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/*

Copyright (C) 1996-1997 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.

*/

// sv_phys.c

#include "quakedef.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.

*/

cvar_t	sv_friction = {"sv_friction","4",false,true};

cvar_t	sv_stopspeed = {"sv_stopspeed","100"};

cvar_t	sv_gravity = {"sv_gravity","800",false,true};

cvar_t	sv_maxvelocity = {"sv_maxvelocity","2000"};

cvar_t	sv_nostep = {"sv_nostep","0"};

#ifdef QUAKE2

static	vec3_t	vec_origin = {0.0, 0.0, 0.0};

#endif

#define	MOVE_EPSILON	0.01

void SV_Physics_Toss (edict_t *ent);

/*

================

SV_CheckAllEnts

================

*/

void SV_CheckAllEnts (void)

{

	int			e;

	edict_t		*check;

// see if any solid entities are inside the final position

	check = NEXT_EDICT(sv.edicts);

	for (e=1 ; e

	{

		if (check->free)

			continue;

		if (check->v.movetype == MOVETYPE_PUSH

		|| check->v.movetype == MOVETYPE_NONE

#ifdef QUAKE2

		|| check->v.movetype == MOVETYPE_FOLLOW

#endif

		|| check->v.movetype == MOVETYPE_NOCLIP)

			continue;

		if (SV_TestEntityPosition (check))

			Con_Printf ("entity in invalid position\n");

	}

}

/*

================

SV_CheckVelocity

================

*/

void SV_CheckVelocity (edict_t *ent)

{

	int		i;

//

// bound velocity

//

	for (i=0 ; i<3 ; i++)

	{

		if (IS_NAN(ent->v.velocity[i]))

		{

			Con_Printf ("Got a NaN velocity on %s\n", pr_strings + ent->v.classname);

			ent->v.velocity[i] = 0;

		}

		if (IS_NAN(ent->v.origin[i]))

		{

			Con_Printf ("Got a NaN origin on %s\n", pr_strings + ent->v.classname);

			ent->v.origin[i] = 0;

		}

		if (ent->v.velocity[i] > sv_maxvelocity.value)

			ent->v.velocity[i] = sv_maxvelocity.value;

		else if (ent->v.velocity[i] < -sv_maxvelocity.value)

			ent->v.velocity[i] = -sv_maxvelocity.value;

	}

}

/*

=============

SV_RunThink

Runs thinking code if time.  There is some play in the exact time the think

function will be called, because it is called before any movement is done

in a frame.  Not used for pushmove objects, because they must be exact.

Returns false if the entity removed itself.

=============

*/

qboolean SV_RunThink (edict_t *ent)

{

	float	thinktime;

	thinktime = ent->v.nextthink;

	if (thinktime <= 0 || thinktime > sv.time + host_frametime)

		return true;

	if (thinktime < sv.time)

		thinktime = sv.time;	// don't let things stay in the past.

								// it is possible to start that way

								// by a trigger with a local time.

	ent->v.nextthink = 0;

	pr_global_struct->time = thinktime;

	pr_global_struct->self = EDICT_TO_PROG(ent);

	pr_global_struct->other = EDICT_TO_PROG(sv.edicts);

	PR_ExecuteProgram (ent->v.think);

	return !ent->free;

}

/*

==================

SV_Impact

Two entities have touched, so run their touch functions

==================

*/

void SV_Impact (edict_t *e1, edict_t *e2)

{

	int		old_self, old_other;

	old_self = pr_global_struct->self;

	old_other = pr_global_struct->other;

	pr_global_struct->time = sv.time;

	if (e1->v.touch && e1->v.solid != SOLID_NOT)

	{

		pr_global_struct->self = EDICT_TO_PROG(e1);

		pr_global_struct->other = EDICT_TO_PROG(e2);

		PR_ExecuteProgram (e1->v.touch);

	}

	if (e2->v.touch && e2->v.solid != SOLID_NOT)

	{

		pr_global_struct->self = EDICT_TO_PROG(e2);

		pr_global_struct->other = EDICT_TO_PROG(e1);

		PR_ExecuteProgram (e2->v.touch);

	}

	pr_global_struct->self = old_self;

	pr_global_struct->other = old_other;

