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Forum Update on Monday, May 27th 2025

Show a 3d point cloud with shaders

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  • oria66O Offline
    oria66O Offline
    oria66
    wrote on last edited by
    #1

    Hello!! I'm trying to show a point cloud in my QML app. I try to use a Scatter3D but the point size it's too large, and the change the color for every point it's kind of very complicated and slow performance. Besides, apps like Cloud Compare don't use Scatter3D or something like that. I checked the Qml Cadaques Chapter about shaders but without achieving anything.

    The problem this:

    1. I check the Qt examples but the lack of documentation plays against the community.
    2. How is the structure of this kind of use in Qt3D in order to use the vertex shaders and the fragment shaders for this application?
    3. Can you provide a simple example?

    Thank you in advance!

    The truth is out there

    DiracsbracketD 1 Reply Last reply
    0
    • oria66O oria66

      Hello!! I'm trying to show a point cloud in my QML app. I try to use a Scatter3D but the point size it's too large, and the change the color for every point it's kind of very complicated and slow performance. Besides, apps like Cloud Compare don't use Scatter3D or something like that. I checked the Qml Cadaques Chapter about shaders but without achieving anything.

      The problem this:

      1. I check the Qt examples but the lack of documentation plays against the community.
      2. How is the structure of this kind of use in Qt3D in order to use the vertex shaders and the fragment shaders for this application?
      3. Can you provide a simple example?

      Thank you in advance!

      DiracsbracketD Offline
      DiracsbracketD Offline
      Diracsbracket
      wrote on last edited by Diracsbracket
      #2

      @oria66 said in Show a 3d point cloud with shaders:

      apps like Cloud Compare don't use Scatter3D or something like that

      I've just downloaded and built Cloud Compare on my Win10, VS2017 and Qt5.11 system for Win64, and it was a breeze. Since its base is completely self-contained (if you include Qt that is), open and based on Qt/OpenGL, can't you have a look at the source code and follow the same approach? Of course, I know that it is easier said than done...

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      • oria66O Offline
        oria66O Offline
        oria66
        wrote on last edited by
        #3

        @Diracsbracket thank you for sharing your approach. I will try. If I achieve something I will post it here. It's kind of confusing this part when you try to learn Qt deeply.

        Again, if anyone knows how to do it in a simple way. Please, I will like to hear your solution.

        The truth is out there

        1 Reply Last reply
        0
        • oria66O Offline
          oria66O Offline
          oria66
          wrote on last edited by
          #4

          Well 3 years later. With the new Qt Quick 3D module is pretty easy to show a 3D point cloud "without" shaders.

          The truth is out there

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          • D Offline
            D Offline
            djdan
            wrote on last edited by
            #5

            Hi! Could you describe how you did it? I cannot use "points" custom geometry, due to small size of points (and cannot change their size because there are some Direct3D limitations, as stated in docs: https://doc.qt.io/qt-6/qml-qtquick3d-defaultmaterial.html#pointSize-prop )

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