DOOM-3-BFG/neo/d3xp/physics/Physics_RigidBody.cpp

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

Doom 3 BFG Edition GPL Source Code
Copyright (C) 1993-2012 id Software LLC, a ZeniMax Media company. 

This file is part of the Doom 3 BFG Edition GPL Source Code ("Doom 3 BFG Edition Source Code").  

Doom 3 BFG Edition Source Code 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 3 of the License, or
(at your option) any later version.

Doom 3 BFG Edition Source Code 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 Doom 3 BFG Edition Source Code.  If not, see <http://www.gnu.org/licenses/>.

In addition, the Doom 3 BFG Edition Source Code is also subject to certain additional terms. You should have received a copy of these additional terms immediately following the terms and conditions of the GNU General Public License which accompanied the Doom 3 BFG Edition Source Code.  If not, please request a copy in writing from id Software at the address below.

If you have questions concerning this license or the applicable additional terms, you may contact in writing id Software LLC, c/o ZeniMax Media Inc., Suite 120, Rockville, Maryland 20850 USA.

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

#pragma hdrstop
#include "../../idlib/precompiled.h"

#include "../Game_local.h"

CLASS_DECLARATION( idPhysics_Base, idPhysics_RigidBody )
END_CLASS

const float STOP_SPEED		= 10.0f;


#undef RB_TIMINGS

#ifdef RB_TIMINGS
static int lastTimerReset = 0;
static int numRigidBodies = 0;
static idTimer timer_total, timer_collision;
#endif


/*
================
RigidBodyDerivatives
================
*/
void RigidBodyDerivatives( const float t, const void *clientData, const float *state, float *derivatives ) {
	const idPhysics_RigidBody *p = (idPhysics_RigidBody *) clientData;
	rigidBodyIState_t *s = (rigidBodyIState_t *) state;
	// NOTE: this struct should be build conform rigidBodyIState_t
	struct rigidBodyDerivatives_s {
		idVec3				linearVelocity;
		idMat3				angularMatrix;
		idVec3				force;
		idVec3				torque;
	} *d = (struct rigidBodyDerivatives_s *) derivatives;
	idVec3 angularVelocity;
	idMat3 inverseWorldInertiaTensor;

	inverseWorldInertiaTensor = s->orientation * p->inverseInertiaTensor * s->orientation.Transpose();
	angularVelocity = inverseWorldInertiaTensor * s->angularMomentum;
	// derivatives
	d->linearVelocity = p->inverseMass * s->linearMomentum;
	d->angularMatrix = SkewSymmetric( angularVelocity ) * s->orientation;
	d->force = - p->linearFriction * s->linearMomentum + p->current.externalForce;
	d->torque = - p->angularFriction * s->angularMomentum + p->current.externalTorque;
}

/*
================
idPhysics_RigidBody::Integrate

  Calculate next state from the current state using an integrator.
================
*/
void idPhysics_RigidBody::Integrate( float deltaTime, rigidBodyPState_t &next_ ) {
	idVec3 position;

	position = current.i.position;
	current.i.position += centerOfMass * current.i.orientation;

	current.i.orientation.TransposeSelf();

	integrator->Evaluate( (float *) &current.i, (float *) &next_.i, 0, deltaTime );
	next_.i.orientation.OrthoNormalizeSelf();

	// apply gravity
	next_.i.linearMomentum += deltaTime * gravityVector * mass;

	current.i.orientation.TransposeSelf();
	next_.i.orientation.TransposeSelf();

	current.i.position = position;
	next_.i.position -= centerOfMass * next_.i.orientation;

	next_.atRest = current.atRest;
}

/*
================
idPhysics_RigidBody::CollisionImpulse

  Calculates the collision impulse using the velocity relative to the collision object.
  The current state should be set to the moment of impact.
================
*/
bool idPhysics_RigidBody::CollisionImpulse( const trace_t &collision, idVec3 &impulse ) {
	idVec3 r, linearVelocity, angularVelocity, velocity;
	idMat3 inverseWorldInertiaTensor;
	float impulseNumerator, impulseDenominator, vel;
	impactInfo_t info;
	idEntity *ent;

	// get info from other entity involved
	ent = gameLocal.entities[collision.c.entityNum];
	ent->GetImpactInfo( self, collision.c.id, collision.c.point, &info );

	// collision point relative to the body center of mass
	r = collision.c.point - ( current.i.position + centerOfMass * current.i.orientation );
	// the velocity at the collision point
	linearVelocity = inverseMass * current.i.linearMomentum;
	inverseWorldInertiaTensor = current.i.orientation.Transpose() * inverseInertiaTensor * current.i.orientation;
	angularVelocity = inverseWorldInertiaTensor * current.i.angularMomentum;
	velocity = linearVelocity + angularVelocity.Cross(r);
	// subtract velocity of other entity
	velocity -= info.velocity;

	// velocity in normal direction
	vel = velocity * collision.c.normal;

	if ( vel > -STOP_SPEED ) {
		impulseNumerator = STOP_SPEED;
	}
	else {
		impulseNumerator = -( 1.0f + bouncyness ) * vel;
	}
	impulseDenominator = inverseMass + ( ( inverseWorldInertiaTensor * r.Cross( collision.c.normal ) ).Cross( r ) * collision.c.normal );
	if ( info.invMass ) {
		impulseDenominator += info.invMass + ( ( info.invInertiaTensor * info.position.Cross( collision.c.normal ) ).Cross( info.position ) * collision.c.normal );
	}
	impulse = (impulseNumerator / impulseDenominator) * collision.c.normal;

	// update linear and angular momentum with impulse
	current.i.linearMomentum += impulse;
	current.i.angularMomentum += r.Cross(impulse);

	// if no movement at all don't blow up
	if ( collision.fraction < 0.0001f ) {
		current.i.linearMomentum *= 0.5f;
		current.i.angularMomentum *= 0.5f;
	}

	// callback to self to let the entity know about the collision
	return self->Collide( collision, velocity );
}

/*
================
idPhysics_RigidBody::CheckForCollisions

  Check for collisions between the current and next state.
  If there is a collision the next state is set to the state at the moment of impact.
================
*/
bool idPhysics_RigidBody::CheckForCollisions( const float deltaTime, rigidBodyPState_t &next_, trace_t &collision ) {
//#define TEST_COLLISION_DETECTION
	idMat3 axis;
	idRotation rotation;
	bool collided = false;

