Event.delta
var delta: Vector2;
Vector2 delta;
delta as Vector2
Description

The relative movement of the mouse compared to last event.

Used in EventType.MouseMove, EventType.MouseDrag, EventType.ScrollWheel events.

See Also: Event.mousePosition.
	// Move the scroll wheel to determine
	// the X & Y scrolling amount.
	function OnGUI() {
		var e : Event = Event.current;
		if (e.isMouse) {
			Debug.Log(e.delta);
		}
	}
using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    void OnGUI() {
        Event e = Event.current;
        if (e.isMouse)
            Debug.Log(e.delta);
        
    }
}
import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	def OnGUI() as void:
		e as Event = Event.current
		if e.isMouse:
			Debug.Log(e.delta)