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DirectX9 3D 快速上手  5

By sssa2000

4/18/2005

    这一章的内容相对很简单,控制Mesh的移动,旋转等等,其实这一切都是在对矩阵进行操作。在 DX中,用到的变换有3种,一种是基于Word坐标系的,一种是基于View坐标系的,还有一种是基于投影的变换。而这些变换都是通过矩阵的运算来实现的,在.Net的托管环境下,实现这些操作相对于非托管来说简单一写,不用对矩阵的每个值运算。

关于矩阵的运算和变换的关系,很多文章都有分析,GameRes也有很多这样的好文章,例如:http://dev.gameres.com/Program/Visual/3D/3DGame.mht 这里就有很详细的介绍。

我们这篇文章不研究细节,因为毕竟是快速开发,我们的目标就是用键盘控制读入的Mesh的运动。

其实在前面一篇文章中我们就有提到几个函数,只是没有介绍。我们来看看我们这一篇中要用到的几个简单的函数,从字面我们就可以判断出这些函数有什么用:

 

Matrix.RotateX方法:public void RotateX(    float angle);

Matrix. RotateY方法:public void RotateY(    float angle);

Matrix.RotateX方法:public void RotateZ(    float angle);

Matrix.Translation方法:public static Matrix Translation(float offsetx, float offsety, float offsetz);

 

好,我们现在重新打开上一次的读入Mesh的那个工程,我们现在要加入新的部分,既然是用键盘控制那么就要首先对键盘的状态进行分析:

         String status=null;//用于保存状态

protected override void OnKeyDown(System.Windows.Forms.KeyEventArgs e)

         {

              // Handle the escape key for quiting

              if (e.KeyCode == Keys.Escape)

              {

                   // Close the form and return

                   this.Close();

                   return;

              }

              // Handle left and right keys

              else if ((e.KeyCode == Keys.Left) || (e.KeyCode == Keys.NumPad4))

              {

                   status="left";  //向左旋转

              }

              else if ((e.KeyCode == Keys.Right) || (e.KeyCode == Keys.NumPad6))

              {

                   status="right";//向右旋转

              }

              else if((e.KeyCode ==Keys.Up )||(e.KeyCode ==Keys.NumPad8 ))

              {

                   status="up";//向上旋转

              }

              else if((e.KeyCode ==Keys.Down  )||(e.KeyCode ==Keys.NumPad2 ))

              {

                   status="down";//向下旋转

              }

              else if(e.KeyCode ==Keys.Enter)

              {

                   status="stop";//停止旋转

              }

              else if(e.KeyCode ==Keys.W  )

              {

                   status="goahead";//向前

 

              }

              else if(e.KeyCode ==Keys.S )

              {

                   status="goback";//向后

              }

              else if(e.KeyCode ==Keys.A)

              {

                   status="goleft";//向左

              }

              else if(e.KeyCode ==Keys.D )

              {

                   status="goright";//向右

              }

             

         }

很简单,以至于没什么可说的,下面就要对Mesh进行移动,由于我们观察的运动都是相对运动,所以无论你是对摄像机进行操作还是进行世界变换都是可以的,随你所好。我们对DrawMesh函数进行修改,主要是对状态的判断,然后对相应的矩阵进行变换:

        private void DrawMesh(string stat)

              if(stat=="left")

              {

                   angle=angle+0.1f;

                   device.Transform.World = Matrix.RotationY (angle);

              }

              else if(stat=="right")

              {

                   angle=angle-0.1f;

                   device.Transform.World = Matrix.RotationY (angle);

              }

              else if(stat=="up")

              {

                   angle=angle+0.1f;

                   device.Transform.World = Matrix.RotationX (angle);

 

 

              }

              else if(stat=="down")

              {

                   angle=angle-0.1f;

                   device.Transform.World = Matrix.RotationX (angle);

 

              }

              else if(stat=="stop")

              {

                   angle=0.0f;

