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整理人: funboy(1999-11-24 09:18:34), 站内信件
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JAVA3D学习系列(8)-----直线的生成
汕头大学机电系 张杰（[email protected]）
我们可以利用JAVA3D的一些对象，生成各种直线。
可以生成直线的对象有：
1. LineArray
LineArray(int vertexCount, int vertexFormat)
2. LineStripArray
LineStripArray(int vertexCount ,int vertexFormat,
int[] stripVertexCounts )
3. IndexedLineArray
IndexedLineArray(int vertexCount, int vertexFormat,
int indexCount )
4. IndexedLineStripArray
IndexedLineStripArray( int vertexCount, int vertexFormat,
int indexCount, int stripIndexCounts[])
一. 利用LineArray生成直线
LineArray对象的定义如下：
LineArray(int vertexCount, int vertexFormat)
这里：
vertexCount表示顶点的个数（必须为偶数）
vertexFormat表示顶点的格式（第七讲有介绍）
由下面的程序我们得知，Line1.java和前面介绍的
Point4.java几乎完全一样，lineShape1.java和
pointShape.java也相差不多。运行Line1.java我们获得
了三条直线，由此得知，LineArray的作用是生成多条直线，
顶点坐标数组的每一对数据构成一条直线。
在编写LineArray生成的直线时，要注意，顶点及颜色
的个数必须相等且为偶数，此数目必须赋值于vertexCount，也即
程序中的vertexCount必须为偶数且不能少于顶点的个数。
-------------------------- 第一条
---------------- 第二条
-------------------------- 第三条
我们可以根据各种不同的情况，生成不同的直线，如
给定宽度的直线、虚线等。相应的的方法有：
setLineWidth(float lineWidth)
setLinePattern(int linePattern)
setLineAntialiasingEnable(boolean state)
对于线型linePattern有以下数据可选：
int PATTERN_SOLID
int PATTERN_DASH
int PATTERN_DOT
int PATTERN_DASH_DOT
这些内容对所有种类的直线都有效。
前面我们利用PointArray生成了六个点，这里，我们
将前面的pointShape.java稍微变化一下，则同样的六个点生
成了三条直线，所用的两个程序为：
//lineShape1.java
import javax.media.j3d.*;
public class lineShape1 extends Shape3D {
private float vert[] = {
.8f, 0.8f,0.0f,
-0.8f, 0.8f,0.0f,
0.5f, 0.0f,0.0f,
-0.5f, 0.0f,0.0f,
-0.8f,-0.8f,0.0f,
0.8f,-0.8f,0.0f,
};
private float color[] = {
0.0f,0.5f,1.0f,
0.5f,0.0f,1.0f,
0.0f,0.8f,2.0f,
1.0f,0.0f,0.3f,
0.0f,1.0f,0.3f,
0.3f,0.8f,0.0f,
};
public lineShape1() {
LineArray line = new LineArray(6,
LineArray.COORDINATES|LineArray.COLOR_3);
line.setCoordinates(0,vert);
line.setColors(0,color);
LineAttributes la = new LineAttributes();
la.setLineWidth(5.0f);
la.setLineAntialiasingEnable(true);
Appearance ap = new Appearance();
ap.setLineAttributes(la);
this.setGeometry(line);
this.setAppearance(ap);
}
}
//end of lineShape1.java
------------------------------------
//Line1.java ---using LineArray object
import java.applet.Applet;
import java.awt.BorderLayout;
import com.sun.j3d.utils.applet.MainFrame;
import com.sun.j3d.utils.universe.*;
import javax.media.j3d.*;
import javax.vecmath.*;
public class Line1 extends Applet {
private BranchGroup createSceneGraph() {
BranchGroup objRoot = new BranchGroup();
Shape3D shape = new lineShape1();
objRoot.addChild(shape);
objRoot.compile();
return objRoot;
}
public Line1() {
setLayout(new BorderLayout());
Canvas3D c = new Canvas3D(null);
add("Center", c);
BranchGroup scene = createSceneGraph();
