ONNET v2.0b - STEREONETS MADE EASY

Contents

Introduction

Onnet exists to make it easy to plot structural information on stereonets. The input files are designed to be easily read and editted by a user. This facilitates it's use in two ways. Field data can be plotted by making an onnet input file with the editor or programs that compute information can write onnet input files. Onnet is then used to translate these English language files into postscript which can be viewed either on screen with a postscript viewer or printed on any postscript printer. This allows you to easily edit plots. For instance you plot field data and then later you can add interpretation symbols to the plot with little extra effort. Also the symbols used to plot data, or the way it is viewed can also be changed with little effort. As the output files are in postscript, they can be read into Adobe Illustrator (or other drafting programs) for further customizing.

Here's an example input file and the output:

# put on a title
title Example 1
#
# draw a plane with dip direction = 20 and E of N and dipping 30 degrees
plane 20 30
#
# draw a small circle centered at an azimuth of 280 degrees, plunging 40 degrees
# and 20 degrees in diameter
small 280 40 20
#
# change the point size of poles to 20 points
pointsize pole 20
#
# draw the pole to the plane mentioned above
pole 20 30

The simplest usage for onnet is to put the commands into an input file (let's call it input) and create a file called output.ps with the command:
% onnet input > output.ps
output.ps can then be viewed with a postscript viewer such as ghostscript or printed on any postscript plotter.

Input files can also be specified by listing them on the command line such as "onnet input". Multiple input files can be specified and will be processed to make one plot. The order of processing goes as follows:
onnet input2 input3 < input1 > output.ps
where the files are processed in the order input1, input2, input3.

Output files are either on standard out. Errors will go to standard error.

This section is the meat of the documentation, it tells you everything onnet can do, and how to structure an input file. Input lines in onnet files are divided into viewing parameters and commands and comment lines. Viewing parameters control how things will be displayed such as the thickness of lines or the color of symbols. Commands actually plot things like planes, poles, or lines.

The input lines can come in any order except:

• viewing parameters only affect commands that come after them so you need to set them before they are to take affect.
• the outer circle of the stereonet is drawn before the first other object is plotted. So the viewing parameters for the circle must be given before the first command except the title which is plotted last no matter when it is given.
• if two commands plot in the same spot on the stereonet the later one will be on top of the earlier one.

• Input lines are in free format. Values should be separated by white space (e.g. blanks or tabs) and numeric values can be given as either integers or floating point numbers.
• Most commands and viewing parameters have long and short names. They can be used interchangably.
• Many of the viewing parameters can set things so they plot differently on the lower and upper hemispheres. For instance the input line "color line blue red" will plot all lines on the lower hemisphere in blue and those on the upper hemisphere in red. However, to set it so things plot identically on both hemispheres you can leave out the upper hemisphere value such as "color line blue" which makes all lines on both hemispheres blue. This is equivalent to "color line blue blue". The optional upper hemisphere values are in square brackets to remind you that they are optional. Note that that some things such as planes and poles always plot on the lower hemisphere and thus setting the upper hemisphere is meaningless.
• Many of the viewing parameters take a "choice" which states which objects the viewing parameter is being set for. For instance in "color line blue" the choice is line. Possible choices are any of the commands (e.g. line, plane, pole, rake, small, great, draw) circle and all. The choice circle sets this parameter for the outer circle of the stereonet. As noted above the vieweing parameters for the circle must be given before the first command other than the title. The choice all sets this parameter for all of the possible choices. Note that some combinations don't make sense such as setting the font of planes which are not text elements or setting any viewing parameter for move (which just moves the pen). Onnet will issue warnings about some of this nonsensical combinations but sometimes it just lets them go without complaining.
• I have attempted to keep onnet backwards compatible to earlier versions.

