Quake-2

g_phys.c (21370B)

---

 /*
 Copyright (C) 1997-2001 Id Software, Inc.
 
 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.
 
 */
 // g_phys.c
 
 #include "g_local.h"
 
 /*
 
 
 pushmove objects do not obey gravity, and do not interact with each other or trigger fields, but block normal movement and push normal objects when they move.
 
 onground is set for toss objects when they come to a complete rest.  it is set for steping or walking objects 
 
 doors, plats, etc are SOLID_BSP, and MOVETYPE_PUSH
 bonus items are SOLID_TRIGGER touch, and MOVETYPE_TOSS
 corpses are SOLID_NOT and MOVETYPE_TOSS
 crates are SOLID_BBOX and MOVETYPE_TOSS
 walking monsters are SOLID_SLIDEBOX and MOVETYPE_STEP
 flying/floating monsters are SOLID_SLIDEBOX and MOVETYPE_FLY
 
 solid_edge items only clip against bsp models.
 
 */
 
 
 /*
 ============
 SV_TestEntityPosition
 
 ============
 */
 edict_t	*SV_TestEntityPosition (edict_t *ent)
 {
 	trace_t	trace;
 	int		mask;
 
 	
 	if (ent->clipmask)
 		mask = ent->clipmask;
 	else
 		mask = MASK_SOLID;
 	trace = gi.trace (ent->s.origin, ent->mins, ent->maxs, ent->s.origin, ent, mask);
 
 	if (trace.startsolid)
 		return g_edicts;
 		
 	return NULL;
 }
 
 
 /*
 ================
 SV_CheckVelocity
 ================
 */
 void SV_CheckVelocity (edict_t *ent)
 {
 	int		i;
 
 //
 // bound velocity
 //
 	for (i=0 ; i<3 ; i++)
 	{
 		if (ent->velocity[i] > sv_maxvelocity->value)
 			ent->velocity[i] = sv_maxvelocity->value;
 		else if (ent->velocity[i] < -sv_maxvelocity->value)
 			ent->velocity[i] = -sv_maxvelocity->value;
 	}
 }
 
 /*
 =============
 SV_RunThink
 
 Runs thinking code for this frame if necessary
 =============
 */
 qboolean SV_RunThink (edict_t *ent)
 {
 	float	thinktime;
 
 	thinktime = ent->nextthink;
 	if (thinktime <= 0)
 		return true;
 	if (thinktime > level.time+0.001)
 		return true;
 	
 	ent->nextthink = 0;
 	if (!ent->think)
 		gi.error ("NULL ent->think");
 	ent->think (ent);
 
 	return false;
 }
 
 /*
 ==================
 SV_Impact
 
 Two entities have touched, so run their touch functions
 ==================
 */
 void SV_Impact (edict_t *e1, trace_t *trace)
 {
 	edict_t		*e2;
 //	cplane_t	backplane;
 
 	e2 = trace->ent;
 
 	if (e1->touch && e1->solid != SOLID_NOT)
 		e1->touch (e1, e2, &trace->plane, trace->surface);
 	
 	if (e2->touch && e2->solid != SOLID_NOT)
 		e2->touch (e2, e1, NULL, NULL);
 }
 
 
 /*
 ==================
 ClipVelocity
 
 Slide off of the impacting object
 returns the blocked flags (1 = floor, 2 = step / wall)
 ==================
 */
 #define	STOP_EPSILON	0.1
 
 int ClipVelocity (vec3_t in, vec3_t normal, vec3_t out, float overbounce)
 {
 	float	backoff;
 	float	change;
 	int		i, blocked;
 	
 	blocked = 0;
 	if (normal[2] > 0)
 		blocked |= 1;		// floor
 	if (!normal[2])
 		blocked |= 2;		// step
 	
 	backoff = DotProduct (in, normal) * overbounce;
 
 	for (i=0 ; i<3 ; i++)
 	{
 		change = normal[i]*backoff;
 		out[i] = in[i] - change;
 		if (out[i] > -STOP_EPSILON && out[i] < STOP_EPSILON)
 			out[i] = 0;
 	}
 	