SimpleUniverse u = new SimpleUniverse(c);
u.getViewingPlatform().setNominalViewingTransform();
u.addBranchGraph(scene);
}
public static void main(String[] args) {
new MainFrame(new Line1(), 400,400);
}
}
//end of Line1.java
二. 利用LineStripArray生成直线
LineStripArray可用来生成多条折线段
LineStripArray对象的定义如下：
LineStripArray(int vertexCount ,int vertexFormat,
int[] stripVertexCounts )
这里：
vertexCount表示顶点的个数（必须为偶数）
vertexFormat表示顶点的格式（第七讲有介绍）
stripVertexCounts为一数组，数组里的每一个数值表示
每条折线段所拥有的顶点数目。
下面我们利用lineShape1.java同样的顶点坐标数组及
颜色数组，用LineStripArray对象生成直线。程序也是两个：
lineShape2.java、Line2.java，并使生成的直线绕着Y轴旋转，
直线线型为虚线，线宽为30个像素。
//lineShape2.java
import javax.media.j3d.*;
public class lineShape2 extends Shape3D {
int StripCount[] = new int[1];
private float vert[] = {
.8f, 0.8f,0.0f,
-0.8f, 0.8f,0.0f,
0.5f, 0.0f,0.0f,
-0.5f, 0.0f,0.0f,
-0.8f,-0.8f,0.0f,
0.8f,-0.8f,0.0f,
};
private float color[] = {
0.0f,0.5f,1.0f,
0.5f,0.0f,1.0f,
0.0f,0.8f,2.0f,
1.0f,0.0f,0.3f,
0.0f,1.0f,0.3f,
0.3f,0.8f,0.0f,
};
public lineShape2() {
StripCount[0] = 6;
LineStripArray line = new LineStripArray(6,
LineStripArray.COORDINATES|
LineStripArray.COLOR_3,StripCount);
line.setCoordinates(0,vert);
line.setColors(0,color);
LineAttributes la = new LineAttributes();
la.setLineWidth(30.0f);
la.setLineAntialiasingEnable(true);
la.setLinePattern(LineAttributes.PATTERN_DASH);
Appearance ap = new Appearance();
ap.setLineAttributes(la);
this.setGeometry(line);
this.setAppearance(ap);
}
}
//end of lineShape2.java
-----------------------------------------
//Line2.java
import java.applet.Applet;
import java.awt.BorderLayout;
import com.sun.j3d.utils.applet.MainFrame;
import com.sun.j3d.utils.universe.*;
import javax.media.j3d.*;
import javax.vecmath.*;
public class Line2 extends Applet {
private BranchGroup createSceneGraph() {
BranchGroup objRoot = new BranchGroup();
objRoot.addChild(createObject());
objRoot.compile();
return objRoot;
}
private Group createObject() {
Transform3D t = new Transform3D();
TransformGroup objTrans = new TransformGroup(t);
objTrans.setCapability(TransformGroup.ALLOW_TRANSFORM_WRITE);
Shape3D shape = new lineShape2();
objTrans.addChild(shape);
Transform3D yAxis = new Transform3D();
Alpha rotationAlpha = new Alpha(-1, Alpha.INCREASING_ENABLE,
0, 0,
4000, 0, 0,
0, 0, 0);
RotationInterpolator rotator =
new RotationInterpolator(rotationAlpha, objTrans, yAxis,
0.0f, (float) Math.PI*2.0f);
BoundingSphere bounds =
new BoundingSphere(new Point3d(0.0,0.0,0.0), 50.0);
rotator.setSchedulingBounds(bounds);
objTrans.addChild(rotator);
return objTrans;
}
public Line2() {
setLayout(new BorderLayout());
Canvas3D c = new Canvas3D(null);
add("Center", c);
BranchGroup scene = createSceneGraph();
SimpleUniverse u = new SimpleUniverse(c);
u.getViewingPlatform().setNominalViewingTransform();
u.addBranchGraph(scene);
