	}
	return(!(thing->flags&MF_SOLID));
}

//---------------------------------------------------------------------------
//
// PIT_CheckOnmobjZ
//
//---------------------------------------------------------------------------

boolean PIT_CheckOnmobjZ(mobj_t *thing)
{
	fixed_t blockdist;

	if(!(thing->flags&(MF_SOLID|MF_SPECIAL|MF_SHOOTABLE)))
	{ // Can't hit thing
		return(true);
	}
	blockdist = thing->radius+tmthing->radius;
	if(abs(thing->x-tmx) >= blockdist || abs(thing->y-tmy) >= blockdist)
	{ // Didn't hit thing
		return(true);
	}
	if(thing == tmthing)
	{ // Don't clip against self
		return(true);
	}
	if(tmthing->z > thing->z+thing->height)
	{	
		return(true);
	}
	else if(tmthing->z+tmthing->height < thing->z)
	{ // under thing
		return(true);
	}
	if(thing->flags&MF_SOLID)
	{
		onmobj = thing;
	}
	return(!(thing->flags&MF_SOLID));
}

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

 						MOVEMENT CLIPPING
 
===============================================================================
*/

//----------------------------------------------------------------------------
//
// FUNC P_TestMobjLocation
//
// Returns true if the mobj is not blocked by anything at its current
// location, otherwise returns false.
//
//----------------------------------------------------------------------------

boolean P_TestMobjLocation(mobj_t *mobj)
{
	int flags;

	flags = mobj->flags;
	mobj->flags &= ~MF_PICKUP;
	if(P_CheckPosition(mobj, mobj->x, mobj->y))
	{ // XY is ok, now check Z
		mobj->flags = flags;
		if((mobj->z < mobj->floorz)
			|| (mobj->z+mobj->height > mobj->ceilingz))
		{ // Bad Z
			return(false);
		}
		return(true);
	}
	mobj->flags = flags;
	return(false);
}

/*
==================
=
= P_CheckPosition
=
= This is purely informative, nothing is modified (except things picked up)

in:
a mobj_t (can be valid or invalid)
a position to be checked (doesn't need to be related to the mobj_t->x,y)

during:
special things are touched if MF_PICKUP
early out on solid lines?

out:
newsubsec
floorz
ceilingz
tmdropoffz		the lowest point contacted (monsters won't move to a dropoff)
speciallines[]
numspeciallines

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

boolean P_CheckPosition (mobj_t *thing, fixed_t x, fixed_t y)
{
	int			xl,xh,yl,yh,bx,by;
	subsector_t		*newsubsec;

	tmthing = thing;
	tmflags = thing->flags;
	
	tmx = x;
	tmy = y;
	
	tmbbox[BOXTOP] = y + tmthing->radius;
	tmbbox[BOXBOTTOM] = y - tmthing->radius;
	tmbbox[BOXRIGHT] = x + tmthing->radius;
	tmbbox[BOXLEFT] = x - tmthing->radius;

	newsubsec = R_PointInSubsector (x,y);
	ceilingline = NULL;
	
//
// the base floor / ceiling is from the subsector that contains the
// point.  Any contacted lines the step closer together will adjust them
//
	tmfloorz = tmdropoffz = newsubsec->sector->floorheight;
	tmceilingz = newsubsec->sector->ceilingheight;
			
	validcount++;
	numspechit = 0;

	if ( tmflags & MF_NOCLIP )
		return true;

//
// check things first, possibly picking things up
// the bounding box is extended by MAXRADIUS because mobj_ts are grouped
// into mapblocks based on their origin point, and can overlap into adjacent
// blocks by up to MAXRADIUS units
//
	xl = (tmbbox[BOXLEFT] - bmaporgx - MAXRADIUS)>>MAPBLOCKSHIFT;
	xh = (tmbbox[BOXRIGHT] - bmaporgx + MAXRADIUS)>>MAPBLOCKSHIFT;
	yl = (tmbbox[BOXBOTTOM] - bmaporgy - MAXRADIUS)>>MAPBLOCKSHIFT;
	yh = (tmbbox[BOXTOP] - bmaporgy + MAXRADIUS)>>MAPBLOCKSHIFT;