#ifdef TEST_COLLISION_DETECTION
	bool startsolid;
	if ( gameLocal.clip.Contents( current.i.position, clipModel, current.i.orientation, clipMask, self ) ) {
		startsolid = true;
	}
#endif

	TransposeMultiply( current.i.orientation, next_.i.orientation, axis );
	rotation = axis.ToRotation();
	rotation.SetOrigin( current.i.position );

	// if there was a collision
	if ( gameLocal.clip.Motion( collision, current.i.position, next_.i.position, rotation, clipModel, current.i.orientation, clipMask, self ) ) {
		// set the next state to the state at the moment of impact
		next_.i.position = collision.endpos;
		next_.i.orientation = collision.endAxis;
		next_.i.linearMomentum = current.i.linearMomentum;
		next_.i.angularMomentum = current.i.angularMomentum;
		collided = true;
	}

#ifdef TEST_COLLISION_DETECTION
	if ( gameLocal.clip.Contents( next.i.position, clipModel, next_.i.orientation, clipMask, self ) ) {
		if ( !startsolid ) {
			int bah = 1;
		}
	}
#endif
	return collided;
}

/*
================
idPhysics_RigidBody::ContactFriction

  Does not solve friction for multiple simultaneous contacts but applies contact friction in isolation.
  Uses absolute velocity at the contact points instead of the velocity relative to the contact object.
================
*/
void idPhysics_RigidBody::ContactFriction( float deltaTime ) {
	int i;
	float magnitude, impulseNumerator, impulseDenominator;
	idMat3 inverseWorldInertiaTensor;
	idVec3 linearVelocity, angularVelocity;
	idVec3 massCenter, r, velocity, normal, impulse, normalVelocity;

	inverseWorldInertiaTensor = current.i.orientation.Transpose() * inverseInertiaTensor * current.i.orientation;

	massCenter = current.i.position + centerOfMass * current.i.orientation;

	for ( i = 0; i < contacts.Num(); i++ ) {

		r = contacts[i].point - massCenter;

		// calculate velocity at contact point
		linearVelocity = inverseMass * current.i.linearMomentum;
		angularVelocity = inverseWorldInertiaTensor * current.i.angularMomentum;
		velocity = linearVelocity + angularVelocity.Cross(r);

		// velocity along normal vector
		normalVelocity = ( velocity * contacts[i].normal ) * contacts[i].normal;

		// calculate friction impulse
		normal = -( velocity - normalVelocity );
		magnitude = normal.Normalize();
		impulseNumerator = contactFriction * magnitude;
		impulseDenominator = inverseMass + ( ( inverseWorldInertiaTensor * r.Cross( normal ) ).Cross( r ) * normal );
		impulse = (impulseNumerator / impulseDenominator) * normal;

		// apply friction impulse
		current.i.linearMomentum += impulse;
		current.i.angularMomentum += r.Cross(impulse);

		// if moving towards the surface at the contact point
		if ( normalVelocity * contacts[i].normal < 0.0f ) {
			// calculate impulse
			normal = -normalVelocity;
			impulseNumerator = normal.Normalize();
			impulseDenominator = inverseMass + ( ( inverseWorldInertiaTensor * r.Cross( normal ) ).Cross( r ) * normal );
			impulse = (impulseNumerator / impulseDenominator) * normal;

			// apply impulse
			current.i.linearMomentum += impulse;
			current.i.angularMomentum += r.Cross( impulse );
		}
	}
}

/*
================
idPhysics_RigidBody::TestIfAtRest

  Returns true if the body is considered at rest.
  Does not catch all cases where the body is at rest but is generally good enough.
================
*/
bool idPhysics_RigidBody::TestIfAtRest() const {
	int i;
	float gv;
	idVec3 v, av, normal, point;
	idMat3 inverseWorldInertiaTensor;
	idFixedWinding contactWinding;

	if ( current.atRest >= 0 ) {
		return true;
	}

	// need at least 3 contact points to come to rest
	if ( contacts.Num() < 3 ) {
		return false;
	}

	// get average contact plane normal
	normal.Zero();
	for ( i = 0; i < contacts.Num(); i++ ) {
		normal += contacts[i].normal;
	}
	normal /= (float) contacts.Num();
	normal.Normalize();

	// if on a too steep surface
	if ( (normal * gravityNormal) > -0.7f ) {
		return false;
	}

	// create bounds for contact points
	contactWinding.Clear();
	for ( i = 0; i < contacts.Num(); i++ ) {
		// project point onto plane through origin orthogonal to the gravity
		point = contacts[i].point - (contacts[i].point * gravityNormal) * gravityNormal;
		contactWinding.AddToConvexHull( point, gravityNormal );
	}

	// need at least 3 contact points to come to rest
	if ( contactWinding.GetNumPoints() < 3 ) {
		return false;
	}

	// center of mass in world space
	point = current.i.position + centerOfMass * current.i.orientation;
	point -= (point * gravityNormal) * gravityNormal;

	// if the point is not inside the winding
	if ( !contactWinding.PointInside( gravityNormal, point, 0 ) ) {
		return false;
	}

	// linear velocity of body
	v = inverseMass * current.i.linearMomentum;
	// linear velocity in gravity direction
	gv = v * gravityNormal;
	// linear velocity orthogonal to gravity direction
	v -= gv * gravityNormal;

	// if too much velocity orthogonal to gravity direction
	if ( v.Length() > STOP_SPEED ) {
		return false;
	}
	// if too much velocity in gravity direction
	if ( gv > 2.0f * STOP_SPEED || gv < -2.0f * STOP_SPEED ) {
		return false;
	}

	// calculate rotational velocity
	inverseWorldInertiaTensor = current.i.orientation * inverseInertiaTensor * current.i.orientation.Transpose();
	av = inverseWorldInertiaTensor * current.i.angularMomentum;

