XNA Game的基础

Windows Game

XNA基础：

添加Camera：

点击鼠标右键，新建项，选择GameComponent，重命名为Camera.cs。

在Camera类中添加两个类级变量（自动实现属性）来表示摄像机的视图和投影矩阵。

22         public Matrix view { get; protected set; }
23         public Matrix projection { get; protected set; }
然后修改构造器，接收3个Vector3变量，它们代表初始的摄像机的位置、目标和up向量。
完整代码：

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 start
{
    //摄像机的视图和投影矩阵
    /// <summary>
    /// This is a game component that implements IUpdateable.
    /// </summary>
    public class Camera : Microsoft.Xna.Framework.GameComponent
    {
        //摄像机的视图和投影矩阵
        public Matrix view { get; protected set; }
        public Matrix projection { get; protected set; }
        public Camera(Game game,Vector3 pos,Vector3 target,Vector3 up)
            : base(game)
        {
            view = Matrix.CreateLookAt(pos,target,up);
            projection = Matrix.CreatePerspectiveFieldOfView(MathHelper.PiOver4,(float)Game.Window.ClientBounds.Width/(float)Game.Window.ClientBounds.Height,1,100);
            // TODO: Construct any child components here
        }

        /// <summary>
        /// Allows the game component to perform any initialization it needs to before starting
        /// to run.  This is where it can query for any required services and load content.
        /// </summary>
        public override void Initialize()
        {
            // TODO: Add your initialization code here

            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)
        {
            // TODO: Add your update code here

            base.Update(gameTime);
        }
    }
}

绘制基元，在XNA中基元为三角形。以下是完整代码：

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 start
{
    /// <summary>
    /// This is the main type for your game
    /// </summary>
    public class Game1 : Microsoft.Xna.Framework.Game
    {
        GraphicsDeviceManager graphics;
        SpriteBatch spriteBatch;
        Camera camera;
        VertexBuffer vertexBuffer;
        VertexPositionColor[] verts;
        BasicEffect effect;
        Matrix world = Matrix.Identity;

        public Game1()
        {
            graphics = new GraphicsDeviceManager(this);
        }

        /// <summary>
        /// Allows the game to perform any initialization it needs to before starting to run.
        /// This is where it can query for any required services and load any non-graphic
        /// related content.  Calling base.Initialize will enumerate through any components
        /// and initialize them as well.
        /// </summary>
        protected override void Initialize()
        {
            camera = new Camera(this,new Vector3(0,0,5),Vector3.Zero,Vector3.Up);
            Components.Add(camera);
            // TODO: Add your initialization logic here

            base.Initialize();
        }

        /// <summary>
        /// LoadContent will be called once per game and is the place to load
        /// all of your content.
        /// </summary>
        protected override void LoadContent()
        {
            verts = new VertexPositionColor[3];
            verts[0] = new VertexPositionColor(new Vector3(0, 1, 0), Color.Blue);
            verts[1] = new VertexPositionColor(new Vector3(1, -1, 0), Color.Red);
            verts[2] = new VertexPositionColor(new Vector3(-1, -1, 0), Color.Green);
            vertexBuffer = new VertexBuffer(GraphicsDevice, typeof(VertexPositionColor), verts.Length, BufferUsage.None);
            vertexBuffer.SetData(verts);
            // Create a new SpriteBatch, which can be used to draw textures.
            spriteBatch = new SpriteBatch(GraphicsDevice);
            //初始化BasicBuffer
            effect = new BasicEffect(GraphicsDevice);
                        Content.RootDirectory = "Content";

            // TODO: use this.Content to load your game content here
        }

        /// <summary>
        /// UnloadContent will be called once per game and is the place to unload
        /// all content.
        /// </summary>
        protected override void UnloadContent()
        {
            // TODO: Unload any non ContentManager content here
        }

        /// <summary>
        /// Allows the game to run logic such as updating the world,
        /// checking for collisions, gathering input, and playing audio.
        /// </summary>
        /// <param name="gameTime">Provides a snapshot of timing values.</param>
        protected override void Update(GameTime gameTime)
        {
            // Allows the game to exit
            if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
                this.Exit();

            // TODO: Add your update logic here
            //平移（Tracelotion）
            KeyboardState keyboardstate = Keyboard.GetState();
            if (keyboardstate.IsKeyDown(Keys.Left))
            {
                world *= Matrix.CreateTranslation(-.01f, 0,0);
                world *= Matrix.CreateRotationY(MathHelper.PiOver4 / 60);
            }
            if (keyboardstate.IsKeyDown(Keys.Right))
            {
                world *= Matrix.CreateTranslation(.01f, 0, 0);
                world *= Matrix.CreateRotationX(MathHelper.PiOver4 / 60);
            }


            base.Update(gameTime);
        }

        /// <summary>
        /// This is called when the game should draw itself.
        /// </summary>
        /// <param name="gameTime">Provides a snapshot of timing values.</param>
        protected override void Draw(GameTime gameTime)
        {
            GraphicsDevice.Clear(Color.CornflowerBlue);
            GraphicsDevice.SetVertexBuffer(vertexBuffer);
            // TODO: Add your drawing code here
            //设置物体和摄像机的信息
            effect.World = world;
            effect.View = camera.view;
            effect.Projection = camera.projection;
            effect.VertexColorEnabled = true;
            //开始效果，并绘制每个Pass
            foreach (EffectPass pass in effect.CurrentTechnique.Passes)
            {
                pass.Apply();
                GraphicsDevice.DrawUserPrimitives<VertexPositionColor>(PrimitiveType.TriangleStrip, verts, 0, 1);
            }

            base.Draw(gameTime);
            
        }
    }
}

keydown，读者自行改变。