Английская Википедия:HP-GL
Шаблон:More citations needed Шаблон:Infobox file format HP-GL, short for Hewlett-Packard Graphics Language and often written as HPGL, is a printer control language created by Hewlett-Packard (HP). HP-GL was the primary printer control language used by HP plotters.[1] It was introduced with the plotter HP-9872 in 1977 and became a standard for almost all plotters. Hewlett-Packard's printers also usually support HP-GL/2 in addition to PCL.[2]
Design
The language is formed from a series of two letter codes (mnemonics), followed by optional parameters. For instance an arc can be drawn on a page by sending the string:
AA100,100,50;
This means Arc Absolute, and the parameters place the center of the arc at absolute coordinates 100,100 on the page, with a starting angle of 50 degrees measured counter-clockwise. A fourth optional parameter (not used here) specifies how far the arc continues, and defaults to 5 degrees.
When first introduced, HP-GL contained the following commands:
| Command | Meaning |
|---|---|
| Vector Group | |
PA x,y{,x,y{...}} |
Plot absolute [i] |
PR x,y{,x,y{....}} |
Plot relative [i] |
PD |
Pen down |
PU |
Pen up |
| Character Group | |
CA n |
Designate alternate character set n [i] |
CP spaces, lines |
Character plot [d] |
CS m |
Designate standard set m [i] |
DI run, rise |
Absolute direction [d] |
DR run, rise |
Relative direction [d] |
LB c, ..., c |
Label ASCII string [c] |
SA |
Select alternate character set |
SI wide, high |
Absolute character size [d] |
SL tan θ |
Absolute character slant (from vertical) [d] |
SR wide, high |
Relative character size [d] |
SS |
Select standard character set |
UC x, y, pen{, ...} |
User defined character [i] |
| Line Type Group | |
LT t{,l} |
Designate line type t and length l [d] |
SM c |
Symbol mode [c] |
SP n |
Select pen [i] |
VA |
Adaptive velocity |
VN |
Normal velocity |
VS v{,n} |
Select velocity v for pen n [i] |
| Digitize Group | |
DC |
Digitize clear |
DP |
Digitize point |
OC |
Output current position and pen status |
OD |
Output digitized point and pen status |
| Axes | |
TL tp{,tn} |
Tick length [d] |
XT |
X axis tick |
YT |
Y axis tick |
| Set-Up Group | |
IP p1x,p1y,p2x,p2y |
Input p1 and p2 [i] |
IW xlo,ylo,xhi,yhi |
Input window [i] |
OP |
Output p1 and p2 [i] |
| Configuration Status | |
AP |
Automatic pen pickup [i] |
DF |
Set default values |
IM e{,s{,p}} |
Input e, s and p masks [i] |
IN |
Initialize |
OE |
Output error [i] |
OS |
Output status [i] |
| Шаблон:Code w,h | set character width and height |
Formats:
- [i]: integer formats between -32767 and 32768. No decimal point.
- [d]: decimal format between +/- 127.9999. Optional decimal point.
- [c]: ASCII character
Examples
Typical HP-GL files start with a few setup commands, followed by a long string of graphics commands. The file was in ASCII (text file) format, for instance:
| Command | Meaning |
|---|---|
| Шаблон:Mono | initialize, start a plotting job |
| Шаблон:Mono | set the scaling points (P1 and P2) to their default positions |
| Шаблон:Mono | select pen 1 |
| Шаблон:Mono | lift Pen Up and move to starting point for next action |
| Шаблон:Mono | put Pen Down and move to the following locations (draw a box around the page) |
| Шаблон:Mono | Pen Up and move to X,Y coordinates 50,50 |
| Шаблон:Mono | draw a circle with radius 25 |
| Шаблон:Mono | select the standard character set |
| Шаблон:Mono | set the text delimiter to the asterisk, and do not print them (the 1, meaning "true") |
| Шаблон:Mono | lift the pen and move to 20,80 |
| Шаблон:Mono | draw a label |
The coordinate system was based on the smallest units one of the HP plotters could support, and was set to 25 µm (i.e. 40 units per millimeter, 1016 per inch). The coordinate space was positive or negative floating point numbers, specifically ±230.
Шаблон:AnchorHP-GL/2
The original HP-GL language did not support definition of line width, as this parameter was determined by the pens loaded into the plotter. With the advent of the first inkjet plotters, line width for the "pens" specified within the HP-GL files had to be set at the printer so it would know what line width to print for each pen, a cumbersome and error-prone process. With Hewlett-Packard Graphics Language/2 aka HP-GL/2, definition of line width was introduced into the language and allowed for elimination of this step. Also, among other improvements a binary file format was defined that allowed for smaller files and shorter file transfer times, and the minimal resolution was reduced.
| Command | Meaning |
|---|---|
| NPx | number of pens; x=1..256 |
| PCx,r,g,b | pen color; x=pen, r=red, g=green, b=blue, 0..255 |
| PWw,x | pen width; w=pen width in mm with decimal point, x=pen |
AGL
HP-GL is related to AGL (A Graphics Language), an extension of the BASIC programming language. AGL was implemented on Hewlett-Packard minicomputers to simplify controlling a plotter. AGL commands describe the desired graphics plotting function, which the computer relays as several HP-GL instructions to the plotter.
See also
- DMPL, another plotter language by Houston Instruments
- Gerber format is another plot-description format
- Logo, a computer language with drawing commands similar to HP-GL
References
Further reading
External links
- Шаблон:Cite web
- Шаблон:Cite web
- Шаблон:Cite web (NB. A Python-based HP-GL plotter control library for using vintage pen plotters with contemporary operating systems.)
