Qt3D Qt3DQuick not in Qt5 source

I hear and see stuff about Qt3D and I’d love to check it out… The Qt3D project page says it’s integrated in Qt5, but I cloned the source from git and don’t see it. I see there is a separate git for Qt3D, but it seems to be for Qt4… Where is Qt3D supposed to be in the Qt5 git, and how do I get it? Thanks for help.