Java Tips - Using LineArray to draw coordinate system

In 3D computer graphics, everything is modeled and rendered with vertex-based data.LineArray object describes a set of vertices, and each two vertices defines the endpoints of a line.

This program uses multiple LineArray objects to draw lines to represent the x, y, and z axis.


public class AxisApp extends JFrame {

  public AxisApp() {

    ....

  }



  public BranchGroup createSceneGraph() {

    BranchGroup objRoot = new BranchGroup();

    

    // Create X axis

    LineArray axisXLines=new LineArray(2,LineArray.COORDINATES);

    objRoot.addChild(new Shape3D(axisXLines));

      

    axisXLines.setCoordinate(0,new Point3f(-1.0f,0.0f,0.0f));

    axisXLines.setCoordinate(1,new Point3f(1.0f,0.0f,0.0f));        

    

    // Create Y axis  

    LineArray axisYLines=new LineArray(2,LineArray.COORDINATES|LineArray.COLOR_3);

    objRoot.addChild(new Shape3D(axisYLines));

      

    axisYLines.setCoordinate(0,new Point3f(0.0f,-1.0f,0.0f));

    axisYLines.setCoordinate(1,new Point3f(0.0f,1.0f,0.0f));

      

    // Create Z axis with arrow

    Point3f z1=new Point3f(0.0f,0.0f,-1.0f);

    Point3f z2=new Point3f(0.0f,0.0f,1.0f);

      

    LineArray axisZLines=new LineArray(10,LineArray.COORDINATES|LineArray.COLOR_3);

    objRoot.addChild(new Shape3D(axisZLines));

      

    axisZLines.setCoordinate(0,z1);

    axisZLines.setCoordinate(1,z2);

    axisZLines.setCoordinate(2,z2);

    axisZLines.setCoordinate(3,new Point3f(0.1f,0.1f,0.9f));

    axisZLines.setCoordinate(4,z2);

    axisZLines.setCoordinate(5,new Point3f(-0.1f,0.1f,0.9f));

    axisZLines.setCoordinate(6,z2);

    axisZLines.setCoordinate(7,new Point3f(0.1f,-0.1f,0.9f));

    axisZLines.setCoordinate(8,z2);

    axisZLines.setCoordinate(9,new Point3f(-0.1f,-0.1f,0.9f));

      

    return objRoot;

  }

}

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