Direct3D 地形
高程图生成三角形网格
3D场景的模拟离不开地形，因此3D地形的模拟在3D程序设计中很重要。在3D场景中，地形的表面都是通过三角形网来表示，即通过高度图（也称影像图）上的对应坐标值来表示规则网格顶点坐标值，从而形成规则的矩阵分布三角网。具体的实现就是通过读取高度图上象元的值来获取该坐标位置的高程，然后根据这些高程值及坐标值形成一个规则的三角网。由于在三角网中相邻三角形都具有公共点，所以为了节约内存可以采用索引编号的方式来实现。在DirectX 中提供了一个VertexBuffer 类用于操作顶点缓冲资源，通过它可以指定使用硬件或软件来处理顶点缓冲方式。在DirectX中还提供了一个IndexBuffer 类用于处理索引缓冲，索引缓冲是用于保存索引的内存资源，使用索引缓冲可以避免不必要重复资源在内存中出现。所以在具体实现时，首先在全局中定义三个变量，分别为顶点缓冲变量、索引缓冲变量和索引号变量，然后可以在定义顶点函数中添加顶点缓冲及顶点的定义，再设定横向三角形单元数目和纵向三角形单元数目以及单元宽度和高度来生成三角形网络。通常高度图都用bmp 格式来保存，在Visual C#中系统提供了一个System.Drawing.Bitmap类用于读取和显示Bitmap图形，该类也提供了很多属性和方法，如获取图片宽度和高度的方法分别为Width和Height，还有获取图片中指定位置的颜色的方法Bitmap.GetPixel()等等。而通过高度图生成三角网主要是先根据高度图的尺寸设置生成三角网中横向和纵向单元数目以及单元尺寸，然后通过读取图片上的像素值来设置高程。具体的实现就可以通过Bitmap类获得BMP图片对象，然后根据其Width属性和Height属性设置生成三角网中横向和纵向单元数，同时设置单元尺寸，在设置高程值中通过获取图片中相应位置的颜色值，然后通过一个相对比例得到一个相对的高程值，最后将该值赋予定义的顶点坐标值。以一个火山的高程图为例，同时响应响应的鼠标操作，以实现拖拽旋转功能。先附上几张效果图如下：
编码实现如下：
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using Microsoft.DirectX;
using Microsoft.DirectX.Direct3D;
namespace HeightMap
{
public partial class MainForm : Form
{
Device m_device = null;
private VertexBuffer vertextBuffer;//定义顶点缓冲变量
private IndexBuffer indexBuffer;//定义索引缓冲变量
private int[] indices;//定义索引号变量
private CustomVertex.PositionColored[] vertices;//定义顶点变量
private int xCount = 5, yCount = 4;//定义横向和纵向网格数目
private float cellHeight = 1f, cellWidth = 1f;//定义单元的宽度和长度
public Vector3 CamPostion = new Vector3(0, 100, 100);//定义摄像机位置
public Vector3 CamTarget = new Vector3(125, 30, 125);//定义摄像机目标位置
private float angleY = 0.01f;//定义绕Y轴旋转变量
private int mouseLastX, mouseLastY;//记录鼠标按下时的坐标位置
private bool isRotateByMouse = false;//记录是否由鼠标控制旋转
private bool isMoveByMouse = false;//记录是否由鼠标控制移动
public MainForm()
{
InitializeComponent();
}
public bool InitializeGraphics()
{
try
{
PresentParameters presentParams = new PresentParameters();
presentParams.Windowed = true;
presentParams.SwapEffect = SwapEffect.Discard;
presentParams.AutoDepthStencilFormat = DepthFormat.D16;
presentParams.EnableAutoDepthStencil = true;
//presentParams.PresentationInterval = PresentInterval.Immediate;
m_device = new Device(0,
DeviceType.Hardware,
this,
CreateFlags.SoftwareVertexProcessing,
presentParams);
m_device.DeviceReset += new System.EventHandler(this.OnResetDevice);
this.OnCreateDevice(m_device, null);
this.OnResetDevice(m_device, null);
}
catch (DirectXException e)
{
MessageBox.Show(e.ToString(), "Error");
return false;
}
return true;
}
public void OnCreateDevice(object sender, EventArgs e)
{
}
public void OnResetDevice(object sender,EventArgs e)
{
Device dev = (Device)sender;
dev.RenderState.CullMode = Cull.None;
dev.RenderState.FillMode = FillMode.WireFrame;//设置以三角网的形式显示
dev.RenderState.Lighting = false;
//SetupMatrices();
//Device dev = (Device)sender;
string szBitmapPath = @"F:\\workdir\\VC# Based DirectX\\heightMap.BMP";
Bitmap bitMap = new Bitmap(szBitmapPath);
xCount = (bitMap.Width - 1) / 2;
yCount = (bitMap.Height - 1) / 2;
cellWidth = bitMap.Width / xCount;
cellHeight = bitMap.Height / yCount;
vertextBuffer = new VertexBuffer(typeof(CustomVertex.PositionColored),
(xCount + 1) * (yCount + 1),
dev,
Usage.Dynamic | Usage.WriteOnly,
CustomVertex.PositionColored.Format,