	for (bx=xl ; bx<=xh ; bx++)
		for (by=yl ; by<=yh ; by++)
			if (!P_BlockThingsIterator(bx,by,PIT_CheckThing))
				return false;
//
// check lines
//
	xl = (tmbbox[BOXLEFT] - bmaporgx)>>MAPBLOCKSHIFT;
	xh = (tmbbox[BOXRIGHT] - bmaporgx)>>MAPBLOCKSHIFT;
	yl = (tmbbox[BOXBOTTOM] - bmaporgy)>>MAPBLOCKSHIFT;
	yh = (tmbbox[BOXTOP] - bmaporgy)>>MAPBLOCKSHIFT;

	for (bx=xl ; bx<=xh ; bx++)
		for (by=yl ; by<=yh ; by++)
			if (!P_BlockLinesIterator (bx,by,PIT_CheckLine))
				return false;

	return true;
}

//=============================================================================
//
// P_CheckOnmobj(mobj_t *thing)
//
// 		Checks if the new Z position is legal
//=============================================================================

mobj_t *P_CheckOnmobj(mobj_t *thing)
{
	int			xl,xh,yl,yh,bx,by;
	subsector_t		*newsubsec;
	fixed_t x;
	fixed_t y;
	mobj_t oldmo;
	
	x = thing->x;
	y = thing->y;
	tmthing = thing;
	tmflags = thing->flags;
	oldmo = *thing; // save the old mobj before the fake zmovement
	P_FakeZMovement(tmthing);
		
	tmx = x;
	tmy = y;
	
	tmbbox[BOXTOP] = y + tmthing->radius;
	tmbbox[BOXBOTTOM] = y - tmthing->radius;
	tmbbox[BOXRIGHT] = x + tmthing->radius;
	tmbbox[BOXLEFT] = x - tmthing->radius;

	newsubsec = R_PointInSubsector (x,y);
	ceilingline = NULL;
	
//
// the base floor / ceiling is from the subsector that contains the
// point.  Any contacted lines the step closer together will adjust them
//
	tmfloorz = tmdropoffz = newsubsec->sector->floorheight;
	tmceilingz = newsubsec->sector->ceilingheight;
			
	validcount++;
	numspechit = 0;

	if ( tmflags & MF_NOCLIP )
		return NULL;

//
// check things first, possibly picking things up
// the bounding box is extended by MAXRADIUS because mobj_ts are grouped
// into mapblocks based on their origin point, and can overlap into adjacent
// blocks by up to MAXRADIUS units
//
	xl = (tmbbox[BOXLEFT] - bmaporgx - MAXRADIUS)>>MAPBLOCKSHIFT;
	xh = (tmbbox[BOXRIGHT] - bmaporgx + MAXRADIUS)>>MAPBLOCKSHIFT;
	yl = (tmbbox[BOXBOTTOM] - bmaporgy - MAXRADIUS)>>MAPBLOCKSHIFT;
	yh = (tmbbox[BOXTOP] - bmaporgy + MAXRADIUS)>>MAPBLOCKSHIFT;

	for (bx=xl ; bx<=xh ; bx++)
		for (by=yl ; by<=yh ; by++)
			if (!P_BlockThingsIterator(bx,by,PIT_CheckOnmobjZ))
			{
				*tmthing = oldmo;
				return onmobj;
			}
	*tmthing = oldmo;
	return NULL;
}

//=============================================================================
//
// P_FakeZMovement
//
// 		Fake the zmovement so that we can check if a move is legal
//=============================================================================

void P_FakeZMovement(mobj_t *mo)
{
	int dist;
	int delta;
//
// adjust height
//
	mo->z += mo->momz;
	if(mo->flags&MF_FLOAT && mo->target)
	{	// float down towards target if too close
		if(!(mo->flags&MF_SKULLFLY) && !(mo->flags&MF_INFLOAT))
		{
			dist = P_AproxDistance(mo->x-mo->target->x, mo->y-mo->target->y);
			delta =( mo->target->z+(mo->height>>1))-mo->z;
			if (delta < 0 && dist < -(delta*3))
				mo->z -= FLOATSPEED;
			else if (delta > 0 && dist < (delta*3))
				mo->z += FLOATSPEED;			
		}
	}
	if(mo->player && mo->flags2&MF2_FLY && !(mo->z <= mo->floorz)
		&& leveltime&2)
	{
		mo->z += finesine[(FINEANGLES/20*leveltime>>2)&FINEMASK];
	}

