source: code/branches/physics/src/bullet/BulletDynamics/Dynamics/btRigidBody.cpp @ 1993

/*
Bullet Continuous Collision Detection and Physics Library
Copyright (c) 2003-2006 Erwin Coumans  http://continuousphysics.com/Bullet/

This software is provided 'as-is', without any express or implied warranty.
In no event will the authors be held liable for any damages arising from the use of this software.
Permission is granted to anyone to use this software for any purpose, 
including commercial applications, and to alter it and redistribute it freely, 
subject to the following restrictions:

1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
*/

#include "btRigidBody.h"
#include "BulletCollision/CollisionShapes/btConvexShape.h"
#include "LinearMath/btMinMax.h"
#include "LinearMath/btTransformUtil.h"
#include "LinearMath/btMotionState.h"
#include "BulletDynamics/ConstraintSolver/btTypedConstraint.h"

//'temporarily' global variables
btScalar        gDeactivationTime = btScalar(2.);
bool    gDisableDeactivation = false;
static int uniqueId = 0;


btRigidBody::btRigidBody(const btRigidBody::btRigidBodyConstructionInfo& constructionInfo)
{
        setupRigidBody(constructionInfo);
}

btRigidBody::btRigidBody(btScalar mass, btMotionState *motionState, btCollisionShape *collisionShape, const btVector3 &localInertia)
{
        btRigidBodyConstructionInfo cinfo(mass,motionState,collisionShape,localInertia);
        setupRigidBody(cinfo);
}

void    btRigidBody::setupRigidBody(const btRigidBody::btRigidBodyConstructionInfo& constructionInfo)
{

        m_internalType=CO_RIGID_BODY;

        m_linearVelocity.setValue(btScalar(0.0), btScalar(0.0), btScalar(0.0));
        m_angularVelocity.setValue(btScalar(0.),btScalar(0.),btScalar(0.));
        m_angularFactor = btScalar(1.);
        m_gravity.setValue(btScalar(0.0), btScalar(0.0), btScalar(0.0));
        m_totalForce.setValue(btScalar(0.0), btScalar(0.0), btScalar(0.0));
        m_totalTorque.setValue(btScalar(0.0), btScalar(0.0), btScalar(0.0)),
        m_linearDamping = btScalar(0.);
        m_angularDamping = btScalar(0.5);
        m_linearSleepingThreshold = constructionInfo.m_linearSleepingThreshold;
        m_angularSleepingThreshold = constructionInfo.m_angularSleepingThreshold;
        m_optionalMotionState = constructionInfo.m_motionState;
        m_contactSolverType = 0;
        m_frictionSolverType = 0;
        m_additionalDamping = constructionInfo.m_additionalDamping;
        m_additionalDampingFactor = constructionInfo.m_additionalDampingFactor;
        m_additionalLinearDampingThresholdSqr = constructionInfo.m_additionalLinearDampingThresholdSqr;
        m_additionalAngularDampingThresholdSqr = constructionInfo.m_additionalAngularDampingThresholdSqr;
        m_additionalAngularDampingFactor = constructionInfo.m_additionalAngularDampingFactor;

        if (m_optionalMotionState)
        {
                m_optionalMotionState->getWorldTransform(m_worldTransform);
        } else
        {
                m_worldTransform = constructionInfo.m_startWorldTransform;
        }

        m_interpolationWorldTransform = m_worldTransform;
        m_interpolationLinearVelocity.setValue(0,0,0);
        m_interpolationAngularVelocity.setValue(0,0,0);
        
        //moved to btCollisionObject
        m_friction = constructionInfo.m_friction;
        m_restitution = constructionInfo.m_restitution;

        setCollisionShape( constructionInfo.m_collisionShape );
        m_debugBodyId = uniqueId++;
        
        setMassProps(constructionInfo.m_mass, constructionInfo.m_localInertia);
    setDamping(constructionInfo.m_linearDamping, constructionInfo.m_angularDamping);
        updateInertiaTensor();

