The input to rods consists of a single text file containing colour information and atomic coordinates in
PDB data bank format. Coordinates are output as Raster3D descriptor records with colours and sphere
radii assigned according to the COLO records described below. Ball-and-stick figures have atoms drawn at
0.2 * VanderWaals radius, connected by rods with a default 0.2A cylindrical radius. Bonds are drawn for
atoms which lie closer to each other than 0.6 * (sum of VanderWaals radii). By default the output file
contains a set of header records as required by the render program. The header is constructed to include
a TMAT matrix corresponding to the transformation matrix contained in file setup.matrix (if it exists),
or to the Eulerian angles contained in file setup.angles (if it exists).
Colours are assigned to atoms using a matching process, using COLOUR records prepended to the input PDB
file. If no COLOUR records are present in the input file, atoms will receive default CPK colors
(C=grey, O=red, N=blue, S=yellow, P=green, other=magenta). Raster3D uses a pseudo-PDB record type with
the same basic layout as the above but with COLO in the first 4 columns:
Columns
1 - 4 COLO
7 - 30 Mask (described below)
31 - 38 Red component
39 - 46 Green component
47 - 54 Blue component
55 - 60 van der Waals radius in Angstroms
61 - 80 Comments
Note that the Red, Green, and Blue components are in the same positions as the X, Y, and Z components of
an ATOM or HETA record, and the van der Waals radius goes in place of the Occupancy. The Red, Green, and
Blue components must all be in the range 0 to 1.
The Mask field is used in the matching process as follows. First the program reads in and stores all the
ATOM, HETA, and COLO records in input order. Then it goes through each stored ATOM/HETA record in turn,
and searches for a COLO record that matches the ATOM/HETA record in all of columns 7 through 30. The
first such COLO record to be found determines the colour and radius of the atom.
In order that one COLO record can provide colour and radius specifications for more than one atom (e.g.,
based on residue or atom type, or any other criterion for which labels can be given somewhere in columns
7 through 30), the "#" symbol is used as a wildcard. I.e. a # in a COLO record matches any character in
the corresponding column in an ATOM or HETA record. All other characters must match literally to count
as a match. Note that the very last COLO record in the input should have # symbols in all of columns 7
through 30 in order to provide a colour for any atom whose ATOM/HETA record fails to match any previous
COLO record. This idea of matching masks for colour specifications is due to Colin Broughton.