pmove.c

Quake 2 Source code for students by Theerthan You can also download from idsoftwares.com

/*
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.

*/

#include "qcommon.h"



#define	STEPSIZE	18

// all of the locals will be zeroed before each
// pmove, just to make damn sure we don't have
// any differences when running on client or server

typedef struct
{
	vec3_t		origin;			// full float precision
	vec3_t		velocity;		// full float precision

	vec3_t		forward, right, up;
	float		frametime;


	csurface_t	*groundsurface;
	cplane_t	groundplane;
	int			groundcontents;

	vec3_t		previous_origin;
	qboolean	ladder;
} pml_t;

pmove_t		*pm;
pml_t		pml;


// movement parameters
float	pm_stopspeed = 100;
float	pm_maxspeed = 300;
float	pm_duckspeed = 100;
float	pm_accelerate = 10;
float	pm_airaccelerate = 0;
float	pm_wateraccelerate = 10;
float	pm_friction = 6;
float	pm_waterfriction = 1;
float	pm_waterspeed = 400;

/*

  walking up a step should kill some velocity

*/


/*
==================
PM_ClipVelocity

Slide off of the impacting object
returns the blocked flags (1 = floor, 2 = step / wall)
==================
*/
#define	STOP_EPSILON	0.1

void PM_ClipVelocity (vec3_t in, vec3_t normal, vec3_t out, float overbounce)
{
	float	backoff;
	float	change;
	int		i;
	
	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;
	}
}




/*
==================
PM_StepSlideMove

Each intersection will try to step over the obstruction instead of
sliding along it.

Returns a new origin, velocity, and contact entity
Does not modify any world state?
==================
*/
#define	MIN_STEP_NORMAL	0.7		// can't step up onto very steep slopes
#define	MAX_CLIP_PLANES	5
void PM_StepSlideMove_ (void)
{
	int			bumpcount, numbumps;
	vec3_t		dir;
	float		d;
	int			numplanes;
	vec3_t		planes[MAX_CLIP_PLANES];
	vec3_t		primal_velocity;
	int			i, j;
	trace_t	trace;
	vec3_t		end;
	float		time_left;
	
	numbumps = 4;
	
	VectorCopy (pml.velocity, primal_velocity);
	numplanes = 0;
	
	time_left = pml.frametime;

	for (bumpcount=0 ; bumpcount<numbumps ; bumpcount++)
	{
		for (i=0 ; i<3 ; i++)
			end[i] = pml.origin[i] + time_left * pml.velocity[i];

		trace = pm->trace (pml.origin, pm->mins, pm->maxs, end);

		if (trace.allsolid)
		{	// entity is trapped in another solid
			pml.velocity[2] = 0;	// don't build up falling damage
			return;
		}

		if (trace.fraction > 0)
		{	// actually covered some distance
			VectorCopy (trace.endpos, pml.origin);
			numplanes = 0;
		}

		if (trace.fraction == 1)
			 break;		// moved the entire distance

		// save entity for contact
		if (pm->numtouch < MAXTOUCH && trace.ent)
		{
			pm->touchents[pm->numtouch] = trace.ent;
			pm->numtouch++;
		}
		
		time_left -= time_left * trace.fraction;

		// slide along this plane
		if (numplanes >= MAX_CLIP_PLANES)
		{	// this shouldn't really happen
			VectorCopy (vec3_origin, pml.velocity);
			break;
		}

		VectorCopy (trace.plane.normal, planes[numplanes]);
		numplanes++;

#if 0
	float		rub;

		//
		// modify velocity so it parallels all of the clip planes
		//
		if (numplanes == 1)
		{	// go along this plane
			VectorCopy (pml.velocity, dir);
			VectorNormalize (dir);
			rub = 1.0 + 0.5 * DotProduct (dir, planes[0]);

			// slide along the plane
			PM_ClipVelocity (pml.velocity, planes[0], pml.velocity, 1.01);
			// rub some extra speed off on xy axis
			// not on Z, or you can scrub down walls
			pml.velocity[0] *= rub;
			pml.velocity[1] *= rub;
			pml.velocity[2] *= rub;
		}
		else if (numplanes == 2)
		{	// go along the crease
			VectorCopy (pml.velocity, dir);
			VectorNormalize (dir);
			rub = 1.0 + 0.5 * DotProduct (dir, planes[0]);

			// slide along the plane
			CrossProduct (planes[0], planes[1], dir);
			d = DotProduct (dir, pml.velocity);
			VectorScale (dir, d, pml.velocity);