}


void btRigidBody::predictIntegratedTransform(btScalar timeStep,btTransform& predictedTransform) 
{
        btTransformUtil::integrateTransform(m_worldTransform,m_linearVelocity,m_angularVelocity,timeStep,predictedTransform);
}

void                    btRigidBody::saveKinematicState(btScalar timeStep)
{
        //todo: clamp to some (user definable) safe minimum timestep, to limit maximum angular/linear velocities
        if (timeStep != btScalar(0.))
        {
                //if we use motionstate to synchronize world transforms, get the new kinematic/animated world transform
                if (getMotionState())
                        getMotionState()->getWorldTransform(m_worldTransform);
                btVector3 linVel,angVel;
                
                btTransformUtil::calculateVelocity(m_interpolationWorldTransform,m_worldTransform,timeStep,m_linearVelocity,m_angularVelocity);
                m_interpolationLinearVelocity = m_linearVelocity;
                m_interpolationAngularVelocity = m_angularVelocity;
                m_interpolationWorldTransform = m_worldTransform;
                //printf("angular = %f %f %f\n",m_angularVelocity.getX(),m_angularVelocity.getY(),m_angularVelocity.getZ());
        }
}
        
void    btRigidBody::getAabb(btVector3& aabbMin,btVector3& aabbMax) const
{
        getCollisionShape()->getAabb(m_worldTransform,aabbMin,aabbMax);
}




void btRigidBody::setGravity(const btVector3& acceleration) 
{
        if (m_inverseMass != btScalar(0.0))
        {
                m_gravity = acceleration * (btScalar(1.0) / m_inverseMass);
        }
}






void btRigidBody::setDamping(btScalar lin_damping, btScalar ang_damping)
{
        m_linearDamping = GEN_clamped(lin_damping, (btScalar)btScalar(0.0), (btScalar)btScalar(1.0));
        m_angularDamping = GEN_clamped(ang_damping, (btScalar)btScalar(0.0), (btScalar)btScalar(1.0));
}




///applyDamping damps the velocity, using the given m_linearDamping and m_angularDamping
void                    btRigidBody::applyDamping(btScalar timeStep)
{
        //On new damping: see discussion/issue report here: http://code.google.com/p/bullet/issues/detail?id=74
        //todo: do some performance comparisons (but other parts of the engine are probably bottleneck anyway

//#define USE_OLD_DAMPING_METHOD 1
#ifdef USE_OLD_DAMPING_METHOD
        m_linearVelocity *= GEN_clamped((btScalar(1.) - timeStep * m_linearDamping), (btScalar)btScalar(0.0), (btScalar)btScalar(1.0));
        m_angularVelocity *= GEN_clamped((btScalar(1.) - timeStep * m_angularDamping), (btScalar)btScalar(0.0), (btScalar)btScalar(1.0));
#else
        m_linearVelocity *= btPow(btScalar(1)-m_linearDamping, timeStep);
        m_angularVelocity *= btPow(btScalar(1)-m_angularDamping, timeStep);
#endif

        if (m_additionalDamping)
        {
                //Additional damping can help avoiding lowpass jitter motion, help stability for ragdolls etc.
                //Such damping is undesirable, so once the overall simulation quality of the rigid body dynamics system has improved, this should become obsolete
                if ((m_angularVelocity.length2() < m_additionalAngularDampingThresholdSqr) &&
                        (m_linearVelocity.length2() < m_additionalLinearDampingThresholdSqr))
                {
                        m_angularVelocity *= m_additionalDampingFactor;
                        m_linearVelocity *= m_additionalDampingFactor;
                }
        

                btScalar speed = m_linearVelocity.length();
                if (speed < m_linearDamping)
                {
                        btScalar dampVel = btScalar(0.005);
                        if (speed > dampVel)
                        {
                                btVector3 dir = m_linearVelocity.normalized();
                                m_linearVelocity -=  dir * dampVel;
                        } else
                        {
                                m_linearVelocity.setValue(btScalar(0.),btScalar(0.),btScalar(0.));
                        }
                }

