XNA 角度不匹配

Question

我有一个精灵射击子弹，但子弹离开的角度比精灵旋转少 90 度。我尝试添加 Math.Pi/2 但它不起作用。精灵开始朝上，精灵旋转的代码是这样的：

Vector2 direction = mousePosition - position;
direction.Normalize();
rotation = (float)Math.Atan2((double)direction.Y,
            (double)direction.X) + ((1f * (float)Math.PI) / 2);

子弹射击和更新如下：

public void UpdateBullets()
        {
            foreach (Bullets bullet in bullets)
            {
                bullet.position += bullet.velocity;
                if (Vector2.Distance(bullet.position, position) > 500)
                    bullet.isVisible = false;
            }
            for (int i = 0; i < bullets.Count; i++)
            {
                if (!bullets[i].isVisible)
                {
                    bullets.RemoveAt(i);
                    i--;
                }
            }
        }



public void Shoot()
        {
            Bullets newBullet = new Bullets(Content.Load<Texture2D>("Sprites/bala"));
            newBullet.velocity = new Vector2((float)Math.Cos(rotation), (float)Math.Sin(rotation)) * 5f;
            newBullet.position = position + newBullet.velocity * 5;
            newBullet.isVisible = true;

            if (bullets.Count() < 20)
                bullets.Add(newBullet);
        }

Answer 1

解决方案是替换：

    newBullet.velocity = new Vector2((float)Math.Cos(rotation),
 (float)Math.Sin(rotation)) * 5f;

与：

    newBullet.velocity = new Vector2((float)Math.Sin(rotation),
-(float)Math.Cos(rotation)) * 5f;