bullet3/examples/FractureDemo/btFractureBody.h

#ifndef BT_FRACTURE_BODY
#define BT_FRACTURE_BODY

class btCollisionShape;
class btDynamicsWorld;
class btCollisionWorld;
class btCompoundShape;
class btManifoldPoint;

#include "LinearMath/btAlignedObjectArray.h"
#include "BulletDynamics/Dynamics/btRigidBody.h"

#define CUSTOM_FRACTURE_TYPE (btRigidBody::CO_USER_TYPE + 1)

struct btConnection
{
	btCollisionShape* m_childShape0;
	btCollisionShape* m_childShape1;
	int m_childIndex0;
	int m_childIndex1;
	btScalar m_strength;
};

class btFractureBody : public btRigidBody
{
	//connections
public:
	btDynamicsWorld* m_world;
	btAlignedObjectArray<btScalar> m_masses;
	btAlignedObjectArray<btConnection> m_connections;

	btFractureBody(const btRigidBodyConstructionInfo& constructionInfo, btDynamicsWorld* world)
		: btRigidBody(constructionInfo),
		  m_world(world)
	{
		m_masses.push_back(constructionInfo.m_mass);
		m_internalType = CUSTOM_FRACTURE_TYPE + CO_RIGID_BODY;
	}

	///btRigidBody constructor for backwards compatibility.
	///To specify friction (etc) during rigid body construction, please use the other constructor (using btRigidBodyConstructionInfo)
	btFractureBody(btScalar mass, btMotionState* motionState, btCollisionShape* collisionShape, const btVector3& localInertia, btScalar* masses, int numMasses, btDynamicsWorld* world)
		: btRigidBody(mass, motionState, collisionShape, localInertia),
		  m_world(world)
	{
		for (int i = 0; i < numMasses; i++)
			m_masses.push_back(masses[i]);

		m_internalType = CUSTOM_FRACTURE_TYPE + CO_RIGID_BODY;
	}

	void recomputeConnectivity(btCollisionWorld* world);

	static btCompoundShape* shiftTransform(btCompoundShape* boxCompound, btScalar* masses, btTransform& shift, btVector3& principalInertia);

	static btCompoundShape* shiftTransformDistributeMass(btCompoundShape* boxCompound, btScalar mass, btTransform& shift);

	static bool collisionCallback(btManifoldPoint& cp, const btCollisionObject* colObj0, int partId0, int index0, const btCollisionObject* colObj1, int partId1, int index1);
};

void fractureCallback(btDynamicsWorld* world, btScalar timeStep);
void glueCallback(btDynamicsWorld* world, btScalar timeStep);

#endif  //BT_FRACTURE_BODY