WPF 3D 小小小小引擎

　　下面給大家演示的是使用在WPF 3D上實(shí)現(xiàn)視角變換，通過(guò)鼠標(biāo)拖動(dòng)來(lái)變換觀察視角，通過(guò)滾輪來(lái)放縮視距。

　　有關(guān)3D的基礎(chǔ)知識(shí)可以參考MSDN文檔：三維圖形概述

　　首先創(chuàng)建一個(gè)3D立方體，立方體是由六個(gè)面構(gòu)成(F1, F2 ....F6)其XAML代碼如下：

<Viewport3D>

    <Viewport3D.Camera>

        <PerspectiveCamera Position="8,8,8" LookDirection="-1 -1 -1"
 FieldOfView="75" UpDirection="-1 1 -1" x:Name="camera"></PerspectiveCamera>

    </Viewport3D.Camera>

    <Viewport3D.Children>

        <ModelVisual3D x:Name="light">

            <ModelVisual3D.Content>

                <AmbientLight />

            </ModelVisual3D.Content>

        </ModelVisual3D>

        <ModelVisual3D x:Name="magicCube">

            <ModelVisual3D.Content>

                <!--    0: 0,0,0    1: 0,0,2    2: 2,0,2    
3: 2,0,0    4: 2,2,0    5: 0,2,0    6: 0,2,2    7: 2,2,2    -->

                <Model3DGroup x:Name="cube">

                    <Model3DGroup.Transform>

                        <TranslateTransform3D OffsetX="-1" OffsetY="-1" OffsetZ="-1" />

                    </Model3DGroup.Transform>

                    <!--F1: 0,3,2,1-->

                    <GeometryModel3D x:Name="F1">

                        <GeometryModel3D.Material>

                            <DiffuseMaterial Brush="Blue"/>

                        </GeometryModel3D.Material>

                        <GeometryModel3D.Geometry>

                            <MeshGeometry3D Positions="0,0,0 2,0,0 2,0,2 0,0,2" 
TriangleIndices="0,1,2 0,2,3"></MeshGeometry3D>

                        </GeometryModel3D.Geometry>

                    </GeometryModel3D>

                    <!--F2: 0,1,6,5-->

                    <GeometryModel3D x:Name="F2">

                        <GeometryModel3D.Material>

                            <DiffuseMaterial Brush="Green"/>

                        </GeometryModel3D.Material>

                        <GeometryModel3D.Geometry>

                            <MeshGeometry3D Positions="0,0,0 0,0,2 0,2,2 0,2,0" 
TriangleIndices="0 1 2 0 2 3"></MeshGeometry3D>

                        </GeometryModel3D.Geometry>

                    </GeometryModel3D>

                    <!--F3: 4,5,6,7-->

                    <GeometryModel3D x:Name="F3">

                        <GeometryModel3D.Material>

                            <DiffuseMaterial Brush="Red"/>

                        </GeometryModel3D.Material>

                        <GeometryModel3D.Geometry>

                            <MeshGeometry3D Positions="2,2,0 0,2,0 0,2,2 2,2,2" 
TriangleIndices="0 1 2 0 2 3"></MeshGeometry3D>

                        </GeometryModel3D.Geometry>

                    </GeometryModel3D>

                    <!--F4: 2,3,4,7-->

                    <GeometryModel3D x:Name="F4">

                        <GeometryModel3D.Material>

                            <DiffuseMaterial Brush="Yellow"/>

                        </GeometryModel3D.Material>

                        <GeometryModel3D.Geometry>

                            <MeshGeometry3D Positions="2,0,2 2,0,0 2,2,0 2,2,2" 
TriangleIndices="0 1 2 0 2 3" TextureCoordinates="0,0 0,1 1,1 1,0">

                            </MeshGeometry3D>

                        </GeometryModel3D.Geometry>

                    </GeometryModel3D>

                    <!--F5: 1,2,7,6-->

                    <GeometryModel3D x:Name="F5">

                        <GeometryModel3D.Material>

                            <DiffuseMaterial Brush="White"/>

                        </GeometryModel3D.Material>

                        <GeometryModel3D.Geometry>

                            <MeshGeometry3D Positions=" 0,0,2 2,0,2 2,2,2 0,2,2" 
TriangleIndices="0 1 2 0 2 3"></MeshGeometry3D>

                        </GeometryModel3D.Geometry>

                    </GeometryModel3D>

                    <!--F6: 0,5,4,3-->

                    <GeometryModel3D x:Name="F6">

                        <GeometryModel3D.Material>

                            <DiffuseMaterial Brush="Orange"/>

                        </GeometryModel3D.Material>

                        <GeometryModel3D.Geometry>

                            <MeshGeometry3D Positions=" 0,0,0 0,2,0 2,2,0 2,0,0" 
TriangleIndices="0 1 2 0 2 3"></MeshGeometry3D>

                        </GeometryModel3D.Geometry>

                    </GeometryModel3D>

                </Model3DGroup>

            </ModelVisual3D.Content>

        </ModelVisual3D>

    </Viewport3D.Children>

</Viewport3D>
     nbsp;

在Viewport中用六個(gè)面構(gòu)成一個(gè)立方體，每一個(gè)面都是一個(gè)GeometryModel3D。

　　下面就是如何來(lái)實(shí)現(xiàn)通過(guò)鼠標(biāo)拖動(dòng)來(lái)變換視角的功能。首先給Window對(duì)象添加幾個(gè)有關(guān)的鼠標(biāo)的事件：MouseMove、MouseLeftButtonDown和MouseWheel。

<Window x:Class="MagicCube.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

Title="MainWindow" Height="295" Width="525" Background="Black" 

