Java 3D——基本图形功能及源代码

坐标系

1、原点O在显示器的中间。
2、Z轴是指向屏幕之外的，也就是观察者。
3、由于观察者眼睛，即观察方向是指向Z轴的反方向，所以当定义好图形之后，光源的方向一定不能是指向Z轴的正方向，否则无法观察到图形。（根据光的反射）

基本体组合的显示实例。

import java.applet.Applet;
import java.awt.BorderLayout;
import java.awt.GraphicsConfiguration;

import javax.media.j3d.*;
import javax.vecmath.Color3f;
import javax.vecmath.Point3d;
import javax.vecmath.Vector3f;

import com.sun.j3d.utils.applet.MainFrame;
import com.sun.j3d.utils.behaviors.mouse.MouseRotate;
import com.sun.j3d.utils.behaviors.mouse.MouseTranslate;
import com.sun.j3d.utils.behaviors.mouse.MouseZoom;
import com.sun.j3d.utils.geometry.Box;
import com.sun.j3d.utils.geometry.Sphere;
import com.sun.j3d.utils.universe.SimpleUniverse;

public class towprimitivedisplay extends Applet {
     
	public BranchGroup createBranchGroup()	
	    {
     
		//定义BranchGroup
		BranchGroup BranchGroupRoot = new BranchGroup ();
		
		//创建球心在坐标系原点球形范围
		BoundingSphere bounds = new BoundingSphere(new Point3d( 0.0,0.0,0.0),100.0);
		
		//定义背景颜色
		Color3f bgColor=new Color3f(.0f,.0f,.0f);
		Background bg=new Background(bgColor);
		bg.setApplicationBounds(bounds);
		BranchGroupRoot.addChild(bg);
		
		//定义平行光、颜色、照射方向与作用范围
		Color3f directionColor=new Color3f(1.f,1.f,1.f);
		Vector3f vec=new Vector3f(1.0f,-1.0f,-1.0f);
		DirectionalLight directionalLight= new DirectionalLight(directionColor,vec);
		directionalLight.setInfluencingBounds(bounds);
		BranchGroupRoot.addChild(directionalLight);
		
		//定义总的TransformGroup:transformgroup
		TransformGroup transformgroup=new TransformGroup();
		
		//设置对该TransformGroup的读写能力
		transformgroup.setCapability(TransformGroup.ALLOW_TRANSFORM_WRITE);
		transformgroup.setCapability(TransformGroup.ALLOW_TRANSFORM_READ);
		
		//将该TransformGroup加入到BranchGroupRoot中
		BranchGroupRoot.addChild(transformgroup);
		
		//定义鼠标对场景的旋转、平移与放大功能
		MouseRotate mouserotate=new MouseRotate();
		mouserotate.setTransformGroup(transformgroup);
		BranchGroupRoot.addChild(mouserotate);
		mouserotate.setSchedulingBounds(bounds);
		
		MouseZoom mousezoom=new MouseZoom();
		mousezoom.setSchedulingBounds(bounds);
		BranchGroupRoot.addChild(mousezoom);
		mousezoom.setSchedulingBounds(bounds);
		
		MouseTranslate mousetranslate=new MouseTranslate();
		mousetranslate.setTransformGroup(transformgroup);
		BranchGroupRoot.addChild(mousetranslate);
		mousetranslate.setSchedulingBounds(bounds);
		
		//定义两个三维型体的外观
		Appearance app1=new Appearance();
		Material material1=new Material();
		material1.setDiffuseColor(new Color3f(1.0f,.0f,0.0f));
		app1.setMaterial(material1);
		
		Appearance app2=new Appearance();
		Material material2=new Material();
		material2.setDiffuseColor(new Color3f(0.0f,1.0f,0.0f));
		app2.setMaterial(material2);
		
		//定义一个球体于一个长方体的大小、外观属性与坐标变换，并定义相应的TransformGroup：ta1、ta2
		TransformGroup tg1=new TransformGroup();
		tg1.addChild(new Sphere(0.3f,app1));
		Transform3D t=new Transform3D();
		t.setTranslation(new Vector3f(0.f,-0.425f,0.f));		
		TransformGroup tg2=new TransformGroup(t);
		tg2.addChild(new Box(0.5f,0.05f,0.5f,app2));
		
