PLOTX : Interface to graphics devices

Authors : Syd Hall, Roeli Olthof-Hazekamp, Howard Flack, James Hester & Ursula Bartsch

Contact: Syd Hall, Crystallography Centre, University of Western Australia, Nedlands 6907, Australia

PLOTX converts graphical information generated by the programs such as CONTRS and ORTEP into plot commands for specific devices.


PLOTX generates data appropriate for the different graphical protocols (e.g. X11, HPGL, PostScript) for use with local plotting devices. A number of new options for setting the postscript papersize have been added.

Scaling And Centring

The positive x-axis of a plot is taken as horizontal from left to right, and the positive y-axis is taken as vertical from bottom to top. Default frame dimensions and resolutions for the different devices are defined for each device at implementation time. They may be changed with the params line. High resolution values (i.e. small values entered in field 7) may result in smoother plots but will run slowly. To magnify or contract a plot, or to translate a plot within the given frame, the user may define the scale factor and/or plot centre manually.

Colour Graphics

The plot command bdf generated by some programs contains subject indices that are used to produce colour plots. This facility allows different subjects, such as atoms, bonds, numbers, characters and contours, to be plotted in different colours. Default colours are set within PLOTX but the user can specify his own colours using the color line. For atoms up to 16 different colours are allowed. Options available on the color line are:

  • fill causes closed areas such as those bounding atoms or bonds to be filled with a specified colour or pattern. The boundary line colour index may be different to the fill colour. This is the default for vdu only.

  • nofill draws atoms without colour filling.

  • bond signals that the integer specifying the colour index of the bonds follows.

  • char signals that the integer specifying the colour index of character strings follows (e.g. atom names and title).

  • numb signals that the integer specifying the colour index of numbers follows (e.g. bond distances).

  • contur signals that the integers specifying the colour indices of contours follow.

    • n1 is the colour of the negative contour levels

    • n2 is the zero contour level colour

    • n3 is the colour of the positive contour levels

    • n4 is the atom site marker colour

    • n5 is the character string colour.

  • nocol causes 1 colour to be plotted. This overrides the default colours for vdu .

Postscript output

The format of postscript output has been modified significantly to make it more amenable to manual editing. It has also been modified to conform to the ADOBE postscript Document Structuring Conventions for multi-page documents. This permits the page selection methods of postscript previewers to be used to step through multi-page plots, such as multi-layered contour diagrams. To support these modifications a postscript prolog file xtalps is supplied with xtal and is included in every postscript output plot. For including single page XTAL postscript images in other image/manipulation packages it may be necessary to edit the first line of the .psfile to indicate that it is to be treated as an encapsulated image. The generated .ps file contains instructions for doing this.

XFIG3.2 output

XFIG is free software for interactively editing vector graphics under X11. XFIG3.2can be obtained from Xtal is not associated with the XFIG project in any way, we merely recommend their software as a useful additional graphical editting tool for post processing Xtal plot files.

File Assignments

  • Reads plot commands from a specified file (default is ort)

  • Writes a plotter output to locally defined devices or files



This produces an ORTEP plot on the graphics screen in X11 protocol.

PLOTX postl nwm

A NEWMAN plot from file nwmis converted to a landscape PostScript file.