}

/*

==================

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

If steptrace is not NULL, the trace of any vertical wall hit will be stored

============

*/

#define	MAX_CLIP_PLANES	5

int SV_FlyMove (edict_t *ent, float time, trace_t *steptrace)

{

	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->v.velocity, original_velocity);

	VectorCopy (ent->v.velocity, primal_velocity);

	numplanes = 0;

	time_left = time;

	for (bumpcount=0 ; bumpcount

	{

		if (!ent->v.velocity[0] && !ent->v.velocity[1] && !ent->v.velocity[2])

			break;

		for (i=0 ; i<3 ; i++)

			end[i] = ent->v.origin[i] + time_left * ent->v.velocity[i];

		trace = SV_Move (ent->v.origin, ent->v.mins, ent->v.maxs, end, false, ent);

		if (trace.allsolid)

		{	// entity is trapped in another solid

			VectorCopy (vec3_origin, ent->v.velocity);

			return 3;

		}

		if (trace.fraction > 0)

		{	// actually covered some distance

			VectorCopy (trace.endpos, ent->v.origin);

			VectorCopy (ent->v.velocity, original_velocity);

			numplanes = 0;

		}

		if (trace.fraction == 1)

			 break;		// moved the entire distance

		if (!trace.ent)

			Sys_Error ("SV_FlyMove: !trace.ent");

		if (trace.plane.normal[2] > 0.7)

		{

			blocked |= 1;		// floor

			if (trace.ent->v.solid == SOLID_BSP)

			{

				ent->v.flags =	(int)ent->v.flags | FL_ONGROUND;

				ent->v.groundentity = EDICT_TO_PROG(trace.ent);

			}

		}

		if (!trace.plane.normal[2])

		{

			blocked |= 2;		// step

			if (steptrace)

				*steptrace = trace;	// save for player extrafriction

		}

//

// run the impact function

//

		SV_Impact (ent, trace.ent);

		if (ent->free)

			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->v.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

		{

			ClipVelocity (original_velocity, planes[i], new_velocity, 1);

			for (j=0 ; 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->v.velocity);

		}

		else

		{	// go along the crease

			if (numplanes != 2)

			{

//				Con_Printf ("clip velocity, numplanes == %i\n",numplanes);

				VectorCopy (vec3_origin, ent->v.velocity);

				return 7;

			}

			CrossProduct (planes[0], planes[1], dir);

			d = DotProduct (dir, ent->v.velocity);

			VectorScale (dir, d, ent->v.velocity);

		}

//

// if original velocity is against the original velocity, stop dead

// to avoid tiny occilations in sloping corners

//

		if (DotProduct (ent->v.velocity, primal_velocity) <= 0)

		{

			VectorCopy (vec3_origin, ent->v.velocity);

			return blocked;

		}

	}

	return blocked;

}

/*

============

SV_AddGravity

============

*/

void SV_AddGravity (edict_t *ent)

{

	float	ent_gravity;

#ifdef QUAKE2

	if (ent->v.gravity)

		ent_gravity = ent->v.gravity;

	else

		ent_gravity = 1.0;

#else

	eval_t	*val;

	val = GetEdictFieldValue(ent, "gravity");

	if (val && val->_float)

		ent_gravity = val->_float;

	else

		ent_gravity = 1.0;

#endif

	ent->v.velocity[2] -= ent_gravity * sv_gravity.value * host_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	end;

	VectorAdd (ent->v.origin, push, end);

	if (ent->v.movetype == MOVETYPE_FLYMISSILE)

		trace = SV_Move (ent->v.origin, ent->v.mins, ent->v.maxs, end, MOVE_MISSILE, ent);

	else if (ent->v.solid == SOLID_TRIGGER || ent->v.solid == SOLID_NOT)

	// only clip against bmodels

		trace = SV_Move (ent->v.origin, ent->v.mins, ent->v.maxs, end, MOVE_NOMONSTERS, ent);

	else

		trace = SV_Move (ent->v.origin, ent->v.mins, ent->v.maxs, end, MOVE_NORMAL, ent);

	VectorCopy (trace.endpos, ent->v.origin);

	SV_LinkEdict (ent, true);

	if (trace.ent)

