Adobe Flash cs4 旋转数学

Question

目前我的对象旋转面对另一个对象时遇到问题。目前它工作正常，就像这张图片一样，我在原点的对象将能够旋转并移动到 3 个象限中的对象，除了带有正的象限90度到180度，我的物体在移动到物体时会旋转几个完整的旋转一段时间，有人知道为什么吗？我用来旋转的句子是rotation += (foodLocationDegrees - (rotation - 90)) * .2;，其中食物是使用

var angle:Number = Math.atan2(foodTarget.y - y, foodTarget.x - x); 
            foodLocationDegrees =Math.floor((angle  * 180 / Math.PI));

y 和 x 是鱼的对象，foodtarget 是食物的对象。

 public function moveToFood():void
        {   

            var dx:Number = x - _destinationX;
            var dy:Number = y - _destinationY;

            trace("Food location degree relative to fish mouth "+foodLocationDegrees);
            var targetRotation:Number = 0;
            if (foodLocationDegrees > 0 && foodLocationDegrees < 90)
            {
            trace("food is on 1st quadrant of the fish mount");
                this.x -= dx / 18;
                this.y -= dy / 18;
            }else if (foodLocationDegrees > 90 && foodLocationDegrees < 180)
            {
            trace("food is on 2nd quadrant of the fish mount"); 

                this.x -= dx / 18;
                this.y -= dy / 18;
            }else if (foodLocationDegrees > -180 && foodLocationDegrees < -90)
            {
                trace("food is on 3nd quadrant of the fish mount");

                this.x -= dx / 18;
                this.y -= dy / 18;
            }else if (foodLocationDegrees < 0 && foodLocationDegrees > -90)
            {
                trace("food is on 4nd quadrant of the fish mount");

                this.x -= dx / 18;
                this.y -= dy / 18;
            }
            trace("Before adding Rotation " + rotation);
            var number:Number = (foodLocationDegrees - (rotation - 90)) * .1;
            trace("rotation to add "+number);
            rotation += (foodLocationDegrees - (rotation - 90)) * .2;

            trace("After adding Rotation " + rotation);

            //removing food when both hit boxes hit
            if (hit.hitTestObject(foodTarget.hit))
            {
                foodInPond--;
                foodTarget.removeSelf();
            }

        }

Answer 1

public function moveToFood(food:Food):void
{
    var speed:Number = 6.5;

    var a:Number = food.x - x;
    var b:Number = food.y - y;
    var ang:Number = Math.atan2(b, a);

    rotation = ang * 180 / Math.PI;

    x += Math.cos(ang) * speed;
    y += Math.sin(ang) * speed;
}

你不能只使用sin 和cos 朝你所面对的方向移动吗？