//
// clip movement
//
	if(mo->z <= mo->floorz)
	{ // Hit the floor
		mo->z = mo->floorz;
		if(mo->momz < 0)
		{
			mo->momz = 0;
		}
		if(mo->flags&MF_SKULLFLY)
		{ // The skull slammed into something
			mo->momz = -mo->momz;
		}
		if(mo->info->crashstate && (mo->flags&MF_CORPSE))
		{
			return;
		}
	}
	else if(mo->flags2&MF2_LOGRAV)
	{
		if(mo->momz == 0)
			mo->momz = -(GRAVITY>>3)*2;
		else
			mo->momz -= GRAVITY>>3;
	}
	else if (! (mo->flags & MF_NOGRAVITY) )
	{
		if (mo->momz == 0)
			mo->momz = -GRAVITY*2;
		else
			mo->momz -= GRAVITY;
	}
	
	if (mo->z + mo->height > mo->ceilingz)
	{	// hit the ceiling
		if (mo->momz > 0)
			mo->momz = 0;
		mo->z = mo->ceilingz - mo->height;		
		if (mo->flags & MF_SKULLFLY)
		{	// the skull slammed into something
			mo->momz = -mo->momz;
		}
	}
}

//==========================================================================
//
// CheckMissileImpact
//
//==========================================================================

void CheckMissileImpact(mobj_t *mobj)
{
	int i;

	if(!numspechit || !(mobj->flags&MF_MISSILE) || !mobj->target)
	{
		return;
	}
	if(!mobj->target->player)
	{
		return;
	}
	for(i = numspechit-1; i >= 0; i--)
	{
		P_ShootSpecialLine(mobj->target, spechit[i]);
	}
}

/*
===================
=
= P_TryMove
=
= Attempt to move to a new position, crossing special lines unless MF_TELEPORT
= is set
=
===================
*/

boolean P_TryMove(mobj_t *thing, fixed_t x, fixed_t y)
{
	fixed_t		oldx, oldy;
	int			side, oldside;
	line_t		*ld;

	floatok = false;
	if(!P_CheckPosition(thing, x, y))
	{ // Solid wall or thing
		CheckMissileImpact(thing);
		return false;
	}
	if(!(thing->flags&MF_NOCLIP))
	{
		if(tmceilingz-tmfloorz < thing->height)
		{ // Doesn't fit
			CheckMissileImpact(thing);
			return false;
		}
		floatok = true;
		if(!(thing->flags&MF_TELEPORT)
			&& tmceilingz-thing->z < thing->height
			&& !(thing->flags2&MF2_FLY))
		{ // mobj must lower itself to fit
			CheckMissileImpact(thing);
			return false;
		}
		if(thing->flags2&MF2_FLY)
		{
			if(thing->z+thing->height > tmceilingz)
			{
				thing->momz = -8*FRACUNIT;
				return false;
			}
			else if(thing->z < tmfloorz && tmfloorz-tmdropoffz > 24*FRACUNIT)
			{
				thing->momz = 8*FRACUNIT;
				return false;
			}
		}
		if(!(thing->flags&MF_TELEPORT)
			// The Minotaur floor fire (MT_MNTRFX2) can step up any amount
			&& thing->type != MT_MNTRFX2
			&& tmfloorz-thing->z > 24*FRACUNIT)
		{ // Too big a step up
			CheckMissileImpact(thing);
			return false;
		}
		if((thing->flags&MF_MISSILE) && tmfloorz > thing->z)
		{
			CheckMissileImpact(thing);
		}
		if(!(thing->flags&(MF_DROPOFF|MF_FLOAT))
			&& tmfloorz-tmdropoffz > 24*FRACUNIT)
		{ // Can't move over a dropoff
			return false;
		}
	}

//
// the move is ok, so link the thing into its new position
//
	P_UnsetThingPosition (thing);

	oldx = thing->x;
	oldy = thing->y;
	thing->floorz = tmfloorz;
	thing->ceilingz = tmceilingz;	
	thing->x = x;
	thing->y = y;

	P_SetThingPosition (thing);
	
	if(thing->flags2&MF2_FOOTCLIP && P_GetThingFloorType(thing) != FLOOR_SOLID)
	{
		thing->flags2 |= MF2_FEETARECLIPPED;
	}
	else if(thing->flags2&MF2_FEETARECLIPPED)
	{
		thing->flags2 &= ~MF2_FEETARECLIPPED;
	}
		
