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);
}}
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原文链接：https://blog.csdn.net/weixin_46369022/article/details/120802562