Rotating the object from the center point

[saklanmazozgur]

Hi,

I can view a 3D object as follows. I want to rotate this object according to certain values, but the object is not rotating from its center point. Object rotates through corner points.

I need to use the RotateAt command instead of the rotate command, but I could not find how to determine the object's center point. Thanks for the information.

`

   private const string MODEL_PATH = "C:\\Users\\SAYKAL-12\\Desktop\\dice.stl";
    
    public MainWindow()
    {
        InitializeComponent();

        ModelVisual3D device3D = new ModelVisual3D();
        device3D.Content = Display3d(MODEL_PATH);
        viewPort3d.Children.Add(device3D);

        var axis = new Vector3D(0, 0, 1);
        var angle = 50;

        var matrix = device3D.Transform.Value;
        matrix.Rotate(new Quaternion(axis, angle));

        device3D.Transform = new MatrixTransform3D(matrix);
    }


    private Model3D Display3d(string model)
    {
        Model3D device = null;
        try
        {
            viewPort3d.RotateGesture = new MouseGesture(MouseAction.LeftClick);

            ModelImporter import = new ModelImporter();

            device = import.Load(model);
        }
        catch (Exception e)
        {
            MessageBox.Show("Exception Error : " + e.StackTrace);
        }
        return device;
    }

`

xaml Code

<helix:HelixViewport3D x:Name="viewPort3d" ZoomExtentsWhenLoaded="true" Margin="0,0,0,66" Cursor="Hand" ShowViewCube="True"> <!-- Remember to add light to the scene --> <helix:SunLight/> </helix:HelixViewport3D>

[holance]

You need to calculate the center point yourself by calculating the center point of the geometry vertices loaded from your model.

[saklanmazozgur]

In my question is a clue of how to find the center point. The uploaded file type is .stl. How can I find the center point of this file with helixtoolkit?

[ju2pom]

I did it in my own project by finding the bounding sphere. If you have a geometry made of several parts you'll need to find the bounding sphere of two spheres. Here is my code that does it:

    private static SharpDX.BoundingSphere Merge(SharpDX.BoundingSphere s1, SharpDX.BoundingSphere s2)
    {
      if (s1.Radius == 0f)
      {
        return s2;
      }

      if (s2.Radius == 0f)
      {
        return s1;
      }

      var s1s2 = s1.Center - s2.Center;
      var distance = s1s2.Length();
      // Co-centric sphere => return biggest one
      if (distance == 0f)
      {
        return s1.Radius > s2.Radius ? s1 : s2;
      }
      // One sphere is fully contained into the other one
      if (distance <= Math.Abs(s1.Radius - s2.Radius))
      {
        return s1.Radius > s2.Radius ? s1 : s2;
      }

      var unit = s1s2.Normalized();
      var point1 = s1.Center + s1.Radius * unit;
      var point2 = s2.Center - s2.Radius * unit;

      var diameter = point2 - point1;
      var radius = diameter.Length() / 2f;
      var center = point1 + diameter.Normalized() * radius;

      return new SharpDX.BoundingSphere(center, radius);
    }

[yziyacakmak]

You can use Size property of model,

... var x_middle_point =device3D.Content.Bounds.SizeX/2; var y_middle_point= device3D.Content.Bounds.SizeY/2; var z_middle_point= device3D.Content.Bounds.SizeZ/2; Point3D middlePoint=new Point3D(x_middle_point ,y_middle_point, z_middle_point); ...