}
public static void main(String[] args) {
new MainFrame(new Line2(), 400,400);
}
}
//end of Line2.java
由上可知，Line2.java这个程序和Point5.java几乎没有
什么差别，除了类的名字于调用的外部程序名不同之外，其余
完全相同。
lineShape1.java和lineShape2.java相差不大，
lineShape2.java多了一个StripCount数组，它可以用来生成
多个折线段，下面的lineShape3.java程序就将Line2.java生成
的一条折线段分成了两条折线段：0、1、2三个点构成了一个折
线段，3、4、5构成了另一条折线段，每个折线段的顶点数目就
构成了数组StripCount，StripCount数组的大小等于折线段的
数目。
//lineShape3.java
import javax.media.j3d.*;
public class lineShape3 extends Shape3D {
int StripCount[] = new int[2];
private float vert[] = {
.8f, 0.8f,0.0f,
-0.8f, 0.8f,0.0f,
0.5f, 0.0f,0.0f,
-0.5f, 0.0f,0.0f,
-0.8f,-0.8f,0.0f,
0.8f,-0.8f,0.0f,
};
private float color[] = {
0.0f,0.5f,1.0f,
0.5f,0.0f,1.0f,
0.0f,0.8f,2.0f,
1.0f,0.0f,0.3f,
0.0f,1.0f,0.3f,
0.3f,0.8f,0.0f,
};
public lineShape3() {
StripCount[0] = 3;
StripCount[1] = 3;
LineStripArray line = new LineStripArray(6,
LineStripArray.COORDINATES|
LineStripArray.COLOR_3,StripCount);
line.setCoordinates(0,vert);
line.setColors(0,color);
LineAttributes la = new LineAttributes();
la.setLineWidth(30.0f);
la.setLineAntialiasingEnable(true);
la.setLinePattern(LineAttributes.PATTERN_DASH);
Appearance ap = new Appearance();
ap.setLineAttributes(la);
this.setGeometry(line);
this.setAppearance(ap);
}
}
//end of lineShape3.java
将lineShape3.java生成的绕Y轴旋转的形体用VRML
程序表示的结果为:
#VRML V2.0 utf8
DEF T Transform{
children Shape {
geometry IndexedLineSet {
coord Coordinate {
point [.8 .8 .0, -.8, .8 0, .5 0 0,
-.5 0 0, -.8 -.8 0, .8 -.8 0]}
coordIndex [0 1 2 -1, 3 4 5 ]
# 两个折线段
color Color{
color [ .0 .5 1., .5 .0 1, 0 .8 .2,
1 0 .3, 0 1 .3, .3 .8 0 ]}
}}}
DEF TS TimeSensor{
cycleInterval 4
loop TRUE}
DEF OI OrientationInterpolator{
key [0 .25 .5 .75 1]
keyValue [0 1 0 1, 0 1 0 1.57, 0 1 0 3.14
0 1 0 4.71 0 1 0 6.28]}
ROUTE TS.fraction TO OI.fraction
ROUTE OI.value TO T.rotation
#end of lineShape3.wrl
三. 利用IndexedLineArray生成直线
IndexedLineArray对象的定义为：
IndexedLineArray(int vertexCount, int vertexFormat,
int indexCount )
这里：
vertexCount表示顶点数组里顶点的个数
vertexFormat表示顶点的格式（第七讲有介绍）
indexCount表示选用的顶点个数，如果一个点用了
几次，则要把几次加进去
在上一节里我们介绍了利用IndexedPoint生成点
的程序，和IndexedPoint相类似，我们可以利用
IndexedLineArray生成直线段。
下面的lineShape4.java利用了IndexedLineArray
从六个点中挑选了3个点，生成了2条直线。
从程序中我们可以看到，下标为0的点使用了两次，
但生成的是两条线，因而参数VertexCount应为4，即
此处的VertexCount的数值应为直线条数的两倍。
//lineShape4.java
import javax.media.j3d.*;
public class lineShape4 extends Shape3D {
int[] index={ 1, 0, 0 , 3, };
int VertexCount=4;
private float vert[] = {
.8f, 0.8f,0.0f,
-0.8f, 0.8f,0.0f,
0.5f, 0.0f,0.0f,
-0.5f, 0.0f,0.0f,
-0.8f,-0.8f,0.0f,
0.8f,-0.8f,0.0f,
};
private float color[] = {
0.0f,0.5f,1.0f,
0.5f,0.0f,1.0f,
0.0f,0.8f,2.0f,
1.0f,0.0f,0.3f,
0.0f,1.0f,0.3f,
0.3f,0.8f,0.0f,
};
public lineShape4() {
IndexedLineArray line = new IndexedLineArray(6,
IndexedLineArray.COORDINATES|
