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Public Domain Aeronautical Software (PDAS)  

The program SKETCH (later superceeded by SILH), written by David Hedgley of the NASA Dryden Flight Research Center has long been famous as the most widely distributed code by the NASA service known as COSMIC. All over the world, people have obtained this program and adapted it to the task of displaying three-dimensional objects as wire-frame pictures in perspective with hidden lines removed. Today, the leading-edge computer graphics wizards are making color pictures with continuous shading that are remarkable in their realism. But, for those of us with black and white printers, wireframe is still the best way to show an object like an airplane so that it can be visualized.

I remember jumping at the chance to use this program in 1982, when I was looking for a way to check the input for an aerodynamic panel code known as PANAIR. I composed a simple program that read a PANAIR input file and called SKETCH to produce the scene. That program is the basis of the program in this collection.

Since that time, NASA has settled on a single consistent format for describing wireframe objects which is referred to as the Langley Wire Frame Geometry Standard (LaWGS). This program HLP (for hidden line program) is an update of the old program (called PANSKETCH) that I wrote, now updated to read LaWGS files and use the newer SILH (for silhouette) program from David Hedgley. The output is a plot file, encoded for gnuplot, of the object in question.

A supplementary program called PrintHLP is also provided that will convert this gnuplot file into appropriate format for printing on a PostScript printer or on a Hewlett-Packard compatible printer.

PDAS home > Contents > Hidden Line
Public Domain Aeronautical Software (PDAS)