		SV_Impact (ent, trace.ent);

	return trace;

}

/*

============

SV_PushMove

============

*/

void SV_PushMove (edict_t *pusher, float movetime)

{

	int			i, e;

	edict_t		*check, *block;

	vec3_t		mins, maxs, move;

	vec3_t		entorig, pushorig;

	int			num_moved;

	edict_t		*moved_edict[MAX_EDICTS];

	vec3_t		moved_from[MAX_EDICTS];

	if (!pusher->v.velocity[0] && !pusher->v.velocity[1] && !pusher->v.velocity[2])

	{

		pusher->v.ltime += movetime;

		return;

	}

	for (i=0 ; i<3 ; i++)

	{

		move[i] = pusher->v.velocity[i] * movetime;

		mins[i] = pusher->v.absmin[i] + move[i];

		maxs[i] = pusher->v.absmax[i] + move[i];

	}

	VectorCopy (pusher->v.origin, pushorig);

// move the pusher to it's final position

	VectorAdd (pusher->v.origin, move, pusher->v.origin);

	pusher->v.ltime += movetime;

	SV_LinkEdict (pusher, false);

// see if any solid entities are inside the final position

	num_moved = 0;

	check = NEXT_EDICT(sv.edicts);

	for (e=1 ; e

	{

		if (check->free)

			continue;

		if (check->v.movetype == MOVETYPE_PUSH

		|| check->v.movetype == MOVETYPE_NONE

#ifdef QUAKE2

		|| check->v.movetype == MOVETYPE_FOLLOW

#endif

		|| check->v.movetype == MOVETYPE_NOCLIP)

			continue;

	// if the entity is standing on the pusher, it will definately be moved

		if ( ! ( ((int)check->v.flags & FL_ONGROUND)

		&& PROG_TO_EDICT(check->v.groundentity) == pusher) )

		{

			if ( check->v.absmin[0] >= maxs[0]

			|| check->v.absmin[1] >= maxs[1]

			|| check->v.absmin[2] >= maxs[2]

			|| check->v.absmax[0] <= mins[0]

			|| check->v.absmax[1] <= mins[1]

			|| check->v.absmax[2] <= mins[2] )

				continue;

		// see if the ent's bbox is inside the pusher's final position

			if (!SV_TestEntityPosition (check))

				continue;

		}

	// remove the onground flag for non-players

		if (check->v.movetype != MOVETYPE_WALK)

			check->v.flags = (int)check->v.flags & ~FL_ONGROUND;

		VectorCopy (check->v.origin, entorig);

		VectorCopy (check->v.origin, moved_from[num_moved]);

		moved_edict[num_moved] = check;

		num_moved++;

		// try moving the contacted entity

		pusher->v.solid = SOLID_NOT;

		SV_PushEntity (check, move);

		pusher->v.solid = SOLID_BSP;

	// if it is still inside the pusher, block

		block = SV_TestEntityPosition (check);

		if (block)

		{	// fail the move

			if (check->v.mins[0] == check->v.maxs[0])

				continue;

			if (check->v.solid == SOLID_NOT || check->v.solid == SOLID_TRIGGER)

			{	// corpse

				check->v.mins[0] = check->v.mins[1] = 0;

				VectorCopy (check->v.mins, check->v.maxs);

				continue;

			}

			VectorCopy (entorig, check->v.origin);

			SV_LinkEdict (check, true);

			VectorCopy (pushorig, pusher->v.origin);

			SV_LinkEdict (pusher, false);

			pusher->v.ltime -= movetime;

			// if the pusher has a "blocked" function, call it

			// otherwise, just stay in place until the obstacle is gone

			if (pusher->v.blocked)

			{

				pr_global_struct->self = EDICT_TO_PROG(pusher);

				pr_global_struct->other = EDICT_TO_PROG(check);

				PR_ExecuteProgram (pusher->v.blocked);

			}

		// move back any entities we already moved

			for (i=0 ; i

			{

				VectorCopy (moved_from[i], moved_edict[i]->v.origin);

				SV_LinkEdict (moved_edict[i], false);

			}

			return;

		}

	}

}

#ifdef QUAKE2

/*

============

SV_PushRotate

============

*/

void SV_PushRotate (edict_t *pusher, float movetime)