Pool.Default);
vertices = new CustomVertex.PositionColored[(xCount + 1) * (yCount + 1)];
for (int i = 0; i < yCount + 1; i++)
for (int j = 0; j < xCount + 1; j++)
{
Color color = bitMap.GetPixel((int)(j * cellWidth), (int)(i * cellHeight));
float height = float.Parse(color.R.ToString()) + float.Parse(color.G.ToString()) + float.Parse(color.B.ToString());
height /= 10;
vertices[j + i * (xCount + 1)].Position = new Vector3(j * cellWidth, height, i * cellHeight);
vertices[j + i * (xCount + 1)].Color = Color.White.ToArgb();
}
vertextBuffer.SetData(vertices, 0, LockFlags.None);
indexBuffer = new IndexBuffer(typeof(int),
6 * xCount * yCount,
dev,
Usage.WriteOnly,
Pool.Default);
indices = new int[6 * xCount * yCount];
for (int i = 0; i < yCount; i++)
{
for (int j = 0; j < xCount; j++)
{
indices[6 * (j + i * xCount)] = j + i * (xCount + 1);
indices[6 * (j + i * xCount) + 1] = j + (i + 1) * (xCount + 1);
indices[6 * (j + i * xCount) + 2] = j + i * (xCount + 1) + 1;
indices[6 * (j + i * xCount) + 3] = j + i * (xCount + 1) + 1;
indices[6 * (j + i * xCount) + 4] = j + (i + 1) * (xCount + 1);
indices[6 * (j + i * xCount) + 5] = j + (i + 1) * (xCount + 1) + 1;
}
}
indexBuffer.SetData(indices, 0, LockFlags.None);
//SetupMatrices();
}
private void SetupMatrices()
{
m_device.Transform.World = Matrix.RotationY(0);
Matrix viewMatrix = Matrix.LookAtLH(
CamPostion,
CamTarget,
new Vector3(0.0f, 1.0f, 0.0f));
m_device.Transform.View = viewMatrix;
m_device.Transform.Projection = Matrix.PerspectiveFovLH(
(float)Math.PI / 4,
this.Width / this.Height,
0.3f, 500.0f);
}
/**
* 通过Bitmap类获得BMP图片对象，然后根据其Width属性和Height属性设置生成三角网中横向和纵向单元数，
* 同时设置单元尺寸，在设置高程值中通过获取图片中相应位置的颜色值，
* 然后通过一个相对比例得到一个相对的高程值，最后将该值赋予定义的顶点坐标值
*/
private void VertexDeclaration()
{
string szBitmapPath = @"F:\\workdir\\VC# Based DirectX\\heightMap.BMP";
Bitmap bitMap = new Bitmap(szBitmapPath);
xCount = (bitMap.Width - 1) / 2;
yCount = (bitMap.Height - 1) / 2;
cellWidth = bitMap.Width / xCount;
cellHeight = bitMap.Height / yCount;
vertextBuffer = new VertexBuffer(typeof(CustomVertex.PositionColored),
(xCount + 1) * (yCount + 1),
m_device,
Usage.Dynamic | Usage.WriteOnly,
CustomVertex.PositionColored.Format,
Pool.Default);
vertices = new CustomVertex.PositionColored[(xCount + 1) * (yCount + 1)];
for(int i=0;i三角形网格纹理贴图
为了显示更加地逼真，可以为其添加纹理。首先导入贴图，然后设置顶点为PositionTextured 类型，定义贴图、材质等变量，同时在定义顶点时设置顶点所对应的贴图坐标。为了避免离摄像机远的图形覆盖了离摄像机近的图形，需要设置深度缓冲，即在图形渲染时按照深度来进行渲染。同样先附上几张效果图：
可以在上一个例子的基础上，稍微修改即可，整个编码实现如下：
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using Microsoft.DirectX;
using Microsoft.DirectX.Direct3D;
namespace 高程图01
{
public partial class MainForm : Form
{
private Device device = null;//定义绘图设备
bool pause = false;
public Vector3 CamPostion = new Vector3(0, 100, 100);//定义摄像机位置
public Vector3 CamTarget = new Vector3(125, 30, 125);//定义摄像机目标位置
private float angleY = 0.01f;//定义绕Y轴旋转变量
private int mouseLastX, mouseLastY;//记录鼠标按下时的坐标位置
private bool isRotateByMouse = false;//记录是否由鼠标控制旋转
private bool isMoveByMouse = false;//记录是否由鼠标控制移动
private CustomVertex.PositionTextured[] vertices;//定义顶点变量
private Texture texture;//定义贴图变量
private Material material;//定义材质变量