	// if too much rotational velocity
	if ( av.LengthSqr() > STOP_SPEED ) {
		return false;
	}

	return true;
}

/*
================
idPhysics_RigidBody::DropToFloorAndRest

  Drops the object straight down to the floor and verifies if the object is at rest on the floor.
================
*/
void idPhysics_RigidBody::DropToFloorAndRest() {
	idVec3 down;
	trace_t tr;

	if ( testSolid ) {

		testSolid = false;

		if ( gameLocal.clip.Contents( current.i.position, clipModel, current.i.orientation, clipMask, self ) ) {
			gameLocal.DWarning( "rigid body in solid for entity '%s' type '%s' at (%s)",
								self->name.c_str(), self->GetType()->classname, current.i.position.ToString(0) );
			Rest();
			dropToFloor = false;
			return;
		}
	}

	// put the body on the floor
	down = current.i.position + gravityNormal * 128.0f;
	gameLocal.clip.Translation( tr, current.i.position, down, clipModel, current.i.orientation, clipMask, self );
	current.i.position = tr.endpos;
	clipModel->Link( gameLocal.clip, self, clipModel->GetId(), tr.endpos, current.i.orientation );

	// if on the floor already
	if ( tr.fraction == 0.0f ) {
		// test if we are really at rest
		EvaluateContacts();
		if ( !TestIfAtRest() ) {
			gameLocal.DWarning( "rigid body not at rest for entity '%s' type '%s' at (%s)",
								self->name.c_str(), self->GetType()->classname, current.i.position.ToString(0) );
		}
		Rest();
		dropToFloor = false;
	} else if ( IsOutsideWorld() ) {
		gameLocal.Warning( "rigid body outside world bounds for entity '%s' type '%s' at (%s)",
							self->name.c_str(), self->GetType()->classname, current.i.position.ToString(0) );
		Rest();
		dropToFloor = false;
	}
}

/*
================
idPhysics_RigidBody::DebugDraw
================
*/
void idPhysics_RigidBody::DebugDraw() {

	if ( rb_showBodies.GetBool() || ( rb_showActive.GetBool() && current.atRest < 0 ) ) {
		collisionModelManager->DrawModel( clipModel->Handle(), clipModel->GetOrigin(), clipModel->GetAxis(), vec3_origin, 0.0f );
	}

	if ( rb_showMass.GetBool() ) {
		gameRenderWorld->DrawText( va( "\n%1.2f", mass ), current.i.position, 0.08f, colorCyan, gameLocal.GetLocalPlayer()->viewAngles.ToMat3(), 1 );
	}

	if ( rb_showInertia.GetBool() ) {
		idMat3 &I = inertiaTensor;
		gameRenderWorld->DrawText( va( "\n\n\n( %.1f %.1f %.1f )\n( %.1f %.1f %.1f )\n( %.1f %.1f %.1f )",
									I[0].x, I[0].y, I[0].z,
									I[1].x, I[1].y, I[1].z,
									I[2].x, I[2].y, I[2].z ),
									current.i.position, 0.05f, colorCyan, gameLocal.GetLocalPlayer()->viewAngles.ToMat3(), 1 );
	}

	if ( rb_showVelocity.GetBool() ) {
		DrawVelocity( clipModel->GetId(), 0.1f, 4.0f );
	}
}

/*
================
idPhysics_RigidBody::idPhysics_RigidBody
================
*/
idPhysics_RigidBody::idPhysics_RigidBody() {

	// set default rigid body properties
	SetClipMask( MASK_SOLID );
	SetBouncyness( 0.6f );
	SetFriction( 0.6f, 0.6f, 0.0f );
	clipModel = NULL;

	current.atRest = -1;
	current.lastTimeStep = 0.0f;

	current.i.position.Zero();
	current.i.orientation.Identity();

	current.i.linearMomentum.Zero();
	current.i.angularMomentum.Zero();

	saved = current;

	mass = 1.0f;
	inverseMass = 1.0f;
	centerOfMass.Zero();
	inertiaTensor.Identity();
	inverseInertiaTensor.Identity();

	// use the least expensive euler integrator
	integrator = new (TAG_PHYSICS) idODE_Euler( sizeof(rigidBodyIState_t) / sizeof(float), RigidBodyDerivatives, this );

	dropToFloor = false;
	noImpact = false;
	noContact = false;

	hasMaster = false;
	isOrientated = false;

#ifdef RB_TIMINGS
	lastTimerReset = 0;
#endif
}

/*
================
idPhysics_RigidBody::~idPhysics_RigidBody
================
*/
idPhysics_RigidBody::~idPhysics_RigidBody() {
	if ( clipModel ) {
		delete clipModel;
		clipModel = NULL;
	}
	delete integrator;
}

/*
================
idPhysics_RigidBody_SavePState
================
*/
void idPhysics_RigidBody_SavePState( idSaveGame *savefile, const rigidBodyPState_t &state ) {
	savefile->WriteInt( state.atRest );
	savefile->WriteFloat( state.lastTimeStep );
	savefile->WriteVec3( state.localOrigin );
	savefile->WriteMat3( state.localAxis );
	savefile->WriteVec6( state.pushVelocity );
	savefile->WriteVec3( state.externalForce );
	savefile->WriteVec3( state.externalTorque );

	savefile->WriteVec3( state.i.position );
	savefile->WriteMat3( state.i.orientation );
	savefile->WriteVec3( state.i.linearMomentum );
	savefile->WriteVec3( state.i.angularMomentum );
}

/*
================
idPhysics_RigidBody_RestorePState
================
*/
void idPhysics_RigidBody_RestorePState( idRestoreGame *savefile, rigidBodyPState_t &state ) {
	savefile->ReadInt( state.atRest );
	savefile->ReadFloat( state.lastTimeStep );
	savefile->ReadVec3( state.localOrigin );
	savefile->ReadMat3( state.localAxis );
	savefile->ReadVec6( state.pushVelocity );
	savefile->ReadVec3( state.externalForce );
	savefile->ReadVec3( state.externalTorque );

	savefile->ReadVec3( state.i.position );
	savefile->ReadMat3( state.i.orientation );
	savefile->ReadVec3( state.i.linearMomentum );
	savefile->ReadVec3( state.i.angularMomentum );
}