 	return blocked;
 }
 
 
 /*
 ============
 SV_FlyMove
 
 The basic solid body movement clip that slides along multiple planes
 Returns the clipflags if the velocity was modified (hit something solid)
 1 = floor
 2 = wall / step
 4 = dead stop
 ============
 */
 #define	MAX_CLIP_PLANES	5
 int SV_FlyMove (edict_t *ent, float time, int mask)
 {
 	edict_t		*hit;
 	int			bumpcount, numbumps;
 	vec3_t		dir;
 	float		d;
 	int			numplanes;
 	vec3_t		planes[MAX_CLIP_PLANES];
 	vec3_t		primal_velocity, original_velocity, new_velocity;
 	int			i, j;
 	trace_t		trace;
 	vec3_t		end;
 	float		time_left;
 	int			blocked;
 	
 	numbumps = 4;
 	
 	blocked = 0;
 	VectorCopy (ent->velocity, original_velocity);
 	VectorCopy (ent->velocity, primal_velocity);
 	numplanes = 0;
 	
 	time_left = time;
 
 	ent->groundentity = NULL;
 	for (bumpcount=0 ; bumpcount<numbumps ; bumpcount++)
 	{
 		for (i=0 ; i<3 ; i++)
 			end[i] = ent->s.origin[i] + time_left * ent->velocity[i];
 
 		trace = gi.trace (ent->s.origin, ent->mins, ent->maxs, end, ent, mask);
 
 		if (trace.allsolid)
 		{	// entity is trapped in another solid
 			VectorCopy (vec3_origin, ent->velocity);
 			return 3;
 		}
 
 		if (trace.fraction > 0)
 		{	// actually covered some distance
 			VectorCopy (trace.endpos, ent->s.origin);
 			VectorCopy (ent->velocity, original_velocity);
 			numplanes = 0;
 		}
 
 		if (trace.fraction == 1)
 			 break;		// moved the entire distance
 
 		hit = trace.ent;
 
 		if (trace.plane.normal[2] > 0.7)
 		{
 			blocked |= 1;		// floor
 			if ( hit->solid == SOLID_BSP)
 			{
 				ent->groundentity = hit;
 				ent->groundentity_linkcount = hit->linkcount;
 			}
 		}
 		if (!trace.plane.normal[2])
 		{
 			blocked |= 2;		// step
 		}
 
 //
 // run the impact function
 //
 		SV_Impact (ent, &trace);
 		if (!ent->inuse)
 			break;		// removed by the impact function
 
 		
 		time_left -= time_left * trace.fraction;
 		
 	// cliped to another plane
 		if (numplanes >= MAX_CLIP_PLANES)
 		{	// this shouldn't really happen
 			VectorCopy (vec3_origin, ent->velocity);
 			return 3;
 		}
 
 		VectorCopy (trace.plane.normal, planes[numplanes]);
 		numplanes++;
 
 //
 // modify original_velocity so it parallels all of the clip planes
 //
 		for (i=0 ; i<numplanes ; i++)
 		{
 			ClipVelocity (original_velocity, planes[i], new_velocity, 1);
 			for (j=0 ; j<numplanes ; j++)
 				if (j != i)
 				{
 					if (DotProduct (new_velocity, planes[j]) < 0)
 						break;	// not ok
 				}
 			if (j == numplanes)
 				break;
 		}
 		
 		if (i != numplanes)
 		{	// go along this plane
 			VectorCopy (new_velocity, ent->velocity);
 		}
 		else
 		{	// go along the crease
 			if (numplanes != 2)
 			{
 //				gi.dprintf ("clip velocity, numplanes == %i\n",numplanes);
 				VectorCopy (vec3_origin, ent->velocity);
 				return 7;
 			}
 			CrossProduct (planes[0], planes[1], dir);
 			d = DotProduct (dir, ent->velocity);
 			VectorScale (dir, d, ent->velocity);
 		}
 
