一、Directx简介

     Directx是微软公司开发的一套功能丰富的底层API ，由C++编写，它可让以Windows为平台的游戏或多媒体程序获得更高的执行效率，加强3d图形和声音效果，并提供设计人员一个共同的硬件驱动标准，让游戏开发者不必为每一品牌的硬件来写不同的驱动程序，也降低用户安装及设置硬件的复杂度。

DirectX并不是一个单纯的图形API，它是由微软公司开发的用途广泛的API，它包含有Direct Graphics(Direct 3D+Direct Draw)、Direct Input、Direct Play、Direct Sound、Direct Show、Direct Setup、Direct Media Objects等多个组件，它提供了一整套的多媒体接口方案。只是其在3D图形方面的优秀表现，让它的其它方面显得暗淡无光。

DirectX的编程方式包括两种1、采用COM接口的方式。2、采用.NET类库的方式。

这里说的是以c#为开发语言和托管direcx类库结合的方式实现的。

二、开始绘制

1、设备初始化，创建设备

        PresentParameters presentParameters = new PresentParameters(); //显示参数private Device device = null;//设备对象    

 private void InitDirectx（）{presentParameters.Windowed = true;  //填充显示参数presentParameters.SwapEffect = SwapEffect.Discard;device = new Device(0, DeviceType.Hardware, this, CreateFlags.SoftwareVertexProcessing, presentParameters); //创建设备2、创建顶点缓存和设备缓存vertexBuffer = new VertexBuffer(typeof(CustomVertex.PositionColored), 8, device, 0, CustomVertex.PositionColored.Format, Pool.Default);      //创建顶点缓冲,有8个顶点indexBuffer = new IndexBuffer(typeof(int), 36, device, 0, Pool.Default);   //创建索引缓存 FillVertexBuffer();       //填充顶点和索引信息}  

        public void FillVertexBuffer(){CustomVertex.PositionColored[] verts = (CustomVertex.PositionColored[])vertexBuffer.Lock(0, 0); //调用lock方法int[] indexs = (int[])indexBuffer.Lock(0, 0);//立方体顶点verts[0] = new CustomVertex.PositionColored(-10.0f, -10.0f, -10.0f,Color.Red.ToArgb());verts[1] = new CustomVertex.PositionColored(-10.0f, 10.0f, -10.0f, Color.Blue.ToArgb());verts[2] = new CustomVertex.PositionColored(10.0f, 10.0f, -10.0f,  Color.Yellow.ToArgb());verts[3] = new CustomVertex.PositionColored(10.0f, -10.0f, -10.0f, Color.Green.ToArgb());verts[4] = new CustomVertex.PositionColored(-10.0f, -10.0f, 10.0f, Color.Red.ToArgb());verts[5] = new CustomVertex.PositionColored(-10.0f, 10.0f, 10.0f,  Color.Blue.ToArgb());verts[6] = new CustomVertex.PositionColored(10.0f, 10.0f, 10.0f,   Color.Yellow.ToArgb());verts[7] = new CustomVertex.PositionColored(10.0f, -10.0f, 10.0f,  Color.Green.ToArgb());//front sideindexs[0] = 0; indexs[1] = 1; indexs[2] = 2;indexs[3] = 0; indexs[4] = 2; indexs[5] = 3;//backsideindexs[6] = 4; indexs[7] = 6; indexs[8] = 5;indexs[9] = 4; indexs[10] = 7; indexs[11] = 6;//left sideindexs[12] = 4; indexs[13] = 5; indexs[14] = 1;indexs[15] = 4; indexs[16] = 1; indexs[17] = 0;//right side indexs[18] = 3; indexs[19] = 2; indexs[20] = 6;indexs[21] = 3; indexs[22] = 6; indexs[23] = 7;//topindexs[24] = 1; indexs[25] = 5; indexs[26] = 6;indexs[27] = 1; indexs[28] = 6; indexs[29] = 2;//bottomindexs[30] = 4; indexs[31] = 0; indexs[32] = 3;indexs[33] = 4; indexs[34] = 3; indexs[35] = 7;vertexBuffer.Unlock();indexBuffer.Unlock();}

3、绘制前准备（绘制流水线）

这一阶段对绘制前 世界坐标系，观察者坐标系，投影等参数进行设置。同时关闭关照和背面消隐。




        private void SetupCamera(){device.Transform.World = Matrix.RotationY(angel);  // 世界坐标系   沿Y轴旋转  //device.Transform.World = Matrix.RotationX(angel);//沿X轴旋转//device.Transform.World = Matrix.RotationZ(angel);device.Transform.View = Matrix.LookAtLH(new Vector3(0.0f, 0.0f, -40f), new Vector3(0.0f, 0.0f, 0.0f), new Vector3(0.0f, 1.0f, 0.0f));  //观察者坐标系device.Transform.Projection = Matrix.PerspectiveFovLH((float)System.Math.PI*0.5f, 1.0f, 1.0f, 100.0f);                //投影device.RenderState.CullMode = Cull.None;                                                                                  //背面消隐关device.RenderState.Lighting = false;                                                                                 //光照关device.RenderState.FillMode = FillMode.WireFrame;//Viewport vp = new Viewport();//视口变换 将顶点坐标从投影窗口转换到屏幕的一个矩形区域中//vp.Width = 600;//vp.Height = 480;//vp.MaxZ = 1;//device.Viewport = vp;}

4、开始绘制过程

   这里采用的是采用顶点缓存和索引存联合的方式进行绘制的，采用的绘制的基本图元是三角形的列表方式。

        public void Render(){if (device == null)return;SetupCamera();                                                         //设置世界，视野和投影矩阵device.Clear(ClearFlags.Target, System.Drawing.Color.Black, 1.0f, 0);  //清空设备device.BeginScene();                                                   //开始场景device.SetStreamSource(0, vertexBuffer, 0);                            //指定数据输入源device.Indices = indexBuffer;device.SetRenderState(RenderStates.ColorVertex, true);                 //指定渲染方式device.VertexFormat = CustomVertex.PositionColored.Format;device.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, 8, 0, 12);//device.DrawPrimitives(PrimitiveType.TriangleList, 0, 12);            //绘制图形，使用的方法为三角形列表device.EndScene();                                                     //结束场景device.Present();                                                      //更新场景}