java 关于VMRL EAI接口的总结

14年前

JAVA 可以通过IE 实现对于VRML的控制

忙了一天终于将EAI实现了，下面是一些总结，希望对于其他的人有所帮助

具体配置如下：

１.jdk version 1.3，一定要1.3的

２.添加vrml97.jar，注意路径，及其环境变量的配置

３.安装cortona插件，这个在cortona vrml 游览插件中，可以找到

classes.zip用于实现SAI

corteai.zip用于实现EAI

根据个人采用的方式，添加相应的包，环境变量也要设置

４.装微软的jvm
５.设置IE
关闭SUN jdk用户Applet执行，并且对于Microsoft VM做如下设置：
启用JAVA控制台(是)
启用JAVA JIT编译器 (是)
启用JAVA记录(否)

下面举一个具体的实例

JAVA文件：helix.java

//
// Program: Helix Spring.
//
// Description:
//    This program calculates coordinates needed to make a helix spring
//    and sets them in 3D scene. spineLimit x crossSectionLimit = 250 x 10
//    = 2500, and thus satisfies vrml97 conformity requirements for
//    Extrusion node. The animation speed may be adjusted by altering
//    thread.sleep value, but too low values may decrease browser
//    rendering performance.
//
// Author: Vilius Jagminas, vilius@extred.com
// Version: 1.0, 12.11.2000
//
// Edited to produce a more concise spec example by Martin Reddy.
//
// Compiled against the Cortona 3 EAI classes, corteai.zip
//

import java.awt.*;
import java.applet.*;
import vrml.eai.field.*;
import vrml.eai.Node;
import vrml.eai.BrowserFactory;
import vrml.eai.Browser;

public class helix extends Applet implements Runnable {

EventInMFVec3f spine = null;
EventInMFVec2f crossSection = null;
Thread thread = null;
Choice choice;

int spineLimit = 250;
float[][] spinue = new float[spineLimit+1][3];
int crossSectionLimit = 10;
float[][] crossSectionValue = new float[crossSectionLimit+1][2];
float numCoils = 5f;

// set up the applet controls
public void init() {
    super.init();
    setBackground(Color.white);
    Panel p1 = new Panel();
    Label lblNCoils = new Label("Number of Coils");
    p1.add(lblNCoils);
    choice= new Choice();
    choice.addItem("5"); choice.addItem("4"); choice.addItem("3");
    choice.addItem("2"); choice.addItem("1");
    p1.add(choice);
    add(p1);
}

public void start() {
    // get the VRML Browser reference
    Browser browser = null;
    for (int count = 0; count < 10; count++) {
      browser = BrowserFactory.getBrowser(this);
      if (browser != null) break;
      try { Thread.sleep (200); } catch (InterruptedException e) {}
    }
    if (browser == null) {
      throw new Error("Failed to get the browser after 10 tries!");
    }

    // get the spine and crossSection fields of the Extrusion node
    try {
      Node coil = browser.getNode("Coil");
      spine = (EventInMFVec3f) coil.getEventIn("set_spine");
      crossSection = (EventInMFVec2f) coil.getEventIn("set_crossSection");
    } catch (vrml.eai.InvalidNodeException ne){
      System.out.println("Node Exception Error:" + ne.getMessage());
    }

    if (thread == null) {
      thread = new Thread(this);
      thread.start();
    } else
      thread.resume();
}

public void stop() {
if (thread != null) thread.suspend();
}

public void destroy() {
thread.stop();
thread = null;
}

public void run() {
    // calculate and set the crossSection values of the Extrusion node
    float thickness = 0.1f;
    float diameter = 1.5f;
    float two_pi = (float) Math.PI * 2.0f;
    for (int j = 0; j <= crossSectionLimit; j++) {
      float angle = j * two_pi / crossSectionLimit;
      crossSectionValue[j][0] = thickness / 2 * (float) Math.sin(angle);
      crossSectionValue[j][1] = thickness / 2 * (float) Math.cos(angle);
    }
    crossSection.setValue(crossSectionValue);

    // oscilate the spring between 0.3 and 1, with 0.05 increments
    float inc = 0.05f;
    float value = 0.3f;
    float springLength = 2f;
    while (true) {
      value += inc;
      //calculate and set the coordinates for the whole spine
      for (int i = 0; i <= spineLimit; i++) {
float stepsPerCoil = (float) Math.round(spineLimit / numCoils);
float angle = i * two_pi / stepsPerCoil;
spinue[i][0] = diameter / 2 * (float) Math.cos(angle);
spinue[i][1] = springLength / numCoils * value * i / stepsPerCoil;
spinue[i][2] = diameter / 2 * (float) Math.sin(angle);
      }
      spine.setValue(spinue);

// sleep for 0.1 seconds
try { thread.sleep(100); } catch (InterruptedException e) {}

      // reverse movement direction
      if (value >= 1f && inc == 0.05f)
inc = -0.05f;
      else if (value <= 0.3 && inc == -0.05f)
inc = 0.05f;
    }
}

// handle input (deprecated Java API)
public boolean handleEvent(Event event) {
    if (event.id == Event.ACTION_EVENT && event.target == choice)
      changeNumCoils();
    return super.handleEvent(event);
}

// changes number of coils in the helix
private void changeNumCoils() {
String number = choice.getSelectedItem();
numCoils = (new Float(number)).floatValue();
}
}

vrml 文件

helix.wrl

#VRML V2.0 utf8

Viewpoint {
position 0 4 5
orientation 1 0 0 -0.5
}

Shape {
   appearance Appearance {
      material Material {
diffuseColor 0.8 0.8 0.9
shininess 1
      }
   }
   geometry DEF Coil Extrusion {
      crossSection []
      spine []
      creaseAngle 3.14
   }
}

HTML文件

<html>
<head><title>Helix Spring</title></head>
<body>

</body>
</html>

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