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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 http://doc.qt.io/qt-5/qtquick- visualcanvas-scenegraph-renderer.html#batching <http://doc.qt.io/qt-5/qtquick-visualcanvas-scenegraph-renderer.html#batching> ? 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 to them pointers to the object of class Data, that required their instantiation. The Triangles refers to the Data and get some values from it and converts them to x,y coordinates. Is it something possible? Do I violate the rule stated here http://doc.qt.io/qt-5/qtquick-visualcanvas -scenegraph.html#scene-graph-and-rendering *"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." ? At first I was thinking about deriving classes like Triangle from QQuickItem and then reparenting them to the View but the direct creation of QSGGeometryNodes seems to me to be less memory requiring approach. Regards, Artem Fedoskin 2016-04-24 16:41 GMT+02:00 Artem Fedoskin <afedosk...@gmail.com>: > 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 > > http://doc.qt.io/qt-5/qtquick-visualcanvas-scenegraph-renderer.html#batching > > <http://doc.qt.io/qt-5/qtquick-visualcanvas-scenegraph-renderer.html#batching> > ? > 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." > 3. > 4. > 5. > 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. > >
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