错误的物理行为与bullet

Question

使用基本的bullet c++模拟，我似乎无法获得正确的物理行为。我正在尝试从一个从STL文件加载的网格中初始化btRigidBody，为此我使用的是lib assimp。

当使用立方体时，物理行为似乎是有效的，但对于矩形形状则不是。在将网格加载到物理中的方式中，我遗漏了什么？

void SimulationManager::addRigidBodyFromMesh (const BodyInfo& bodyInfo, const aiMesh* mesh) {

    btTriangleMesh* trimesh = new btTriangleMesh();

    for (int i=0;i<mesh->mNumFaces; ++i) {

        const aiFace& face = mesh->mFaces[i];

        aiVector3D v0 = mesh->mVertices[face.mIndices[0]];
        aiVector3D v1 = mesh->mVertices[face.mIndices[1]];
        aiVector3D v2 = mesh->mVertices[face.mIndices[2]];

        trimesh->addTriangle(
            btVector3(v0.x, v0.y, v0.z),
            btVector3(v1.x, v1.y, v1.z),
            btVector3(v2.x, v2.y, v2.z));
    }

    btCollisionShape* colShape = new btConvexTriangleMeshShape(trimesh);

    //static, non-moving world environment geometry
    //bool useQuantization = true;
    //shape  = new btBvhTriangleMeshShape(trimesh,useQuantization);

    this->_collisionShapes.push_back(colShape);

    btTransform transform;
    transform.setIdentity();

    btScalar mass(1.f);
    btVector3 localInertia(0, 0, 0);
    colShape->calculateLocalInertia(mass, localInertia);

    transform.setOrigin(btVector3(bodyInfo.x, bodyInfo.y, bodyInfo.z));

    btDefaultMotionState* motionState = new btDefaultMotionState(transform);
    btRigidBody::btRigidBodyConstructionInfo rbInfo(mass, motionState, colShape, localInertia);
    btRigidBody* body = new btRigidBody(rbInfo);

    body->setAngularVelocity(btVector3(bodyInfo.aX, bodyInfo.aY, bodyInfo.aZ));

    this->_pDynamicsWorld->addRigidBody(body);
}

然后，我更新模拟并检索刚体变换，如下所示：

void SimulationManager::update(double dt, std::vector<BodyTransform>& transforms){

    this->_pDynamicsWorld->stepSimulation(dt, 10);

    for (int i = 0; i < this->_pDynamicsWorld->getNumCollisionObjects(); ++i) {

        btCollisionObject* obj = this->_pDynamicsWorld->getCollisionObjectArray()[i];
        btRigidBody* body = btRigidBody::upcast(obj);

        float invMass = body->getInvMass();

        if (invMass > 0) {

            btTransform trans;
            body->getMotionState()->getWorldTransform(trans);

            BodyTransform bodyTransform;

            bodyTransform.matrix = new btScalar[16];

            trans.getOpenGLMatrix(bodyTransform.matrix);

            transforms.push_back(bodyTransform);
        }
    }
};

并按如下方式更新opengl网格：

std::vector<BodyTransform> transforms;

simulationManager.update(0.005, transforms);

for (std::vector<BodyTransform>::iterator it = transforms.begin() ; it != transforms.end(); ++it) {

    glPushMatrix();
    glMultMatrixf((GLfloat*)it->matrix);
    drawModel(bar);
    glPopMatrix();

    delete [] it->matrix;
}

这是我的模拟在立方体中的样子：

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但是对于矩形，网格最初放置在地板上，它们垂直稳定，这很奇怪：

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我将非常感谢在这个主题上的任何帮助。谢谢!

Answer 1

经过一段时间的努力，我发现了问题所在，所以我会回答我自己的问题，以防它对其他人有用: bullet希望网格的重心放在它的原点，如果不是这样，你会得到上面看到的奇怪行为。