Swarm and VisAD via HDF5

[Marcus G. Daniels]

Here's an example of using VisAD, a Java3D-based package for data
visualization, in conjunction with Swarm.  (This uses HDF5, but since
VisAD is a Java library, you can use it directly in Swarm too.)

Instructions are for Windows NT:

1) Get and install Java 3D(TM) from:
   http://java.sun.com/products/java-media/3D

   (Java3D most easily works by overlaying your existing JDK
   installation, so check paths carefully.)

2. Start up a Swarm terminal, and create a subdirectory for work files:

   $ mkdir visad
   $ cd visad

3. Download the Java DLL for HDF5:

   $ wget 
ftp://hdf.ncsa.uiuc.edu/HDF5/current/java-hdf5/JHI5_1_1_bin/lib/win/jhdf5.dll

4. Download the VisAD jar file:

   $ wget ftp://www.ssec.wisc.edu/pub/visad-2.0/visad.jar

5. Create a HDF5 data file using a Swarm program like below.
   (Note that a Swarm list is used here instead of a java.util.* list.
   Java collections aren't yet supported by the Swarm serialization,
   although simple Java objects are.)

   $ cat Cones.java
import swarm.Globals;
import swarm.defobj.HDF5ArchiverImpl;
import swarm.defobj.Archiver;
import swarm.collections.ListImpl;
import swarm.collections.List;

public class Cones {
  class Coord {
    public double x, y, z;

    Coord (double x, double y, double z) {
      this.x = x;
      this.y = y;
      this.z = z;
    }
  }

  public List coneCoords;
  
  public Cones () {
    double thetaStep = 2 * Math.PI / 100;

    int pos = 0, zi, ti;

    coneCoords = new ListImpl (Globals.env.globalZone);

    for (zi = 0; zi < 100; zi++)
      {
        double z = zi - 50;
        double r = 50 - Math.abs (z);
        
        for (ti = 0; ti < 100; ti++)
          {
            double theta = ti * thetaStep;
            
            coneCoords.addLast (new Coord (z,
                                           r * Math.sin (theta), 
                                           r * Math.cos (theta)));
          }
      }
  }
  
  void save (Archiver archiver) {
    archiver.putShallow$object ("cones", coneCoords);
  }

  static void main (String args[]) {
    Globals.env.initSwarm ("Cones", "0.0",
                           "address@hidden", args);
      

    Cones test = new Cones ();
    test.save (new HDF5ArchiverImpl (Globals.env.globalZone, "cones.hdf"));
  }
}

6.  Compile it:

    $ javacswarm Cones.java

7.  Run it:

    $ javaswarm Cones

8.  Run the VisAD spreadsheet using Sun JDK 1.2.2:

    $ jdkswarm -cp visad.jar visad.ss.SpreadSheet

8a. Select "File/Import data" menu item, then select "cones.hdf"

8b. Select "Cell/Edit mappings" menu item, then select "Clear all"

8c. Make new variable mappings:
8c1. Click on "x" on the left, and then the X> icon.
8c2. Click on "y" on the left, and then the Y^ icon.
8c3. Click on "z" on the left, and then the Z/ icon.
8c4. Click "Done".

You should now see a 3D two-ended cone you can rotate, etc.
     
Note that this data file can be loaded and saved by `R' as well:

$ /rw1000/bin/Rgui 
> library(hdf5)
> hdf5load("cones.hdf")
> plot(cones$x,cones$y)

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