/*
================
idPhysics_RigidBody::Save
================
*/
void idPhysics_RigidBody::Save( idSaveGame *savefile ) const {

	idPhysics_RigidBody_SavePState( savefile, current );
	idPhysics_RigidBody_SavePState( savefile, saved );

	savefile->WriteFloat( linearFriction );
	savefile->WriteFloat( angularFriction );
	savefile->WriteFloat( contactFriction );
	savefile->WriteFloat( bouncyness );
	savefile->WriteClipModel( clipModel );

	savefile->WriteFloat( mass );
	savefile->WriteFloat( inverseMass );
	savefile->WriteVec3( centerOfMass );
	savefile->WriteMat3( inertiaTensor );
	savefile->WriteMat3( inverseInertiaTensor );

	savefile->WriteBool( dropToFloor );
	savefile->WriteBool( testSolid );
	savefile->WriteBool( noImpact );
	savefile->WriteBool( noContact );

	savefile->WriteBool( hasMaster );
	savefile->WriteBool( isOrientated );
}

/*
================
idPhysics_RigidBody::Restore
================
*/
void idPhysics_RigidBody::Restore( idRestoreGame *savefile ) {

	idPhysics_RigidBody_RestorePState( savefile, current );
	idPhysics_RigidBody_RestorePState( savefile, saved );

	savefile->ReadFloat( linearFriction );
	savefile->ReadFloat( angularFriction );
	savefile->ReadFloat( contactFriction );
	savefile->ReadFloat( bouncyness );
	savefile->ReadClipModel( clipModel );

	savefile->ReadFloat( mass );
	savefile->ReadFloat( inverseMass );
	savefile->ReadVec3( centerOfMass );
	savefile->ReadMat3( inertiaTensor );
	savefile->ReadMat3( inverseInertiaTensor );

	savefile->ReadBool( dropToFloor );
	savefile->ReadBool( testSolid );
	savefile->ReadBool( noImpact );
	savefile->ReadBool( noContact );

	savefile->ReadBool( hasMaster );
	savefile->ReadBool( isOrientated );
}

/*
================
idPhysics_RigidBody::SetClipModel
================
*/
#define MAX_INERTIA_SCALE		10.0f

void idPhysics_RigidBody::SetClipModel( idClipModel *model, const float density, int id, bool freeOld ) {
	int minIndex;
	idMat3 inertiaScale;

	assert( self );
	assert( model );					// we need a clip model
	assert( model->IsTraceModel() );	// and it should be a trace model
	assert( density > 0.0f );			// density should be valid

	if ( clipModel && clipModel != model && freeOld ) {
		delete clipModel;
	}
	clipModel = model;
	clipModel->Link( gameLocal.clip, self, 0, current.i.position, current.i.orientation );

	// get mass properties from the trace model
	clipModel->GetMassProperties( density, mass, centerOfMass, inertiaTensor );

	// check whether or not the clip model has valid mass properties
	if ( mass <= 0.0f || IEEE_FLT_IS_NAN( mass ) ) {
		gameLocal.Warning( "idPhysics_RigidBody::SetClipModel: invalid mass for entity '%s' type '%s'",
							self->name.c_str(), self->GetType()->classname );
		mass = 1.0f;
		centerOfMass.Zero();
		inertiaTensor.Identity();
	}

	// check whether or not the inertia tensor is balanced
	minIndex = Min3Index( inertiaTensor[0][0], inertiaTensor[1][1], inertiaTensor[2][2] );
	inertiaScale.Identity();
	inertiaScale[0][0] = inertiaTensor[0][0] / inertiaTensor[minIndex][minIndex];
	inertiaScale[1][1] = inertiaTensor[1][1] / inertiaTensor[minIndex][minIndex];
	inertiaScale[2][2] = inertiaTensor[2][2] / inertiaTensor[minIndex][minIndex];

	if ( inertiaScale[0][0] > MAX_INERTIA_SCALE || inertiaScale[1][1] > MAX_INERTIA_SCALE || inertiaScale[2][2] > MAX_INERTIA_SCALE ) {
		gameLocal.DWarning( "idPhysics_RigidBody::SetClipModel: unbalanced inertia tensor for entity '%s' type '%s'",
							self->name.c_str(), self->GetType()->classname );
		float min = inertiaTensor[minIndex][minIndex] * MAX_INERTIA_SCALE;
		inertiaScale[(minIndex+1)%3][(minIndex+1)%3] = min / inertiaTensor[(minIndex+1)%3][(minIndex+1)%3];
		inertiaScale[(minIndex+2)%3][(minIndex+2)%3] = min / inertiaTensor[(minIndex+2)%3][(minIndex+2)%3];
		inertiaTensor *= inertiaScale;
	}

	inverseMass = 1.0f / mass;
	inverseInertiaTensor = inertiaTensor.Inverse() * ( 1.0f / 6.0f );

	current.i.linearMomentum.Zero();
	current.i.angularMomentum.Zero();
}

/*
================
idPhysics_RigidBody::GetClipModel
================
*/
idClipModel *idPhysics_RigidBody::GetClipModel( int id ) const {
	return clipModel;
}

/*
================
idPhysics_RigidBody::GetNumClipModels
================
*/
int idPhysics_RigidBody::GetNumClipModels() const {
	return 1;
}

/*
================
idPhysics_RigidBody::SetMass
================
*/
void idPhysics_RigidBody::SetMass( float mass, int id ) {
	assert( mass > 0.0f );
	inertiaTensor *= mass / this->mass;
	inverseInertiaTensor = inertiaTensor.Inverse() * (1.0f / 6.0f);
	this->mass = mass;
	inverseMass = 1.0f / mass;
}

/*
================
idPhysics_RigidBody::GetMass
================
*/
float idPhysics_RigidBody::GetMass( int id ) const {
	return mass;
}

/*
================
idPhysics_RigidBody::SetFriction
================
*/
void idPhysics_RigidBody::SetFriction( const float linear, const float angular, const float contact ) {
	if (	linear < 0.0f || linear > 1.0f ||
			angular < 0.0f || angular > 1.0f ||
			contact < 0.0f || contact > 1.0f ) {
		return;
	}
	linearFriction = linear;
	angularFriction = angular;
	contactFriction = contact;
}

/*
================
idPhysics_RigidBody::SetBouncyness
================
*/
void idPhysics_RigidBody::SetBouncyness( const float b ) {
	if ( b < 0.0f || b > 1.0f ) {
		return;
	}
	bouncyness = b;
}

