question about Tour3D(the source of the Andrew Davison 's book)

[jiyanliang]

In Tour3D’Obstacles class,i want to use BoundingBox instead of BoundingSphere.But it doesn’t work.
Here is source:

// Obstacles.java
// Andrew Davison, April 2005, ad@fivedots.coe.psu.ac.th

/* Obstacles stores a 2D boolean array (obs) representing the
   XZ plane. The row index is the z-axis, the column index
   is the x-axis. obs[0][0] is the back left hand corner of
   the plane, which is the (x,z) point (0-FLOOR_LEN/2, 0-FLOOR_LEN/2).

   Obstacles can only be positioned at integer positions due
   to the use of array subscripts to mark the obstacle positions.
*/

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


public class Obstacles
{
  private final static float RADIUS = 0.1f;   // radius of obstacle
  private final static float HEIGHT = 1.0f;   // height of obstacle

  private final static int FLOOR_LEN = 50;  
      // should be the same as the floor size in CheckerFloor, and be even

  // colours for obs material
  private final static Color3f black = new Color3f(0.0f, 0.0f, 0.0f);
  private final static Color3f specular = new Color3f(1.0f, 1.0f, 1.0f);
  private final static Color3f red = new Color3f(0.9f, 0.1f, 0.2f);


  private boolean obs[][];    // whether a (x,z) has an obstacle
  //private BoundingSphere obsBounds[][];   // the bounding sphere for obs
  private BoundingBox obsBounds[][];   // the bounding sphere for obs
  private Group obsGroup;     // group of 3d obstacles shown in world


  public Obstacles()
  {
    obs = new boolean[FLOOR_LEN+1][FLOOR_LEN+1];    // larger than FLOOR_LEN*FLOOR_LEN
    //obsBounds = new BoundingSphere[FLOOR_LEN+1][FLOOR_LEN+1];
    obsBounds = new BoundingBox[FLOOR_LEN+1][FLOOR_LEN+1];
    for (int z=0; z <= FLOOR_LEN; z++)
      for(int x=0; x <= FLOOR_LEN; x++) {
        obs[z][x] = false;
        obsBounds[z][x] = null;
       // obsBounds2[z][x] = null;
      }

    obsGroup = new Group();

  }  // end of Obstacles()


  public void store(String line)
  /* The line will have the format:
        (x1,z1) (x2,z2) ...
  */
  {
    int x=0, z=0;
    String coordStr;
    StringTokenizer points;
    StringTokenizer coords = new StringTokenizer(line);
    while (coords.hasMoreTokens()) {
      coordStr = coords.nextToken();    // should be a single (x,z)
      points = new StringTokenizer(coordStr, "(,)");
      try {
        x = Integer.parseInt(points.nextToken());
        z = Integer.parseInt(points.nextToken());
      }
      catch (NumberFormatException ex){ 
        System.out.println("Incorrect format for obstacle data in tours file"); 
        break;
      } 
      markObstacle(x,z);
    }
  }  // end of store()
  
  public void store2(String line)
  /* The line will have the format:
        (x1,z1) (x2,z2) ...
  */
  {
    int x=0, z=0;
    String coordStr;
    StringTokenizer points;
    StringTokenizer coords = new StringTokenizer(line);
    while (coords.hasMoreTokens()) {
      coordStr = coords.nextToken();    // should be a single (x,z)
      points = new StringTokenizer(coordStr, "(,)");
      try {
        x = Integer.parseInt(points.nextToken());
        z = Integer.parseInt(points.nextToken());
      }
      catch (NumberFormatException ex){ 
        System.out.println("Incorrect format for obstacle data in tours file"); 
        break;
      } 
      markObstacle2(x,z);
    }
  }  // end of store()


  private void markObstacle(int x, int z)
  {
    if ((x < -FLOOR_LEN/2) || (x > FLOOR_LEN/2)) {
      System.out.println("Obstacle x point out of bounds: " + x);
      x = 0;
    }
    if ((z < -FLOOR_LEN/2) || (z > FLOOR_LEN/2)) {
      System.out.println("Obstacle z point out of bounds: " + z);
      z = 0;
    }
    obs[z+(FLOOR_LEN/2)][x+(FLOOR_LEN/2)] = true;
    obsBounds[z+(FLOOR_LEN/2)][x+(FLOOR_LEN/2)] =
			new BoundingBox( new Point3d(x-0.5, 0.0, z+0.5), new Point3d(x+0.5, 1.0, z-0.5));
    

   obsGroup.addChild( makeObs(x, z));

  }  // end of markObstacle()
  
  private void markObstacle2(int x, int z)
  {
    if ((x < -FLOOR_LEN/2) || (x > FLOOR_LEN/2)) {
      System.out.println("Obstacle x point out of bounds: " + x);
      x = 0;
    }
    if ((z < -FLOOR_LEN/2) || (z > FLOOR_LEN/2)) {
      System.out.println("Obstacle z point out of bounds: " + z);
      z = 0;
    }
    obs[z+(FLOOR_LEN/2)][x+(FLOOR_LEN/2)] = true;
    /*obsBounds[z+(FLOOR_LEN/2)][x+(FLOOR_LEN/2)] =
			new BoundingSphere( new Point3d(x, 0.0, z), RADIUS);*/
    obsBounds[z+(FLOOR_LEN/2)][x+(FLOOR_LEN/2)] =
		new BoundingBox( new Point3d(x-0.5, 0.0, z+0.5), new Point3d(x+0.5, 2.0, z-0.5));

   obsGroup.addChild( makeObs2(x, z));