{

	int			i, e;

	edict_t		*check, *block;

	vec3_t		move, a, amove;

	vec3_t		entorig, pushorig;

	int			num_moved;

	edict_t		*moved_edict[MAX_EDICTS];

	vec3_t		moved_from[MAX_EDICTS];

	vec3_t		org, org2;

	vec3_t		forward, right, up;

	if (!pusher->v.avelocity[0] && !pusher->v.avelocity[1] && !pusher->v.avelocity[2])

	{

		pusher->v.ltime += movetime;

		return;

	}

	for (i=0 ; i<3 ; i++)

		amove[i] = pusher->v.avelocity[i] * movetime;

	VectorSubtract (vec3_origin, amove, a);

	AngleVectors (a, forward, right, up);

	VectorCopy (pusher->v.angles, pushorig);

// move the pusher to it's final position

	VectorAdd (pusher->v.angles, amove, pusher->v.angles);

	pusher->v.ltime += movetime;

	SV_LinkEdict (pusher, false);

// see if any solid entities are inside the final position

	num_moved = 0;

	check = NEXT_EDICT(sv.edicts);

	for (e=1 ; e

	{

		if (check->free)

			continue;

		if (check->v.movetype == MOVETYPE_PUSH

		|| check->v.movetype == MOVETYPE_NONE

		|| check->v.movetype == MOVETYPE_FOLLOW

		|| check->v.movetype == MOVETYPE_NOCLIP)

			continue;

	// if the entity is standing on the pusher, it will definately be moved

		if ( ! ( ((int)check->v.flags & FL_ONGROUND)

		&& PROG_TO_EDICT(check->v.groundentity) == pusher) )

		{

			if ( check->v.absmin[0] >= pusher->v.absmax[0]

			|| check->v.absmin[1] >= pusher->v.absmax[1]

			|| check->v.absmin[2] >= pusher->v.absmax[2]

			|| check->v.absmax[0] <= pusher->v.absmin[0]

			|| check->v.absmax[1] <= pusher->v.absmin[1]

			|| check->v.absmax[2] <= pusher->v.absmin[2] )

				continue;

		// see if the ent's bbox is inside the pusher's final position

			if (!SV_TestEntityPosition (check))

				continue;

		}

	// remove the onground flag for non-players

		if (check->v.movetype != MOVETYPE_WALK)

			check->v.flags = (int)check->v.flags & ~FL_ONGROUND;

		VectorCopy (check->v.origin, entorig);

		VectorCopy (check->v.origin, moved_from[num_moved]);

		moved_edict[num_moved] = check;

		num_moved++;

		// calculate destination position

		VectorSubtract (check->v.origin, pusher->v.origin, org);

		org2[0] = DotProduct (org, forward);

		org2[1] = -DotProduct (org, right);

		org2[2] = DotProduct (org, up);

		VectorSubtract (org2, org, move);

		// try moving the contacted entity

		pusher->v.solid = SOLID_NOT;

		SV_PushEntity (check, move);

		pusher->v.solid = SOLID_BSP;

	// if it is still inside the pusher, block

		block = SV_TestEntityPosition (check);

		if (block)

		{	// fail the move

			if (check->v.mins[0] == check->v.maxs[0])

				continue;

			if (check->v.solid == SOLID_NOT || check->v.solid == SOLID_TRIGGER)

			{	// corpse

				check->v.mins[0] = check->v.mins[1] = 0;

				VectorCopy (check->v.mins, check->v.maxs);

				continue;

			}

			VectorCopy (entorig, check->v.origin);

			SV_LinkEdict (check, true);

			VectorCopy (pushorig, pusher->v.angles);

			SV_LinkEdict (pusher, false);

			pusher->v.ltime -= movetime;

			// if the pusher has a "blocked" function, call it

			// otherwise, just stay in place until the obstacle is gone

			if (pusher->v.blocked)

			{

				pr_global_struct->self = EDICT_TO_PROG(pusher);

				pr_global_struct->other = EDICT_TO_PROG(check);

				PR_ExecuteProgram (pusher->v.blocked);

			}

		// move back any entities we already moved

			for (i=0 ; i

			{

				VectorCopy (moved_from[i], moved_edict[i]->v.origin);