//
// if any special lines were hit, do the effect
//
	if (! (thing->flags&(MF_TELEPORT|MF_NOCLIP)) )
		while (numspechit--)
		{
		// see if the line was crossed
			ld = spechit[numspechit];
			side = P_PointOnLineSide (thing->x, thing->y, ld);
			oldside = P_PointOnLineSide (oldx, oldy, ld);
			if (side != oldside)
			{
				if (ld->special)
					P_CrossSpecialLine (ld-lines, oldside, thing);
			}
		}

	return true;
}

/*
==================
=
= P_ThingHeightClip
=
= Takes a valid thing and adjusts the thing->floorz, thing->ceilingz,
= anf possibly thing->z
=
= This is called for all nearby monsters whenever a sector changes height
=
= If the thing doesn't fit, the z will be set to the lowest value and
= false will be returned
==================
*/

boolean P_ThingHeightClip (mobj_t *thing)
{
	boolean		onfloor;
	
	onfloor = (thing->z == thing->floorz);
	
	P_CheckPosition (thing, thing->x, thing->y);	
	// what about stranding a monster partially off an edge?
	
	thing->floorz = tmfloorz;
	thing->ceilingz = tmceilingz;
	
	if (onfloor)
	// walking monsters rise and fall with the floor
		thing->z = thing->floorz;
	else
	{	// don't adjust a floating monster unless forced to
		if (thing->z+thing->height > thing->ceilingz)
			thing->z = thing->ceilingz - thing->height;
	}
	
	if (thing->ceilingz - thing->floorz < thing->height)
		return false;
		
	return true;
}


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

							SLIDE MOVE

Allows the player to slide along any angled walls

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

fixed_t		bestslidefrac, secondslidefrac;
line_t		*bestslideline, *secondslideline;
mobj_t		*slidemo;

fixed_t		tmxmove, tmymove;

/*
==================
=
= P_HitSlideLine
=
= Adjusts the xmove / ymove so that the next move will slide along the wall
==================
*/

void P_HitSlideLine (line_t *ld)
{
	int			side;
	angle_t		lineangle, moveangle, deltaangle;
	fixed_t		movelen, newlen;
	
	
	if (ld->slopetype == ST_HORIZONTAL)
	{
		tmymove = 0;
		return;
	}
	if (ld->slopetype == ST_VERTICAL)
	{
		tmxmove = 0;
		return;
	}
	
	side = P_PointOnLineSide (slidemo->x, slidemo->y, ld);
	
	lineangle = R_PointToAngle2 (0,0, ld->dx, ld->dy);
	if (side == 1)
		lineangle += ANG180;
	moveangle = R_PointToAngle2 (0,0, tmxmove, tmymove);
	deltaangle = moveangle-lineangle;
	if (deltaangle > ANG180)
		deltaangle += ANG180;
//		I_Error ("SlideLine: ang>ANG180");

	lineangle >>= ANGLETOFINESHIFT;
	deltaangle >>= ANGLETOFINESHIFT;
	
	movelen = P_AproxDistance (tmxmove, tmymove);
	newlen = FixedMul (movelen, finecosine[deltaangle]);
	tmxmove = FixedMul (newlen, finecosine[lineangle]);	
	tmymove = FixedMul (newlen, finesine[lineangle]);	
}

/*
==============
=
= PTR_SlideTraverse
=
==============
*/

boolean		PTR_SlideTraverse (intercept_t *in)
{
	line_t	*li;
	
	if (!in->isaline)
		I_Error ("PTR_SlideTraverse: not a line?");
		
	li = in->d.line;
	if ( ! (li->flags & ML_TWOSIDED) )
	{
		if (P_PointOnLineSide (slidemo->x, slidemo->y, li))
			return true;		// don't hit the back side
		goto isblocking;
	}

