How to get mouse location on world canvas? [Unity 4.6]

Questions & Answers
1

I’m trying to build an inventory menu system using a canvas in world space. I’m trying to add drag-and-drop functionality, which requires me to know where the mouse is on the canvas so I know where to draw the item icon.

Does anybody know how to get that value?

2

I found the answer. There’s an great set of examples on the new GUI at:

http://forum.unity3d.com/threads/ui-example-project.263418/

One of the examples is on how to setup a drag-and-drop system. The canvas in the example isn’t in world space, but it does work in world space.

Specific to my project, I did the following:

  1. In the class that was going to be dragged, I added:

    using UnityEngine.EventSystems;

    and inherited the following interfaces:

    IBeginDragHandler, IDragHandler, IEndDragHandler

    Each interface only has one function:

OnBeginDrag: I created an icon and set its parent to the Canvas.

OnEndDrag: I destroy the icon.

OnDrag: I call this function (this came from one of the examples linked to earlier):

<pre><code>private void SetDraggedPosition(PointerEventData data)
	{
		if (dragOnSurfaces && data.pointerEnter != null && data.pointerEnter.transform as RectTransform != null)
			m_DraggingPlane = data.pointerEnter.transform as RectTransform;
		var rt = m_DraggingIcon.GetComponent{RectTransform}();
		Vector3 globalMousePos;
		if (RectTransformUtility.ScreenPointToWorldPointInRectangle(m_DraggingPlane, data.position, data.pressEventCamera, out globalMousePos))
		{
			rt.position = globalMousePos;
			rt.rotation = m_DraggingPlane.rotation;
		}
	}

EDIT: I can’t seem to get the code formatting correct, so replace { and } with the correct brackets…

  1. In the class that will receive the dragged item, I inherited the interface:

    IDropHandler

    This interface also only has one function:

OnDrop: The variable data.pointerDrag contains the GameObject that was being dragged. You can deal with the dropping logic how you want.

The SetDraggedPosition function from the example was what I was specifically looking for, but I hope the rest of the information is helpful, too.