				VectorSubtract (moved_edict[i]->v.angles, amove, moved_edict[i]->v.angles);

				SV_LinkEdict (moved_edict[i], false);

			}

			return;

		}

		else

		{

			VectorAdd (check->v.angles, amove, check->v.angles);

		}

	}

}

#endif

/*

================

SV_Physics_Pusher

================

*/

void SV_Physics_Pusher (edict_t *ent)

{

	float	thinktime;

	float	oldltime;

	float	movetime;

	oldltime = ent->v.ltime;

	thinktime = ent->v.nextthink;

	if (thinktime < ent->v.ltime + host_frametime)

	{

		movetime = thinktime - ent->v.ltime;

		if (movetime < 0)

			movetime = 0;

	}

	else

		movetime = host_frametime;

	if (movetime)

	{

#ifdef QUAKE2

		if (ent->v.avelocity[0] || ent->v.avelocity[1] || ent->v.avelocity[2])

			SV_PushRotate (ent, movetime);

		else

#endif

			SV_PushMove (ent, movetime);	// advances ent->v.ltime if not blocked

	}

	if (thinktime > oldltime && thinktime <= ent->v.ltime)

	{

		ent->v.nextthink = 0;

		pr_global_struct->time = sv.time;

		pr_global_struct->self = EDICT_TO_PROG(ent);

		pr_global_struct->other = EDICT_TO_PROG(sv.edicts);

		PR_ExecuteProgram (ent->v.think);

		if (ent->free)

			return;

	}

}

/*

===============================================================================

CLIENT MOVEMENT

===============================================================================

*/

/*

=============

SV_CheckStuck

This is a big hack to try and fix the rare case of getting stuck in the world

clipping hull.

=============

*/

void SV_CheckStuck (edict_t *ent)

{

	int		i, j;

	int		z;

	vec3_t	org;

	if (!SV_TestEntityPosition(ent))

	{

		VectorCopy (ent->v.origin, ent->v.oldorigin);

		return;

	}

	VectorCopy (ent->v.origin, org);

	VectorCopy (ent->v.oldorigin, ent->v.origin);

	if (!SV_TestEntityPosition(ent))

	{

		Con_DPrintf ("Unstuck.\n");

		SV_LinkEdict (ent, true);

		return;

	}

	for (z=0 ; z< 18 ; z++)

		for (i=-1 ; i <= 1 ; i++)

			for (j=-1 ; j <= 1 ; j++)

			{

				ent->v.origin[0] = org[0] + i;

				ent->v.origin[1] = org[1] + j;

				ent->v.origin[2] = org[2] + z;

				if (!SV_TestEntityPosition(ent))

				{

					Con_DPrintf ("Unstuck.\n");

					SV_LinkEdict (ent, true);

					return;

				}

			}

	VectorCopy (org, ent->v.origin);

	Con_DPrintf ("player is stuck.\n");

}

/*

=============

SV_CheckWater

=============

*/

qboolean SV_CheckWater (edict_t *ent)

{

	vec3_t	point;

	int		cont;

#ifdef QUAKE2

	int		truecont;

#endif

	point[0] = ent->v.origin[0];

	point[1] = ent->v.origin[1];

	point[2] = ent->v.origin[2] + ent->v.mins[2] + 1;

	ent->v.waterlevel = 0;

	ent->v.watertype = CONTENTS_EMPTY;

	cont = SV_PointContents (point);

	if (cont <= CONTENTS_WATER)

	{

#ifdef QUAKE2

		truecont = SV_TruePointContents (point);

#endif

		ent->v.watertype = cont;

		ent->v.waterlevel = 1;

		point[2] = ent->v.origin[2] + (ent->v.mins[2] + ent->v.maxs[2])*0.5;

		cont = SV_PointContents (point);

		if (cont <= CONTENTS_WATER)

		{

			ent->v.waterlevel = 2;

			point[2] = ent->v.origin[2] + ent->v.view_ofs[2];

			cont = SV_PointContents (point);

			if (cont <= CONTENTS_WATER)

				ent->v.waterlevel = 3;

		}

#ifdef QUAKE2

		if (truecont <= CONTENTS_CURRENT_0 && truecont >= CONTENTS_CURRENT_DOWN)

