PySide2 Qt3D mesh does not show up

Question

I'm diving into Qt3D framework and have decided to replicate a simplified version of this c++ example

Unfortunately, I don't see a torus mesh on application start. I've created all required entities and enabled a mesh in SceneModifier class.

What could be a problem with it? I thought that I've had a bad camera implementation, but it seems ok. Same with point light.

import sys
from PySide2 import QtWidgets, QtCore, QtGui
from PySide2.Qt3DCore import Qt3DCore
from PySide2.Qt3DExtras import Qt3DExtras
from PySide2.Qt3DRender import Qt3DRender


class SceneModifier(QtCore.QObject):
    def __init__(self, root_entity=None):
        super().__init__()

        # Scene entity
        self._m_root_entity = Qt3DCore.QEntity(root_entity)

        # Torus shape data
        self.m_torus = Qt3DExtras.QTorusMesh()
        self.m_torus.setRadius(1.0)
        self.m_torus.setMinorRadius(0.4)
        self.m_torus.setRings(100)
        self.m_torus.setSlices(20)

        # Torus transform
        torus_transform = Qt3DCore.QTransform()
        torus_transform.setScale(2.0)
        torus_transform.setRotation(QtGui.QQuaternion.fromAxisAndAngle(QtGui.QVector3D(0.0, 0.1, 0.0), 25.0))
        torus_transform.setTranslation(QtGui.QVector3D(0.0, 0.0, 0.0))

        # Torus material
        torus_mat = Qt3DExtras.QPhongMaterial()
        torus_mat.setDiffuse(QtGui.QColor(255, 102, 0))

        # Torus mesh
        self.m_torus_entity = Qt3DCore.QEntity(self._m_root_entity)
        self.m_torus_entity.addComponent(self.m_torus)
        self.m_torus_entity.addComponent(torus_mat)
        self.m_torus_entity.addComponent(torus_transform)

        self.m_torus_entity.setEnabled(True)


if __name__ == '__main__':
    app = QtWidgets.QApplication(sys.argv)

    view = Qt3DExtras.Qt3DWindow()
    view.defaultFrameGraph().setClearColor(QtGui.QColor(89, 89, 89))

    container = QtWidgets.QWidget.createWindowContainer(view)
    screen_size = QtCore.QSize(view.screen().size())
    container.setMinimumSize(QtCore.QSize(720, 680))
    container.setMaximumSize(QtCore.QSize(screen_size))

    root_entity = Qt3DCore.QEntity()

    camera_entity = Qt3DRender.QCamera(view.camera())
    camera_entity.lens().setPerspectiveProjection(45.0, 16.0/9.0, 0.1, 1000.0)
    camera_entity.setPosition(QtGui.QVector3D(0, 0, 20.0))
    camera_entity.setUpVector(QtGui.QVector3D(0, 1, 0))
    camera_entity.setViewCenter(QtGui.QVector3D(0, 0, 0))

    light_entity = Qt3DCore.QEntity(root_entity)
    point_light = Qt3DRender.QPointLight(light_entity)
    point_light.setColor("white")
    point_light.setIntensity(1)
    light_entity.addComponent(point_light)
    light_transform = Qt3DCore.QTransform(light_entity)
    light_transform.setTranslation(camera_entity.position())
    light_entity.addComponent(light_transform)

    cam_control = Qt3DExtras.QFirstPersonCameraController(root_entity)
    cam_control.setCamera(camera_entity)

    modifier = SceneModifier(root_entity=root_entity)

    view.setRootEntity(root_entity)

    widget = QtWidgets.QWidget()
    h_layout = QtWidgets.QHBoxLayout()
    h_layout.addWidget(container)
    widget.setLayout(h_layout)

    widget.show()

    sys.exit(app.exec_())

Answer 1

I have implemented the translation of example Qt 3D: Basic Shapes C++ Example into PySide2:

import sys
from PySide2 import QtWidgets, QtCore, QtGui
from PySide2.Qt3DCore import Qt3DCore
from PySide2.Qt3DExtras import Qt3DExtras
from PySide2.Qt3DRender import Qt3DRender
from PySide2.Qt3DInput import Qt3DInput


class SceneModifier(QtCore.QObject):
    def __init__(self, root_entity=None):
        super().__init__()
        self.m_rootEntity = root_entity

        self.m_torus = Qt3DExtras.QTorusMesh(
            radius=1.0, minorRadius=0.4, rings=100, slices=20
        )

        self.torusTransform = Qt3DCore.QTransform(
            scale=2.0,
            rotation=QtGui.QQuaternion.fromAxisAndAngle(
                QtGui.QVector3D(0.0, 1.0, 0.0), 25.0
            ),
            translation=QtGui.QVector3D(5.0, 4.0, 0.0),
        )