/*
================
idPhysics_RigidBody::Rest
================
*/
void idPhysics_RigidBody::Rest() {
	current.atRest = gameLocal.time;
	current.i.linearMomentum.Zero();
	current.i.angularMomentum.Zero();
	self->BecomeInactive( TH_PHYSICS );
}

/*
================
idPhysics_RigidBody::DropToFloor
================
*/
void idPhysics_RigidBody::DropToFloor() {
	dropToFloor = true;
	testSolid = true;
}

/*
================
idPhysics_RigidBody::NoContact
================
*/
void idPhysics_RigidBody::NoContact() {
	noContact = true;
}

/*
================
idPhysics_RigidBody::Activate
================
*/
void idPhysics_RigidBody::Activate() {
	current.atRest = -1;
	self->BecomeActive( TH_PHYSICS );
}

/*
================
idPhysics_RigidBody::PutToRest

  put to rest untill something collides with this physics object
================
*/
void idPhysics_RigidBody::PutToRest() {
	Rest();
}

/*
================
idPhysics_RigidBody::EnableImpact
================
*/
void idPhysics_RigidBody::EnableImpact() {
	noImpact = false;
}

/*
================
idPhysics_RigidBody::DisableImpact
================
*/
void idPhysics_RigidBody::DisableImpact() {
	noImpact = true;
}

/*
================
idPhysics_RigidBody::SetContents
================
*/
void idPhysics_RigidBody::SetContents( int contents, int id ) {
	clipModel->SetContents( contents );
}

/*
================
idPhysics_RigidBody::GetContents
================
*/
int idPhysics_RigidBody::GetContents( int id ) const {
	return clipModel->GetContents();
}

/*
================
idPhysics_RigidBody::GetBounds
================
*/
const idBounds &idPhysics_RigidBody::GetBounds( int id ) const {
	return clipModel->GetBounds();
}

/*
================
idPhysics_RigidBody::GetAbsBounds
================
*/
const idBounds &idPhysics_RigidBody::GetAbsBounds( int id ) const {
	return clipModel->GetAbsBounds();
}

/*
================
idPhysics_RigidBody::Evaluate

  Evaluate the impulse based rigid body physics.
  When a collision occurs an impulse is applied at the moment of impact but
  the remaining time after the collision is ignored.
================
*/
bool idPhysics_RigidBody::Evaluate( int timeStepMSec, int endTimeMSec ) {
	rigidBodyPState_t next_step;
	idAngles angles;
	trace_t collision;
	idVec3 impulse;
	idEntity *ent;
	idVec3 oldOrigin, masterOrigin;
	idMat3 oldAxis, masterAxis;
	float timeStep;
	bool collided, cameToRest = false;

	timeStep = MS2SEC( timeStepMSec );
	current.lastTimeStep = timeStep;

	if ( hasMaster ) {
		oldOrigin = current.i.position;
		oldAxis = current.i.orientation;
		self->GetMasterPosition( masterOrigin, masterAxis );
		current.i.position = masterOrigin + current.localOrigin * masterAxis;
		if ( isOrientated ) {
			current.i.orientation = current.localAxis * masterAxis;
		}
		else {
			current.i.orientation = current.localAxis;
		}
		clipModel->Link( gameLocal.clip, self, clipModel->GetId(), current.i.position, current.i.orientation );
		current.i.linearMomentum = mass * ( ( current.i.position - oldOrigin ) / timeStep );
		current.i.angularMomentum = inertiaTensor * ( ( current.i.orientation * oldAxis.Transpose() ).ToAngularVelocity() / timeStep );
		current.externalForce.Zero();
		current.externalTorque.Zero();

		return ( current.i.position != oldOrigin || current.i.orientation != oldAxis );
	}

	// if the body is at rest
	if ( current.atRest >= 0 || timeStep <= 0.0f ) {
		DebugDraw();
		return false;
	}

	// if putting the body to rest
	if ( dropToFloor ) {
		DropToFloorAndRest();
		current.externalForce.Zero();
		current.externalTorque.Zero();
		return true;
	}

#ifdef RB_TIMINGS
	timer_total.Start();
#endif

	// move the rigid body velocity into the frame of a pusher
//	current.i.linearMomentum -= current.pushVelocity.SubVec3( 0 ) * mass;
//	current.i.angularMomentum -= current.pushVelocity.SubVec3( 1 ) * inertiaTensor;

	clipModel->Unlink();

	next_step = current;

	// calculate next position and orientation
	Integrate( timeStep, next_step );

#ifdef RB_TIMINGS
	timer_collision.Start();
#endif

	// check for collisions from the current to the next state
	collided = CheckForCollisions( timeStep, next_step, collision );

#ifdef RB_TIMINGS
	timer_collision.Stop();
#endif

	// set the new state
	current = next_step;

	if ( collided ) {
		// apply collision impulse
		if ( CollisionImpulse( collision, impulse ) ) {
			current.atRest = gameLocal.time;
		}
	}

	// update the position of the clip model
	clipModel->Link( gameLocal.clip, self, clipModel->GetId(), current.i.position, current.i.orientation );

	DebugDraw();

	if ( !noContact ) {

#ifdef RB_TIMINGS
		timer_collision.Start();
#endif
		// get contacts
		EvaluateContacts();

#ifdef RB_TIMINGS
		timer_collision.Stop();
#endif

		// check if the body has come to rest
		if ( TestIfAtRest() ) {
			// put to rest
			Rest();
			cameToRest = true;
		}  else {
			// apply contact friction
			ContactFriction( timeStep );
		}
	}

	if ( current.atRest < 0 ) {
		ActivateContactEntities();
	}

	if ( collided ) {
		// if the rigid body didn't come to rest or the other entity is not at rest
		ent = gameLocal.entities[collision.c.entityNum];
		if ( ent && ( !cameToRest || !ent->IsAtRest() ) ) {
			// apply impact to other entity
			ent->ApplyImpulse( self, collision.c.id, collision.c.point, -impulse );
		}
	}