private VertexBuffer vertexBuffer;//定义顶点缓冲变量
private IndexBuffer indexBuffer;//定义索引缓冲变量
private int[] indices;//定义索引号变量
private int xCount = 5, yCount = 4;//定义横向和纵向网格数目
private float cellHeight = 1f, cellWidth = 1f;//定义单元的宽度和长度
public MainForm()
{
InitializeComponent();
}
public bool InitializeDirect3D()
{
try
{
PresentParameters presentParams = new PresentParameters();
presentParams.Windowed = true; //指定以Windows窗体形式显示
presentParams.SwapEffect = SwapEffect.Discard; //当前屏幕绘制后它将自动从内存中删除
presentParams.AutoDepthStencilFormat = DepthFormat.D16;
presentParams.EnableAutoDepthStencil = true;
presentParams.PresentationInterval = PresentInterval.Immediate;
device = new Device(0, DeviceType.Hardware, this, CreateFlags.SoftwareVertexProcessing, presentParams); //实例化device对象
device.DeviceReset += new System.EventHandler(this.OnResetDevice);
this.OnCreateDevice(device, null);
this.OnResetDevice(device, null);
}
catch (DirectXException e)
{
MessageBox.Show(e.ToString(), "Error"); //处理异常
return false;
}
return true;
}
//导入贴图和材质
public void OnCreateDevice(object sender, EventArgs e)
{
Device device = (Device)sender;
material = new Material();
material.Diffuse = Color.White;
material.Specular = Color.LightGray;
material.SpecularSharpness = 15.0F;
device.Material = material;
texture = TextureLoader.FromFile(device, @"F:\\workdir\\VC# Based DirectX\\texture.jpg");
}
/**
* 通过Bitmap类获得BMP图片对象，然后根据其Width属性和Height属性设置生成三角网中横向和纵向单元数，
* 同时设置单元尺寸，在设置高程值中通过获取图片中相应位置的颜色值，
* 然后通过一个相对比例得到一个相对的高程值，最后将该值赋予定义的顶点坐标值
*/
public void OnResetDevice(object sender, EventArgs e)
{
Device device = (Device)sender;
string bitmapPath = @"F:\\workdir\\VC# Based DirectX\\height.BMP";
Bitmap bitmap = new Bitmap(bitmapPath);
xCount = (bitmap.Width - 1) / 2;
yCount = (bitmap.Height - 1) / 2;
cellWidth = bitmap.Width / xCount;
cellHeight = bitmap.Height / yCount;
vertexBuffer = new VertexBuffer(typeof(CustomVertex.PositionTextured), (xCount + 1) * (yCount + 1), device,
Usage.Dynamic | Usage.WriteOnly, CustomVertex.PositionColored.Format, Pool.Default);
vertices = new CustomVertex.PositionTextured[(xCount + 1) * (yCount + 1)];//定义顶点
for (int i = 0; i < yCount + 1; i++)
{
for (int j = 0; j < xCount + 1; j++)
{
Color color = bitmap.GetPixel((int)(j * cellWidth), (int)(i * cellHeight));
float height = float.Parse(color.R.ToString()) + float.Parse(color.G.ToString()) + float.Parse(color.B.ToString());
height /= 10;
vertices[j + i * (xCount + 1)].Position = new Vector3(j * cellWidth, height, i * cellHeight);
vertices[j + i * (xCount + 1)].Tu = (float)j / (xCount + 1);
vertices[j + i * (xCount + 1)].Tv = (float)i / (yCount + 1);
}
}
vertexBuffer.SetData(vertices, 0, LockFlags.None);
CamTarget = new Vector3(bitmap.Width / 2, 0f, bitmap.Height / 2);//设置摄像机目标位置
indexBuffer = new IndexBuffer(typeof(int), 6 * xCount * yCount, device, Usage.WriteOnly, Pool.Default);
indices = new int[6 * xCount * yCount];
for (int i = 0; i < yCount; i++)
{
for (int j = 0; j < xCount; j++)
{
indices[6 * (j + i * xCount)] = j + i * (xCount + 1);
indices[6 * (j + i * xCount) + 1] = j + (i + 1) * (xCount + 1);
indices[6 * (j + i * xCount) + 2] = j + i * (xCount + 1) + 1;
indices[6 * (j + i * xCount) + 3] = j + i * (xCount + 1) + 1;
