[Development] Missing features in Quick3D

[Paul Lemire]

Hi,

  I've been working and solving some Qt3D bugs on my own for the past few  
months.
  During that time I've found some important features to be missing. I'm  
talking more specifically
  about the Qml bindings of Qt3D, Quick3D rather than Qt3D itself.

  First of all, being able to render a QQ2 UI on Item3D's meshes would be  
marvellous. I've tried to implement
  this but everytime I take a different approach I end up at the same  
point. It seems to be the topic of this bug QTBUG-19902.

  What I tried to do is to render a QQuickItem in a FBO. This is basically  
what the QQuickShaderEffectSource
  element in QQ2 is doing. Unfortunately it uses a QSGRenderer which is not  
available in the public API. Maybe there
  is another way to do it but I don't see it.

  Having the FBO, it could then easily be used in a QQuickEffect item to be  
mapped on an Item3D's mesh. Moreover, Quick3D
  rendering is done before the QQ2 scenegraph rendering which might be  
another issue as the fbo binded on the mesh would not have  been filled  
yet. There is also a chance mouse coordinates on the QQ2  textured UI  
might not be mapped properly if at all.

  Another missing feature is that there is no way to move an Item3D in  
space. I've played with Qt3D and added a signal onHoverMove available in  
Qml with the corresponding x and y window coordinates of the mouse. As  
there is no way to unproject the mouse coordinates to get the them in  
object space (using gluUnProject or something similar), I once again don't  
see how to do it.

  By the way sorry if this is not the right place to post, I'm quite  
confused between the forum, the bug tracker and the mailing list.

  Good day everyone,

  Paul Lemire