	P_LineOpening (li);			// set openrange, opentop, openbottom
	if (openrange < slidemo->height)
		goto isblocking;		// doesn't fit
		
	if (opentop - slidemo->z < slidemo->height)
		goto isblocking;		// mobj is too high

	if (openbottom - slidemo->z > 24*FRACUNIT )
		goto isblocking;		// too big a step up

	return true;		// this line doesn't block movement
	
// the line does block movement, see if it is closer than best so far
isblocking:		
	if (in->frac < bestslidefrac)
	{
		secondslidefrac = bestslidefrac;
		secondslideline = bestslideline;
		bestslidefrac = in->frac;
		bestslideline = li;
	}
	
	return false;	// stop
}


/*
==================
=
= P_SlideMove
=
= The momx / momy move is bad, so try to slide along a wall
=
= Find the first line hit, move flush to it, and slide along it
=
= This is a kludgy mess.
==================
*/

void P_SlideMove (mobj_t *mo)
{
	fixed_t		leadx, leady;
	fixed_t		trailx, traily;
	fixed_t		newx, newy;
	int			hitcount;
		
	slidemo = mo;
	hitcount = 0;
retry:
	if (++hitcount == 3)
		goto stairstep;			// don't loop forever
			
//
// trace along the three leading corners
//
	if (mo->momx > 0)
	{
		leadx = mo->x + mo->radius;
		trailx = mo->x - mo->radius;
	}
	else
	{
		leadx = mo->x - mo->radius;
		trailx = mo->x + mo->radius;
	}
	
	if (mo->momy > 0)
	{
		leady = mo->y + mo->radius;
		traily = mo->y - mo->radius;
	}
	else
	{
		leady = mo->y - mo->radius;
		traily = mo->y + mo->radius;
	}
		
	bestslidefrac = FRACUNIT+1;
	
	P_PathTraverse ( leadx, leady, leadx+mo->momx, leady+mo->momy,
	 PT_ADDLINES, PTR_SlideTraverse );
	P_PathTraverse ( trailx, leady, trailx+mo->momx, leady+mo->momy,
	 PT_ADDLINES, PTR_SlideTraverse );
	P_PathTraverse ( leadx, traily, leadx+mo->momx, traily+mo->momy,
	 PT_ADDLINES, PTR_SlideTraverse );

//
// move up to the wall
//
	if (bestslidefrac == FRACUNIT+1)
	{	// the move most have hit the middle, so stairstep
stairstep:
		if (!P_TryMove (mo, mo->x, mo->y + mo->momy))
			P_TryMove (mo, mo->x + mo->momx, mo->y);
		return;
	}
	
	bestslidefrac -= 0x800;	// fudge a bit to make sure it doesn't hit
	if (bestslidefrac > 0)
	{
		newx = FixedMul (mo->momx, bestslidefrac);
		newy = FixedMul (mo->momy, bestslidefrac);
		if (!P_TryMove (mo, mo->x+newx, mo->y+newy))
			goto stairstep;
	}
		
//
// now continue along the wall
//
	bestslidefrac = FRACUNIT-(bestslidefrac+0x800);	// remainder
	if (bestslidefrac > FRACUNIT)
		bestslidefrac = FRACUNIT;
	if (bestslidefrac <= 0)
		return;
		
	tmxmove = FixedMul (mo->momx, bestslidefrac);
	tmymove = FixedMul (mo->momy, bestslidefrac);

	P_HitSlideLine (bestslideline);				// clip the moves

	mo->momx = tmxmove;
	mo->momy = tmymove;
		
	if (!P_TryMove (mo, mo->x+tmxmove, mo->y+tmymove))
	{
		goto retry;
	}
}



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

							P_LineAttack

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


mobj_t		*linetarget;			// who got hit (or NULL)
mobj_t		*shootthing;
fixed_t		shootz;					// height if not aiming up or down
									// ???: use slope for monsters?
int			la_damage;
fixed_t		attackrange;

fixed_t		aimslope;

extern	fixed_t		topslope, bottomslope;	// slopes to top and bottom of target

/*
===============================================================================
=
= PTR_AimTraverse
=
= Sets linetaget and aimslope when a target is aimed at
===============================================================================
*/

boolean		PTR_AimTraverse (intercept_t *in)
{
	line_t		*li;
	mobj_t		*th;
	fixed_t		slope, thingtopslope, thingbottomslope;
	fixed_t		dist;
		
	if (in->isaline)
	{
		li = in->d.line;
		if ( !(li->flags & ML_TWOSIDED) )
			return false;		// stop
//
// crosses a two sided line
// a two sided line will restrict the possible target ranges
		P_LineOpening (li);
	
		if (openbottom >= opentop)
			return false;		// stop
	
		dist = FixedMul (attackrange, in->frac);