indices[6 * (j + i * xCount) + 4] = j + (i + 1) * (xCount + 1);
indices[6 * (j + i * xCount) + 5] = j + (i + 1) * (xCount + 1) + 1;
}
}
indexBuffer.SetData(indices, 0, LockFlags.None);
device.SamplerState[0].MagFilter = TextureFilter.Linear;//使用纹理滤波器进行线性滤波
}
public void Render()//渲染
{
if (device == null) //如果device为空则不渲染
return;
if (pause) //如果窗口被切换或者最小化则停止渲染，减少CPU压力
return;
Matrix viewMatrix = Matrix.LookAtLH(CamPostion, CamTarget, new Vector3(0, 1, 0));
device.Transform.Projection = Matrix.PerspectiveFovLH((float)Math.PI / 4, this.Width / this.Height, 0.3f, 500f);
device.Transform.View = viewMatrix;
device.Clear(ClearFlags.Target | ClearFlags.ZBuffer, Color.DarkSlateBlue, 1.0f, 0); //清除windows界面为深蓝色
device.BeginScene();
//在此添加渲染图形代码
device.RenderState.CullMode = Cull.None;
device.RenderState.FillMode = FillMode.Solid;
device.RenderState.Lighting = false;
device.SetTexture(0, texture);//设置贴图
device.VertexFormat = CustomVertex.PositionTextured.Format;
device.SetStreamSource(0, vertexBuffer, 0);
device.Indices = indexBuffer;
device.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, (xCount + 1) * (yCount + 1), 0, indices.Length / 3);
device.EndScene();
device.Present();
}
private void Form1_Load(object sender, EventArgs e)
{
InitializeDirect3D();
this.Show();
Render();
}
private void OnKeyDown(object sender, KeyEventArgs e)
{
Vector4 tempV4;
Matrix currentView = device.Transform.View;//当前摄像机的视图矩阵
switch (e.KeyCode)
{
case Keys.Left:
CamPostion.Subtract(CamTarget);
tempV4 = Vector3.Transform(CamPostion, Matrix.RotationQuaternion(
Quaternion.RotationAxis(new Vector3(currentView.M12, currentView.M22, currentView.M32), -angleY)));
CamPostion.X = tempV4.X + CamTarget.X;
CamPostion.Y = tempV4.Y + CamTarget.Y;
CamPostion.Z = tempV4.Z + CamTarget.Z;
break;
case Keys.Right:
CamPostion.Subtract(CamTarget);
tempV4 = Vector3.Transform(CamPostion, Matrix.RotationQuaternion(
Quaternion.RotationAxis(new Vector3(currentView.M12, currentView.M22, currentView.M32), angleY)));
CamPostion.X = tempV4.X + CamTarget.X;
CamPostion.Y = tempV4.Y + CamTarget.Y;
CamPostion.Z = tempV4.Z + CamTarget.Z;
break;
case Keys.Up:
CamPostion.Subtract(CamTarget);
tempV4 = Vector3.Transform(CamPostion, Matrix.RotationQuaternion(
Quaternion.RotationAxis(new Vector3(device.Transform.View.M11
, device.Transform.View.M21, device.Transform.View.M31), -angleY)));
CamPostion.X = tempV4.X + CamTarget.X;
CamPostion.Y = tempV4.Y + CamTarget.Y;
CamPostion.Z = tempV4.Z + CamTarget.Z;
break;
case Keys.Down:
CamPostion.Subtract(CamTarget);
tempV4 = Vector3.Transform(CamPostion, Matrix.RotationQuaternion(
Quaternion.RotationAxis(new Vector3(device.Transform.View.M11
, device.Transform.View.M21, device.Transform.View.M31), angleY)));
CamPostion.X = tempV4.X + CamTarget.X;
CamPostion.Y = tempV4.Y + CamTarget.Y;
CamPostion.Z = tempV4.Z + CamTarget.Z;
break;
case Keys.Add:
CamPostion.Subtract(CamTarget);
CamPostion.Scale(0.95f);
CamPostion.Add(CamTarget);
break;
case Keys.Subtract:
CamPostion.Subtract(CamTarget);
CamPostion.Scale(1.05f);
CamPostion.Add(CamTarget);
break;
}
Matrix viewMatrix = Matrix.LookAtLH(CamPostion, CamTarget, new Vector3(0, 1, 0));
