Java3d TriangleFanArray错误

Question

我正在尝试使用多个凸多边形绘制一个凸面多面体py。我使用java3d的triangleFanArray来表示每个多边形。

package ucl.physiol.neuroconstruct.j3D;

import com.sun.j3d.utils.geometry.*;
import javax.vecmath.*;
import javax.media.j3d.*;

import quickhull3d.Point3d;

import java.io.*;

public class Polygon extends Primitive
{

    int divisions;

    //vertices are Point3d and the indices are integers

    Point3d vertices[];
    int faces[][];

    int flags;

    /**
     * Returns the flags of primitive (generate normal, textures, caching, etc).
     */

    @Override
    public int getPrimitiveFlags()
    {
      return flags;
    }

    /*
    public Polygon()
    {
        this(0.5f, 2.0f, GENERATE_NORMALS, DEFAULT_DIVISIONS, null);
    }
    */

    public Polygon (Point3d vertices[],int faces[][])
    {
        this(vertices, faces, GENERATE_NORMALS, null);
    }


    public Polygon (Point3d vertices[],int faces[][], Appearance ap)
    {
        this(vertices,faces, GENERATE_NORMALS, ap);
    }



    public Shape3D getShape(int partId)
    {
        if (partId >= this.faces.length || partId < 0) return null;
        return (Shape3D) getChild(partId);
    }


    public void setAppearance(Appearance ap)
    {

        for(int i=0;i<faces.length;i++)
        {
            ((Shape3D)getChild(i)).setAppearance(ap);

        }

    }


    public Appearance getAppearance(int partId)
    {
        if (partId >= faces.length || partId < 0)return null;
        return getShape(partId).getAppearance();
    }



    public Polygon(Point3d vert[], int fac[][], int primflags, Appearance ap)
    {
      super();
      this.flags = primflags;


      vertices=vert;
      faces=fac;

      Shape3D shape[] = new Shape3D[fac.length];


      System.out.println("We are here inside Polygon1");

        for(int i=0;i<fac.length;i++)
        {

            int k=faces[i].length;
            javax.vecmath.Point3d face_vertices[]=new javax.vecmath.Point3d[k];
            System.out.println(" Between 1 and 2");
            for(int j=0;j<k;j++)
            {
                face_vertices[i]=new javax.vecmath.Point3d(vert[faces[i][j]].x,vert[faces[i][j]].y,vert[faces[i][j]].z);
            }

            System.out.println(face_vertices.length);

            System.out.println("We are here inside Polygon2");
            TriangleFanArray face = new TriangleFanArray(face_vertices.length,TriangleFanArray.COORDINATES |TriangleFanArray.NORMALS,new int[]{face_vertices.length});

            System.out.println("We are between Polygon 2 and 3");



            ***face.setCoordinates(0, face_vertices);***


            System.out.println("We are between Polygon 2 and 3");


            shape[i] = new Shape3D(face);
            this.addChild(shape[i]);

            System.out.println("We are here inside Polygon3");
            if ( (flags & ENABLE_APPEARANCE_MODIFY) != 0)
            {
                (shape[i]).setCapability(Shape3D.ALLOW_APPEARANCE_READ);
                (shape[i]).setCapability(Shape3D.ALLOW_APPEARANCE_WRITE);
            }

            if ( (flags & ENABLE_GEOMETRY_PICKING) != 0)
            {
                (shape[i]).setCapability(Shape3D.ALLOW_GEOMETRY_READ);
            }


        }
        System.out.println("We are here inside Polygon4");

      if (ap == null)
      {
          setAppearance();
      }
      else setAppearance(ap);
 }


    public Node cloneNode(boolean forceDuplicate) {
        Polygon c = new Polygon(vertices, faces, flags, getAppearance());
        c.duplicateNode(this, forceDuplicate);
        return c;
    }


    public void duplicateNode(Node originalNode, boolean forceDuplicate) {
        super.duplicateNode(originalNode, forceDuplicate);
    }


}

调用TriangleFanArray.setCoordinates（int，Point3d）时出现NullPointerException。我无法找到任何理由。