 //
 // if original velocity is against the original velocity, stop dead
 // to avoid tiny occilations in sloping corners
 //
 		if (DotProduct (ent->velocity, primal_velocity) <= 0)
 		{
 			VectorCopy (vec3_origin, ent->velocity);
 			return blocked;
 		}
 	}
 
 	return blocked;
 }
 
 
 /*
 ============
 SV_AddGravity
 
 ============
 */
 void SV_AddGravity (edict_t *ent)
 {
 	ent->velocity[2] -= ent->gravity * sv_gravity->value * FRAMETIME;
 }
 
 /*
 ===============================================================================
 
 PUSHMOVE
 
 ===============================================================================
 */
 
 /*
 ============
 SV_PushEntity
 
 Does not change the entities velocity at all
 ============
 */
 trace_t SV_PushEntity (edict_t *ent, vec3_t push)
 {
 	trace_t	trace;
 	vec3_t	start;
 	vec3_t	end;
 	int		mask;
 
 	VectorCopy (ent->s.origin, start);
 	VectorAdd (start, push, end);
 
 retry:
 	if (ent->clipmask)
 		mask = ent->clipmask;
 	else
 		mask = MASK_SOLID;
 
 	trace = gi.trace (start, ent->mins, ent->maxs, end, ent, mask);
 	
 	VectorCopy (trace.endpos, ent->s.origin);
 	gi.linkentity (ent);
 
 	if (trace.fraction != 1.0)
 	{
 		SV_Impact (ent, &trace);
 
 		// if the pushed entity went away and the pusher is still there
 		if (!trace.ent->inuse && ent->inuse)
 		{
 			// move the pusher back and try again
 			VectorCopy (start, ent->s.origin);
 			gi.linkentity (ent);
 			goto retry;
 		}
 	}
 
 	if (ent->inuse)
 		G_TouchTriggers (ent);
 
 	return trace;
 }					
 
 
 typedef struct
 {
 	edict_t	*ent;
 	vec3_t	origin;
 	vec3_t	angles;
 	float	deltayaw;
 } pushed_t;
 pushed_t	pushed[MAX_EDICTS], *pushed_p;
 
 edict_t	*obstacle;
 
 /*
 ============
 SV_Push
 
 Objects need to be moved back on a failed push,
 otherwise riders would continue to slide.
 ============
 */
 qboolean SV_Push (edict_t *pusher, vec3_t move, vec3_t amove)
 {
 	int			i, e;
 	edict_t		*check, *block;
 	vec3_t		mins, maxs;
 	pushed_t	*p;
 	vec3_t		org, org2, move2, forward, right, up;
 
 	// clamp the move to 1/8 units, so the position will
 	// be accurate for client side prediction
 	for (i=0 ; i<3 ; i++)
 	{
 		float	temp;
 		temp = move[i]*8.0;
 		if (temp > 0.0)
 			temp += 0.5;
 		else
 			temp -= 0.5;
 		move[i] = 0.125 * (int)temp;
 	}
 
 	// find the bounding box
 	for (i=0 ; i<3 ; i++)
 	{
 		mins[i] = pusher->absmin[i] + move[i];
 		maxs[i] = pusher->absmax[i] + move[i];
 	}
 
 // we need this for pushing things later
 	VectorSubtract (vec3_origin, amove, org);
 	AngleVectors (org, forward, right, up);
 
 // save the pusher's original position
 	pushed_p->ent = pusher;
 	VectorCopy (pusher->s.origin, pushed_p->origin);
 	VectorCopy (pusher->s.angles, pushed_p->angles);
 	if (pusher->client)
 		pushed_p->deltayaw = pusher->client->ps.pmove.delta_angles[YAW];
 	pushed_p++;
 
 // move the pusher to it's final position
 	VectorAdd (pusher->s.origin, move, pusher->s.origin);
 	VectorAdd (pusher->s.angles, amove, pusher->s.angles);
 	gi.linkentity (pusher);
 
