Detect whether i am close to rigid body

Questions & Answers
1

I have this DragRigidbody script which picks up rigidbodies, but at any distance. How can i make it pick up the rigidbodies at only a certain distance (when im nearby) Thanks?

var spring = 50.0;
var damper = 5.0;
var drag = 10.0;
var angularDrag = 5.0;
var distance = 0.2;
var attachToCenterOfMass = false;



private var springJoint : SpringJoint;







function Update ()
{
	// Make sure the user pressed the mouse down
	if (!Input.GetMouseButtonDown (0))
		return;

	var mainCamera = FindCamera();
		
	// We need to actually hit an object
	var hit : RaycastHit;
	if (!Physics.Raycast(mainCamera.ScreenPointToRay(Input.mousePosition),  hit, 100))
		return;
	// We need to hit a rigidbody that is not kinematic
	if (!hit.rigidbody || hit.rigidbody.isKinematic)
		return;
	
	if (!springJoint)
	{
		var go = new GameObject("Rigidbody dragger");
		var body : Rigidbody = go.AddComponent ("Rigidbody") as Rigidbody;
		springJoint = go.AddComponent ("SpringJoint");
		body.isKinematic = true;
	}
	
	springJoint.transform.position = hit.point;
	if (attachToCenterOfMass)
	{
		var anchor = transform.TransformDirection(hit.rigidbody.centerOfMass) + hit.rigidbody.transform.position;
		anchor = springJoint.transform.InverseTransformPoint(anchor);
		springJoint.anchor = anchor;
	}
	else
	{
		springJoint.anchor = Vector3.zero;
	}
	
	springJoint.spring = spring;
	springJoint.damper = damper;
	springJoint.maxDistance = distance;
	springJoint.connectedBody = hit.rigidbody;
	
	StartCoroutine ("DragObject", hit.distance);
	
}

function DragObject (distance : float)
{
	var oldDrag = springJoint.connectedBody.drag;
	var oldAngularDrag = springJoint.connectedBody.angularDrag;
	springJoint.connectedBody.drag = drag;
	springJoint.connectedBody.angularDrag = angularDrag;
	var mainCamera = FindCamera();
	while (Input.GetMouseButton (0))
	{
		var ray = mainCamera.ScreenPointToRay (Input.mousePosition);
		springJoint.transform.position = ray.GetPoint(distance);
		yield;
	}
	if (springJoint.connectedBody)
	{
		springJoint.connectedBody.drag = oldDrag;
		springJoint.connectedBody.angularDrag = oldAngularDrag;
		springJoint.connectedBody = null;
	}
}

function FindCamera ()
{
	if (camera)
		return camera;
	else
		return Camera.main;
}
2

Nearby is a relative term given that you are running a mouse over a 2D screen looking into a 3D space. I’m going to assume that near means near to the camera. All you have to do is change the last parameter of the Raycast() on line 28.

if (!Physics.Raycast(mainCamera.ScreenPointToRay(Input.mousePosition),  hit, 100))

The ‘100’ is the distance of the raycast. Just set this value to whatever limit you want. If your scene is similar to the default scene you get when you do a new scene, try values in the range of (1 - 10).