		//将定义好的两个TransformGroup(tg1、tg2)加入到总的transformgroup
		transformgroup.addChild(tg1);
		transformgroup.addChild(tg2);
		
		//对BranchGroupRoot预编译
		BranchGroupRoot.compile();
		
		//通过方法名返回BranchGroupRoot
		return BranchGroupRoot;
		}
	    public towprimitivedisplay()
	   {
     
	    //设置显示界面的相关参数
	    setLayout(new BorderLayout());
	    //创建投影平面Canvas3D
	    GraphicsConfiguration gc=SimpleUniverse.getPreferredConfiguration();
	    Canvas3D c=new Canvas3D(gc);
	    //将投影平面上的图像显示在显示平面的中间
	    add("Center",c);
	    //设置SimpleUniverse，由系统选择视点在z轴的正向，观察方向沿z轴反向
	    BranchGroup BranchGroupScene=createBranchGroup();
	    SimpleUniverse u=new SimpleUniverse(c);
	    u.getViewingPlatform().setNominalViewingTransform();
	    //将BranchGroup:BranchGroupScene加入到SimpleUniverse:u中
	    u.addBranchGraph(BranchGroupScene);
	   }
	    
	    public static void main(String[] args)
	    {
     //通过MainFrame显示图像
	    	
	    	new MainFrame(new towprimitivedisplay(),300,300);
	    	
	    }
}

由于光源方向是：
Vector3f vec=new Vector3f(-1.f,-1.f,-1.0f); 即指向第七象限。所以结果是：

如果改变光源方向：
Vector3f vec=new Vector3f(0.0f,0.0f,-1.0f);光源指向Z轴反方向

Vector3f vec=new Vector3f(-1.0f,0.0f,0.0f);光源指向X轴反方向

三角面图形

以一维数组给出顶点的坐标值，从前向后一次以3个顶点形成一个三角形，并且上一个三角形与下一个三角形之间没有公共顶点。

import java.awt.BorderLayout;
import java.awt.GraphicsConfiguration;

import javax.media.j3d.Appearance;
import javax.media.j3d.Background;
import javax.media.j3d.BoundingSphere;
import javax.media.j3d.BranchGroup;
import javax.media.j3d.Canvas3D;
import javax.media.j3d.DirectionalLight;
import javax.media.j3d.PolygonAttributes;
import javax.media.j3d.Shape3D;

import javax.media.j3d.TransformGroup;
import javax.media.j3d.TriangleArray;
import javax.vecmath.Color3f;
import javax.vecmath.Point3d;
import javax.vecmath.Vector3f;

import com.sun.j3d.utils.applet.MainFrame;
import com.sun.j3d.utils.behaviors.mouse.MouseRotate;
import com.sun.j3d.utils.behaviors.mouse.MouseTranslate;
import com.sun.j3d.utils.behaviors.mouse.MouseZoom;

import com.sun.j3d.utils.universe.SimpleUniverse;

import java.applet.Applet;


public class DisplayTriangles extends Applet {
     
	public BranchGroup createBranchGroup() {
     
		BranchGroup BranchGroupRoot = new BranchGroup();
		BoundingSphere bounds = new BoundingSphere(new Point3d(0.0, 0.0, 0.0), 100.0);
		Color3f bgColor = new Color3f(1.0f, 1.0f, 1.0f);
		Background bg = new Background(bgColor);
		bg.setApplicationBounds(bounds);
		BranchGroupRoot.addChild(bg);
		
		Color3f directionalColor = new Color3f(1.f, 0.f, 0.f);
		Vector3f vec = new Vector3f(0.f, 0.f, -1.0f);
		DirectionalLight directionalLight = new DirectionalLight(directionalColor, vec);
		directionalLight.setInfluencingBounds(bounds);
		BranchGroupRoot.addChild(directionalLight);
		