		if (li->frontsector->floorheight != li->backsector->floorheight)
		{
			slope = FixedDiv (openbottom - shootz , dist);
			if (slope > bottomslope)
				bottomslope = slope;
		}
		
		if (li->frontsector->ceilingheight != li->backsector->ceilingheight)
		{
			slope = FixedDiv (opentop - shootz , dist);
			if (slope < topslope)
				topslope = slope;
		}
		
		if (topslope <= bottomslope)
			return false;		// stop
			
		return true;		// shot continues
	}
	
//
// shoot a thing
//
	th = in->d.thing;
	if (th == shootthing)
		return true;		// can't shoot self
	if (!(th->flags&MF_SHOOTABLE))
		return true;		// corpse or something
	if(th->type == MT_POD)
	{ // Can't auto-aim at pods
		return(true);
	}

// check angles to see if the thing can be aimed at

	dist = FixedMul (attackrange, in->frac);
	thingtopslope = FixedDiv (th->z+th->height - shootz , dist);
	if (thingtopslope < bottomslope)
		return true;		// shot over the thing
	thingbottomslope = FixedDiv (th->z - shootz, dist);
	if (thingbottomslope > topslope)
		return true;		// shot under the thing

//
// this thing can be hit!
//
	if (thingtopslope > topslope)
		thingtopslope = topslope;
	if (thingbottomslope < bottomslope)
		thingbottomslope = bottomslope;

	aimslope = (thingtopslope+thingbottomslope)/2;
	linetarget = th;

	return false;			// don't go any farther
}


/*
==============================================================================
=
= PTR_ShootTraverse
=
==============================================================================
*/

boolean		PTR_ShootTraverse (intercept_t *in)
{
	fixed_t		x,y,z;
	fixed_t		frac;
	line_t		*li;
	mobj_t		*th;
	fixed_t		slope;
	fixed_t		dist;
	fixed_t		thingtopslope, thingbottomslope;
	mobj_t *mo;

	if (in->isaline)
	{
		li = in->d.line;
		if (li->special)
			P_ShootSpecialLine (shootthing, li);
		if ( !(li->flags & ML_TWOSIDED) )
			goto hitline;

//
// crosses a two sided line
//
		P_LineOpening (li);
		
		dist = FixedMul (attackrange, in->frac);

		if (li->frontsector->floorheight != li->backsector->floorheight)
		{
			slope = FixedDiv (openbottom - shootz , dist);
			if (slope > aimslope)
				goto hitline;
		}
		
		if (li->frontsector->ceilingheight != li->backsector->ceilingheight)
		{
			slope = FixedDiv (opentop - shootz , dist);
			if (slope < aimslope)
				goto hitline;
		}
			
		return true;		// shot continues
//
// hit line
//
hitline:
		// position a bit closer
		frac = in->frac - FixedDiv (4*FRACUNIT,attackrange);
		x = trace.x + FixedMul (trace.dx, frac);
		y = trace.y + FixedMul (trace.dy, frac);
		z = shootz + FixedMul (aimslope, FixedMul(frac, attackrange));

		if (li->frontsector->ceilingpic == skyflatnum)
		{
			if (z > li->frontsector->ceilingheight)
				return false;		// don't shoot the sky!
			if	(li->backsector && li->backsector->ceilingpic == skyflatnum)
				return false;		// it's a sky hack wall
		}
				
		P_SpawnPuff (x,y,z);
		return false;			// don't go any farther
	}
	
//
// shoot a thing
//
	th = in->d.thing;
	if (th == shootthing)
		return true;		// can't shoot self
	if (!(th->flags&MF_SHOOTABLE))
		return true;		// corpse or something

//
// check for physical attacks on a ghost
//
	if(th->flags&MF_SHADOW && shootthing->player->readyweapon == wp_staff)
	{
		return(true);
	}

// check angles to see if the thing can be aimed at
	dist = FixedMul (attackrange, in->frac);
	thingtopslope = FixedDiv (th->z+th->height - shootz , dist);
	if (thingtopslope < aimslope)
		return true;		// shot over the thing
	thingbottomslope = FixedDiv (th->z - shootz, dist);
	if (thingbottomslope > aimslope)
		return true;		// shot under the thing

