Steven Jones wrote:
How are density (.df3) files made?  This seems like an intriguing feature,
yet the documentation is scarce on this matter.
Feel like creating them by hand ??
If so try the following in FRHED http://www.tu-darmstadt.de/~rkibria (Win32 only)
Create a new file that is x*y*z + 6 bytes in length (use the append feature; extra 6 bytes are for dimensions)
(File->New, Edit->Append)

With the cursor in the first byte enter an unsigned decimal value of word length that is x
(Home key, Edit->Enter decimal value)
Do the same on the 3rd and 5th bytes for the y and z dimensions

On every byte after the 6th (not-including) add a byte length number (0-255), which will be the density for that voxel
The x, y and z  positions (1 based indexes) are calculated somehow as follows, where p = position in the file, a = p - 6, xx,yy&zz are the dimensions of the volume and floor is a func that returns the next integer below its input
z = floor(p / (xx*yy)) + 1
x = (p mod (xx*yy) ) mod xx
y = floor((p mod (xx*yy) ) / yy)
I think these are right - Anyone else know