Pinch and rotate around a point using MRTK and Hololens 1

Question

I'm trying to rotate a beam/cuboid around a pivot using MRTK, Unity, and the Hololens 1 when you're doing the pinch and hold gesture. The beam should remain in place once you've let go of the pinch.

My initial thoughts were to get the cartesian coordinates of the pinch and based on their position relative to the pivot, have the beam rotate by however many degrees needed. E.g. the hand position while pinching is (1,1,0), and the pivot position is (0,0,0). Thus, the beam should be rotated at 45 deg in the XY plane (we ignore the z components). I'm not sure how to go about doing this as the documentation seems to indicate that the only way to get the coordinates of the hand/pinch only works for the Hololens 2. (https://microsoft.github.io/MixedRealityToolkit-Unity/Documentation/Input/HandTracking.html#hand-tracking-events & https://microsoft.github.io/MixedRealityToolkit-Unity/api/Microsoft.MixedReality.Toolkit.Input.IMixedRealityHand.html#Microsoft_MixedReality_Toolkit_Input_IMixedRealityHand_TryGetJoint_).

Does anyone know how to go about doing this or at least point me in the right direction (tutorials/code/assets would be much appreciated!)

Thank you!

Answer 1

I'm not sure how to go about doing this as the documentation seems to indicate that the only way to get the coordinates of the hand/pinch only works for the Hololens 2

Yes, HoloLens1 does not support hand tracking, such as touching holograms directly with your hands or pointing and committing with hands. It is recommended that you try to use the interaction model Gaze and commit, so that you can easily get the position of GGVPointer.

Answer 2

Pinch to rotate interaction can be achieved by adding the ManipulationHandler component from MRTK to your cube. The component can be configured to allow two hand manipulation like this.

I'm not sure how to go about doing this as the documentation seems to indicate that the only way to get the coordinates of the hand/pinch only works for the Hololens 2.

There are a few ways to query pointer position. The code below should return the Right GGVPointer position for the hololens.

    Vector3 pos;
    GGVPointer pointer = PointerUtils.GetPointer<GGVPointer>(Handedness.Right);

    if(pointer != null)
    {
        pos = pointer.Position;
    }

Answer 3

In case you just want to rotate the Object around its center,you can use the Boundingbox Component. It creates handles that can be pinched and moved to rotate an object. you can disable the axis you don't want. It works even on the HoloLens 1.