device.Transform.View = viewMatrix;
Render();
}
private void Form1_Paint(object sender, PaintEventArgs e)
{
this.Render();
}
private void OnMouseDown(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
mouseLastX = e.X;
mouseLastY = e.Y;
isRotateByMouse = true;
}
else if (e.Button == MouseButtons.Middle)
{
mouseLastX = e.X;
mouseLastY = e.Y;
isMoveByMouse = true;
}
}
private void OnMouseUp(object sender, MouseEventArgs e)
{
isRotateByMouse = false;
isMoveByMouse = false;
}
private void OnMouseMove(object sender, MouseEventArgs e)
{
if (isRotateByMouse)
{
Matrix currentView = device.Transform.View;//当前摄像机的视图矩阵
float tempAngleY = 2 * (float)(e.X - mouseLastX) / this.Width;
CamPostion.Subtract(CamTarget);
Vector4 tempV4 = Vector3.Transform(CamPostion, Matrix.RotationQuaternion(
Quaternion.RotationAxis(new Vector3(currentView.M12, currentView.M22, currentView.M32), tempAngleY)));
CamPostion.X = tempV4.X;
CamPostion.Y = tempV4.Y;
CamPostion.Z = tempV4.Z;
float tempAngleX = 4 * (float)(e.Y - mouseLastY) / this.Height;
tempV4 = Vector3.Transform(CamPostion, Matrix.RotationQuaternion(
Quaternion.RotationAxis(new Vector3(currentView.M11, currentView.M21, currentView.M31), tempAngleX)));
CamPostion.X = tempV4.X + CamTarget.X;
CamPostion.Y = tempV4.Y + CamTarget.Y;
CamPostion.Z = tempV4.Z + CamTarget.Z;
Matrix viewMatrix = Matrix.LookAtLH(CamPostion, CamTarget, new Vector3(0, 1, 0));
device.Transform.View = viewMatrix;
mouseLastX = e.X;
mouseLastY = e.Y;
Render();
}
else if (isMoveByMouse)
{
Matrix currentView = device.Transform.View;//当前摄像机的视图矩阵
float moveFactor = 0.01f;
CamTarget.X += -moveFactor * ((e.X - mouseLastX) * currentView.M11 - (e.Y - mouseLastY) * currentView.M12);
CamTarget.Y += -moveFactor * ((e.X - mouseLastX) * currentView.M21 - (e.Y - mouseLastY) * currentView.M22);
CamTarget.Z += -moveFactor * ((e.X - mouseLastX) * currentView.M31 - (e.Y - mouseLastY) * currentView.M32);
CamPostion.X += -moveFactor * ((e.X - mouseLastX) * currentView.M11 - (e.Y - mouseLastY) * currentView.M12);
CamPostion.Y += -moveFactor * ((e.X - mouseLastX) * currentView.M21 - (e.Y - mouseLastY) * currentView.M22);
CamPostion.Z += -moveFactor * ((e.X - mouseLastX) * currentView.M31 - (e.Y - mouseLastY) * currentView.M32);
Matrix viewMatrix = Matrix.LookAtLH(CamPostion, CamTarget, new Vector3(0, 1, 0));
device.Transform.View = viewMatrix;
mouseLastX = e.X;
mouseLastY = e.Y;
Render();
}
}
private void OnMouseWheel(object sender, MouseEventArgs e)
{
float scaleFactor = -(float)e.Delta / 2000 + 1f;
CamPostion.Subtract(CamTarget);
CamPostion.Scale(scaleFactor);
CamPostion.Add(CamTarget);
Matrix viewMatrix = Matrix.LookAtLH(CamPostion, CamTarget, new Vector3(0, 1, 0));
device.Transform.View = viewMatrix;
Render();
}
private void Form1_Resize(object sender, EventArgs e)//窗口切换时停止渲染
{
pause = ((this.WindowState == FormWindowState.Minimized) || !this.Visible);
}
}
}
Ref:
基于 Visual C# 的DirectX开发实例
Direct 3D和XNA游戏开发基础
CodeProject
http://www.codeproject.com/Articles/11681/D-Terrain-Visualisation-in-Managed-DirectX-and
在CodeProject上意外发现了一个很有意思的道路轨迹编辑器，感兴趣可以自己研究一下，用了两个第三方的库文件。
http://www.codeproject.com/Articles/30620/A-C-Track-Editor