			// rub some extra speed off
			VectorScale (pml.velocity, rub, pml.velocity);
		}
		else
		{
//			Con_Printf ("clip velocity, numplanes == %i\n",numplanes);
			VectorCopy (vec3_origin, pml.velocity);
			break;
		}

#else
//
// modify original_velocity so it parallels all of the clip planes
//
		for (i=0 ; i<numplanes ; i++)
		{
			PM_ClipVelocity (pml.velocity, planes[i], pml.velocity, 1.01);
			for (j=0 ; j<numplanes ; j++)
				if (j != i)
				{
					if (DotProduct (pml.velocity, planes[j]) < 0)
						break;	// not ok
				}
			if (j == numplanes)
				break;
		}
		
		if (i != numplanes)
		{	// go along this plane
		}
		else
		{	// go along the crease
			if (numplanes != 2)
			{
//				Con_Printf ("clip velocity, numplanes == %i\n",numplanes);
				VectorCopy (vec3_origin, pml.velocity);
				break;
			}
			CrossProduct (planes[0], planes[1], dir);
			d = DotProduct (dir, pml.velocity);
			VectorScale (dir, d, pml.velocity);
		}
#endif
		//
		// if velocity is against the original velocity, stop dead
		// to avoid tiny occilations in sloping corners
		//
		if (DotProduct (pml.velocity, primal_velocity) <= 0)
		{
			VectorCopy (vec3_origin, pml.velocity);
			break;
		}
	}

	if (pm->s.pm_time)
	{
		VectorCopy (primal_velocity, pml.velocity);
	}
}

/*
==================
PM_StepSlideMove

==================
*/
void PM_StepSlideMove (void)
{
	vec3_t		start_o, start_v;
	vec3_t		down_o, down_v;
	trace_t		trace;
	float		down_dist, up_dist;
//	vec3_t		delta;
	vec3_t		up, down;

	VectorCopy (pml.origin, start_o);
	VectorCopy (pml.velocity, start_v);

	PM_StepSlideMove_ ();

	VectorCopy (pml.origin, down_o);
	VectorCopy (pml.velocity, down_v);

	VectorCopy (start_o, up);
	up[2] += STEPSIZE;

	trace = pm->trace (up, pm->mins, pm->maxs, up);
	if (trace.allsolid)
		return;		// can't step up

	// try sliding above
	VectorCopy (up, pml.origin);
	VectorCopy (start_v, pml.velocity);

	PM_StepSlideMove_ ();

	// push down the final amount
	VectorCopy (pml.origin, down);
	down[2] -= STEPSIZE;
	trace = pm->trace (pml.origin, pm->mins, pm->maxs, down);
	if (!trace.allsolid)
	{
		VectorCopy (trace.endpos, pml.origin);
	}

#if 0
	VectorSubtract (pml.origin, up, delta);
	up_dist = DotProduct (delta, start_v);

	VectorSubtract (down_o, start_o, delta);
	down_dist = DotProduct (delta, start_v);
#else
	VectorCopy(pml.origin, up);

	// decide which one went farther
    down_dist = (down_o[0] - start_o[0])*(down_o[0] - start_o[0])
        + (down_o[1] - start_o[1])*(down_o[1] - start_o[1]);
    up_dist = (up[0] - start_o[0])*(up[0] - start_o[0])
        + (up[1] - start_o[1])*(up[1] - start_o[1]);
#endif

	if (down_dist > up_dist || trace.plane.normal[2] < MIN_STEP_NORMAL)
	{
		VectorCopy (down_o, pml.origin);
		VectorCopy (down_v, pml.velocity);
		return;
	}
	//!! Special case
	// if we were walking along a plane, then we need to copy the Z over
	pml.velocity[2] = down_v[2];
}


/*
==================
PM_Friction

Handles both ground friction and water friction
==================
*/
void PM_Friction (void)
{
	float	*vel;
	float	speed, newspeed, control;
	float	friction;
	float	drop;
	
	vel = pml.velocity;
	
	speed = sqrt(vel[0]*vel[0] +vel[1]*vel[1] + vel[2]*vel[2]);
	if (speed < 1)
	{
		vel[0] = 0;
		vel[1] = 0;
		return;
	}

	drop = 0;

