[Interest] Few questions regarding Qt Quick Scene Graph

Artem Fedoskin afedoskin3 at gmail.com
Sun Apr 24 16:41:55 CEST 2016

Hello everybody. I have a project where a lot of objects are painted on the
screen whenever the user interacts with the app (pan, zoom, move) I would
be really grateful to you if you could answer a few questions regarding the
internals of Qt Quick Scene Graph:

   1. Imagine that I add 1000 nodes with the same color inside
   QQuickItem::updatePaintNode() function of some QQuickItem derived class.
   Will they be drawn in batch as described in
   2. Can I call the function of some other class in
   QQuickItem::updatePaintNode()? I have some class named Data, class named
   View and a subclass of QSGGeometryNode Triangle. Imagine that after objects
   of these classes are created the Data asks View to create 10 Triangles. The
   View creates 10 Triangles during the updatePaintNode() call and passes
   pointers to the object of class Data, that required their instantiation.
   The Triangles refers to the Data and get coordinates from it. Is it
   something possible. Do I violate the rule stated here *"Warning:* It is
   crucial that OpenGL operations and interaction with the scene graph happens
   exclusively on the render thread, primarily during the updatePaintNode()
   call. The rule of thumb is to only use classes with the "QSG" prefix inside
   the QQuickItem::updatePaintNode
   <http://doc.qt.io/qt-5/qquickitem.html#updatePaintNode>() function."
   6. For example, I want to get new coordinates of the object and to do
   that I should refer to function of some other not QSGNode derived object
   and then use these coordinates for rendering one of the nodes.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.qt-project.org/pipermail/interest/attachments/20160424/b69da7f0/attachment.html>

More information about the Interest mailing list