IndexedLineArray.COLOR_3,VertexCount);
line.setCoordinates(0,vert);
line.setColors(0,color);
line.setCoordinateIndices(0,index);
line.setColorIndices(0,index);
LineAttributes la = new LineAttributes();
la.setLineWidth(30.0f);
la.setLineAntialiasingEnable(true);
la.setLinePattern(LineAttributes.PATTERN_DASH);
Appearance ap = new Appearance();
ap.setLineAttributes(la);
this.setGeometry(line);
this.setAppearance(ap);
}
}
//end of lineShape4.java
将lineShape4.java翻译成VRML的相应程序为：
#VRML V2.0 utf8
DEF T Transform{
children Shape {
geometry IndexedLineSet {
coord Coordinate {
point [.8 .8 .0, -.8, .8 0, .5 0 0,
-.5 0 0, -.8 -.8 0, .8 -.8 0]}
coordIndex [1 0 -1 0 3]
color Color{
color [ .0 .5 1., .5 .0 1, 0 .8 .2,
1 0 .3, 0 1 .3, .3 .8 0 ]}
}}}
DEF TS TimeSensor{
cycleInterval 4
loop TRUE}
DEF OI OrientationInterpolator{
key [0 .25 .5 .75 1]
keyValue [0 1 0 1, 0 1 0 1.57, 0 1 0 3.14
0 1 0 4.71 0 1 0 6.28]}
ROUTE TS.fraction TO OI.fraction
ROUTE OI.value TO T.rotation
四. 利用IndexedLineStripArray生成直线
IndexedLineStripArray对象的定义如下：
IndexedLineStripArray( int vertexCount, int vertexFormat,
int indexCount, int stripIndexCounts[])
这里：
vertexCount表示顶点数组里顶点的个数
vertexFormat表示顶点的格式（第七讲有介绍）
indexCount表示选用的顶点的个数
stripIndexCounts为一数组，数组里的每一个数值表示
每条折线段所拥有的顶点数目。
下面的程序里，我们给出10个顶点，
--0-- --1--
--2-- --3--
--4-- --5--
--6-- --7--
--8-- --9--
然后我们用IndexedLineStripArray生成三个折线段，第一个
折线段为：0 1 3 2，第二个折线段为3、5、4，第三个折线段为
6、7、8、6，最后一个点没有用到。所有的直线宽度为30像数。
这时我们只用了10个点中的9个点，但有2个点用了两次，因而程序
中的vertexCount为11，
程序如下：
//lineShape5.java
import javax.media.j3d.*;
public class lineShape5 extends Shape3D {
int StripCount[] = new int[3];
int[] index={ 0 , 1 , 3 , 2 , 3 , 5 ,
4 , 6 , 7 , 8 , 6 } ;
int vertexCount = 11;
private float vert[] = {
-.3f , .8f , .0f,
.3f , .8f , .0f,
-.3f , .4f , .0f,
.3f , .4f , .0f,
-.3f , .0f , .0f,
.3f , .0f , .0f,
-.3f , -.4f , .0f,
.3f , -.4f , .0f,
-.3f , -.8f , .0f,
.3f , -.8f , .0f,
};
private float color[] = {
0.0f,0.5f,1.0f,
0.5f,0.0f,1.0f,
0.0f,0.8f,2.0f,
1.0f,0.0f,0.3f,
0.0f,1.0f,0.3f,
0.3f,0.8f,0.0f,
0.0f,0.5f,1.0f,
0.5f,0.0f,1.0f,
0.0f,0.8f,2.0f,
1.0f,0.0f,0.3f
};
public lineShape5() {
StripCount[0] = 4;
StripCount[1] = 3;
StripCount[2] = 4;
IndexedLineStripArray line = new IndexedLineStripArray(10 ,
IndexedLineStripArray.COORDINATES|
IndexedLineStripArray.COLOR_3, vertexCount , StripCo
unt);
line.setCoordinates(0,vert);
line.setColors(0,color);
line.setCoordinateIndices(0,index);
line.setColorIndices(0,index);
LineAttributes la = new LineAttributes();
la.setLineWidth(30.0f);
la.setLineAntialiasingEnable(true);
la.setLinePattern(LineAttributes.PATTERN_DASH);
Appearance ap = new Appearance();
ap.setLineAttributes(la);
this.setGeometry(line);
this.setAppearance(ap);
}
}
//end of lineShape5.java
--
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