CODEWITHSUNDEEP
c++qtqt3d
yunlong wang
yunlong wang

Reputation: 11

Memory leak in Qt3D

In my project, I made a class,shown below,

class MyQt3D: public Qt3DExtras::Qt3DWindow
{
public:
    MyQt3D()
    {

        // Root entity
        m_rootEntity = new Qt3DCore::QEntity();
        setRootEntity(m_rootEntity);

        // Camera
        Qt3DRender::QCamera* cameraEntity = camera();


        cameraEntity->lens()->setPerspectiveProjection(45.0f, 16.0f/9.0f, 0.1f, 1000.0f);
        cameraEntity->setPosition(QVector3D(0, 0, 40.0f));
        cameraEntity->setUpVector(QVector3D(0, 1, 0));
        cameraEntity->setViewCenter(QVector3D(0, 0, 0));

        // For camera controls
        Qt3DExtras::QOrbitCameraController *camController = new Qt3DExtras::QOrbitCameraController(m_rootEntity);
        camController->setCamera(cameraEntity);

        auto m_coneEntity = new Qt3DCore::QEntity(m_rootEntity);

        // Cone shape data
        Qt3DExtras::QConeMesh *cone = new Qt3DExtras::QConeMesh(m_coneEntity);
        cone->setTopRadius(0.5);
        cone->setBottomRadius(1);
        cone->setLength(3);
        cone->setRings(50);
        cone->setSlices(20);

        // ConeMesh Transform
        Qt3DCore::QTransform *coneTransform = new Qt3DCore::QTransform(m_coneEntity);
        coneTransform->setScale(1.5f);
        coneTransform->setRotation(QQuaternion::fromAxisAndAngle(QVector3D(1.0f, 0.0f, 0.0f), 45.0f));
        coneTransform->setTranslation(QVector3D(0.0f, 4.0f, -1.5));

        Qt3DExtras::QPhongMaterial *coneMaterial = new Qt3DExtras::QPhongMaterial(m_coneEntity);
        coneMaterial->setDiffuse(QColor(QRgb(0x928327)));

        // Cone
        m_coneEntity->addComponent(cone);
        m_coneEntity->addComponent(coneMaterial);
        m_coneEntity->addComponent(coneTransform);




    }

    ~MyQt3D()
    {
        delete m_rootEntity;
    }

protected:
    Qt3DCore::QEntity *m_rootEntity;
};

As I need to dynamically create and destory the object of the class "MyQt3D", I use the following for loop to show the memory leak,

for(int i=0;i<20;i++)
{
    MyQt3D* pView = new MyQt3D();
    delete pView;
}

At the beginning, the memory usage is 20 MB. After the for loop, the memory usage is 80 MB.

The source code project files can be found in, https://drive.google.com/drive/folders/1r8ZPaJVBOlYKywm7K-Se0J0ylQjbJILY?usp=sharing

How to sovle the memory leak problem? Thank you.

Upvotes: 1

Views: 588

Answers (1)

yunlong wang
yunlong wang

Reputation: 11

Thank you all. With your help, the memory leak problem is solved.

I did a little experiment by using the example code from Qt3D, "BasicShape", which will display a window, as shown below, The running window of the project

I did a little modification of the project. That is, I add the following code,

for(int i=0;i<1000;i++)
{
    Qt3DCore::QEntity *TempRootEntity = new Qt3DCore::QEntity();
    SceneModifier *modifier = new SceneModifier(TempRootEntity);
    delete modifier;
    delete TempRootEntity;
    qDebug()<<"delet!!!"<<i<< "\n";
}

before

SceneModifier *modifier = new SceneModifier(rootEntity);

Then, run this progam. You can find that there is now memory leak, even though we have done the for loop for 1000 times. The key point is

delete TempRootEntity;

because all the entities in SceneModifier is the children of TempRootEntity. Only delete modifier is not enough!

Upvotes: 0

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