                   //device.Reset ()

              }

              else if(stat=="goahead")

              {

                   v=v+0.1f;

              }

              else if(stat=="goback")

              {

                   v=v-0.1f;

              }

              else if(stat=="goleft")

              {

                   offsetx=offsetx+0.01f;

 

                   device.Transform.World = Matrix.Translation(offsetx,0,0);

              }

              else if(stat=="goright")

              {

                   offsetx=offsetx-0.01f;

                   device.Transform.World = Matrix.Translation(offsetx,0,0);

 

              }

 

            for (int i = 0; i < meshMaterials.Length; i++)

            {

                device.Material = meshMaterials[i];

                device.SetTexture(0, meshTextures[i]);

                mesh.DrawSubset(i);

            }

        }

这里我们处理小车前后移动的时候,没有直接使用世界变换,而是对摄影机进行了操作,这也很好理解,为了达到这个目的,我把SetupCamera函数小小的修改了一下:

  private void SetupCamera(float deep )

        {

            device.Transform.Projection = Matrix.PerspectiveFovLH((float)Math.PI / 4, this.Width / this.Height, 1.0f, 10000.0f);

            device.Transform.View = Matrix.LookAtLH(new Vector3(0,0, 10.0f+deep), new Vector3(), new Vector3(0,1,0));

            device.Lights[0].Type = LightType.Directional;

            device.Lights[0].Diffuse = Color.White;

            device.Lights[0].Direction = new Vector3(0, -1, -1);

            device.Lights[0].Update();

            device.Lights[0].Enabled = true;

        }

我给它加了一个参数,这个参数就是摄像机在Z轴的位置,我们只需要修改摄像机在Z轴的位置就可以实现透视效果,用这个方法实现我们这个简单的需求是很恰当的

这里再来对这里面的2个函数分析一下:

device.Transform.Projection用来获取或者设置投影变换矩阵,它本身也是一个Matrix型的变量。Matrix.PerspectiveFovLH方法:

public static Matrix PerspectiveFovLH(
    float fieldOfViewY, //Y
方向的视觉范围,弧度表示,即Y方向的视域角

    float aspectRatio, //
视觉范围的长宽比
    float znearPlane, //
*裁减*面      
    float zfarPlane//
远裁减*面

);

和非托管的相比,仅仅少了一个参数。定义宽高比的作用是,如果用户改变了窗口的大小,那么仍然就可以正确的显示物体的大小。最后两个参数是 *远裁减*面,必须为这两个*面指定2Z值,一般来说,假设物体将在Z轴的1.0f1000f之间运动时,就分别把这两个参数设为1.0f1000.0f

再来看看另外方法:Matrix.LookAtLH方法。 在使用观察矩阵来建立一个立体的照相机模型后,允许玩家通过一系列不同的观察点来看世界,使用Matrix.LookAtLH方法建立的照相机模型,是一种十分高效的照相机模型,但是注意,这一种模型不能绕所有的轴做三维转动。

public static Matrix LookAtLH(
    Vector3 cameraPosition,//
相机位置
    Vector3 cameraTarget,   //
相机的方向
    Vector3 cameraUpVector  //
相机的Up向量
);

其中第二个参数为相机的面对方向,假设相机面对的是Z轴的方向,那么就设置为(0,0,1)。好,现在也许有人要问,那如果面对的是Z轴的负方向呢?这也就是第3个参数的目的,第三个参数定一个Up向量,所以如果相机是正着放的,那么第3个参数就应该是(0,1,0),如果是倒着放的就是(0,-1,0)。所以如果面对的是Z的负方向,第三个参数就是(0,-1,0)

利用这个方法我们可以轻易的建立一个跟随式的相机(follow-up camera),例如实现第一人称视角,只需要把第2个参数指向跟随物体的方向,把相机位置设置为这个物体的周围。前面我们提过,这类相机不能绕自身旋转。

好,让我们来简单实现这个功能,我们想让汽车前进后退的时候能让摄像机来跟随它,首先,我们必须得到读入的Meshx,y,z这样才能给摄像机提供第一个参数,其次我们要确定朝向,在这里,很好确定,因为汽车就是朝Z方向开的,好了,都确定下来我们就可以写代码了。为了得到mesh的位置,就要使用Mesh内置的定点缓冲。

……………………………………..

