What is difference Qt.matrix4x4 and QMatrix4x4? - qt

Question

I am learning the Qt 3D module. I found the Qt.matrix4x4 provide different API than QMatrix4x4 in C++ side (by using F1 check the API doc).
look likes Qt.matrix4x4 don't have such scale or rotation operations. even not in autocomplete.
BUT! these functions do exist and work!
var m = Qt.matrix4x4(1, 0, 0, -0.5, 0, 1, 0, 0, 0, 0, 1, 0.5, 0, 0, 0, 1)
m.scale(2)
console.log(m)
// qml: QMatrix4x4(2, 0, 0, -0.5, 0, 2, 0, 0, 0, 0, 2, 0.5, 0, 0, 0, 1)
// the type shows QMatrix4x4
https://doc.qt.io/qt-5/qmatrix4x4.html vs https://doc.qt.io/qt-5/qml-matrix4x4.html
I understand what these is, But why the API show different in API doc and autocomplete?

Answer 1

It is interesting to note that in Qt6 the documentation appears different than Qt5. In Qt6 we see clearly there are methods for constructing the matrix4x4 basic type from a vector and for multiplying them with vectors.
// translate(vector3d)
var m = Qt.matrix4x4();
m.translate(Qt.vector3d(1,2,3));
console.log(m.toString());
// QMatrix4x4(1, 0, 0, 1, 0, 1, 0, 2, 0, 0, 1, 3, 0, 0, 0, 1)
// matrix multiplication
var m = Qt.matrix4x4();
m.translate(Qt.vector3d(1,2,3));
console.log(m.toString());
// QMatrix4x4(1, 0, 0, 1, 0, 1, 0, 2, 0, 0, 1, 3, 0, 0, 0, 1)
// applying a matrix to a vector
var a = Qt.matrix4x4(1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16);
var b = Qt.vector3d(5,6,7);
var c = a.times(b);
console.log(c.toString()); // QVector3D(0.155556, 0.437037, 0.718518)
Note I tried all of the above in Qt5.15.6 but it doesn't work. So it appears that support for this type really kicks in at Qt6.
For further information see: https://doc.qt.io/qt-6/qml-matrix4x4.html