Qt 3D: Basic Shapes C++ Example

Basic Shapes shows four basic shapes that Qt 3D offers: a torus, a cylinder, a cube, and a sphere. The example also shows how to embed a Qt 3D scene into a widget and connect with other widgets.

Running the Example

You can run the example from:

• Qt Creator

  Open the Welcome mode and select the example from Examples. For more information, see Qt Creator: Tutorial: Build and run.

• Qt Extension for Visual Studio Code

  Run the Qt: Open Qt examples command from the Command Palette, and select the example from the list. For more information, see Qt Extension for Visual Studio Code: Tutorial: Build and run.

Setting Up a Torus Mesh

As an example, we go through how to set up a torus mesh. First, we instantiate the QTorusMesh, and then we set the mesh specific parameters, which for torus are radius, minor radius, and the number of rings and slices.

 m_torus = new Qt3DExtras::QTorusMesh();
 m_torus->setRadius(1.0f);
 m_torus->setMinorRadius(0.4f);
 m_torus->setRings(100);
 m_torus->setSlices(20);

The size and position of the torus can be adjusted with transform components. We create scale, translation, and rotation components and add them into the QTransform component.

 Qt3DCore::QTransform *torusTransform = new Qt3DCore::QTransform();
 torusTransform->setScale(2.0f);
 torusTransform->setRotation(QQuaternion::fromAxisAndAngle(QVector3D(0.0f, 1.0f, 0.0f), 25.0f));
 torusTransform->setTranslation(QVector3D(5.0f, 4.0f, 0.0f));

To change the diffuse color of the mesh, we create a QPhongMaterial and set its diffuse color.

 Qt3DExtras::QPhongMaterial *torusMaterial = new Qt3DExtras::QPhongMaterial();
 torusMaterial->setDiffuse(QColor(QRgb(0xbeb32b)));

The final step is to add the torus into an entity tree, and we do that by creating a QEntity with a parent entity and adding the previously created mesh, material, and transform components into it.

 m_torusEntity = new Qt3DCore::QEntity(m_rootEntity);
 m_torusEntity->addComponent(m_torus);
 m_torusEntity->addComponent(torusMaterial);
 m_torusEntity->addComponent(torusTransform);

We can control the visibility of the entity by defining whether it has a parent or not. That is, whether it is part of an entity tree or not.

 void SceneModifier::enableTorus(bool enabled)
 {
     m_torusEntity->setEnabled(enabled);
 }

Example project @ code.qt.io