C++ Qt3DExtras::QTorusMesh – cannot be rotated in Z direction

[JulianM]

Hello Everyone,
It could be me, but I tried to make very quickly Rotation Gizmo in C++ Qt3D – and I noticed that there is a problem with QTorusMesh – rotation in Z.
I thought is something wrong in my fast code – but even when I tried Torus in basic shapes demo – also doesn’t work. Here is an example code

// Torus shape data
    //! [0]
    m_torus = new Qt3DExtras::QTorusMesh();
    m_torus->setRadius(1.0f);
    m_torus->setMinorRadius(0.4f);
    m_torus->setRings(100);
    m_torus->setSlices(20);
    //! [0]

    // TorusMesh Transform
    //! [1]
    Qt3DCore::QTransform *torusTransform = new Qt3DCore::QTransform();
    torusTransform->setScale(2.0f);
    torusTransform->setRotation(QQuaternion::fromAxisAndAngle(QVector3D(0.0f, 1.0f, 0.0f), 90.0f));
	torusTransform->setRotationZ(45.0f);
    torusTransform->setTranslation(QVector3D(5.0f, 4.0f, 0.0f));

I added only ….. torusTransform->setRotationZ(45.0f);
I expected this to be rotated in 90 around Y and then 45 around Z.
So the result should be something like that / I cannot upload picture here/

  -                                          -
  -   -        in fact is only  90 deg       -     
      -                                      -

[SGaist]

Hi,

You should also add what version of Qt you are using.
And the platform as well.

[JulianM]

Hi SGaist,

Sorry about that.
I'm using 5.12 on Windows 10.

My concern is that this looks like there is a problem in Qt3DCore::QTransform which is core module from a long time / 5.5 or earlier/.
I was away of Qt for the last few years but before I love it - was solid as rock - now ... there are obvious small bugs even in the demos.
Documentation is close to nothing ... really sad.

BTW Just to update for information - i made custom entity Circle and attached to it - Qt3DCore::QTransform and I got the same result - does't work - that's why I got suspicious in QTransform . I looked in the the code - some eigen vector comprising is "fishy" - but i went in another direction - using directly Matrices and now works- but then QTransform looks useless - and nobody to not catch it till now- means nobody use it? Probably because of the priority of QML.

[JohanSolo]

Might it be your 45° rotation is performed around the torus symmetry axis?

[JulianM]

@JohanSolo said in C++ Qt3DExtras::QTorusMesh – cannot be rotated in Z direction:

torus symmetry axis

I don't think so.
As I mentioned I made rotation Gizmo as 3D modeling software for rotation - so I have 3 "donuts" - one facing X; one facing Y and one facing Z;
For this one that is facing Z - it will be clear that even rotation to happen it will not be visible for the viewer in Z direction.
That is probably your point if I can get you correctly.
Anyway my problem were the other two / facing X and Y/ when i rotate them in Z - QTransform attached to this Entity report rotationZ - number but there is not rotation of the particular torus.
Any rotation of a torus in Z refuse to happen.

[JulianM]

Ok I found what is causing that - the torus is created facing Z.

Thanks.