	// move the rigid body velocity back into the world frame
//	current.i.linearMomentum += current.pushVelocity.SubVec3( 0 ) * mass;
//	current.i.angularMomentum += current.pushVelocity.SubVec3( 1 ) * inertiaTensor;
	current.pushVelocity.Zero();

	current.lastTimeStep = timeStep;
	current.externalForce.Zero();
	current.externalTorque.Zero();

	if ( IsOutsideWorld() ) {
		gameLocal.Warning( "rigid body moved outside world bounds for entity '%s' type '%s' at (%s)",
					self->name.c_str(), self->GetType()->classname, current.i.position.ToString(0) );
		Rest();
	}

#ifdef RB_TIMINGS
	timer_total.Stop();

	if ( rb_showTimings->integer == 1 ) {
		gameLocal.Printf( "%12s: t %1.4f cd %1.4f\n",
						self->name.c_str(),
						timer_total.Milliseconds(), timer_collision.Milliseconds() );
		lastTimerReset = 0;
	}
	else if ( rb_showTimings->integer == 2 ) {
		numRigidBodies++;
		if ( endTimeMSec > lastTimerReset ) {
			gameLocal.Printf( "rb %d: t %1.4f cd %1.4f\n",
							numRigidBodies,
							timer_total.Milliseconds(), timer_collision.Milliseconds() );
		}
	}
	if ( endTimeMSec > lastTimerReset ) {
		lastTimerReset = endTimeMSec;
		numRigidBodies = 0;
		timer_total.Clear();
		timer_collision.Clear();
	}
#endif

	return true;
}

/*
================
idPhysics_RigidBody::Interpolate

  Simply interpolate between snapshots of the state of the rigid body
  for MP clients.
================
*/
bool idPhysics_RigidBody::Interpolate( const float fraction ) {
	if ( !self ) {
		return false;
	}
	
	if ( self->GetInterpolationBehavior() == idEntity::USE_LATEST_SNAP_ONLY ) {
		current = next;
		return true;
	} else if ( self->GetInterpolationBehavior() == idEntity::USE_INTERPOLATION ) {
		current.i.position = Lerp( previous.i.position, next.i.position, fraction );
		current.i.orientation = idQuat().Slerp( previous.i.orientation.ToQuat(), next.i.orientation.ToQuat(), fraction ).ToMat3();
		current.i.linearMomentum = Lerp( previous.i.linearMomentum, next.i.linearMomentum, fraction );
		return true;
	}

	return false;
}

/*
================
idPhysics_RigidBody::ResetInterpolationState
================
*/
void idPhysics_RigidBody::ResetInterpolationState( const idVec3 & origin, const idMat3 & axis ) {
	previous = current;
	next = current;
}

/*
================
idPhysics_RigidBody::UpdateTime
================
*/
void idPhysics_RigidBody::UpdateTime( int endTimeMSec ) {
}

/*
================
idPhysics_RigidBody::GetTime
================
*/
int idPhysics_RigidBody::GetTime() const {
	return gameLocal.time;
}

/*
================
idPhysics_RigidBody::GetImpactInfo
================
*/
void idPhysics_RigidBody::GetImpactInfo( const int id, const idVec3 &point, impactInfo_t *info ) const {
	idVec3 linearVelocity, angularVelocity;
	idMat3 inverseWorldInertiaTensor;

	linearVelocity = inverseMass * current.i.linearMomentum;
	inverseWorldInertiaTensor = current.i.orientation.Transpose() * inverseInertiaTensor * current.i.orientation;
	angularVelocity = inverseWorldInertiaTensor * current.i.angularMomentum;

	info->invMass = inverseMass;
	info->invInertiaTensor = inverseWorldInertiaTensor;
	info->position = point - ( current.i.position + centerOfMass * current.i.orientation );
	info->velocity = linearVelocity + angularVelocity.Cross( info->position );
}

/*
================
idPhysics_RigidBody::ApplyImpulse
================
*/
void idPhysics_RigidBody::ApplyImpulse( const int id, const idVec3 &point, const idVec3 &impulse ) {
	if ( noImpact ) {
		return;
	}
	current.i.linearMomentum += impulse;
	current.i.angularMomentum += ( point - ( current.i.position + centerOfMass * current.i.orientation ) ).Cross( impulse );
	Activate();
}

/*
================
idPhysics_RigidBody::AddForce
================
*/
void idPhysics_RigidBody::AddForce( const int id, const idVec3 &point, const idVec3 &force ) {
	if ( noImpact ) {
		return;
	}
	current.externalForce += force;
	current.externalTorque += ( point - ( current.i.position + centerOfMass * current.i.orientation ) ).Cross( force );
	Activate();
}

/*
================
idPhysics_RigidBody::IsAtRest
================
*/
bool idPhysics_RigidBody::IsAtRest() const {
	return current.atRest >= 0;
}

/*
================
idPhysics_RigidBody::GetRestStartTime
================
*/
int idPhysics_RigidBody::GetRestStartTime() const {
	return current.atRest;
}

/*
================
idPhysics_RigidBody::IsPushable
================
*/
bool idPhysics_RigidBody::IsPushable() const {
	return ( !noImpact && !hasMaster );
}

/*
================
idPhysics_RigidBody::SaveState
================
*/
void idPhysics_RigidBody::SaveState() {
	saved = current;
}

/*
================
idPhysics_RigidBody::RestoreState
================
*/
void idPhysics_RigidBody::RestoreState() {
	current = saved;

	clipModel->Link( gameLocal.clip, self, clipModel->GetId(), current.i.position, current.i.orientation );

	EvaluateContacts();
}

/*
================
idPhysics::SetOrigin
================
*/
void idPhysics_RigidBody::SetOrigin( const idVec3 &newOrigin, int id ) {
	idVec3 masterOrigin;
	idMat3 masterAxis;

	current.localOrigin = newOrigin;
	if ( hasMaster ) {
		self->GetMasterPosition( masterOrigin, masterAxis );
		current.i.position = masterOrigin + newOrigin * masterAxis;
	}
	else {
		current.i.position = newOrigin;
	}

	clipModel->Link( gameLocal.clip, self, clipModel->GetId(), current.i.position, clipModel->GetAxis() );

