上节内容中，我们已经有了一个三维的空间，本节中我们就来结识3D中最基本的图元——三角形 在3D开发中，三角形占有重要的地位。它是3D模型的最小基元，无论多复杂的3D模型，最终都可以表示成若干个三角形的组合。图形处理芯片也对三角形渲染进行了硬件支持。可见三角形虽然简单，但在3D开发中的重要性。下面我们就从这个最简单的三角形开始。 沿用上节我们建好的XNA项目，在VS2010中打开该项目。打开Game1.cs文件，我们来修改Game1类。 要想构建三角形，我们首先想到的是需要三个顶点的坐标。在XNA中提供了VertexPositionColor类型，用于表示一个空间中的顶点的位置和颜色信息，在此我们只用到位置信息，颜色会在后文中使用。 为Game1类添加用于保存三角形顶点信息成员变量：VertexPositionColor[] triangle; 然后在LoadContent()方法中定义三个顶点： ~~~            triangle = newVertexPositionColor[]{                new VertexPositionColor(newVector3(0, 1, 0), Color.Red),                new VertexPositionColor(newVector3(1, -1, 0), Color.Green),                new VertexPositionColor(newVector3(-1,-1, 0), Color.Blue)            }; ~~~ 这三个顶点坐标正好是一个三角形。然后在Draw()方法中将其绘制输出： GraphicsDevice.DrawUserPrimitives<VertexPositionColor>(PrimitiveType.TriangleStrip,triangle, 0, 1); ~~~       DrawUserPrimitives()方法用于绘制图元，方法的原型如下：       public voidDrawUserPrimitives<T>(              PrimitiveTypeprimitiveType,   //图元类型              T[]vertexData,   //顶点数据              intvertexOffset,  //读顶点数据的起始位置              intprimitiveCount  //图元个数       ) ~~~ 其中PrimitiveType用于描述图元类型，在Windows Phone中有四个取值，含义是： -        TriangleList：三角形列表 -        TriangleStrip：三角形带 -        LineList：线段列表 -        LineStrip：线段带 例如同样的6个顶点坐标，当使用TriangleList时得到的图形如下（注：图片来源于网络）：  当使用TriangleStrip时得到的图形如下（注：图片来源于网络）：  运行程序，在模拟器中将看到如下结果：  虽然很简陋，不过这确实是在3D空间中绘制的，如果有兴趣，不妨修改一下摄像机的位置或者三角形的坐标等参数，也可以绘制其他图元，体会运行结果的变化。下节中我们将进行三维物体的运动处理。 附本节Game1类的完整源码： ~~~ public class Game1 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; Camera camera; Matrix world = Matrix.Identity; BasicEffect basicEffect; VertexPositionColor[] triangle; public Game1() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; // Frame rate is 30 fps by default for Windows Phone. TargetElapsedTime = TimeSpan.FromTicks(333333); // Extend battery life under lock. InactiveSleepTime = TimeSpan.FromSeconds(1); graphics.IsFullScreen = true; } /// <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() { // 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() { camera = new Camera(this, new Vector3(0, 0, 5), Vector3.Zero, Vector3.Up, MathHelper.PiOver4, GraphicsDevice.Viewport.AspectRatio, 1.0f, 50.0f); Components.Add(camera); basicEffect = new BasicEffect(GraphicsDevice); triangle = new VertexPositionColor[]{ new VertexPositionColor(new Vector3(0, 1, 0), Color.Red), new VertexPositionColor(new Vector3(1, -1, 0), Color.Green), new VertexPositionColor(new Vector3(-1,-1, 0), Color.Blue) }; } /// <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 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); basicEffect.World = world; basicEffect.View = camera.view; basicEffect.Projection = camera.projection; foreach (EffectPass pass in basicEffect.CurrentTechnique.Passes) { pass.Apply(); GraphicsDevice.DrawUserPrimitives<VertexPositionColor>(PrimitiveType.TriangleStrip, triangle, 0, 1); } base.Draw(gameTime); } } ~~~ ——欢迎转载，请注明出处 [http://blog.csdn.net/caowenbin](http://blog.csdn.net/caowenbin) ——