groundcover.java

java3D game engine design of the source [three-dimensionalvirtualrealitynetworkprogram] - "virtual

// GroundCover.java
// Andrew Davison, August 2003, [e-mail]

/* GroundCover decorates the landscape with ground cover objects
   specified in a 'GC' file.

   GroundCover reads in a 'GC' file, which should have the
   name /models/<fnm>GC.txt

   The format of the file is:
       range [ <min> <max> ]
       <gc file1> <scale1> <number1>
       <gc file2> <scale2> <number2>
           :

   The range specifies the height range within which the ground
   cover should appear. Note: the 'range' word must be included
   even if there are no <min> or <max> values supplied.

   The 'range' keyword triggers the loading of the .obj file called
   /models/<fnm>.obj as a text file, so that the (x,y,z) coordinates
   of its mesh can be stored as Vector3d objects in the coords
   ArrayList.

   Each of the <gc file>s are loaded using a GroundShape object.
   The GroundShape object is wrapped in a SharedGroup node, so that
   only one object is needed rather than <number> of them.
 
   Each shared version of the GroundShape object is placed at a random
   location somewhere on the surface of the landscape, by randomly
   selecting a coordinate from the coords list.

   <scale> will scale the ground cover image. Experiment until the
   image looks right! 90 is a good starting value.
*/

import java.io.*;
import java.util.*;

import javax.media.j3d.*;
import javax.vecmath.*;


public class GroundCover
{
  private ArrayList coords;     // OBJ file mesh coordinates (as Vector3d objects)
  private BranchGroup coverBG;  // top-level BG for all the ground cover

  public GroundCover(String fnm)
  {
    coords = new ArrayList();
    coverBG = new BranchGroup();

    loadCoverInfo(fnm);
  }  // end of GroundCover()


 //--------------- loading methods ----------------------

  private void loadCoverInfo(String fnm)
  // load the 'GC' file /models/<fnm>GC.txt
  {
    String gcFile = new String("models/" + fnm + "GC.txt");
    System.out.println("Loading ground cover file: " + gcFile);
    try {
      BufferedReader br = new BufferedReader( new FileReader(gcFile) );
      String line;

      if ((line = br.readLine()) != null)     // the range [ <min> <max> ] line
        loadObj(fnm, line);
      else {
        System.out.println(gcFile + " is empty!");
        return;
      }

      // read in the multiple <gc file> <scale> <number> lines
      StringTokenizer tokens;
      String gcFnm;
      int numItems = 0;
      while((line = br.readLine()) != null) {
        tokens = new StringTokenizer(line);
        gcFnm = tokens.nextToken();
        double scale = Double.parseDouble( tokens.nextToken() );
        int gcNo = Integer.parseInt( tokens.nextToken() );
        loadGC(gcFnm, scale, gcNo);    // load a GroundShape object for this gc
        numItems++;
      }
      System.out.println(numItems + " ground cover types");
      br.close();
    } 
    catch (Exception e) 
    {  System.out.println(e); }
  }  // end of loadCoverInfo()



  private void loadObj(String fnm, String line)
  /* line is    range [ <min> <max> ]
     The OBJ file /models/<fnm>.obj is loaded as a text file, and
     the coordinates of its mesh are stored in the ArrayList coords.

     However, any coordinates with heights outside the range min-max 
     are not stored.
  */


  { StringTokenizer tokens = new StringTokenizer(line);
    tokens.nextToken();   // skip 'range' word

    if (tokens.hasMoreTokens()) {
      try {
        double min = Double.parseDouble( tokens.nextToken() );
        double max = Double.parseDouble( tokens.nextToken() );
        readObj(fnm, min, max, true);
        System.out.println("Ground cover ranges -- min: " + min + "; max: " + max);
        return;
      }
      catch (NumberFormatException ex)
      { System.out.println("min/max values must be double"); }
    }

    readObj(fnm, 0, 0, false);    // default loading; min == max == 0
  }  // end of loadObj()




  private void readObj(String fnm, double min, double max, boolean hasRange)
  /* The OBJ file is loaded as a text file. The data present should
     be a series of mesh coordinates, of the format:
           v x-coord y-coord z-coord

     The coords are added to the coords ArrayList as Vector3d objects,
     except for ones with heights (z-axis values) outside the min-max
     range. We also exclude points on the edge of the landscape when
     x or y == 0.