             LoadMesh(@"..\..\sr.x");

             vb=mesh.VertexBuffer; //取得读入mesh的中心

              try

              {

                   Vector3 max;

                   Vector3 min;

                   GraphicsStream gs = vb.Lock(0, 0, LockFlags.None);

                   Geometry.ComputeBoundingBox(gs, mesh.NumberVertices, mesh.VertexFormat, out min, out max); //取得mesh的边框

                   float tx = (max.X - min.X)/2;

                   float ty =( max.Y - min.Y)/2;

                   float tz =( max.Z - min.Z);

                   pos.X =tx-0.9f;  //试出来的,这样才能使摄像机*似在车子中心

                   pos.Y =ty+0.6f;

                   pos.Z =tz-1.8f;

                   //float cameraHeadingH=

                   lookat = new Vector3 (0,0,1);

              }

              finally

              {

                   vb.Unlock();

                   vb.Dispose();

              }

修改KeyDown并且修改SetupCamera函数判断摄像机的选择。

private void SetupCamera(float deep )

        {

            device.Transform.Projection = Matrix.PerspectiveFovLH((float)Math.PI / 4, this.Width / this.Height, 1.0f, 10000.0f);

              if(camera%2!=0)

                device.Transform.View = Matrix.LookAtLH(new Vector3(0,0, 10.0f+deep), new Vector3(), new Vector3(0,1,0));

              else

                   device.Transform .View =Matrix.LookAtLH (pos,new Vector3 (0,1,0),new Vector3 (0,1,0));

 

            device.Lights[0].Type = LightType.Directional;

            device.Lights[0].Diffuse = Color.White;

            device.Lights[0].Direction = new Vector3(0, -1, -1);

            device.Lights[0].Update();

            device.Lights[0].Enabled = true;

        }

 

这样就完成了这个功能,不过这里只是简单模拟一下,只有在前进后退的时候才有效果,不过由于没有参照物,在前进后退的时候看不出画面的变化。下面贴出完整的代码:

using System;

using System.Drawing;

using System.Collections;

using System.ComponentModel;

using System.Windows.Forms;

using System.Data;

using Microsoft.DirectX;

using Microsoft.DirectX.Direct3D;

 

namespace Chapter5Code

{

     /// <summary>

     /// Summary description for Form1.

     /// </summary>

     public class Form1 : System.Windows.Forms.Form

     {

        private Device device = null;

         PresentParameters presentParams =null;

        private Mesh mesh = null;

        private Material[] meshMaterials;

        private Texture[] meshTextures;

 

         private Mesh mesh2=null;

         Material[] meshMaterials2;

         Texture[] meshTextures2;

 

        string status=null; //小车状态,向左转动还是向右转动,或者停止

         private VertexBuffer vb = null;

         Vector3 pos;

         Vector3 lookat;

 

         int camera=1;

         float angle=0.0f;

         float v=0.1f;

         float offsetx=0.1f;

 

         /// <summary>

         /// Required designer variable.

