The syntax of the O graphics descriptor language

The O graphic descriptor language can be used to draw anything the user wants. In fact, some of the pictures generated by O are done via the graphics descriptors, e.g. the CPK models. The picture must be defined in terms of a number of drawing instruction, that are saved in a text datablock. The contents of this text datablock can the be drawn on the screen using the command Draw_object. The current list of recognised instructions is as follows:

begin_object

[name] -- start object with give name

end_object

- end current object

colour

[value] -- name (e.g. red) or packed integer defining a new colour

line_type

[type] -- character value (dashed, solid, dotted, dash_dot)

move

[x, y, z] -- moveto (x, y, z)

line

[x, y, z] -- lineto (x, y, z)

move_atom

[mol residue atom] -- move to (x, y, z) of the atom

line_atom

[mol residue atom] -- line to (x, y, z) of the atom

dot

[ x, y, z] -- place dot at (x, y, z)

text

[x y z string] -- place text string at (x, y, z)

text_size

[value] -- real value 0 -> 1.0, (small -> large)

text_colour

[integer value] -- name (e.g. red) or packed integer defining a new colour

poly

[number of vertices] [vertex](i) -- polygon using current colour

poly_colour

[colour] -- Set the polygon colour

instance

[object] [datablock] -- Object to be instanced and datablock containing tranformation.

sphere_atom

[mol res atom radius colour] -- sphere at coords mol/residue/atom with radius and colour

sphere_xyz

[x, y, z radius] -- sphere at coords x ,y, z with the given radius.

stick

[mol res atm] [mol res atm] [radius] -- Draw a solid stick between 2 atoms, with given radius.

stick_xyz

[x1, y1, z1] [x2, y2, z2] [radius] -- Draw a solid stick between two points in space, with the given radius.

mode

[solid/line] -- Set the solid or line drawing mode.

cell

[cell parameters] -- Set the crystallographic unit cell for the following commands.

fmove

[x, y, z] -- Move to (x, y, z), given in fractional coordinates.

fline

[x, y, z] -- Line to (x, y, z), given in fractional coordinates.

ftext

[x y z string] -- place text string at (x, y, z), given in fractional coordinates.