//
// hit thing
//
	// position a bit closer
	frac = in->frac - FixedDiv (10*FRACUNIT,attackrange);
	x = trace.x + FixedMul(trace.dx, frac);
	y = trace.y + FixedMul(trace.dy, frac);
	z = shootz + FixedMul(aimslope, FixedMul(frac, attackrange));
	if(PuffType == MT_BLASTERPUFF1)
	{ // Make blaster big puff
		mo = P_SpawnMobj(x, y, z, MT_BLASTERPUFF2);
		S_StartSound(mo, sfx_blshit);
	}
	else
	{
		P_SpawnPuff(x, y, z);
	}
	if(la_damage)
	{
		if(!(in->d.thing->flags&MF_NOBLOOD) && P_Random() < 192)
		{
			P_BloodSplatter(x, y, z, in->d.thing);
		}
		P_DamageMobj(th, shootthing, shootthing, la_damage);
	}
	return(false); // don't go any farther
}

/*
=================
=
= P_AimLineAttack
=
=================
*/

fixed_t P_AimLineAttack (mobj_t *t1, angle_t angle, fixed_t distance)
{
	fixed_t		x2, y2;
	
	angle >>= ANGLETOFINESHIFT;
	shootthing = t1;
	x2 = t1->x + (distance>>FRACBITS)*finecosine[angle];
	y2 = t1->y + (distance>>FRACBITS)*finesine[angle];
	shootz = t1->z + (t1->height>>1) + 8*FRACUNIT;
	topslope = 100*FRACUNIT/160;	// can't shoot outside view angles
	bottomslope = -100*FRACUNIT/160;
	attackrange = distance;
	linetarget = NULL;
	
	P_PathTraverse ( t1->x, t1->y, x2, y2
		, PT_ADDLINES|PT_ADDTHINGS, PTR_AimTraverse );
		
	if (linetarget)
		return aimslope;
	return 0;
}



/*
=================
=
= P_LineAttack
=
= if damage == 0, it is just a test trace that will leave linetarget set
=
=================
*/

void P_LineAttack (mobj_t *t1, angle_t angle, fixed_t distance, fixed_t slope, int damage)
{
	fixed_t		x2, y2;
	
	angle >>= ANGLETOFINESHIFT;
	shootthing = t1;
	la_damage = damage;
	x2 = t1->x + (distance>>FRACBITS)*finecosine[angle];
	y2 = t1->y + (distance>>FRACBITS)*finesine[angle];
	shootz = t1->z + (t1->height>>1) + 8*FRACUNIT;
	if(t1->flags2&MF2_FEETARECLIPPED)
	{
		shootz -= FOOTCLIPSIZE;
	}
	attackrange = distance;
	aimslope = slope;
		
	P_PathTraverse ( t1->x, t1->y, x2, y2
		, PT_ADDLINES|PT_ADDTHINGS, PTR_ShootTraverse );
}



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

							USE LINES

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

mobj_t		*usething;

boolean		PTR_UseTraverse (intercept_t *in)
{
	if (!in->d.line->special)
	{
		P_LineOpening (in->d.line);
		if (openrange <= 0)
		{
			//S_StartSound (usething, sfx_noway);
			return false;	// can't use through a wall
		}
		return true ;		// not a special line, but keep checking
	}
		
	if (P_PointOnLineSide (usething->x, usething->y, in->d.line) == 1)
		return false;		// don't use back sides
		
	P_UseSpecialLine (usething, in->d.line);

	return false;			// can't use for than one special line in a row
}


/*
================
=
= P_UseLines
=
= Looks for special lines in front of the player to activate
================ 
*/

void P_UseLines (player_t *player)
{
	int			angle;
	fixed_t		x1, y1, x2, y2;
	
	usething = player->mo;
		
	angle = player->mo->angle >> ANGLETOFINESHIFT;
	x1 = player->mo->x;
	y1 = player->mo->y;
	x2 = x1 + (USERANGE>>FRACBITS)*finecosine[angle];
	y2 = y1 + (USERANGE>>FRACBITS)*finesine[angle];
	
	P_PathTraverse ( x1, y1, x2, y2, PT_ADDLINES, PTR_UseTraverse );
}



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

							RADIUS ATTACK

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

mobj_t		*bombsource;
mobj_t		*bombspot;
int			bombdamage;

