How to drag an object

Unity Engine
,
1

Hey guys,

I’m using this code to allow me to drag my objects in my game scene:

// Moves object according to finger movement on the screen
var speed:float = 0.1;
function Update () {
    if (iPhoneInput.touchCount > 0  iPhoneInput.GetTouch(0).phase == iPhoneTouchPhase.Moved) {
    
        // Get movement of the finger since last frame
        var touchDeltaPosition:Vector2 = iPhoneInput.GetTouch(0).deltaPosition;
        
        // Move object across XY plane
        transform.Translate (touchDeltaPosition.x * speed, touchDeltaPosition.y * speed, 0);
    }
}

The problem is, that it does not matter where I put my finger on the screen the object is still selected, as you can imagine this will be a problem when the scene has multiple objects.

Is there a simple way to edit the code to make sure the users finger is actually on the object before allowing them to drag it?

Thanks

2

I’m stuggling to get past this, people have mentioned raycasting before on the forums, could this be appropriate?

3

There is a simple raycast example in this thread. Also, you might want to look at adding an OnMouseDown function to the draggable object’s script.

4

Thanks andeeee that worked nicely.

I’m having a problem implementing the draging part of the script, heres what I mangaged to do:

http://pastie.org/1014997

Thanks

5

I still cant seem to implement the dragging action, any thoughts on how to tackle this?

Thanks

6

I’ve attached a script that shows a way to drag an object in the plane of the camera. You can add it to any convenient object in the scene.

332885–11714–$dragobj_313.js (818 Bytes)

7

Thanks that works great :slight_smile:

The only problem is that all objects become draggable, not just the one it is attached to?

8

Any ideas on this ?

Thanks :slight_smile:

9

Heres a video of the problem : http://tiny.cc/2v6ux

As you can see , as I move my mouse across the wall I seem to somehow allow cubes to pass through them -as if I’m moving the collider?

Although I can also move cubes ( which is the part I want)

I really dont know whats wrong with the code. I have added in 2 extra checks and that did not make a difference.

private var currTarget: Transform;
private var dragging: boolean;
private var clickOffset: Vector3;


function Update () {
	var objPlane: Plane;
	var hitDist: float;
	var hit: RaycastHit;


			if (Input.GetMouseButton(0)  gameObject.name =="enemy")  {
		ray = Camera.main.ScreenPointToRay(Input.mousePosition);

		if (dragging) {	
			objPlane = new Plane(Camera.main.transform.forward, currTarget.position);
			objPlane.Raycast(ray, hitDist);
			currTarget.position = ray.GetPoint(hitDist) + clickOffset;
		} else if (Physics.Raycast(ray, hit)  Input.GetMouseButtonDown(0) gameObject.name =="enemy") {
			dragging = true;
			currTarget = hit.transform;
			
			objPlane = new Plane(Camera.main.transform.forward, currTarget.position);
			objPlane.Raycast(ray, hitDist);
			clickOffset = currTarget.position - ray.GetPoint(hitDist);
		}
	} else {
		dragging = false;
	}
}
10

Sorry, I should have thought of that…

Anyway, the best place to check is on the “else if” line:-

else if (Physics.Raycast(ray, hit)  Input.GetMouseButtonDown(0)  hit.gameObject.name == "enemy") { ...

This is how you would identify the target by name, but you could just as easily do it by the tag, etc.

11

Thanks andeee, I seem to be getting this error when I make the change:

‘gameObject’ is not a member of ‘UnityEngine.RaycastHit’

12

D’Oh! Sorry, it should be “hit.transform.name”, not “hit.gameObject.name”.

13

Andeeee: Im struggling a bit to convert your nice dragObject script into something I can use for my Xoom.

I changed something in your script here:

function OnMouseDown ()
{
	[B]if(Input.touchCount > 0)[/B]
	{
	canMove = true;
	myTransform.Translate(Vector3.up*addHeightWhenClicked);
	gravitySetting = myRigidbody.useGravity;
	freezeRotationSetting = myRigidbody.freezeRotation;
	myRigidbody.useGravity = false;
	myRigidbody.freezeRotation = freezeRotationOnDrag;
	yPos = myTransform.position.y;
	}
}

I have a vague hunch about leaving out the entire OnMouse… functions, but struggling with understanding the Touch part of UNity.
Any pointers are really welcomed!

Edit: I tried throwing in this code I found in the reference:

// Moves object according to finger movement on the screen

var speed : float = 0.1;
function Update () {
if (Input.touchCount > 0 
Input.GetTouch(0).phase == TouchPhase.Moved) {

// Get movement of the finger since last frame
var touchDeltaPosition:Vector2 = Input.GetTouch(0).deltaPosition;

// Move object across XY plane
transform.Translate (-touchDeltaPosition.x * speed,
-touchDeltaPosition.y * speed, 0);
}
}

My objects are touchable, but they just fly like little mentals :slight_smile: