Before QT5 Qt3D was a separate project and was maintained separately. Now it is offered along with other official plugins.
QT3D supports the addition of 3D elements. In order to install it this is needed:
Clone the git Qt3D repository
$ git clone git://gitorious.org/qt/qt3d.git
Using the Qmake that you already created when installing Qt5, this will setup the Makefile in order to cross compile the plugin.
$ qmake
$ make
$ sudo make install
Ready to play with Qt3D!
This is the HelloWorld of 3D, teapot.bez is a bezier curves file with the forms of the famous teapot.
import QtQuick 2.0
import Qt3D 1.0
Viewport{
width: 640; height: 480
Item3D{
id: teapot
mesh: Mesh { source: "teapot.bez" }
effect: Effect {}
}
}