A single-class btDiscreteDynamicsWorld wrapper

bullet.hpp

#ifndef INCLUDED_BULLET_HPP_
#define INCLUDED_BULLET_HPP_

#include "btBulletDynamicsCommon.h"

namespace bullet_wrapper {

// 使うクラスの目次がわりのtypedef

typedef btDiscreteDynamicsWorld World;
typedef btDefaultCollisionConfiguration Config;
typedef btCollisionDispatcher Dispatcher;
typedef btSequentialImpulseConstraintSolver Solver;
typedef btAxisSweep3 Cache;
typedef btInternalTickCallback BulletTickCallback;
typedef btIDebugDraw IDebugDraw;

typedef btCollisionShape Shape;
typedef btSphereShape SphereShape;
typedef btStaticPlaneShape PlaneShape;
typedef btBoxShape BoxShape;
typedef btDefaultMotionState MotionState;
typedef btRigidBody Body;
typedef Body::btRigidBodyConstructionInfo BodyConstructionInfo;
typedef btTypedConstraint Constraint;
typedef btGeneric6DofConstraint DofConstraint;

typedef btVector3 Vector;
typedef btScalar Scalar;
typedef btTransform Transform;
typedef btQuaternion Quaternion;

// btDiscreteDynamicsWorldを使いたいだけのラッパー
class Bullet
{
    Config config;
    Dispatcher dispatcher;
    Cache cache;
    Solver solver;
    World world;

public:
    Bullet(const Vector &from, const Vector &to, unsigned short max_bodies)
        :
        config(),
        dispatcher(&config),
        cache(from, to, max_bodies),
        solver(),
        world(&dispatcher, &cache, &solver, &config)
    {
    }
    
    // クラスの外部からnewして挿入したオブジェクトの類を親切にもdeleteする
    ~Bullet()
    {
        // 登録されたbtConstraintを全てdeleteして削除
        for (int i = world.getNumConstraints() - 1; i >= 0; i--)
        {
            Constraint *constraint = world.getConstraint(i);
            world.removeConstraint(constraint);
            delete constraint;
        }

        btCollisionObjectArray &objects = world.getCollisionObjectArray();

        for (int i = objects.size() - 1; i >= 0; i--)
        {
            // これから削除するbtCollisionObject
            btCollisionObject *object = objects[i];
            
            // 紐付いたbtCollisionShapeを削除
            if (btCollisionShape *shape = object->getCollisionShape())
            {
                // object間で共有してる場合の二重deleteを防ぐ
                for (int j = 0; j < i; j++)
                {
                    if (objects[j]->getCollisionShape() == shape)
                    {
                        objects[j]->setCollisionShape(NULL);
                    }
                }

                delete shape;
            }

            // 紐付いたbtMotionStateを削除
            if (Body *body = Body::upcast(object))
            {
                if (btMotionState *state = body->getMotionState())
                {
                    delete state;
                }
            }

            world.removeCollisionObject(object);

            delete object;
        }
    }

    /* miso */

    void step(btScalar delta = btScalar(1 / 60.0))
    {
        world.stepSimulation(delta);
    }

    void draw()
    {
        world.debugDrawWorld();
    }

    /* getter / setter */

    void set_debug_draw(IDebugDraw *drawer)
    {
        world.setDebugDrawer(drawer);
    }

    void add_body(Body *body)
    {
        world.addRigidBody(body);
    }

    void remove_body(Body *body)
    {
        world.removeRigidBody(body);
    }

    void add_constraint(Constraint *constraint, bool disableCollisionsBetweenLinkedBodies)
    {
        world.addConstraint(constraint, disableCollisionsBetweenLinkedBodies);
    }

    void set_tick_callback(BulletTickCallback callback, void *callback_context, bool pre_tick)
    {
        world.setInternalTickCallback(callback, callback_context, pre_tick);
    }

    // predicates

    // taken from http://www.bulletphysics.org/mediawiki-1.5.8/index.php?title=Collision_Callbacks_and_Triggers
    bool is_colliding(btCollisionObject *a, btCollisionObject *b)
    {
        typedef World::ContactResultCallback CallbackBase;
        
        struct Callback : public CallbackBase
        {
            bool result;

            virtual btScalar addSingleResult(btManifoldPoint&, const btCollisionObjectWrapper*, int, int, const btCollisionObjectWrapper*, int, int)
            {
                result = true;
                return 0;
            }
        };

        Callback callback;
        callback.result = false;
        world.contactPairTest(a, b, callback);

        return callback.result;
    }
};

} /* namespace bullet_wrapper */

#endif /* !defined(INCLUDED_BULLET_HPP_) */