		{

			static vec3_t current_table[] =

			{

				{1, 0, 0},

				{0, 1, 0},

				{-1, 0, 0},

				{0, -1, 0},

				{0, 0, 1},

				{0, 0, -1}

			};

			VectorMA (ent->v.basevelocity, 150.0*ent->v.waterlevel/3.0, current_table[CONTENTS_CURRENT_0 - truecont], ent->v.basevelocity);

		}

#endif

	}

	return ent->v.waterlevel > 1;

}

/*

============

SV_WallFriction

============

*/

void SV_WallFriction (edict_t *ent, trace_t *trace)

{

	vec3_t		forward, right, up;

	float		d, i;

	vec3_t		into, side;

	AngleVectors (ent->v.v_angle, forward, right, up);

	d = DotProduct (trace->plane.normal, forward);

	d += 0.5;

	if (d >= 0)

		return;

// cut the tangential velocity

	i = DotProduct (trace->plane.normal, ent->v.velocity);

	VectorScale (trace->plane.normal, i, into);

	VectorSubtract (ent->v.velocity, into, side);

	ent->v.velocity[0] = side[0] * (1 + d);

	ent->v.velocity[1] = side[1] * (1 + d);

}

/*

=====================

SV_TryUnstick

Player has come to a dead stop, possibly due to the problem with limited

float precision at some angle joins in the BSP hull.

Try fixing by pushing one pixel in each direction.

This is a hack, but in the interest of good gameplay...

======================

*/

int SV_TryUnstick (edict_t *ent, vec3_t oldvel)

{

	int		i;

	vec3_t	oldorg;

	vec3_t	dir;

	int		clip;

	trace_t	steptrace;

	VectorCopy (ent->v.origin, oldorg);

	VectorCopy (vec3_origin, dir);

	for (i=0 ; i<8 ; i++)

	{

// try pushing a little in an axial direction

		switch (i)

		{

			case 0:	dir[0] = 2; dir[1] = 0; break;

			case 1:	dir[0] = 0; dir[1] = 2; break;

			case 2:	dir[0] = -2; dir[1] = 0; break;

			case 3:	dir[0] = 0; dir[1] = -2; break;

			case 4:	dir[0] = 2; dir[1] = 2; break;

			case 5:	dir[0] = -2; dir[1] = 2; break;

			case 6:	dir[0] = 2; dir[1] = -2; break;

			case 7:	dir[0] = -2; dir[1] = -2; break;

		}

		SV_PushEntity (ent, dir);

// retry the original move

		ent->v.velocity[0] = oldvel[0];

		ent->v. velocity[1] = oldvel[1];

		ent->v. velocity[2] = 0;

		clip = SV_FlyMove (ent, 0.1, &steptrace);

		if ( fabs(oldorg[1] - ent->v.origin[1]) > 4

		|| fabs(oldorg[0] - ent->v.origin[0]) > 4 )

		{

//Con_DPrintf ("unstuck!\n");

			return clip;

		}

// go back to the original pos and try again

		VectorCopy (oldorg, ent->v.origin);

	}

	VectorCopy (vec3_origin, ent->v.velocity);

	return 7;		// still not moving

}

/*

=====================

SV_WalkMove

Only used by players

======================

*/

#define	STEPSIZE	18

void SV_WalkMove (edict_t *ent)

{

	vec3_t		upmove, downmove;

	vec3_t		oldorg, oldvel;

	vec3_t		nosteporg, nostepvel;

	int			clip;

	int			oldonground;

	trace_t		steptrace, downtrace;

//

// do a regular slide move unless it looks like you ran into a step

//

	oldonground = (int)ent->v.flags & FL_ONGROUND;

	ent->v.flags = (int)ent->v.flags & ~FL_ONGROUND;

	VectorCopy (ent->v.origin, oldorg);

	VectorCopy (ent->v.velocity, oldvel);

	clip = SV_FlyMove (ent, host_frametime, &steptrace);

	if ( !(clip & 2) )

		return;		// move didn't block on a step

	if (!oldonground && ent->v.waterlevel == 0)

		return;		// don't stair up while jumping

	if (ent->v.movetype != MOVETYPE_WALK)

		return;		// gibbed by a trigger

	if (sv_nostep.value)

		return;

	if ( (int)sv_player->v.flags & FL_WATERJUMP )

		return;