  }  // end of markObstacle()


  public void print()
  {
    // header - markers for each 5 units, and a line
    for(int x=(-FLOOR_LEN/2); x <= (FLOOR_LEN/2); x++) {
      if (x == 0)
        System.out.print("0");
      else if (x%5 == 0)
        System.out.print("*");
      else
        System.out.print(" ");
    }
    System.out.println("");
    for(int x=(-FLOOR_LEN/2); x <= (FLOOR_LEN/2); x++)
      System.out.print("-");
    System.out.println("");

    // body of table: O's and a z-axis at the end of each line
    for (int z=0; z <= FLOOR_LEN; z++) {
      for(int x=0; x <= FLOOR_LEN; x++) {
        if (obs[z][x])
          System.out.print("O");
        else
          System.out.print(" ");
      }
      if ((z-FLOOR_LEN/2)%5 == 0)
        System.out.println("| " + (z-FLOOR_LEN/2));
      else 
        System.out.println("|");
    }

    // footer: a line
    for(int x=(-FLOOR_LEN/2); x <= (FLOOR_LEN/2); x++)
      System.out.print("-");
    System.out.println("");
  }  // end of print()


  public boolean nearObstacle(Point3d pos, double radius)
  /* posn is not allowed to be outside the floor area.
     Also, every obstacle's bounding sphere is checked against pos
  */
  {
    if ((pos.x < -FLOOR_LEN/2) || (pos.x > FLOOR_LEN/2) ||
        (pos.z < -FLOOR_LEN/2) || (pos.z > FLOOR_LEN/2))     // off the floor
      return true;

    // check if near any obstacles
    BoundingBox bs = new BoundingBox( new Point3d(pos.x-0.5,pos.y,pos.z+0.5), new Point3d(pos.x+0.5,pos.y+1,pos.z-0.5));
    for (int z=0; z <= FLOOR_LEN; z++)
      for(int x=0; x <= FLOOR_LEN; x++)
        if (obs[z][x]) {
          if (obsBounds[z][x].intersect(bs))
            return true;
        }
     return false;
   }  // end of nearObstacle()



  private TransformGroup makeObs(int x, int z)
  // a red cylinder whose base is on (x,z)
  {
    // create obstacle node
    Appearance obsApp = new Appearance();
    Material mat = new Material(black, black, red, specular, 100.f);
    mat.setLightingEnable(true);
    obsApp.setMaterial( mat );
    Cylinder obs = new Cylinder( RADIUS, HEIGHT, 
						Cylinder.GENERATE_NORMALS, obsApp);

    // fix obs's position
    TransformGroup posnTG = new TransformGroup();
    Transform3D trans = new Transform3D();
    trans.setTranslation( new Vector3d(x, HEIGHT/2, z) );
    posnTG.setTransform(trans);
    posnTG.addChild(obs); 
    return posnTG;
  }  // end of makeObs()
  
  private TransformGroup makeObs2(int x, int z)
  // a red cylinder whose base is on (x,z)
  {
    // create obstacle node
    Appearance obsApp = new Appearance();
    Material mat = new Material(black, black, red, specular, 100.f);
    mat.setLightingEnable(true);
    obsApp.setMaterial( mat );
    
    Box obs = new Box((float)0.2, (float)1.0,(float)1.0,obsApp);

    // fix obs's position
    TransformGroup posnTG = new TransformGroup();
    Transform3D trans = new Transform3D();
    trans.setTranslation( new Vector3d(x, HEIGHT/2, z) );
    posnTG.setTransform(trans);
    posnTG.addChild(obs); 
    return posnTG;
  }  // end of makeObs()


  public Group getObsGroup()
  {  return obsGroup;  }



}  // end of Obstacles class

[dandrew]

Dear jiyanliang,

The best way to get help from a forum is to post a specific question, focussed on a single problem which you’ve already had a good look at yourself.

Saying that something “doesn’t work”, and posting the entire class, is less likely to get a good response.

For example, you should at least tell people what the error message is, whether the error occurs at run time or compile time, and narrow down the problem to a particular method.

I suggest you have a look at “How To Ask Questions The Smart Way” by Eric Raymond at http://www.catb.org/~esr/faqs/smart-questions.html.

For questions about my code, all of the above applies, and it’s also a good idea to send questions to me directly at ad@fivedots.coe.psu.ac.th. I don’t “prowl” these forums everyday.

• Andrew

[jiyanliang]

Dear Andrew Davison:
I am sorry i didn’t describe the question detailly;
Thanks for your detail reply.
I want to know is there are any differents between BoundingBox and BoundingSphere in Java 3D api.Now I want to build obstacles whitch is box like (1.0,10.0,2.0),but the BoundingSphere is a sphere.
In tour3D, you build the bounds with BoundingSphere.and now i want to build the Bounds with BoundingBox.
I know both BoundingSphere and BoundingBox have intersect() method.But this method doesn’t take effect after i use BoundingBox instead of BoundingSphere.the TourSprite can go througt of the obstacles.
I am the biginner of Java 3D programming.

Thank you again!!

sunnyan

[dandrew]

You need to read the documentation for the two Bounding classes, and then you’ll find out for yourself what the differences are between them.

“the method doesn’t take effect” is not enough information for me to help you.

1. Try debugging the code yourself first.

2. If you still have problems, send me an e-mail DIRECTLY. The e-mail should contain debugging information.