         /// </summary>

         private System.ComponentModel.Container components = null;

 

         public Form1()

         {

              //

              // Required for Windows Form Designer support

              //

              InitializeComponent();

 

            this.SetStyle(ControlStyles.AllPaintingInWmPaint | ControlStyles.Opaque, true);

         }

 

        /// <summary>

        /// We will initialize our graphics device here

        /// </summary>

        public void InitializeGraphics()

        {

            // Set our presentation parameters

            PresentParameters presentParams = new PresentParameters();

 

            presentParams.Windowed = true;

            presentParams.SwapEffect = SwapEffect.Discard;

            presentParams.AutoDepthStencilFormat = DepthFormat.D16;

            presentParams.EnableAutoDepthStencil = true;

 

            // Create our device

            device = new Device(0, DeviceType.Hardware, this, CreateFlags.SoftwareVertexProcessing, presentParams);

            // Load our mesh

             LoadMesh(@"..\..\sr.x");

 

              vb=mesh.VertexBuffer; //取得读入mesh的中心

              try

              {

                   Vector3 max;

                   Vector3 min;

                   GraphicsStream gs = vb.Lock(0, 0, LockFlags.None);

                   Geometry.ComputeBoundingBox(gs, mesh.NumberVertices, mesh.VertexFormat, out min, out max);

                   float tx = (max.X - min.X)/2;

                   float ty =( max.Y - min.Y)/2;

                   float tz =( max.Z - min.Z);

                   pos.X =tx-0.9f;

                   pos.Y =ty+0.6f;

                   pos.Z =tz-1.8f;

                   //float cameraHeadingH=

                   lookat = new Vector3 (0,0,1);

 

              }

              finally

              {

                   vb.Unlock();

                   vb.Dispose();

              }

        }

 

        private void LoadMesh(string file)

        {

            ExtendedMaterial[] mtrl;

 

            // Load our mesh

            mesh = Mesh.FromFile(file, MeshFlags.Managed, device, out mtrl);

             // If we have any materials, store them

            if ((mtrl != null) && (mtrl.Length > 0))

            {

                meshMaterials = new Material[mtrl.Length];

                meshTextures = new Texture[mtrl.Length];

 

                // Store each material and texture

                for (int i = 0; i < mtrl.Length; i++)

                {

                    meshMaterials[i] = mtrl[i].Material3D;

                    if ((mtrl[i].TextureFilename != null) && (mtrl[i].TextureFilename != string.Empty))

                    {

                        // We have a texture, try to load it

                        meshTextures[i] = TextureLoader.FromFile(device, @"..\..\" + mtrl[i].TextureFilename);

                    }

                }

            }

        }

 

 

 

         protected override void OnKeyDown(System.Windows.Forms.KeyEventArgs e)

         {

              // Handle the escape key for quiting

              if (e.KeyCode == Keys.Escape)

              {

                   // Close the form and return

                   this.Close();

                   return;

              }

              // Handle left and right keys

              else if ((e.KeyCode == Keys.Left) || (e.KeyCode == Keys.NumPad4))

              {

                   status="left";

              }

              else if ((e.KeyCode == Keys.Right) || (e.KeyCode == Keys.NumPad6))

              {

                   status="right";

              }

              else if((e.KeyCode ==Keys.Up )||(e.KeyCode ==Keys.NumPad8 ))

              {

                   status="up";

              }

              else if((e.KeyCode ==Keys.Down  )||(e.KeyCode ==Keys.NumPad2 ))

              {

                   status="down";

              }

              else if(e.KeyCode ==Keys.Enter)

              {

                   status="stop";

              }

              else if(e.KeyCode ==Keys.W  )

              {

                   status="goahead";

 

              }

              else if(e.KeyCode ==Keys.S )

              {

                   status="goback";

              }

              else if(e.KeyCode ==Keys.A)

              {

                   status="goleft";

              }

              else if(e.KeyCode ==Keys.D )

              {

                   status="goright";

              }

              else if(e.KeyCode ==Keys.C)

              {

                   camera++;

              }

 

             

 

         }

 

        private void SetupCamera(float deep )

        {

            device.Transform.Projection = Matrix.PerspectiveFovLH((float)Math.PI / 4, this.Width / this.Height, 1.0f, 10000.0f);

              if(camera%2!=0)

                device.Transform.View = Matrix.LookAtLH(new Vector3(0,0, 10.0f+deep), new Vector3(), new Vector3(0,1,0));

              else

                   device.Transform .View =Matrix.LookAtLH (pos,new Vector3 (0,1,0),new Vector3 (0,1,0));

