g_phys.c

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

		{
			// 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);			
	}
}