     The only other data generated by Terragen is face info, of
     the form:
          f index1 index2 index3
     which is ignored here.

     A good description of the OBJ file format can be found in Java 3D's
     documentation for the ObjectFile class.

     An OBJ file can be opened by any good text editor, but one that
     is capable of loading multi-megabyte size files.
  */
  {
    String objFile = new String("models/" + fnm + ".obj");
    System.out.println("Loading terrain mesh file: " + objFile);

    try {
      BufferedReader br = new BufferedReader( new FileReader(objFile) );
      String line, token;
      StringTokenizer tokens;
      double xCoord, yCoord, zCoord;
      int numExcluded = 0;

      while((line = br.readLine()) != null) {
        // System.out.println(line);
        if(line.startsWith("v")) {  
          tokens = new StringTokenizer(line);   // line is   v  x y z
          tokens.nextToken();   // skip 'v'
          xCoord = Double.parseDouble( tokens.nextToken() );
          yCoord = Double.parseDouble( tokens.nextToken() );
          zCoord = Double.parseDouble( tokens.nextToken() );

          //System.out.println(" (" + xCoord + ", " + yCoord + 
          //                           ", " + zCoord + ")");
          if (hasRange) {
            if ((zCoord >= min) && (zCoord <= max))
              coords.add( new Vector3d(xCoord, yCoord, zCoord) );
            else 
              numExcluded++;
          }
          else {
            if ((xCoord != 0) && (zCoord != 0))
              coords.add( new Vector3d(xCoord, yCoord, zCoord) );
            else
              numExcluded++;
          }
        }
      }
      br.close();
      // System.out.println("No. of coords: " + coords.size());
      // System.out.println("Coords excluded: " + numExcluded);
    } 
    catch (Exception e) 
    { System.out.println("Error reading: " + objFile); }
  }  // end of readObj()



  private void loadGC(String gcFnm, double scale, int gcNo)
  /* Each GC file is loaded as a GroundShape object, then wrapped
     in a SharedGroup (SG) node so that only one object is required 
     rather than gcNo of them.

     Multiple TransfromGroups are created, which place the SG
     at random positions on the landscape.
  */
  { String gcFile = new String("models/" + gcFnm);
    System.out.println("Loading GC file: " + gcFile + "; scale: " +
               scale + "; " + gcNo + " copies");

    SharedGroup gcSG = new SharedGroup();
    gcSG.addChild( new GroundShape((float) scale, gcFile) );
    gcSG.setPickable(false);   // so not pickable in scene

    Vector3d coordVec;  
    for(int i=0; i < gcNo; i++) {   // create multiple TGs using same SG
      coordVec = selectCoord();
      placeCover(gcSG, coordVec);
    }
  }  // end of loadGC()


  private Vector3d selectCoord()
  // randomly select a landscape coordinate
  { int index = (int) Math.floor( Math.random()*coords.size());
    return (Vector3d) coords.get(index);
  }


  private void placeCover(SharedGroup gcSG, Vector3d coordVec)
  /* Place ground cover onto the landscape at coordVec.
     The resulting subgraph is:
       coverBG -----> posTG ----> rotTG ----> Link ---> gcSG

     Multiple copies of the ground cover will have their own
     position, rotation, and Link nodes, but the Link nodes
     all link to the same SharedGroup node.
  */
  { 
    Transform3D t3d = new Transform3D();
    t3d.rotX( Math.PI/2.0 );    // to counter the -ve rotation of the land
                                // since using XY as floor
    TransformGroup rotTG = new TransformGroup(t3d);
    rotTG.addChild( new Link(gcSG) );

    Transform3D t3d1 = new Transform3D();
    t3d1.set( coordVec ); 
    TransformGroup posTG = new TransformGroup(t3d1);
    posTG.addChild( rotTG ); 

    coverBG.addChild( posTG );
  }  // end of placeCover()



  public BranchGroup getCoverBG()
  // used by the Landscape object
  {  return coverBG;  }

}  // end of GroundCover class