旋转和平移对象

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.

Answer 1

You have to mess with the Transform fields directly, instead of replacing the entire Transform , ie 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);

Answer 2

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.

Answer 3

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