Using GrabAngle to detect grab (with Orion SDK)

[Martichoras]

Hi,

I am currently trying out the Orion SDK for a University VR-project (grabbing objects and manipulating orientation in a virtual supermarket).

The documentation seems to suggest, that you can access the method by Hand(GrabAngle), but I can't seem to make it work with the below code. I also tried 'float grabAngle = Leap.Hand.GrabAngle;'.

Do you have any suggestions to what I am doing wrong?

using UnityEngine;
using System.Collections.Generic;
using Leap;

public class LeapTest : MonoBehaviour {

	void Start ()
	{
		Controller controller = new Controller ();
		Frame frame = controller.Frame (); 	

		if(frame.Hands.Count > 0){
			List<Hand> hands = frame.Hands;
			Hand firstHand = hands [0];
			//Hand secondHand = hands [1];
		}
	}

	void Update ()
	{
		float grabAngle = firstHand(GrabAngle);
		if (grabAngle < 1.0) { // between 0.0 and 3.1415...etc ??
			print("Grab detected!");
		}
	}
}

[Joe_Ward]

There are a few problems with that script.

1. Start() is run once, when a game object is created. Since hands come and go, you want to get a new hand every update, not just once at the beginning. Move everything except the new Controller() statement to Update().

2. In Start(), you declare controller as a local variable so it will only exist until Start() is finished. Move the declaration outside so it is a class variable and just set it in the method:

   Controller controller;
   void Start(){
   controller = new Controller();
   }

3. If you are using our assets, you usually want to get the Frame data from LeapServiceProvider using CurrentFrame, not directly from the Controller. The data from the LeapServiceProvider is already transformed into the Unity coordinate system; data directly from the controller is still in the Leap Motion coordinate system.

4. The proper way to access the angle is Leap.Hand.GrabAngle. The statement firstHand(GrabAngle) shouldn't even compile.

5. A GrabAngle of 0 means the hand is open. 3.14... radians (180 degrees means the hand is fully closed or grabbing.
   

[Martichoras]

Thanks for the reply, and what you're suggesting makes sense. However, I can't seem to find any documentation on CurrentFrame only currentFramesPerSecond(). How would I use Leap.Hand.GrabAngle with the LeapServiceProvider? (a short snippet would be appreciated).

I have also played a bit around with the pinch utility, but has encountered a problem when LeapRTS-script is applied to more than one object. both objects rotate around the Leap Pinch Detector origin. Is there a way to instantiate this per object?

[Death111]

Like that

public class Test{
    private LeapServiceProvider provider;
    
    // Use this for initialization
    private void Start()
    {
        provider = FindObjectOfType<LeapServiceProvider>();
    }
    private void Update()
    {
        Frame currentFrame = provider.CurrentFrame;
        foreach (Hand hand in currentFrame.Hands)
        {
            Debug.Log("Hand with id '" + hand.Id + "' has an grabAngle of '" + hand.GrabAngle + "'.");
        }
    }
}

[jhamman]

Thanks @Death111 ! - just a small correction, in the start function, controller should be replaced with provider variable.

[Death111]

Ah yes. Did forget it there yep. I changed it.

[Martichoras]

Thanks a bunch @Death111 and @Joe_Ward !

[meetshah7296]

Can you share your code with me? or can you help me to figure out how I can use Pinch Detector script which is given in core assets? They provided us the script but I don't know on which object should I attach the script.
Thank you in advance!