Strange problem with Drag Script

Target Platforms Mobile
1

I have a script that allows me to drag objects, the problem is that as I move the selected object up/down it seems to go further into/out of the screen.

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))  {
		ray = Camera.main.ScreenPointToRay(Input.mousePosition);

		if (dragging &currTarget) {	
			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)) {
			dragging = true;
			currTarget = hit.transform;
			
			objPlane = new Plane(Camera.main.transform.up, currTarget.position);						objPlane.Raycast(ray, hitDist);
			clickOffset = currTarget.position - ray.GetPoint(hitDist);
		
	} else {
		dragging = false;
	}
	}
}

Any ideas on why this could be ?

I’ve tried playing around with objPlane = new Plane(-Camera.main.transform.forward, currTarget.position); trying right and up and negitive right and up but I haven’t had much success.

2

It seems to be ok when I go left and right, its only when I move up/down that seems to cause the problem?

3

I think the problem has something to do with the object selected sometimes moving in the z-axis as in trying to move towards the camera rather than being confined to just the x and y-axis, is there a way to fix this?

4

Sorry to be a pain but I’ve not had much luck with this.

Any thoughts on what could be done?

5

You need to use the camera’s transform.forward vector as the plane’s normal rather than transform.up.

6

Hi andeeee,

I tried changing my code to this like you suggested:

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))  { 
      ray = Camera.main.ScreenPointToRay(Input.mousePosition); 

      if (dragging &currTarget) {    
         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)) { 
         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; 
   } 
   } 
   
   if (dragging == false)
    {
     	 // Move the object 
    	var translation = Time.deltaTime * 5;
    	transform.Translate (translation, 0, 0);   
    }
}

Although it works the problem is if I click somewhere a cube will snap to that position for some reason?