 // see if any solid entities are inside the final position
 	check = g_edicts+1;
 	for (e = 1; e < globals.num_edicts; e++, check++)
 	{
 		if (!check->inuse)
 			continue;
 		if (check->movetype == MOVETYPE_PUSH
 		|| check->movetype == MOVETYPE_STOP
 		|| check->movetype == MOVETYPE_NONE
 		|| check->movetype == MOVETYPE_NOCLIP)
 			continue;
 
 		if (!check->area.prev)
 			continue;		// not linked in anywhere
 
 	// if the entity is standing on the pusher, it will definitely be moved
 		if (check->groundentity != pusher)
 		{
 			// see if the ent needs to be tested
 			if ( check->absmin[0] >= maxs[0]
 			|| check->absmin[1] >= maxs[1]
 			|| check->absmin[2] >= maxs[2]
 			|| check->absmax[0] <= mins[0]
 			|| check->absmax[1] <= mins[1]
 			|| check->absmax[2] <= mins[2] )
 				continue;
 
 			// see if the ent's bbox is inside the pusher's final position
 			if (!SV_TestEntityPosition (check))
 				continue;
 		}
 
 		if ((pusher->movetype == MOVETYPE_PUSH) || (check->groundentity == pusher))
 		{
 			// move this entity
 			pushed_p->ent = check;
 			VectorCopy (check->s.origin, pushed_p->origin);
 			VectorCopy (check->s.angles, pushed_p->angles);
 			pushed_p++;
 
 			// try moving the contacted entity 
 			VectorAdd (check->s.origin, move, check->s.origin);
 			if (check->client)
 			{	// FIXME: doesn't rotate monsters?
 				check->client->ps.pmove.delta_angles[YAW] += amove[YAW];
 			}
 
 			// figure movement due to the pusher's amove
 			VectorSubtract (check->s.origin, pusher->s.origin, org);
 			org2[0] = DotProduct (org, forward);
 			org2[1] = -DotProduct (org, right);
 			org2[2] = DotProduct (org, up);
 			VectorSubtract (org2, org, move2);
 			VectorAdd (check->s.origin, move2, check->s.origin);
 
 			// may have pushed them off an edge
 			if (check->groundentity != pusher)
 				check->groundentity = NULL;
 
 			block = SV_TestEntityPosition (check);
 			if (!block)
 			{	// pushed ok
 				gi.linkentity (check);
 				// impact?
 				continue;
 			}
 
 			// if it is ok to leave in the old position, do it
 			// this is only relevent for riding entities, not pushed
 			// FIXME: this doesn't acount for rotation
 			VectorSubtract (check->s.origin, move, check->s.origin);
 			block = SV_TestEntityPosition (check);
 			if (!block)
 			{
 				pushed_p--;
 				continue;
 			}
 		}
 		
 		// save off the obstacle so we can call the block function
 		obstacle = check;
 
 		// move back any entities we already moved
 		// go backwards, so if the same entity was pushed
 		// twice, it goes back to the original position
 		for (p=pushed_p-1 ; p>=pushed ; p--)
 		{
 			VectorCopy (p->origin, p->ent->s.origin);
 			VectorCopy (p->angles, p->ent->s.angles);
 			if (p->ent->client)
 			{
 				p->ent->client->ps.pmove.delta_angles[YAW] = p->deltayaw;
 			}
 			gi.linkentity (p->ent);
 		}
 		return false;
 	}
 
 //FIXME: is there a better way to handle this?
 	// see if anything we moved has touched a trigger
 	for (p=pushed_p-1 ; p>=pushed ; p--)
 		G_TouchTriggers (p->ent);
 
 	return true;
 }
 
 /*
 ================
 SV_Physics_Pusher
 
 Bmodel objects don't interact with each other, but
 push all box objects
 ================
 */
 void SV_Physics_Pusher (edict_t *ent)
 {
 	vec3_t		move, amove;
 	edict_t		*part, *mv;
 
 	// if not a team captain, so movement will be handled elsewhere
 	if ( ent->flags & FL_TEAMSLAVE)
 		return;
 