	Activate();
}

/*
================
idPhysics::SetAxis
================
*/
void idPhysics_RigidBody::SetAxis( const idMat3 &newAxis, int id ) {
	idVec3 masterOrigin;
	idMat3 masterAxis;

	current.localAxis = newAxis;
	if ( hasMaster && isOrientated ) {
		self->GetMasterPosition( masterOrigin, masterAxis );
		current.i.orientation = newAxis * masterAxis;
	}
	else {
		current.i.orientation = newAxis;
	}

	clipModel->Link( gameLocal.clip, self, clipModel->GetId(), clipModel->GetOrigin(), current.i.orientation );

	Activate();
}

/*
================
idPhysics::Move
================
*/
void idPhysics_RigidBody::Translate( const idVec3 &translation, int id ) {

	current.localOrigin += translation;
	current.i.position += translation;

	clipModel->Link( gameLocal.clip, self, clipModel->GetId(), current.i.position, clipModel->GetAxis() );

	Activate();
}

/*
================
idPhysics::Rotate
================
*/
void idPhysics_RigidBody::Rotate( const idRotation &rotation, int id ) {
	idVec3 masterOrigin;
	idMat3 masterAxis;

	current.i.orientation *= rotation.ToMat3();
	current.i.position *= rotation;

	if ( hasMaster ) {
		self->GetMasterPosition( masterOrigin, masterAxis );
		current.localAxis *= rotation.ToMat3();
		current.localOrigin = ( current.i.position - masterOrigin ) * masterAxis.Transpose();
	}
	else {
		current.localAxis = current.i.orientation;
		current.localOrigin = current.i.position;
	}

	clipModel->Link( gameLocal.clip, self, clipModel->GetId(), current.i.position, current.i.orientation );

	Activate();
}

/*
================
idPhysics_RigidBody::GetOrigin
================
*/
const idVec3 &idPhysics_RigidBody::GetOrigin( int id ) const {
	return current.i.position;
}

/*
================
idPhysics_RigidBody::GetAxis
================
*/
const idMat3 &idPhysics_RigidBody::GetAxis( int id ) const {
	return current.i.orientation;
}

/*
================
idPhysics_RigidBody::SetLinearVelocity
================
*/
void idPhysics_RigidBody::SetLinearVelocity( const idVec3 &newLinearVelocity, int id ) {
	current.i.linearMomentum = newLinearVelocity * mass;
	Activate();
}

/*
================
idPhysics_RigidBody::SetAngularVelocity
================
*/
void idPhysics_RigidBody::SetAngularVelocity( const idVec3 &newAngularVelocity, int id ) {
	current.i.angularMomentum = newAngularVelocity * inertiaTensor;
	Activate();
}

/*
================
idPhysics_RigidBody::GetLinearVelocity
================
*/
const idVec3 &idPhysics_RigidBody::GetLinearVelocity( int id ) const {
	static idVec3 curLinearVelocity;
	curLinearVelocity = current.i.linearMomentum * inverseMass;
	return curLinearVelocity;
}

/*
================
idPhysics_RigidBody::GetAngularVelocity
================
*/
const idVec3 &idPhysics_RigidBody::GetAngularVelocity( int id ) const {
	static idVec3 curAngularVelocity;
	idMat3 inverseWorldInertiaTensor;

	inverseWorldInertiaTensor = current.i.orientation.Transpose() * inverseInertiaTensor * current.i.orientation;
	curAngularVelocity = inverseWorldInertiaTensor * current.i.angularMomentum;
	return curAngularVelocity;
}

/*
================
idPhysics_RigidBody::ClipTranslation
================
*/
void idPhysics_RigidBody::ClipTranslation( trace_t &results, const idVec3 &translation, const idClipModel *model ) const {
	if ( model ) {
		gameLocal.clip.TranslationModel( results, clipModel->GetOrigin(), clipModel->GetOrigin() + translation,
											clipModel, clipModel->GetAxis(), clipMask,
											model->Handle(), model->GetOrigin(), model->GetAxis() );
	}
	else {
		gameLocal.clip.Translation( results, clipModel->GetOrigin(), clipModel->GetOrigin() + translation,
											clipModel, clipModel->GetAxis(), clipMask, self );
	}
}

/*
================
idPhysics_RigidBody::ClipRotation
================
*/
void idPhysics_RigidBody::ClipRotation( trace_t &results, const idRotation &rotation, const idClipModel *model ) const {
	if ( model ) {
		gameLocal.clip.RotationModel( results, clipModel->GetOrigin(), rotation,
											clipModel, clipModel->GetAxis(), clipMask,
											model->Handle(), model->GetOrigin(), model->GetAxis() );
	}
	else {
		gameLocal.clip.Rotation( results, clipModel->GetOrigin(), rotation,
											clipModel, clipModel->GetAxis(), clipMask, self );
	}
}

/*
================
idPhysics_RigidBody::ClipContents
================
*/
int idPhysics_RigidBody::ClipContents( const idClipModel *model ) const {
	if ( model ) {
		return gameLocal.clip.ContentsModel( clipModel->GetOrigin(), clipModel, clipModel->GetAxis(), -1,
									model->Handle(), model->GetOrigin(), model->GetAxis() );
	}
	else {
		return gameLocal.clip.Contents( clipModel->GetOrigin(), clipModel, clipModel->GetAxis(), -1, NULL );
	}
}

/*
================
idPhysics_RigidBody::DisableClip
================
*/
void idPhysics_RigidBody::DisableClip() {
	clipModel->Disable();
}

/*
================
idPhysics_RigidBody::EnableClip
================
*/
void idPhysics_RigidBody::EnableClip() {
	clipModel->Enable();
}

/*
================
idPhysics_RigidBody::UnlinkClip
================
*/
void idPhysics_RigidBody::UnlinkClip() {
	clipModel->Unlink();
}

/*
================
idPhysics_RigidBody::LinkClip
================
*/
void idPhysics_RigidBody::LinkClip() {
	clipModel->Link( gameLocal.clip, self, clipModel->GetId(), current.i.position, current.i.orientation );
}

/*
================
idPhysics_RigidBody::EvaluateContacts
================
*/
bool idPhysics_RigidBody::EvaluateContacts() {
	idVec6 dir;
	int num;