	VectorCopy (ent->v.origin, nosteporg);

	VectorCopy (ent->v.velocity, nostepvel);

//

// try moving up and forward to go up a step

//

	VectorCopy (oldorg, ent->v.origin);	// back to start pos

	VectorCopy (vec3_origin, upmove);

	VectorCopy (vec3_origin, downmove);

	upmove[2] = STEPSIZE;

	downmove[2] = -STEPSIZE + oldvel[2]*host_frametime;

// move up

	SV_PushEntity (ent, upmove);	// FIXME: don't link?

// move forward

	ent->v.velocity[0] = oldvel[0];

	ent->v. velocity[1] = oldvel[1];

	ent->v. velocity[2] = 0;

	clip = SV_FlyMove (ent, host_frametime, &steptrace);

// check for stuckness, possibly due to the limited precision of floats

// in the clipping hulls

	if (clip)

	{

		if ( fabs(oldorg[1] - ent->v.origin[1]) < 0.03125

		&& fabs(oldorg[0] - ent->v.origin[0]) < 0.03125 )

		{	// stepping up didn't make any progress

			clip = SV_TryUnstick (ent, oldvel);

		}

	}

// extra friction based on view angle

	if ( clip & 2 )

		SV_WallFriction (ent, &steptrace);

// move down

	downtrace = SV_PushEntity (ent, downmove);	// FIXME: don't link?

	if (downtrace.plane.normal[2] > 0.7)

	{

		if (ent->v.solid == SOLID_BSP)

		{

			ent->v.flags =	(int)ent->v.flags | FL_ONGROUND;

			ent->v.groundentity = EDICT_TO_PROG(downtrace.ent);

		}

	}

	else

	{

// if the push down didn't end up on good ground, use the move without

// the step up.  This happens near wall / slope combinations, and can

// cause the player to hop up higher on a slope too steep to climb

		VectorCopy (nosteporg, ent->v.origin);

		VectorCopy (nostepvel, ent->v.velocity);

	}

}

/*

================

SV_Physics_Client

Player character actions

================

*/

void SV_Physics_Client (edict_t	*ent, int num)

{

	if ( ! svs.clients[num-1].active )

		return;		// unconnected slot

//

// call standard client pre-think

//

	pr_global_struct->time = sv.time;

	pr_global_struct->self = EDICT_TO_PROG(ent);

	PR_ExecuteProgram (pr_global_struct->PlayerPreThink);

//

// do a move

//

	SV_CheckVelocity (ent);

//

// decide which move function to call

//

	switch ((int)ent->v.movetype)

	{

	case MOVETYPE_NONE:

		if (!SV_RunThink (ent))

			return;

		break;

	case MOVETYPE_WALK:

		if (!SV_RunThink (ent))

			return;

		if (!SV_CheckWater (ent) && ! ((int)ent->v.flags & FL_WATERJUMP) )

			SV_AddGravity (ent);

		SV_CheckStuck (ent);

#ifdef QUAKE2

		VectorAdd (ent->v.velocity, ent->v.basevelocity, ent->v.velocity);

#endif

		SV_WalkMove (ent);

#ifdef QUAKE2

		VectorSubtract (ent->v.velocity, ent->v.basevelocity, ent->v.velocity);

#endif

		break;

	case MOVETYPE_TOSS:

	case MOVETYPE_BOUNCE:

		SV_Physics_Toss (ent);

		break;

	case MOVETYPE_FLY:

		if (!SV_RunThink (ent))

			return;

		SV_FlyMove (ent, host_frametime, NULL);

		break;

	case MOVETYPE_NOCLIP:

		if (!SV_RunThink (ent))

			return;

		VectorMA (ent->v.origin, host_frametime, ent->v.velocity, ent->v.origin);

		break;

	default:

		Sys_Error ("SV_Physics_client: bad movetype %i", (int)ent->v.movetype);

	}

//

// call standard player post-think

//

	SV_LinkEdict (ent, true);

	pr_global_struct->time = sv.time;

	pr_global_struct->self = EDICT_TO_PROG(ent);