/*
=================
=
= PIT_RadiusAttack
=
= Source is the creature that casued the explosion at spot
=================
*/

boolean PIT_RadiusAttack (mobj_t *thing)
{
	fixed_t dx, dy, dist;

	if(!(thing->flags&MF_SHOOTABLE))
	{
		return true;
	}
	if(thing->type == MT_MINOTAUR || thing->type == MT_SORCERER1
		|| thing->type == MT_SORCERER2)
	{ // Episode 2 and 3 bosses take no damage from PIT_RadiusAttack
		return(true);
	}
	dx = abs(thing->x - bombspot->x);
	dy = abs(thing->y - bombspot->y);
	dist = dx > dy ? dx : dy;
	dist = (dist - thing->radius) >> FRACBITS;
	if(dist < 0)
	{
		dist = 0;
	}
	if(dist >= bombdamage)
	{ // Out of range
		return true;
	}
	if(P_CheckSight(thing, bombspot))
	{ // OK to damage, target is in direct path
		P_DamageMobj(thing, bombspot, bombsource, bombdamage - dist);
	}
	return(true);
}

/*
=================
=
= P_RadiusAttack
=
= Source is the creature that casued the explosion at spot
=================
*/

void P_RadiusAttack (mobj_t *spot, mobj_t *source, int damage)
{
	int			x,y, xl, xh, yl, yh;
	fixed_t		dist;
	
	dist = (damage+MAXRADIUS)<<FRACBITS;
	yh = (spot->y + dist - bmaporgy)>>MAPBLOCKSHIFT;
	yl = (spot->y - dist - bmaporgy)>>MAPBLOCKSHIFT;
	xh = (spot->x + dist - bmaporgx)>>MAPBLOCKSHIFT;
	xl = (spot->x - dist - bmaporgx)>>MAPBLOCKSHIFT;
	bombspot = spot;
	if(spot->type == MT_POD && spot->target)
	{
		bombsource = spot->target;
	}
	else
	{
		bombsource = source;
	}
	bombdamage = damage;
	for (y=yl ; y<=yh ; y++)
		for (x=xl ; x<=xh ; x++)
			P_BlockThingsIterator (x, y, PIT_RadiusAttack );
}


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

						SECTOR HEIGHT CHANGING

= After modifying a sectors floor or ceiling height, call this
= routine to adjust the positions of all things that touch the
= sector.
=
= If anything doesn't fit anymore, true will be returned.
= If crunch is true, they will take damage as they are being crushed
= If Crunch is false, you should set the sector height back the way it
= was and call P_ChangeSector again to undo the changes
==============================================================================
*/

boolean		crushchange;
boolean		nofit;

/*
===============
=
= PIT_ChangeSector
=
===============
*/

boolean PIT_ChangeSector (mobj_t *thing)
{
	mobj_t		*mo;
	
	if (P_ThingHeightClip (thing))
		return true;		// keep checking

	// crunch bodies to giblets
	if (thing->health <= 0)
	{
		//P_SetMobjState (thing, S_GIBS);
		thing->height = 0;
		thing->radius = 0;
		return true;		// keep checking
	}

	// crunch dropped items
	if (thing->flags & MF_DROPPED)
	{
		P_RemoveMobj (thing);
		return true;		// keep checking
	}

	if (! (thing->flags & MF_SHOOTABLE) )
		return true;				// assume it is bloody gibs or something
		
	nofit = true;
	if (crushchange && !(leveltime&3) )
	{
		P_DamageMobj(thing,NULL,NULL,10);
		// spray blood in a random direction
		mo = P_SpawnMobj (thing->x, thing->y, thing->z + thing->height/2, MT_BLOOD);
		mo->momx = (P_Random() - P_Random ())<<12;
		mo->momy = (P_Random() - P_Random ())<<12;
	}
		
	return true;		// keep checking (crush other things)	
}

/*
===============
=
= P_ChangeSector
=
===============
*/

boolean P_ChangeSector (sector_t *sector, boolean crunch)
{
	int			x,y;
	
	nofit = false;
	crushchange = crunch;
	
// recheck heights for all things near the moving sector

	for (x=sector->blockbox[BOXLEFT] ; x<= sector->blockbox[BOXRIGHT] ; x++)
		for (y=sector->blockbox[BOXBOTTOM];y<= sector->blockbox[BOXTOP] ; y++)
			P_BlockThingsIterator (x, y, PIT_ChangeSector);
	
	
	return nofit;
}