为什么此相机无法连续偏航

所以，我正在XNA中制作一个第三人称游戏。我已经创建了一个可以在限制范围内俯仰的相机，并且应该能够偏转整个360度。

该类如下所示：

using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.GamerServices;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Media;

namespace Assignment_3_Redesign
{
    /// <summary>
    /// This is a game component that implements IUpdateable.
    /// </summary>
    public class Camera : Microsoft.Xna.Framework.GameComponent
    {
        //Constrain where our camera can wander in the X and Z plane
        public Rectangle XZBoundingBox;
        //Angular bounds for camera.
        float minPitchIncr = -12;
        float maxPitchIncr = 38;
        float currentPitchIncr = 12;
        float currentYawAngle = 0;
        //Matrices to pass to effects.
        public Matrix view { get; protected set; }
        public Matrix projection { get; protected set; }
        //Important directional vars.
        public Vector3 pos;
        public Vector3 look;
        private Vector3 up;
        //Mouse Input 
        //X -- yaw; Y-- pitch
        private MouseState prevMouseState;
        private MouseState tempMS;
        private KeyboardState keyboardState;
        //Speed to move camera at for translates.
        float Speed = 3;
        public Camera(Game game, Vector3 pos, Vector3 target, Vector3 up, Rectangle bounding)
            : base(game)
        {
            this.pos = pos;
            this.look = (target - pos);
            this.look.Normalize();
            this.up = up;
            this.view = Matrix.CreateLookAt(pos, target, up);
            XZBoundingBox = bounding;
            this.projection = Matrix.CreatePerspectiveFieldOfView
                (MathHelper.PiOver4,
                (float)Game.Window.ClientBounds.Width /
                (float)Game.Window.ClientBounds.Height,
                1, 500);
        }
        private void CreateLookAt()
        { view = Matrix.CreateLookAt(pos, pos + look, up); }
        //Returns current camera direction as vector.
        public Vector3 GetCameraDirection
        { get { return look; } }
        /// 
        public override void Initialize()
        {
            // TODO: Add your initialization code here
            Mouse.SetPosition(Game.Window.ClientBounds.Width / 2,
                Game.Window.ClientBounds.Height / 2);
            prevMouseState = Mouse.GetState();
            base.Initialize();
        }
        /// <summary>
        /// Allows the game component to update itself.
        /// </summary>
        /// <param name="gameTime">Provides a snapshot of timing values.</param>
        public override void Update(GameTime gameTime)
        {
            Vector3 tempPos= new Vector3(0.0f,0.0f,0.0f);
            //Get keyboard commands
            keyboardState = Keyboard.GetState();
            /*
            //Select object
            if (keyboard.IsKeyDown(Keys.D1))
                objSelected = 0;
            if (keyboard.IsKeyDown(Keys.D2))
                objSelected = 1;*/
            //Translation
            if (keyboardState.IsKeyDown(Keys.A)) //strafe +X (rel)
            {
                tempPos -= Vector3.Cross(up, look) * Speed;
                tempPos.Y = 0.0f;
                if (XZBoundingBox.Contains((int)(pos - Vector3.Normalize(tempPos) * Speed).X, 
                    (int)(pos - Vector3.Normalize(tempPos) * Speed).Z))
                    pos -= Vector3.Normalize(tempPos) * Speed;
            }
            if (keyboardState.IsKeyDown(Keys.D)) //strafe -X (rel)
            {
                tempPos -= Vector3.Cross(up, look) * Speed;
                tempPos.Y = 0.0f;
                if (XZBoundingBox.Contains((int)(pos - Vector3.Normalize(tempPos) * Speed).X,
                    (int)(pos - Vector3.Normalize(tempPos) * Speed).Z))
                    pos += Vector3.Normalize(tempPos) * Speed;
            }
            if (keyboardState.IsKeyDown(Keys.W)) //+Z (rel)
            {
                tempPos += look * Speed;
                tempPos.Y = 0.0f;
                if (XZBoundingBox.Contains((int)(pos - Vector3.Normalize(tempPos) * Speed).X,
                    (int)(pos - Vector3.Normalize(tempPos) * Speed).Z))
                    pos += Vector3.Normalize(tempPos) * Speed;
            }
            if (keyboardState.IsKeyDown(Keys.S)) //-Z (rel)
            {
                tempPos -= look;
                tempPos.Y = 0.0f;
                if (XZBoundingBox.Contains((int)(pos - Vector3.Normalize(tempPos) * Speed).X,
                    (int)(pos - Vector3.Normalize(tempPos) * Speed).Z))
                    pos -= Vector3.Normalize(tempPos) * Speed;
            }
            //Get mouse commands to control camera direction;
            //Yaw rot.
            tempMS = Mouse.GetState();
            if (tempMS != prevMouseState)
            {
                currentYawAngle += (tempMS.X - prevMouseState.X) * (-MathHelper.PiOver4 / 150);
                currentYawAngle = MathHelper.WrapAngle(currentYawAngle);
                if (currentPitchIncr + (tempMS.Y - prevMouseState.Y) < maxPitchIncr &&
                    currentPitchIncr + (tempMS.Y - prevMouseState.Y) > minPitchIncr)
                    currentPitchIncr += tempMS.Y - prevMouseState.Y;
                if (currentPitchIncr > maxPitchIncr) currentPitchIncr = maxPitchIncr;
                else if (currentPitchIncr < minPitchIncr) currentPitchIncr = minPitchIncr;
                look = Vector3.Transform(Vector3.Forward,
                    Matrix.CreateFromYawPitchRoll(currentYawAngle,
                    currentPitchIncr * (-MathHelper.PiOver4 / 150), 0.0f));
            }
            //reset prevMouseState
            prevMouseState = Mouse.GetState();
            base.Update(gameTime);
            CreateLookAt();
        }
    }
}

现在这是我想要的。。。几乎问题是，当我旋转时，它在偏航时不会超过Pi/-Pi。换句话说，你不能做一个完整的360旋转。

我是不是犯了一些条件错误？（我不会怀疑……我盯着它看太久了，玩它，打碎东西。）

下面是一个示例声明：

   camera = new Camera(this, new Vector3(0, 20, 40), Vector3.Zero, Vector3.Up,
                   new Rectangle(-800,-800,1600,1600));

对整个摄像课有什么想法吗？

谢谢你的帮助！

编辑1
从技术上讲，这是一个#classproject。为了清楚起见，我想提一下。任务是开放式的，我正在努力投入更多的时间，因为我想制作一个坚实的框架来制作WinPhone游戏。。。