        self.torusMaterial = Qt3DExtras.QPhongMaterial(diffuse=QtGui.QColor("#beb32b"))

        self.m_torusEntity = Qt3DCore.QEntity(self.m_rootEntity)
        self.m_torusEntity.addComponent(self.m_torus)
        self.m_torusEntity.addComponent(self.torusMaterial)
        self.m_torusEntity.addComponent(self.torusTransform)

        self.cone = Qt3DExtras.QConeMesh(
            topRadius=0.5, bottomRadius=1, length=3, rings=50, slices=20
        )

        self.coneTransform = Qt3DCore.QTransform(
            scale=1.5,
            rotation=QtGui.QQuaternion.fromAxisAndAngle(
                QtGui.QVector3D(1.0, 4.0, -1.5), 45.0
            ),
            translation=QtGui.QVector3D(0.0, 4.0, -1.5),
        )

        self.coneMaterial = Qt3DExtras.QPhongMaterial(diffuse=QtGui.QColor("#928327"))

        self.m_coneEntity = Qt3DCore.QEntity(self.m_rootEntity)
        self.m_coneEntity.addComponent(self.cone)
        self.m_coneEntity.addComponent(self.coneMaterial)
        self.m_coneEntity.addComponent(self.coneTransform)

        self.cylinder = Qt3DExtras.QCylinderMesh(
            radius=1, length=3, rings=100, slices=20
        )

        self.cylinderTransform = Qt3DCore.QTransform(
            scale=1.5,
            rotation=QtGui.QQuaternion.fromAxisAndAngle(
                QtGui.QVector3D(1.0, 0.0, 0.0), 45.0
            ),
            translation=QtGui.QVector3D(-5.0, 4.0, -1.5),
        )

        self.cylinderMaterial = Qt3DExtras.QPhongMaterial(
            diffuse=QtGui.QColor("#928327")
        )

        self.m_cylinderEntity = Qt3DCore.QEntity(self.m_rootEntity)
        self.m_cylinderEntity.addComponent(self.cylinder)
        self.m_cylinderEntity.addComponent(self.cylinderMaterial)
        self.m_cylinderEntity.addComponent(self.cylinderTransform)

        self.cuboid = Qt3DExtras.QCuboidMesh()

        self.cuboidTransform = Qt3DCore.QTransform(
            scale=4.0, translation=QtGui.QVector3D(5.0, -4.0, 0.0),
        )

        self.cuboidMaterial = Qt3DExtras.QPhongMaterial(diffuse=QtGui.QColor("#665423"))

        self.m_cuboidEntity = Qt3DCore.QEntity(self.m_rootEntity)
        self.m_cuboidEntity.addComponent(self.cuboid)
        self.m_cuboidEntity.addComponent(self.cuboidMaterial)
        self.m_cuboidEntity.addComponent(self.cuboidTransform)

        self.planeMesh = Qt3DExtras.QPlaneMesh(width=2, height=2)

        self.planeTransform = Qt3DCore.QTransform(
            scale=1.3,
            rotation=QtGui.QQuaternion.fromAxisAndAngle(
                QtGui.QVector3D(1.0, 0.0, 0.0), 45.0
            ),
            translation=QtGui.QVector3D(0.0, -4.0, 0.0),
        )

        self.planeMaterial = Qt3DExtras.QPhongMaterial(diffuse=QtGui.QColor("#a69929"))

        self.m_planeEntity = Qt3DCore.QEntity(self.m_rootEntity)
        self.m_planeEntity.addComponent(self.planeMesh)
        self.m_planeEntity.addComponent(self.planeMaterial)
        self.m_planeEntity.addComponent(self.planeTransform)

        self.sphereMesh = Qt3DExtras.QSphereMesh(rings=20, slices=20, radius=2)

        self.sphereTransform = Qt3DCore.QTransform(
            scale=1.3, translation=QtGui.QVector3D(-5.0, -4.0, 0.0),
        )

        self.sphereMaterial = Qt3DExtras.QPhongMaterial(diffuse=QtGui.QColor("#a69929"))

        self.m_sphereEntity = Qt3DCore.QEntity(self.m_rootEntity)
        self.m_sphereEntity.addComponent(self.sphereMesh)
        self.m_sphereEntity.addComponent(self.sphereMaterial)
        self.m_sphereEntity.addComponent(self.sphereTransform)

    @QtCore.Slot(bool)
    def enableTorus(self, enabled):
        self.m_torusEntity.setEnabled(enabled)

    @QtCore.Slot(bool)
    def enableCone(self, enabled):
        self.m_coneEntity.setEnabled(enabled)

