Unsolved Need Advice using QML DataVisualisation or QML QpaintedItem ? .. or not QML ...

[Lo Public Name]

Hello all

I would need some advice on witch technologies to use.

I need to visualize 2D points ( captured real time form laser scanning ) , make to create/edit selections over those points as poly Lines . I will need also to Zoom / pan in the view to edit selection properly.

I was thinking to use DATAVISUALISATION Scatter3D and orthographic projection to switch back to 2D .
This way i could benefit from all the pan/rotate/ zoom inbuilt handling of the scene3D . But i see no clue in documentation how to draw polyLine in the scene . Neither to individually change point color

The other way would be to use QPaintedItem, but i would need to write a lot of stuff from scratch ...

Any advices ?
Thanks

[oria66]

@Lo-Public-Name i. I had struggled in your position in the past. First, take a look at these articles:

• https://forum.qt.io/topic/111022/pixel-framebuffer-data-in-c-to-qml-application-using-the-gpu-as-much-as-possible.
• https://tobiasmarciszko.github.io/custom-drawing-in-qml/t

From my point of view, do not take the path of Scatter 3D if your point cloud is big. My recommendation is to use a QQuickItem (with the Scenegraph, of course) with a mature implementation like https://github.com/QUItCoding/qnanopainter.

Believe me, I implemented an application like yours (3mill ~ 7 mill of points in a 2D picture) with QQuickPaintedItem from scratch and the performance was awful unlike the QNanopainter approach (QQuickItem).

If you have any other doubts let me know.

[Lo Public Name]

Thanks, i will check.