 	// make sure all team slaves can move before commiting
 	// any moves or calling any think functions
 	// if the move is blocked, all moved objects will be backed out
 //retry:
 	pushed_p = pushed;
 	for (part = ent ; part ; part=part->teamchain)
 	{
 		if (part->velocity[0] || part->velocity[1] || part->velocity[2] ||
 			part->avelocity[0] || part->avelocity[1] || part->avelocity[2]
 			)
 		{	// object is moving
 			VectorScale (part->velocity, FRAMETIME, move);
 			VectorScale (part->avelocity, FRAMETIME, amove);
 
 			if (!SV_Push (part, move, amove))
 				break;	// move was blocked
 		}
 	}
 	if (pushed_p > &pushed[MAX_EDICTS])
 		gi.error (ERR_FATAL, "pushed_p > &pushed[MAX_EDICTS], memory corrupted");
 
 	if (part)
 	{
 		// the move failed, bump all nextthink times and back out moves
 		for (mv = ent ; mv ; mv=mv->teamchain)
 		{
 			if (mv->nextthink > 0)
 				mv->nextthink += FRAMETIME;
 		}
 
 		// if the pusher has a "blocked" function, call it
 		// otherwise, just stay in place until the obstacle is gone
 		if (part->blocked)
 			part->blocked (part, obstacle);
 #if 0
 		// if the pushed entity went away and the pusher is still there
 		if (!obstacle->inuse && part->inuse)
 			goto retry;
 #endif
 	}
 	else
 	{
 		// the move succeeded, so call all think functions
 		for (part = ent ; part ; part=part->teamchain)
 		{
 			SV_RunThink (part);
 		}
 	}
 }
 
 //==================================================================
 
 /*
 =============
 SV_Physics_None
 
 Non moving objects can only think
 =============
 */
 void SV_Physics_None (edict_t *ent)
 {
 // regular thinking
 	SV_RunThink (ent);
 }
 
 /*
 =============
 SV_Physics_Noclip
 
 A moving object that doesn't obey physics
 =============
 */
 void SV_Physics_Noclip (edict_t *ent)
 {
 // regular thinking
 	if (!SV_RunThink (ent))
 		return;
 	
 	VectorMA (ent->s.angles, FRAMETIME, ent->avelocity, ent->s.angles);
 	VectorMA (ent->s.origin, FRAMETIME, ent->velocity, ent->s.origin);
 
 	gi.linkentity (ent);
 }
 
 /*
 ==============================================================================
 
 TOSS / BOUNCE
 
 ==============================================================================
 */
 
 /*
 =============
 SV_Physics_Toss
 
 Toss, bounce, and fly movement.  When onground, do nothing.
 =============
 */
 void SV_Physics_Toss (edict_t *ent)
 {
 	trace_t		trace;
 	vec3_t		move;
 	float		backoff;
 	edict_t		*slave;
 	qboolean	wasinwater;
 	qboolean	isinwater;
 	vec3_t		old_origin;
 
 // regular thinking
 	SV_RunThink (ent);
 
 	// if not a team captain, so movement will be handled elsewhere
 	if ( ent->flags & FL_TEAMSLAVE)
 		return;
 
 	if (ent->velocity[2] > 0)
 		ent->groundentity = NULL;
 
 // check for the groundentity going away
 	if (ent->groundentity)
 		if (!ent->groundentity->inuse)
 			ent->groundentity = NULL;
 
 // if onground, return without moving
 	if ( ent->groundentity )
 		return;
 
 	VectorCopy (ent->s.origin, old_origin);
 
 	SV_CheckVelocity (ent);
 
 // add gravity
 	if (ent->movetype != MOVETYPE_FLY
 	&& ent->movetype != MOVETYPE_FLYMISSILE)
 		SV_AddGravity (ent);
 
 // move angles
 	VectorMA (ent->s.angles, FRAMETIME, ent->avelocity, ent->s.angles);
 
