bullet3/examples/MultiBody/MultiBodySoftContact.cpp

#include "MultiBodySoftContact.h"

#include "BulletDynamics/Featherstone/btMultiBodyLinkCollider.h"
#include "BulletDynamics/Featherstone/btMultiBodyJointFeedback.h"
							
#include "../CommonInterfaces/CommonMultiBodyBase.h"
#include "../Utils/b3ResourcePath.h"

//static btScalar radius(0.2);

struct MultiBodySoftContact : public CommonMultiBodyBase
{
    btMultiBody* m_multiBody;
	btAlignedObjectArray<btMultiBodyJointFeedback*> m_jointFeedbacks;

    bool m_once;
public:

    MultiBodySoftContact(struct GUIHelperInterface* helper);
    virtual ~MultiBodySoftContact();

    virtual void initPhysics();

    virtual void stepSimulation(float deltaTime);

	virtual void resetCamera()
	{
		float dist = 5;
		float pitch = -21;
		float yaw = 270;
		float targetPos[3]={0,0,0};
		m_guiHelper->resetCamera(dist,yaw,pitch,targetPos[0],targetPos[1],targetPos[2]);
	}


};



MultiBodySoftContact::MultiBodySoftContact(struct GUIHelperInterface* helper)
:CommonMultiBodyBase(helper),
m_once(true)
{
}

MultiBodySoftContact::~MultiBodySoftContact()
{
    
}




void MultiBodySoftContact::initPhysics()
{
	  
    int upAxis = 2;

	m_guiHelper->setUpAxis(upAxis);

    btVector4 colors[4] =
    {
        btVector4(1,0,0,1),
        btVector4(0,1,0,1),
        btVector4(0,1,1,1),
        btVector4(1,1,0,1),
    };
    int curColor = 0;


    

	this->createEmptyDynamicsWorld();
		m_dynamicsWorld->setGravity(btVector3(0,0,-10));

	m_guiHelper->createPhysicsDebugDrawer(m_dynamicsWorld);
    m_dynamicsWorld->getDebugDrawer()->setDebugMode(
        //btIDebugDraw::DBG_DrawConstraints
        +btIDebugDraw::DBG_DrawWireframe
        +btIDebugDraw::DBG_DrawContactPoints
        +btIDebugDraw::DBG_DrawAabb
        );//+btIDebugDraw::DBG_DrawConstraintLimits);

	

    //create a static ground object
    if (1)
        {
            btVector3 groundHalfExtents(50,50,50);
            btBoxShape* box = new btBoxShape(groundHalfExtents);
            box->initializePolyhedralFeatures();

            m_guiHelper->createCollisionShapeGraphicsObject(box);
            btTransform start; start.setIdentity();
            btVector3 groundOrigin(0,0,-50.5);
			start.setOrigin(groundOrigin);
		//	start.setRotation(groundOrn);
            btRigidBody* body =  createRigidBody(0,start,box);
            
            //setContactStiffnessAndDamping will enable compliant rigid body contact
            body->setContactStiffnessAndDamping(300,10);
            btVector4 color = colors[curColor];
			curColor++;
			curColor&=3;
            m_guiHelper->createRigidBodyGraphicsObject(body,color);

        }

	{
		btCollisionShape* childShape = new btSphereShape(btScalar(0.5));
		m_guiHelper->createCollisionShapeGraphicsObject(childShape);

		btScalar mass = 1;
		btVector3 baseInertiaDiag;
		bool isFixed = (mass == 0);
		childShape->calculateLocalInertia(mass,baseInertiaDiag);
	  btMultiBody *pMultiBody = new btMultiBody(0, 1, baseInertiaDiag, false, false);
	  btTransform startTrans;
	  startTrans.setIdentity();
	  startTrans.setOrigin(btVector3(0,0,3));

	  pMultiBody->setBaseWorldTransform(startTrans);

	   btMultiBodyLinkCollider* col= new btMultiBodyLinkCollider(pMultiBody, -1);
		col->setCollisionShape(childShape);
		pMultiBody->setBaseCollider(col);
			bool isDynamic = (mass > 0 && !isFixed);
		int collisionFilterGroup = isDynamic? int(btBroadphaseProxy::DefaultFilter) : int(btBroadphaseProxy::StaticFilter);
		int collisionFilterMask = isDynamic? 	int(btBroadphaseProxy::AllFilter) : 	int(btBroadphaseProxy::AllFilter ^ btBroadphaseProxy::StaticFilter);

        m_dynamicsWorld->addCollisionObject(col,collisionFilterGroup,collisionFilterMask);//, 2,1+2);


		pMultiBody->finalizeMultiDof();
	
		m_dynamicsWorld->addMultiBody(pMultiBody);
	
		btAlignedObjectArray<btQuaternion> scratch_q;
		btAlignedObjectArray<btVector3> scratch_m;
		pMultiBody->forwardKinematics(scratch_q,scratch_m);
		btAlignedObjectArray<btQuaternion> world_to_local;
		btAlignedObjectArray<btVector3> local_origin;
		pMultiBody->updateCollisionObjectWorldTransforms(world_to_local,local_origin);
	}
	m_guiHelper->autogenerateGraphicsObjects(m_dynamicsWorld);


}

void MultiBodySoftContact::stepSimulation(float deltaTime)
{
	
    if (0)//m_once)
    {
       m_once=false;
        m_multiBody->addJointTorque(0, 10.0);
    
        btScalar torque = m_multiBody->getJointTorque(0);
        b3Printf("t = %f,%f,%f\n",torque,torque,torque);//[0],torque[1],torque[2]);
    }
    
    m_dynamicsWorld->stepSimulation(deltaTime);

	
    
}


class CommonExampleInterface*    MultiBodySoftContactCreateFunc(struct CommonExampleOptions& options)
{
	return new MultiBodySoftContact(options.m_guiHelper);
}