On 3 Apr 2013, at 11:25 AM, Sletta Gunnar wrote: > > On Apr 3, 2013, at 10:51 AM, Dmitrii Volosnykh <[email protected]> > wrote: > >> Hi, Gunnar. >> >> At first glance scenegraph module and Qt3D have similar feature sets. > > Not at all :) > > The scene graph in Qt Quick is a very tiny api, meant to formally structure > OpenGL graphics calls so that we can optimally render a 2D interface with > bling (it supports 3D transformations and geometry, but it doesn't manage 3D > geometry per se). The primary purpose is to allow sorting, reordering of the > GL calls and > > It is meant to be tiny and fast when supporting the usecase of highly > dynamic, lots of small things chaning all the time, with bling and some > light-weight 3D. It will do worse when trying to render something like > google-earth :) > > Qt3D in its current state is more like QGraphicsView. It puts items into a > scene and renders them without any logic to try to improve on the > performance. It does contain a scene graph, but it is purely procedural in > its execution. Sean Harmer posted a mail a while back outlining how he > envisions Qt3D evolving into a proper 3D engine, something which will be > suitable for larger 3D apps. This solves a different usecase from what the > scene graph and will not be suitable for UI rendering, for instance.
What happens when you try to combine the two, are they just in layers? For example I tried to make a piano app as a multi-point touch demo, and found it difficult to make fake semi-3D-looking piano keys. One can rotate a Rectangle in any direction around any axis, so I thought I could have a 90-degree rotated rectangle for the front of the key, and a rotated woodgrain texture for the sides. But when you rotate to 90 degrees, it disappears, even if you then rotate the entire key by a few degrees. I got something a little better by tweaking the angles slightly and tweaking the length heavily, but it didn't scale well. So the ideal might be to render using a 3D model, but every key top should have a MultiPointTouchArea. Or else the 2D scene graph should handle the rotated cases more realistically; is that doable, or is there not much hope because we want to avoid using perspective rendering in typical 2D apps? _______________________________________________ Development mailing list [email protected] http://lists.qt-project.org/mailman/listinfo/development