 // move origin
 	VectorScale (ent->velocity, FRAMETIME, move);
 	trace = SV_PushEntity (ent, move);
 	if (!ent->inuse)
 		return;
 
 	if (trace.fraction < 1)
 	{
 		if (ent->movetype == MOVETYPE_BOUNCE)
 			backoff = 1.5;
 		else
 			backoff = 1;
 
 		ClipVelocity (ent->velocity, trace.plane.normal, ent->velocity, backoff);
 
 	// stop if on ground
 		if (trace.plane.normal[2] > 0.7)
 		{		
 			if (ent->velocity[2] < 60 || ent->movetype != MOVETYPE_BOUNCE )
 			{
 				ent->groundentity = trace.ent;
 				ent->groundentity_linkcount = trace.ent->linkcount;
 				VectorCopy (vec3_origin, ent->velocity);
 				VectorCopy (vec3_origin, ent->avelocity);
 			}
 		}
 
 //		if (ent->touch)
 //			ent->touch (ent, trace.ent, &trace.plane, trace.surface);
 	}
 	
 // check for water transition
 	wasinwater = (ent->watertype & MASK_WATER);
 	ent->watertype = gi.pointcontents (ent->s.origin);
 	isinwater = ent->watertype & MASK_WATER;
 
 	if (isinwater)
 		ent->waterlevel = 1;
 	else
 		ent->waterlevel = 0;
 
 	if (!wasinwater && isinwater)
 		gi.positioned_sound (old_origin, g_edicts, CHAN_AUTO, gi.soundindex("misc/h2ohit1.wav"), 1, 1, 0);
 	else if (wasinwater && !isinwater)
 		gi.positioned_sound (ent->s.origin, g_edicts, CHAN_AUTO, gi.soundindex("misc/h2ohit1.wav"), 1, 1, 0);
 
 // move teamslaves
 	for (slave = ent->teamchain; slave; slave = slave->teamchain)
 	{
 		VectorCopy (ent->s.origin, slave->s.origin);
 		gi.linkentity (slave);
 	}
 }
 
 /*
 ===============================================================================
 
 STEPPING MOVEMENT
 
 ===============================================================================
 */
 
 /*
 =============
 SV_Physics_Step
 
 Monsters freefall when they don't have a ground entity, otherwise
 all movement is done with discrete steps.
 
 This is also used for objects that have become still on the ground, but
 will fall if the floor is pulled out from under them.
 FIXME: is this true?
 =============
 */
 
 //FIXME: hacked in for E3 demo
 #define	sv_stopspeed		100
 #define sv_friction			6
 #define sv_waterfriction	1
 
 void SV_AddRotationalFriction (edict_t *ent)
 {
 	int		n;
 	float	adjustment;
 
 	VectorMA (ent->s.angles, FRAMETIME, ent->avelocity, ent->s.angles);
 	adjustment = FRAMETIME * sv_stopspeed * sv_friction;
 	for (n = 0; n < 3; n++)
 	{
 		if (ent->avelocity[n] > 0)
 		{
 			ent->avelocity[n] -= adjustment;
 			if (ent->avelocity[n] < 0)
 				ent->avelocity[n] = 0;
 		}
 		else
 		{
 			ent->avelocity[n] += adjustment;
 			if (ent->avelocity[n] > 0)
 				ent->avelocity[n] = 0;
 		}
 	}
 }
 
 void SV_Physics_Step (edict_t *ent)
 {
 	qboolean	wasonground;
 	qboolean	hitsound = false;
 	float		*vel;
 	float		speed, newspeed, control;
 	float		friction;
 	edict_t		*groundentity;
 	int			mask;
 
 	// airborn monsters should always check for ground
 	if (!ent->groundentity)
 		M_CheckGround (ent);
 
 	groundentity = ent->groundentity;
 
 	SV_CheckVelocity (ent);
 
 	if (groundentity)
 		wasonground = true;
 	else
 		wasonground = false;
 		
 	if (ent->avelocity[0] || ent->avelocity[1] || ent->avelocity[2])
 		SV_AddRotationalFriction (ent);
 