MouseMove="Viewport3D_MouseMove" 

MouseLeftButtonDown="Viewport3D_MouseLeftButtonDown"

MouseWheel="Viewport3D_MouseWheel"

KeyDown="Window_KeyDown">

<Viewport3D …>

</Window>

　　說(shuō)明一下使用到的幾個(gè)變量：

　　其中MouseLeftButtonDown是用來(lái)獲取鼠標(biāo)在進(jìn)入拖動(dòng)狀態(tài)之前的位置，這樣我們就可以根據(jù)鼠標(biāo)位置的改變類變換視角。

Point mouseLastPosition;
private void Viewport3D_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)

{

mouseLastPosition = e.GetPosition(this);

}

　　下面是MouseMove事件，實(shí)現(xiàn)視角的變換。首先鼠標(biāo)在拖動(dòng)的過(guò)程中，可能發(fā)生水平方向上的變化和垂直方向上的變化，所以，我們將對(duì)不同的變化方向進(jìn)行不同的變換。這里我將水平變換和垂直變換已經(jīng)分別封裝至兩個(gè)方法中：HorizontalTransform(水平變換)和VerticalTransform(垂直變換)

private void Viewport3D_MouseMove(object sender, MouseEventArgs e)

{

if (Mouse.LeftButton == MouseButtonState.Pressed)

{

Point newMousePosition = e.GetPosition(this); 

if (mouseLastPosition.X != newMousePosition.X)

{

HorizontalTransform(mouseLastPosition.X < newMousePosition.X, mouseDeltaFactor);//水平變換

} 

if (mouseLastPosition.Y != newMousePosition.Y)// change position in the horizontal direction

{ 

VerticalTransform(mouseLastPosition.Y > newMousePosition.Y, mouseDeltaFactor);//垂直變換 

}

mouseLastPosition = newMousePosition;

}

}

　　接下來(lái)我們就來(lái)看一下這兩個(gè)變換方法的具體實(shí)現(xiàn)：

　　垂直變換：

private void VerticalTransform(bool upDown, double angleDeltaFactor)
{
Vector3D postion = new Vector3D(camera.Position.X, camera.Position.Y, camera.Position.Z);
Vector3D rotateAxis = Vector3D.CrossProduct(postion, camera.UpDirection);
RotateTransform3D rt3d = new RotateTransform3D();
AxisAngleRotation3D rotate = new AxisAngleRotation3D(rotateAxis, angleDeltaFactor * (upDown ? -1 : 1));
rt3d.Rotation = rotate;
Matrix3D matrix = rt3d.Value;
Point3D newPostition = matrix.Transform(camera.Position);
camera.Position = newPostition;
camera.LookDirection = new Vector3D(-newPostition.X, -newPostition.Y, -newPostition.Z);

//update the up direction
Vector3D newUpDirection = Vector3D.CrossProduct(camera.LookDirection, rotateAxis);
newUpDirection.Normalize();
camera.UpDirection = newUpDirection;
}

　　水平變換：

private void HorizontalTransform(bool leftRight, double angleDeltaFactor)
{
Vector3D postion = new Vector3D(camera.Position.X, camera.Position.Y, camera.Position.Z);
Vector3D rotateAxis = camera.UpDirection;
RotateTransform3D rt3d = new RotateTransform3D();
AxisAngleRotation3D rotate = new AxisAngleRotation3D(rotateAxis, angleDeltaFactor * (leftRight ? -1 : 1));
rt3d.Rotation = rotate;
Matrix3D matrix = rt3d.Value;
Point3D newPostition = matrix.Transform(camera.Position);
camera.Position = newPostition;
camera.LookDirection = new Vector3D(-newPostition.X, -newPostition.Y, -newPostition.Z);
}

　　最后還有一個(gè)鼠標(biāo)滾輪調(diào)節(jié)視距的變換，如下：

private void Viewport3D_MouseWheel(object sender, MouseWheelEventArgs e)
{
double scaleFactor = 3;
//120 near , -120 far
System.Diagnostics.Debug.WriteLine(e.Delta.ToString());
Point3D currentPosition = camera.Position;
Vector3D lookDirection = camera.LookDirection;//new Vector3D(camera.LookDirection.X, camera.LookDirection.Y, camera.LookDirection.Z);
lookDirection.Normalize();

lookDirection *= scaleFactor;

if (e.Delta == 120)//getting near
{
if ((currentPosition.X + lookDirection.X) * currentPosition.X > 0)
{
currentPosition += lookDirection;
}
}
if (e.Delta == -120)//getting far
{
currentPosition -= lookDirection;
}

Point3DAnimation positionAnimation = new Point3DAnimation();
positionAnimation.BeginTime = new TimeSpan(0, 0, 0);
positionAnimation.Duration = TimeSpan.FromMilliseconds(100);
positionAnimation.To = currentPosition; 
positionAnimation.From = camera.Position;
positionAnimation.Completed += new EventHandler(positionAnimation_Completed);
camera.BeginAnimation(PerspectiveCamera.PositionProperty, positionAnimation, HandoffBehavior.Compose);
}

　　有了這個(gè)小程序之后，我們以后如果需要制作WPF 3D實(shí)體，也可以通過(guò)它來(lái)360度全方位地觀測(cè)構(gòu)建的3D實(shí)體。

演示程序

源碼下載

本文來(lái)自Kevin Pan的博客，原文地址:http://www.cnblogs.com/KevinPan/archive/2011/04/14/1834080.html

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WPF 3D 小小小小引擎

WPF 3D 小小小小引擎 - ·WPF 3D變換應(yīng)用