Smooth Turning

An easy method to make an object aim at a location (in this case, the mouse cursor) but turn smoothly.

by ChevyRay 24 Mar 2013

Embed

/**
 * Copyright ChevyRay ( http://wonderfl.net/user/ChevyRay )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/pvmT
 */

package
{
    import flash.geom.Point;
    import flash.events.Event;
    import flash.display.Shape;
    import flash.display.Sprite;
    
    public class SmoothTurning extends Sprite
    {
        public var leftTurret:Shape;
        public var rightTurret:Shape;
        
        public var targetNormal:Point = new Point(1, 0);
        public var currentNormal:Point = new Point(1, 0);
        public var lookEase:Number = 0.3;
        
        public function SmoothTurning()
        {
            stage.frameRate = 60;
            
            leftTurret = createTurret(100, 200);
            rightTurret = createTurret(300, 200);
            
            addEventListener(Event.ENTER_FRAME, update);
        }
        
        public function update(e:Event):void
        {
            //Left turret looks immediately
            leftTurret.rotation = Math.atan2(mouseY - leftTurret.y, mouseX - leftTurret.x) * (180 / Math.PI);
            
            //Right turret turns smoothly
            targetNormal.x = mouseX - rightTurret.x;
            targetNormal.y = mouseY - rightTurret.y;
            targetNormal.normalize(1);
            currentNormal.x += (targetNormal.x - currentNormal.x) * lookEase;
            currentNormal.y += (targetNormal.y - currentNormal.y) * lookEase;
            currentNormal.normalize(1);
            rightTurret.rotation = Math.atan2(currentNormal.y, currentNormal.x) * (180 / Math.PI);
        }
        
        public function createTurret(x:int, y:int):Shape
        {
            var turret:Shape = new Shape();
            turret.x = x;
            turret.y = y;
            turret.graphics.beginFill(0x000000);
            turret.graphics.drawCircle(0, 0, 25);
            turret.graphics.beginFill(0xFF0000);
            turret.graphics.drawRect(-5, -5, 50, 10);
            addChild(turret);
            return turret;
        }
    }
}