	ClearContacts();

	contacts.SetNum( 10 );

	dir.SubVec3(0) = current.i.linearMomentum + current.lastTimeStep * gravityVector * mass;
	dir.SubVec3(1) = current.i.angularMomentum;
	dir.SubVec3(0).Normalize();
	dir.SubVec3(1).Normalize();
	num = gameLocal.clip.Contacts( &contacts[0], 10, clipModel->GetOrigin(),
					dir, CONTACT_EPSILON, clipModel, clipModel->GetAxis(), clipMask, self );
	contacts.SetNum( num );

	AddContactEntitiesForContacts();

	return ( contacts.Num() != 0 );
}

/*
================
idPhysics_RigidBody::SetPushed
================
*/
void idPhysics_RigidBody::SetPushed( int deltaTime ) {
	idRotation rotation;

	rotation = ( saved.i.orientation * current.i.orientation ).ToRotation();

	// velocity with which the af is pushed
	current.pushVelocity.SubVec3(0) += ( current.i.position - saved.i.position ) / ( deltaTime * idMath::M_MS2SEC );
	current.pushVelocity.SubVec3(1) += rotation.GetVec() * -DEG2RAD( rotation.GetAngle() ) / ( deltaTime * idMath::M_MS2SEC );
}

/*
================
idPhysics_RigidBody::GetPushedLinearVelocity
================
*/
const idVec3 &idPhysics_RigidBody::GetPushedLinearVelocity( const int id ) const {
	return current.pushVelocity.SubVec3(0);
}

/*
================
idPhysics_RigidBody::GetPushedAngularVelocity
================
*/
const idVec3 &idPhysics_RigidBody::GetPushedAngularVelocity( const int id ) const {
	return current.pushVelocity.SubVec3(1);
}

/*
================
idPhysics_RigidBody::SetMaster
================
*/
void idPhysics_RigidBody::SetMaster( idEntity *master, const bool orientated ) {
	idVec3 masterOrigin;
	idMat3 masterAxis;

	if ( master ) {
		if ( !hasMaster ) {
			// transform from world space to master space
			self->GetMasterPosition( masterOrigin, masterAxis );
			current.localOrigin = ( current.i.position - masterOrigin ) * masterAxis.Transpose();
			if ( orientated ) {
				current.localAxis = current.i.orientation * masterAxis.Transpose();
			}
			else {
				current.localAxis = current.i.orientation;
			}
			hasMaster = true;
			isOrientated = orientated;
			ClearContacts();
		}
	}
	else {
		if ( hasMaster ) {
			hasMaster = false;
			Activate();
		}
	}
}

const float	RB_VELOCITY_MAX				= 16000;
const int	RB_VELOCITY_TOTAL_BITS		= 16;
const int	RB_VELOCITY_EXPONENT_BITS	= idMath::BitsForInteger( idMath::BitsForFloat( RB_VELOCITY_MAX ) ) + 1;
const int	RB_VELOCITY_MANTISSA_BITS	= RB_VELOCITY_TOTAL_BITS - 1 - RB_VELOCITY_EXPONENT_BITS;
const float	RB_MOMENTUM_MAX				= 1e20f;
const int	RB_MOMENTUM_TOTAL_BITS		= 16;
const int	RB_MOMENTUM_EXPONENT_BITS	= idMath::BitsForInteger( idMath::BitsForFloat( RB_MOMENTUM_MAX ) ) + 1;
const int	RB_MOMENTUM_MANTISSA_BITS	= RB_MOMENTUM_TOTAL_BITS - 1 - RB_MOMENTUM_EXPONENT_BITS;
const float	RB_FORCE_MAX				= 1e20f;
const int	RB_FORCE_TOTAL_BITS			= 16;
const int	RB_FORCE_EXPONENT_BITS		= idMath::BitsForInteger( idMath::BitsForFloat( RB_FORCE_MAX ) ) + 1;
const int	RB_FORCE_MANTISSA_BITS		= RB_FORCE_TOTAL_BITS - 1 - RB_FORCE_EXPONENT_BITS;

/*
================
idPhysics_RigidBody::WriteToSnapshot
================
*/
void idPhysics_RigidBody::WriteToSnapshot( idBitMsg &msg ) const {
	idCQuat quat, localQuat;

	quat = current.i.orientation.ToCQuat();

	msg.WriteFloat( current.i.position[0] );
	msg.WriteFloat( current.i.position[1] );
	msg.WriteFloat( current.i.position[2] );
	msg.WriteFloat( quat.x );
	msg.WriteFloat( quat.y );
	msg.WriteFloat( quat.z );
	msg.WriteFloat( current.i.linearMomentum[0], RB_MOMENTUM_EXPONENT_BITS, RB_MOMENTUM_MANTISSA_BITS );
	msg.WriteFloat( current.i.linearMomentum[1], RB_MOMENTUM_EXPONENT_BITS, RB_MOMENTUM_MANTISSA_BITS );
	msg.WriteFloat( current.i.linearMomentum[2], RB_MOMENTUM_EXPONENT_BITS, RB_MOMENTUM_MANTISSA_BITS );
}

/*
================
idPhysics_RigidBody::ReadFromSnapshot
================
*/
void idPhysics_RigidBody::ReadFromSnapshot( const idBitMsg &msg ) {
	idCQuat quat, localQuat;
	
	previous = next;

	next.i.position[0] = msg.ReadFloat();
	next.i.position[1] = msg.ReadFloat();
	next.i.position[2] = msg.ReadFloat();
	quat.x = msg.ReadFloat();
	quat.y = msg.ReadFloat();
	quat.z = msg.ReadFloat();
	next.i.linearMomentum[0] = msg.ReadFloat( RB_MOMENTUM_EXPONENT_BITS, RB_MOMENTUM_MANTISSA_BITS );
	next.i.linearMomentum[1] = msg.ReadFloat( RB_MOMENTUM_EXPONENT_BITS, RB_MOMENTUM_MANTISSA_BITS );
	next.i.linearMomentum[2] = msg.ReadFloat( RB_MOMENTUM_EXPONENT_BITS, RB_MOMENTUM_MANTISSA_BITS );

	next.i.orientation = quat.ToMat3();

	// Make sure to initially set them up. Dont try to interpolate yet.
	if( self->GetNumSnapshotsReceived() <= 1 ) {
		current = next;
	}

	if ( clipModel ) {
		clipModel->Link( gameLocal.clip, self, clipModel->GetId(), next.i.position, next.i.orientation );
	}
}