 

            //device.RenderState.Ambient = Color.DarkBlue;

            device.Lights[0].Type = LightType.Directional;

            device.Lights[0].Diffuse = Color.White;

            device.Lights[0].Direction = new Vector3(0, -1, -1);

            device.Lights[0].Update();

            device.Lights[0].Enabled = true;

 

        }

 

        protected override void OnPaint(System.Windows.Forms.PaintEventArgs e)

        {

            device.Clear(ClearFlags.Target | ClearFlags.ZBuffer, Color.CornflowerBlue, 1.0f, 0);

 

            SetupCamera(v );

 

            device.BeginScene();

 

            // Draw our Mesh

            DrawMesh(status);

 

            device.EndScene();

 

            device.Present();

 

            this.Invalidate();

        }

 

        private void DrawMesh(string stat)

        {

         //   angle += 0.01f;

 

        //    device.Transform.World = Matrix.RotationYawPitchRoll(yaw, pitch, roll) * Matrix.Translation(x, y, z);

              if(stat=="left")

              {

                   angle=angle+0.1f;

                   device.Transform.World = Matrix.RotationY (angle);

              }

              else if(stat=="right")

              {

                   angle=angle-0.1f;

                   device.Transform.World = Matrix.RotationY (angle);

              }

              else if(stat=="up")

              {

                   angle=angle+0.1f;

                   device.Transform.World = Matrix.RotationX (angle);

 

 

              }

              else if(stat=="down")

              {

                   angle=angle-0.1f;

                   device.Transform.World = Matrix.RotationX (angle);

 

              }

              else if(stat=="stop")

              {

                   angle=0.0f;

                   //device.Reset ()

              }

              else if(stat=="goahead")

              {

                   v=v+0.1f;

              }

              else if(stat=="goback")

              {

                   v=v-0.1f;

              }

              else if(stat=="goleft")

              {

                   offsetx=offsetx+0.001f;

 

                   device.Transform.World = Matrix.Translation(offsetx,0,0);

                   //device.Transform .View =Matrix.Translation(offsetx,0,0);

              //   pos.X -=offsetx;

              //   device.Transform .View =Matrix.LookAtLH(pos,new Vector3 (0,0,1),new Vector3 (0,1,0));

              }

              else if(stat=="goright")

              {

                   offsetx=offsetx-0.001f;

                   device.Transform.World = Matrix.Translation(offsetx,0,0);

 

 

              }

 

 

            for (int i = 0; i < meshMaterials.Length; i++)

            {

                device.Material = meshMaterials[i];

                device.SetTexture(0, meshTextures[i]);

                mesh.DrawSubset(i);

            }

        }

 

        /// <summary>

         /// Clean up any resources being used.

         /// </summary>

         protected override void Dispose( bool disposing )

         {

              if( disposing )

              {

                   if (components != null)

                   {

                       components.Dispose();

                  }

              }

              base.Dispose( disposing );

         }

 

         #region Windows Form Designer generated code

         /// <summary>

         /// Required method for Designer support - do not modify

         /// the contents of this method with the code editor.

         /// </summary>

         private void InitializeComponent()

         {

              this.components = new System.ComponentModel.Container();

              this.Size = new Size(800,600);

              this.Text = "Form1";

         }

         #endregion

 

         /// <summary>

         /// The main entry point for the application.

         /// </summary>

        static void Main()

        {

            using (Form1 frm = new Form1())

            {

                // Show our form and initialize our graphics engine

                frm.Show();

                frm.InitializeGraphics();

                Application.Run(frm);

            }

        }

     }

}

 

好累,结束。

By sssa2000

4/18/2005

posted on 2005-04-18 23:46  大河马和小魔鱼  阅读(1594)  评论(1编辑  收藏  举报