// apply ground friction
	if ((pm->groundentity && pml.groundsurface && !(pml.groundsurface->flags & SURF_SLICK) ) || (pml.ladder) )
	{
		friction = pm_friction;
		control = speed < pm_stopspeed ? pm_stopspeed : speed;
		drop += control*friction*pml.frametime;
	}

// apply water friction
	if (pm->waterlevel && !pml.ladder)
		drop += speed*pm_waterfriction*pm->waterlevel*pml.frametime;

// scale the velocity
	newspeed = speed - drop;
	if (newspeed < 0)
	{
		newspeed = 0;
	}
	newspeed /= speed;

	vel[0] = vel[0] * newspeed;
	vel[1] = vel[1] * newspeed;
	vel[2] = vel[2] * newspeed;
}


/*
==============
PM_Accelerate

Handles user intended acceleration
==============
*/
void PM_Accelerate (vec3_t wishdir, float wishspeed, float accel)
{
	int			i;
	float		addspeed, accelspeed, currentspeed;

	currentspeed = DotProduct (pml.velocity, wishdir);
	addspeed = wishspeed - currentspeed;
	if (addspeed <= 0)
		return;
	accelspeed = accel*pml.frametime*wishspeed;
	if (accelspeed > addspeed)
		accelspeed = addspeed;
	
	for (i=0 ; i<3 ; i++)
		pml.velocity[i] += accelspeed*wishdir[i];	
}

void PM_AirAccelerate (vec3_t wishdir, float wishspeed, float accel)
{
	int			i;
	float		addspeed, accelspeed, currentspeed, wishspd = wishspeed;
		
	if (wishspd > 30)
		wishspd = 30;
	currentspeed = DotProduct (pml.velocity, wishdir);
	addspeed = wishspd - currentspeed;
	if (addspeed <= 0)
		return;
	accelspeed = accel * wishspeed * pml.frametime;
	if (accelspeed > addspeed)
		accelspeed = addspeed;
	
	for (i=0 ; i<3 ; i++)
		pml.velocity[i] += accelspeed*wishdir[i];	
}

/*
=============
PM_AddCurrents
=============
*/
void PM_AddCurrents (vec3_t	wishvel)
{
	vec3_t	v;
	float	s;

	//
	// account for ladders
	//

	if (pml.ladder && fabs(pml.velocity[2]) <= 200)
	{
		if ((pm->viewangles[PITCH] <= -15) && (pm->cmd.forwardmove > 0))
			wishvel[2] = 200;
		else if ((pm->viewangles[PITCH] >= 15) && (pm->cmd.forwardmove > 0))
			wishvel[2] = -200;
		else if (pm->cmd.upmove > 0)
			wishvel[2] = 200;
		else if (pm->cmd.upmove < 0)
			wishvel[2] = -200;
		else
			wishvel[2] = 0;

		// limit horizontal speed when on a ladder
		if (wishvel[0] < -25)
			wishvel[0] = -25;
		else if (wishvel[0] > 25)
			wishvel[0] = 25;

		if (wishvel[1] < -25)
			wishvel[1] = -25;
		else if (wishvel[1] > 25)
			wishvel[1] = 25;
	}


	//
	// add water currents
	//

	if (pm->watertype & MASK_CURRENT)
	{
		VectorClear (v);

		if (pm->watertype & CONTENTS_CURRENT_0)
			v[0] += 1;
		if (pm->watertype & CONTENTS_CURRENT_90)
			v[1] += 1;
		if (pm->watertype & CONTENTS_CURRENT_180)
			v[0] -= 1;
		if (pm->watertype & CONTENTS_CURRENT_270)
			v[1] -= 1;
		if (pm->watertype & CONTENTS_CURRENT_UP)
			v[2] += 1;
		if (pm->watertype & CONTENTS_CURRENT_DOWN)
			v[2] -= 1;

		s = pm_waterspeed;
		if ((pm->waterlevel == 1) && (pm->groundentity))
			s /= 2;

		VectorMA (wishvel, s, v, wishvel);
	}

	//
	// add conveyor belt velocities
	//

	if (pm->groundentity)
	{
		VectorClear (v);

		if (pml.groundcontents & CONTENTS_CURRENT_0)
			v[0] += 1;
		if (pml.groundcontents & CONTENTS_CURRENT_90)
			v[1] += 1;
		if (pml.groundcontents & CONTENTS_CURRENT_180)
			v[0] -= 1;
		if (pml.groundcontents & CONTENTS_CURRENT_270)
			v[1] -= 1;
		if (pml.groundcontents & CONTENTS_CURRENT_UP)
			v[2] += 1;
		if (pml.groundcontents & CONTENTS_CURRENT_DOWN)
			v[2] -= 1;

