Rotate and translate an object

Question

I need to rotate and translate an object. I have a problem with that, I can only do one of them. I use this code:

RotateTransform3D myRotate = new RotateTransform3D(new AxisAngleRotation3D(new Vector3D(0, 0, 1), Convert.ToDouble(180)), new Point3D(0, 0, 0));
TranslateTransform3D myTranslate = new TranslateTransform3D(0, 0, 100);
ModelVisual3D device3D2 = new ModelVisual3D();
device3D2.Content = Display3d(MODEL_PATH2);
device3D2.Transform = myRotate;
device3D2.Transform = myTranslate;
viewPort3d.Children.Add(device3D2);

The problem is that it only does the last transform. I mean, if I apply "myRotate" the second one, it rotates the object, but it doesn't apply the "myTranslate" operation. I need to do both transforms.

I am using HelixToolkit too.

I don't know anything about that framework, but it's clear the problem is that you are setting the `Transform` property, and then changing it. So by the time it comes to be used (via the viewport) then only the last one is used. There must be a way to either *combine* transform object, or create a collection. — musefan, Oct 20 '15 at 14:58
yes, you are correct, thanks! but... any ideas how to improve that? :) — Imrik, Oct 20 '15 at 15:01
Had a quick look, but couldn't see anything obvious. Personally I would probably play with Intellisense and look for classes/methods that look like they might help, then try them — musefan, Oct 20 '15 at 15:04

score 1 · Answer 1 · answered Oct 20 '15 at 15:23

1

You have to mess with the Transform fields directly, instead of replacing the entire Transform, i.e. transform.position, transform.rotation, transform.localPosition, transform.localEulerAngles, transform.scale, transform.localScale, etc.

device3D2.Transform.rotation *= new Quaternion.AngleAxis(180f, new Vector3(0f, 0f, 1f));
device3D2.Transform.Translate(0, 0, 100);

answered Oct 20 '15 at 15:23

maraaaaaaaa

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device3D2.Transform.rotation is not accessible for me. – Ivan P. Jan 14 '21 at 13:13

score 1 · Answer 2 · answered Nov 07 '15 at 17:34

You need to use a Transform3DGroup object. You then add the different transformations to it:

Transform3DGroup  myTransformer = new Transform3DGroup;  
RotateTransform3D myRotate = new RotateTransform3D(new AxisAngleRotation3D    (new Vector3D(0, 0, 1), Convert.ToDouble(180)), new Point3D(0, 0, 0));
TranslateTransform3D myTranslate = new TranslateTransform3D(0, 0, 100);
myTransformer.Children.Add(myRotate);
myTransformer.Children.Add(myTranslate);
ModelVisual3D device3D2 = new ModelVisual3D();
device3D2.Content = Display3d(MODEL_PATH2);
device3D2.Transform = myTransformer;
viewPort3d.Children.Add(device3D2);

Pay attention to the sequence in which you add the individual transformers.

What if there are multiple transforms? Or if transform is controlled from keyboard by user and there will be a ton of objects sitting in collection — Ivan P., Jan 14 '21 at 09:24

score 0 · Answer 3 · answered Jan 14 '21 at 13:12

I am using HelixToolkit as well.

Here I create model and translate it on scene:

            ModelVisual3D mdl = new ModelVisual3D();
            mdl.Content = getModel3D();
            if ((thecurrentBox.upperLeft.X != 0)||(thecurrentBox.bottomRight.Y!=0))  {
                Matrix3D mm = mdl.Transform.Value;
                mm.Translate(new Vector3D(-thecurrentBox.upperLeft.X, 0, -thecurrentBox.bottomRight.Y));
// you can do even more transformations here. 
//you can make mm as private field and transform it whenever you like
                mdl.Transform = new MatrixTransform3D(mm);
            }
// add mdl to Children of scene

I get a current value of transformation matrix, do ops on it then set up a transform on ModelVisual3D instance. Here is link to another example: https://github.com/wolfoerster/WFTools3D/blob/50cc33f9f9929d4651d0855c386d38e6861382b2/WFTools3D/Basics/Object3D.cs#L142

Rotate and translate an object

3 Answers3