 	// add gravity except:
 	//   flying monsters
 	//   swimming monsters who are in the water
 	if (! wasonground)
 		if (!(ent->flags & FL_FLY))
 			if (!((ent->flags & FL_SWIM) && (ent->waterlevel > 2)))
 			{
 				if (ent->velocity[2] < sv_gravity->value*-0.1)
 					hitsound = true;
 				if (ent->waterlevel == 0)
 					SV_AddGravity (ent);
 			}
 
 	// friction for flying monsters that have been given vertical velocity
 	if ((ent->flags & FL_FLY) && (ent->velocity[2] != 0))
 	{
 		speed = fabs(ent->velocity[2]);
 		control = speed < sv_stopspeed ? sv_stopspeed : speed;
 		friction = sv_friction/3;
 		newspeed = speed - (FRAMETIME * control * friction);
 		if (newspeed < 0)
 			newspeed = 0;
 		newspeed /= speed;
 		ent->velocity[2] *= newspeed;
 	}
 
 	// friction for flying monsters that have been given vertical velocity
 	if ((ent->flags & FL_SWIM) && (ent->velocity[2] != 0))
 	{
 		speed = fabs(ent->velocity[2]);
 		control = speed < sv_stopspeed ? sv_stopspeed : speed;
 		newspeed = speed - (FRAMETIME * control * sv_waterfriction * ent->waterlevel);
 		if (newspeed < 0)
 			newspeed = 0;
 		newspeed /= speed;
 		ent->velocity[2] *= newspeed;
 	}
 
 	if (ent->velocity[2] || ent->velocity[1] || ent->velocity[0])
 	{
 		// apply friction
 		// let dead monsters who aren't completely onground slide
 		if ((wasonground) || (ent->flags & (FL_SWIM|FL_FLY)))
 			if (!(ent->health <= 0.0 && !M_CheckBottom(ent)))
 			{
 				vel = ent->velocity;
 				speed = sqrt(vel[0]*vel[0] +vel[1]*vel[1]);
 				if (speed)
 				{
 					friction = sv_friction;
 
 					control = speed < sv_stopspeed ? sv_stopspeed : speed;
 					newspeed = speed - FRAMETIME*control*friction;
 
 					if (newspeed < 0)
 						newspeed = 0;
 					newspeed /= speed;
 
 					vel[0] *= newspeed;
 					vel[1] *= newspeed;
 				}
 			}
 
 		if (ent->svflags & SVF_MONSTER)
 			mask = MASK_MONSTERSOLID;
 		else
 			mask = MASK_SOLID;
 		SV_FlyMove (ent, FRAMETIME, mask);
 
 		gi.linkentity (ent);
 		G_TouchTriggers (ent);
 
 		if (ent->groundentity)
 			if (!wasonground)
 				if (hitsound)
 					gi.sound (ent, 0, gi.soundindex("world/land.wav"), 1, 1, 0);
 	}
 
 // regular thinking
 	SV_RunThink (ent);
 }
 
 //============================================================================
 /*
 ================
 G_RunEntity
 
 ================
 */
 void G_RunEntity (edict_t *ent)
 {
 	if (ent->prethink)
 		ent->prethink (ent);
 
 	switch ( (int)ent->movetype)
 	{
 	case MOVETYPE_PUSH:
 	case MOVETYPE_STOP:
 		SV_Physics_Pusher (ent);
 		break;
 	case MOVETYPE_NONE:
 		SV_Physics_None (ent);
 		break;
 	case MOVETYPE_NOCLIP:
 		SV_Physics_Noclip (ent);
 		break;
 	case MOVETYPE_STEP:
 		SV_Physics_Step (ent);
 		break;
 	case MOVETYPE_TOSS:
 	case MOVETYPE_BOUNCE:
 	case MOVETYPE_FLY:
 	case MOVETYPE_FLYMISSILE:
 		SV_Physics_Toss (ent);
 		break;
 	default:
 		gi.error ("SV_Physics: bad movetype %i", (int)ent->movetype);			
 	}
 }