Galaxy Advanced Engineering

GAE Graphics Software Products and Plot-10 Compatibility

Galaxy Advanced Engineering, Inc. presents a migration bridge for callable PLOT-10 routines within your existing FORTRAN program via its high level FORTRAN graphics library Language which is called UGL. UGL is a Scientific Graphics Subroutine Library for any computing system such as Main, Micro and Mini - Computers with its given Operating System. UGL presently supports hardware such as HP/UNIX, SUN/SOLARIS, Alpha/OpenVMS, VAX/VMS and Windows 95/NT or DOS.

UGL-GRAPHICS was developed to provide a migration path with a CA-DISSPLA, GKS, PLOT-10, CalComp, PLOT88 and DIGLIB (from Lawrence Livermore Lab.) graphics interface in the PC and VAX as well as UNIX environment and provides the same high graphics standards found on the main frames using the above graphics libraries. The most common subset of CA-DISSPLA routine (more than %95) and rest of the mentioned graphics libraries are supported directly and any particular ones may be provided upon request. If the users have an existing code using any of these graphics library routines within them, they do not have to change their calls. The bridge that are built with UGL-GRAPHICS library of Galaxy advanced Engineering, Inc. will distinguish these routines and maps them to its own routine against these calls for direct porting of the user code to its new environment supported by UGL-GRAPHICS.

What is PLOT-10?

Plot 10 is a collection of subroutines developed by Tektronix Inc. for use with Tektronix graphics terminals. The routines can be called by a user's FORTRAN program to enable the user to obtain high quality graphic images on Tektronix and Tektronix-compatible terminals (including a properly configured X-windows xterm).

Currently, many graphics terminals are raster scan devices and are similar to a television's CRT. The screen is scanned continuously from top to bottom, and individual picture elements ("pixels") of phosphor may be chosen for illumination by firing an electron beam at the pixel location. An image is built from suitable patterns of illuminated pixels so that points, lines, and surfaces can be recognized. The graphics terminal memory keeps track of which pixels should be activated with each pass of the electron beam. In the case of a computer terminal with a raster scan device, the advantages include speed enough to enable animation of images, and the possibility of different levels of gray or color at each pixel. The disadvantage is that picture resolution is not very high. Since lines are formed by activation of adjacent elements (or cells), most lines other than horizontal or vertical show evidence of "aliasing," a jagged or stair-case appearance.

Plot 10 was developed in the 70's, before electronic memory was so inexpensive.Instead of using raster scan screens, the graphics terminals produced by Tektronix were "storage tube" devices. The back of the screen was coated with a phosphor, and instead of a beam that continuously scanned the screen, the storage tube has an image drawn by an electron beam only once, and then electronic means are used to insure that the brightened phosphor persists. An advantage is very high resolution of the resultant images that are "flicker-free", but images can not be animated because the screen can not be selectively erased. Color is also a difficulty. However, since extensive electronic memory was not necessary, this type of device became a standard for graphics. Plot 10 has since been enhanced to operate with other more sophisticated display devices, but it was designed for this type of simple storage tube device. It is now sort of a "lowest common denominator" graphics standard.

The Tektronix terminals were designed so that the basic controllable operations were to move the aim of the electron beam, to turn the beam on and off,and to erase the entire screen. Part of Plot 10 is concerned with sending special characters (called an escape sequence) from the host computer to control these basic terminal functions. In addition, Plot 10 provides higher level functions such as the means to scale, rotate, clip and label graphic images.

For purposes of controlling the location of the beam's aim, the rectangular screen has 1024 addressable locations (0-1023) in the horizontal x direction,and 780 addressable locations (0-779) in the vertical y direction. (The origin is in the lower left hand corner of the screen.)

The Tektronix terminals can be used by users to generate graphics with their FORTRAN programs by calling Plot 10 subroutines to perform specific functions. When the user's program is executed, the Plot 10 library of routines is linked to the user's compiled FORTRAN code. The Plot 10 User's Manual describes all of the functions.

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