    @QtCore.Slot(bool)
    def enableCylinder(self, enabled):
        self.m_cylinderEntity.setEnabled(enabled)

    @QtCore.Slot(bool)
    def enableCuboid(self, enabled):
        self.m_cuboidEntity.setEnabled(enabled)

    @QtCore.Slot(bool)
    def enablePlane(self, enabled):
        self.m_planeEntity.setEnabled(enabled)

    @QtCore.Slot(bool)
    def enableSphere(self, enabled):
        self.m_sphereEntity.setEnabled(enabled)


if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)

    view = Qt3DExtras.Qt3DWindow()
    view.defaultFrameGraph().setClearColor(QtGui.QColor("#4d4d4f"))
    container = QtWidgets.QWidget.createWindowContainer(view)
    screenSize = view.screen().size()
    container.setMinimumSize(QtCore.QSize(200, 100))
    container.setMaximumSize(screenSize)

    widget = QtWidgets.QWidget()
    hLayout = QtWidgets.QHBoxLayout(widget)
    vLayout = QtWidgets.QVBoxLayout()
    vLayout.setAlignment(QtCore.Qt.AlignTop)
    hLayout.addWidget(container, 1)
    hLayout.addLayout(vLayout)

    widget.setWindowTitle("Basic shapes")

    input_ = Qt3DInput.QInputAspect()
    view.registerAspect(input_)

    rootEntity = Qt3DCore.QEntity()

    cameraEntity = view.camera()

    cameraEntity.lens().setPerspectiveProjection(45.0, 16.0 / 9.0, 0.1, 1000.0)
    cameraEntity.setPosition(QtGui.QVector3D(0, 0, 20.0))
    cameraEntity.setUpVector(QtGui.QVector3D(0, 1, 0))
    cameraEntity.setViewCenter(QtGui.QVector3D(0, 0, 0))

    lightEntity = Qt3DCore.QEntity(rootEntity)
    light = Qt3DRender.QPointLight(lightEntity)
    light.setColor("white")
    light.setIntensity(1)
    lightEntity.addComponent(light)

    lightTransform = Qt3DCore.QTransform(lightEntity)
    lightTransform.setTranslation(cameraEntity.position())
    lightEntity.addComponent(lightTransform)

    camController = Qt3DExtras.QFirstPersonCameraController(rootEntity)
    camController.setCamera(cameraEntity)

    modifier = SceneModifier(rootEntity)

    view.setRootEntity(rootEntity)

    info = QtWidgets.QCommandLinkButton()
    info.setText("Qt3D ready-made meshes")
    info.setDescription(
        "Qt3D provides several ready-made meshes, like torus, cylinder, cone, cube, plane and sphere."
    )
    info.setIconSize(QtCore.QSize(0, 0))

    torusCB = QtWidgets.QCheckBox(widget)
    torusCB.setChecked(True)
    torusCB.setText("Torus")

    coneCB = QtWidgets.QCheckBox(widget)
    coneCB.setChecked(True)
    coneCB.setText("Cone")

    cylinderCB = QtWidgets.QCheckBox(widget)
    cylinderCB.setChecked(True)
    cylinderCB.setText("Cylinder")

    cuboidCB = QtWidgets.QCheckBox(widget)
    cuboidCB.setChecked(True)
    cuboidCB.setText("Cuboid")

    planeCB = QtWidgets.QCheckBox(widget)
    planeCB.setChecked(True)
    planeCB.setText("Plane")

    sphereCB = QtWidgets.QCheckBox(widget)
    sphereCB.setChecked(True)
    sphereCB.setText("Sphere")

    vLayout.addWidget(info)
    vLayout.addWidget(torusCB)
    vLayout.addWidget(coneCB)
    vLayout.addWidget(cylinderCB)
    vLayout.addWidget(cuboidCB)
    vLayout.addWidget(planeCB)
    vLayout.addWidget(sphereCB)

    torusCB.stateChanged.connect(modifier.enableTorus)
    coneCB.stateChanged.connect(modifier.enableCone)
    cylinderCB.stateChanged.connect(modifier.enableCylinder)
    cuboidCB.stateChanged.connect(modifier.enableCuboid)
    planeCB.stateChanged.connect(modifier.enablePlane)
    sphereCB.stateChanged.connect(modifier.enableSphere)

    torusCB.setChecked(True)
    coneCB.setChecked(True)
    cylinderCB.setChecked(True)
    cuboidCB.setChecked(True)
    planeCB.setChecked(True)
    sphereCB.setChecked(True)

    widget.show()
    widget.resize(1200, 800)

    sys.exit(app.exec_())