		TransformGroup transformgroup = new TransformGroup();
		transformgroup.setCapability(TransformGroup.ALLOW_TRANSFORM_WRITE);
		transformgroup.setCapability(TransformGroup.ALLOW_TRANSFORM_READ);
		BranchGroupRoot.addChild(transformgroup);
		
		MouseRotate mouserotate = new MouseRotate();
		mouserotate.setTransformGroup(transformgroup);
		BranchGroupRoot.addChild(mouserotate);
		mouserotate.setSchedulingBounds(bounds);
		MouseZoom mousezoom = new MouseZoom();
		mousezoom.setTransformGroup(transformgroup);
		BranchGroupRoot.addChild(mousezoom);
		mousezoom.setSchedulingBounds(bounds);
		MouseTranslate mousetranslate = new MouseTranslate();
		mousetranslate.setTransformGroup(transformgroup);
		BranchGroupRoot.addChild(mousetranslate);
		mousetranslate.setSchedulingBounds(bounds);
		
		transformgroup.addChild(new TriangleArrays());
		BranchGroupRoot.compile();
		return BranchGroupRoot;
	}

	public DisplayTriangles() {
     
		setLayout(new BorderLayout());
		GraphicsConfiguration gc = SimpleUniverse.getPreferredConfiguration();
		Canvas3D c = new Canvas3D(gc);
		add("Center", c);
		BranchGroup BranchGroupScene = createBranchGroup();
		SimpleUniverse u = new SimpleUniverse(c);
		u.getViewingPlatform().setNominalViewingTransform();
		u.addBranchGraph(BranchGroupScene);
	}

	public static void main(String[] args) {
     
		new MainFrame(new DisplayTriangles(), 300, 300);
	}
}

//outsideclass
class TriangleArrays extends Shape3D {
     
	public TriangleArrays() {
     
		int vCount = 12;
		float vertexes[] = {
      -0.6f,0.9f,0.0f,  -0.6f,-0.9f,0.2f,
				             -0.4f, 0.9f, -0.2f, -0.2f, -0.9f, 0.2f, 
				              0.0f, 0.9f,-0.2f,   0.0f, -0.9f, 0.2f, 
				              0.2f, 0.7f, 0.0f,   0.2f, -0.9f, 0.3f,
				              0.5f, 0.8f, -0.3f,   0.6f, -.9f, 0.0f,
				              0.8f, 0.9f, 0.2f,   0.8f, -0.8f, 0.3f };
		float colors[] = {
      0.0f,0.5f,1.0f,    0.0f,0.5f,1.0f,
                0.0f,0.8f,.0f,    1.0f,0.0f,0.3f,
                0.0f,1.0f,0.5f,   0.9f,1.0f,0.0f,
                0.5f,0.0f,1.0f,   0.0f,0.5f,1.0f,
                1.0f,0.5f,0.0f,   1.0f,0.0f,0.5f,
                1.0f,0.8f,0.0f,   1.0f,0.5f,0.0f};
		TriangleArray trianglearray = new TriangleArray(vCount, TriangleArray.COORDINATES | TriangleArray.COLOR_3);
		trianglearray.setCoordinates(0, vertexes);
		trianglearray.setColors(0, colors);
		PolygonAttributes polygonattributes = new PolygonAttributes();
		//polygonattributes.setCullFace(PolygonAttributes.CULL_NONE);
//polygonattributes.setCullFace(PolygonAttributes.CULL_FRONT);
polygonattributes.setCullFace(PolygonAttributes.CULL_BACK);
		Appearance app = new Appearance();
		app.setPolygonAttributes(polygonattributes);
		this.setGeometry(trianglearray);
		this.setAppearance(app);
	}
}