                btScalar angSpeed = m_angularVelocity.length();
                if (angSpeed < m_angularDamping)
                {
                        btScalar angDampVel = btScalar(0.005);
                        if (angSpeed > angDampVel)
                        {
                                btVector3 dir = m_angularVelocity.normalized();
                                m_angularVelocity -=  dir * angDampVel;
                        } else
                        {
                                m_angularVelocity.setValue(btScalar(0.),btScalar(0.),btScalar(0.));
                        }
                }
        }
}


void btRigidBody::applyGravity()
{
        if (isStaticOrKinematicObject())
                return;
        
        applyCentralForce(m_gravity);   

}

void btRigidBody::proceedToTransform(const btTransform& newTrans)
{
        setCenterOfMassTransform( newTrans );
}
        

void btRigidBody::setMassProps(btScalar mass, const btVector3& inertia)
{
        if (mass == btScalar(0.))
        {
                m_collisionFlags |= btCollisionObject::CF_STATIC_OBJECT;
                m_inverseMass = btScalar(0.);
        } else
        {
                m_collisionFlags &= (~btCollisionObject::CF_STATIC_OBJECT);
                m_inverseMass = btScalar(1.0) / mass;
        }
        
        m_invInertiaLocal.setValue(inertia.x() != btScalar(0.0) ? btScalar(1.0) / inertia.x(): btScalar(0.0),
                                   inertia.y() != btScalar(0.0) ? btScalar(1.0) / inertia.y(): btScalar(0.0),
                                   inertia.z() != btScalar(0.0) ? btScalar(1.0) / inertia.z(): btScalar(0.0));

}

        

void btRigidBody::updateInertiaTensor() 
{
        m_invInertiaTensorWorld = m_worldTransform.getBasis().scaled(m_invInertiaLocal) * m_worldTransform.getBasis().transpose();
}


void btRigidBody::integrateVelocities(btScalar step) 
{
        if (isStaticOrKinematicObject())
                return;

        m_linearVelocity += m_totalForce * (m_inverseMass * step);
        m_angularVelocity += m_invInertiaTensorWorld * m_totalTorque * step;

#define MAX_ANGVEL SIMD_HALF_PI
        /// clamp angular velocity. collision calculations will fail on higher angular velocities       
        btScalar angvel = m_angularVelocity.length();
        if (angvel*step > MAX_ANGVEL)
        {
                m_angularVelocity *= (MAX_ANGVEL/step) /angvel;
        }

}

btQuaternion btRigidBody::getOrientation() const
{
                btQuaternion orn;
                m_worldTransform.getBasis().getRotation(orn);
                return orn;
}
        
        
void btRigidBody::setCenterOfMassTransform(const btTransform& xform)
{

        if (isStaticOrKinematicObject())
        {
                m_interpolationWorldTransform = m_worldTransform;
        } else
        {
                m_interpolationWorldTransform = xform;
        }
        m_interpolationLinearVelocity = getLinearVelocity();
        m_interpolationAngularVelocity = getAngularVelocity();
        m_worldTransform = xform;
        updateInertiaTensor();
}


bool btRigidBody::checkCollideWithOverride(btCollisionObject* co)
{
        btRigidBody* otherRb = btRigidBody::upcast(co);
        if (!otherRb)
                return true;

        for (int i = 0; i < m_constraintRefs.size(); ++i)
        {
                btTypedConstraint* c = m_constraintRefs[i];
                if (&c->getRigidBodyA() == otherRb || &c->getRigidBodyB() == otherRb)
                        return false;
        }

        return true;
}

void btRigidBody::addConstraintRef(btTypedConstraint* c)
{
        int index = m_constraintRefs.findLinearSearch(c);
        if (index == m_constraintRefs.size())
                m_constraintRefs.push_back(c); 

        m_checkCollideWith = true;
}

void btRigidBody::removeConstraintRef(btTypedConstraint* c)
{
        m_constraintRefs.remove(c);
        m_checkCollideWith = m_constraintRefs.size() > 0;
}