		VectorMA (wishvel, 100 /* pm->groundentity->speed */, v, wishvel);
	}
}


/*
===================
PM_WaterMove

===================
*/
void PM_WaterMove (void)
{
	int		i;
	vec3_t	wishvel;
	float	wishspeed;
	vec3_t	wishdir;

//
// user intentions
//
	for (i=0 ; i<3 ; i++)
		wishvel[i] = pml.forward[i]*pm->cmd.forwardmove + pml.right[i]*pm->cmd.sidemove;

	if (!pm->cmd.forwardmove && !pm->cmd.sidemove && !pm->cmd.upmove)
		wishvel[2] -= 60;		// drift towards bottom
	else
		wishvel[2] += pm->cmd.upmove;

	PM_AddCurrents (wishvel);

	VectorCopy (wishvel, wishdir);
	wishspeed = VectorNormalize(wishdir);

	if (wishspeed > pm_maxspeed)
	{
		VectorScale (wishvel, pm_maxspeed/wishspeed, wishvel);
		wishspeed = pm_maxspeed;
	}
	wishspeed *= 0.5;

	PM_Accelerate (wishdir, wishspeed, pm_wateraccelerate);

	PM_StepSlideMove ();
}


/*
===================
PM_AirMove

===================
*/
void PM_AirMove (void)
{
	int			i;
	vec3_t		wishvel;
	float		fmove, smove;
	vec3_t		wishdir;
	float		wishspeed;
	float		maxspeed;

	fmove = pm->cmd.forwardmove;
	smove = pm->cmd.sidemove;
	
//!!!!! pitch should be 1/3 so this isn't needed??!
#if 0
	pml.forward[2] = 0;
	pml.right[2] = 0;
	VectorNormalize (pml.forward);
	VectorNormalize (pml.right);
#endif

	for (i=0 ; i<2 ; i++)
		wishvel[i] = pml.forward[i]*fmove + pml.right[i]*smove;
	wishvel[2] = 0;

	PM_AddCurrents (wishvel);

	VectorCopy (wishvel, wishdir);
	wishspeed = VectorNormalize(wishdir);

//
// clamp to server defined max speed
//
	maxspeed = (pm->s.pm_flags & PMF_DUCKED) ? pm_duckspeed : pm_maxspeed;

	if (wishspeed > maxspeed)
	{
		VectorScale (wishvel, maxspeed/wishspeed, wishvel);
		wishspeed = maxspeed;
	}
	
	if ( pml.ladder )
	{
		PM_Accelerate (wishdir, wishspeed, pm_accelerate);
		if (!wishvel[2])
		{
			if (pml.velocity[2] > 0)
			{
				pml.velocity[2] -= pm->s.gravity * pml.frametime;
				if (pml.velocity[2] < 0)
					pml.velocity[2]  = 0;
			}
			else
			{
				pml.velocity[2] += pm->s.gravity * pml.frametime;
				if (pml.velocity[2] > 0)
					pml.velocity[2]  = 0;
			}
		}
		PM_StepSlideMove ();
	}
	else if ( pm->groundentity )
	{	// walking on ground
		pml.velocity[2] = 0; //!!! this is before the accel
		PM_Accelerate (wishdir, wishspeed, pm_accelerate);

// PGM	-- fix for negative trigger_gravity fields
//		pml.velocity[2] = 0;
		if(pm->s.gravity > 0)
			pml.velocity[2] = 0;
		else
			pml.velocity[2] -= pm->s.gravity * pml.frametime;
// PGM

		if (!pml.velocity[0] && !pml.velocity[1])
			return;
		PM_StepSlideMove ();
	}
	else
	{	// not on ground, so little effect on velocity
		if (pm_airaccelerate)
			PM_AirAccelerate (wishdir, wishspeed, pm_accelerate);
		else
			PM_Accelerate (wishdir, wishspeed, 1);
		// add gravity
		pml.velocity[2] -= pm->s.gravity * pml.frametime;
		PM_StepSlideMove ();
	}
}



/*
=============
PM_CatagorizePosition
=============
*/
void PM_CatagorizePosition (void)
{
	vec3_t		point;
	int			cont;
	trace_t		trace;
	int			sample1;
	int			sample2;

// if the player hull point one unit down is solid, the player
// is on ground