三角扇图形

以第一个顶点为公用顶点，依次与其余顶点分别连接形成三角形。其中给定的定点数至少为3个。

class ShapeTriangleFanArray extends Shape3D {
     
	public ShapeTriangleFanArray() {
     
		int vertexesCount = 12;
		int stripCount[] = new int[1];
//int stripCount[]=new int[2];
//int stripCount[]=new int[3];
		float vertexes[] = {
      .0f, 0.9f, 0.0f, -1.f, -0.8f, 0.f, 
				-0.8f, -0.6f, -0.2f, -0.6f, -0.9f, 0.2f,
				-0.4f, -0.8f,-0.2f, 0.f, -0.8f, 0.2f, 
				0.2f, -0.5f, 0.0f, 0.4f, -0.6f, -0.5f, 
				0.6f, -0.8f, -0.3f, 0.8f, -0.9f, -0.2f,
				0.9f, -0.7f, -0.2f, 1.1f, -0.8f, -0.3f 
				};
		float colors[] = {
      0.0f, 0.5f, 1.0f, 0.0f, 0.5f, 1.0f, 
				0.0f, 0.8f, .0f, 1.0f, 0.0f, 0.3f, 
				0.0f, 1.0f, 0.5f,0.9f, 1.0f, 0.0f, 
				0.5f, 0.0f, 1.0f, 0.0f, 0.5f, 1.0f, 
				1.0f, 0.5f, 0.0f, 1.0f, 0.0f, 0.5f, 
				1.0f, 0.8f,0.0f, 1.0f, 0.5f, 0.0f };
		stripCount[0] = 12;
//stripCount[1]=4;
//stripCount[2]=4;
		TriangleFanArray triangleFanarray = new TriangleFanArray(vertexesCount,
				TriangleFanArray.COORDINATES | TriangleFanArray.COLOR_3, stripCount);
		triangleFanarray.setCoordinates(0, vertexes);
		triangleFanarray.setColors(0, colors);
		PolygonAttributes polygonattributes = new PolygonAttributes();
		polygonattributes.setCullFace(PolygonAttributes.CULL_NONE);
		Appearance app = new Appearance();
		app.setPolygonAttributes(polygonattributes);
		this.setGeometry(triangleFanarray);
		this.setAppearance(app);
	}
}

int stripCount[];数组表示生成的三角扇个数
eg：总共十二个顶点
new stripCount[1]，表示生成一个扇区。所以stripCount[0]=12，这一个扇区有十二个点。

该程序，用顶点颜色插值生成线与面颜色，这种颜色无需光照，也能显示。

四边面图形

以顶点坐标数组中给出的一维顶点数组，从前向后依次以4个顶点形成一个四边形面，并且相邻两个四边形面之间没有公用顶点。给定的总的顶点数必须是4的倍数。

class ShapeQuadArray extends Shape3D 
{
     public ShapeQuadArray() 
{
     int vertexCount=12;
float vertexes[]={
      -0.8f,0.9f,0.0f, -0.8f,-0.8f,0.f,
                   -0.6f,-0.8f,0.f, -0.6f,0.9f,0.f,
                   -0.4f,0.9f,0.f,  -0.4f,-0.7f,-0.9f,
                    0.4f,-0.8f,0.f,  0.4f,0.8f,0.0f,
                    0.5f,0.8f,0.f,   0.6f,-0.8f,0.0f,
                    0.8f,-0.7f,0.f,  0.8f,0.8f,0.f};
float colors[]={
     0.0f,0.5f,1.0f,  0.0f,0.5f,1.0f,
                0.0f,0.8f,.0f,   1.0f,0.0f,0.3f,
                0.0f,1.0f,0.5f,  0.9f,1.0f,0.0f,
                0.5f,0.0f,1.0f,  0.0f,0.5f,1.0f,
                1.0f,0.5f,0.0f,  1.0f,0.0f,0.5f,
                1.0f,0.8f,0.0f,  1.0f,0.5f,0.0f };
QuadArray quadarray=new QuadArray(vertexCount,
QuadArray.COORDINATES|QuadArray.COLOR_3);
quadarray.setCoordinates(0,vertexes);
quadarray.setColors(0,colors);
PolygonAttributes polygonattributes=new PolygonAttributes();
polygonattributes.setCullFace(PolygonAttributes.CULL_NONE);
//polygonattributes.setCullFace(PolygonAttributes.CULL_BACK);
//polygonattributes.setCullFace(PolygonAttributes.CULL_FRONT);
Appearance app=new Appearance();
app.setPolygonAttributes(polygonattributes);
this.setGeometry(quadarray);
this.setAppearance(app);
}}