Viewing Parameters

angle choice lower [upper]

angle sets the angle text will be plotted at for the text plotting choices such as line, pole, rake, text, and title. Lower and upper are numbers from 0 to 360 and the defaults are 0. Angles are measured counter-clockwise from horizontal. The short name is a.

color choice lower [upper]

color changes the color that the lines or symbols for the command choice to lower and/or upper. Lower and upper can be either an integer from 0 to 7 or one of the corresponding following color names: black 0, blue 1, red 2, purple 3, green 4, skyblue 5, yellow 6, and white 7. Or lower and upper can be replaced with three numbers from 0 to 255 that will be used as rgb values. For example: "color line 1" will make all later lines blue it is equivalent to "color line blue" and "color line 0 0 255". However, do not mix types of color specifications on the same line. In other words, "color line blue red" will work but I'm not promising that "color line blue 2" will do the same thing. The short name is c.

fat lower [upper]

This exists for backwards compatibility and new files should use the width command. It is the equivalent of "fatness all lower [upper]". The units are as explained for the fatness viewing parameter.

fatness choice lower [upper]

fatness exists for backwards compatibility, the preferred command is width. fatness changes the thickness of the lines or symbols for the command choice to the values given for lower and/or upper. The units are in the archaic 1/33 of an inch from the outdated Stanford Geophysics vplot plotting system. fatness no longer affects the line, pole, title, text or rake commands because these now use real fonts and not attempts to draw letters with vectors. To affect how these commands appear try the font command where you can select regular or bold fonts. The short name is f.

focal

causes all plunges after the commands to be interpreted as take-off angles which are 0 at vertical down, 90 at horizontal, and 180 at vertical up. This affects the line, text, small, move, draw, and great commands. This can be handy for plotting earthquake first motions. The default is notfocal.

font choice lower [upper]

font changes the font for the text choices such as line, pole, rake, text, and title. Lower and upper are integers corresponding to the GMT fonts. The fonts available are: 0 = Helvetica, 1 = H. Bold, 2 = H. Oblique, 3 = H. Bold-Oblique, 4 = Times, 5 = T. Bold, 6 = T. Italic, 7 = T. Bold Italic, 8 = Courier, 9 = C. Bold, 10 = C Oblique, 11 = C Bold Oblique, 12 = Symbol, 13 = AvantGarde-Book, 14 = A.-BookOblique, 15 = A.-Demi, 16 = A.-DemiOblique, 17 = Bookman-Demi, 18 = B.-DemiItalic, 19 = B.-Light, 20 = B.-LightItalic, 21 = Helvetica-Narrow, 22 = H-N-Bold, 23 = H-N-Oblique, 24 = H-N-BoldOblique, 25 = NewCenturySchlbk-Roman, 26 = N.-Italic, 27 = N.-Bold, 28 = N.-BoldItalic, 29 = Palatino-Roman, 30 = P.-Italic, 31 = P.-Bold, 32 = P.-BoldItalic, 33 = ZapfChancery-MediumItalic. If lower or upper are outside this range, it is set to 0. The short name is fo.

pointsize choice lower [upper]

pointsize sets the point size of the text plotted with the choices such as line, pole, rake, text, and title. Lower and upper are numbers and the units are points (1/72 of an inch). The short name is ps.

gray choice lower [upper]

gray acts exactly like color except that the lower and upper values are integers from 0 to 255 and this integer will be used for all three of the rgb values. For instance, "gray line 200 100" is the same as "color line 200 200 200 100 100 100". This just makes it easier to set grayscale values.

notfocal

causes all plunges after the command to be interpreted as plunges. This is the default. notfocal will rarely be called, and usually only if focal was called earlier in the file.

radius x

radius changes the radius of the plot to x centimeters. This is the most constrained command because it must come before any commands that actually draw things (e.g. plane, pole, rake, line, small, move, draw, great). You should give it at the top of the file. The default is 8 cm. The short form of the command is r.

reflect

causes all information on the upper hemisphere to be reflected about the center of the sphere and plotted on the lower hemisphere. This is the default, if neither reflect or through are specified reflect will be used. Although upper hemisphere information is reflected onto the lower hemisphere to locate it, the viewing parameters for the upper hemishpere are used. For instance, you can use different colors or fonts for the two hemispheres.

schmidt

causes the Schmidt equal-area projection to be used for all items after it is called. It is the default and will be used if neither schmidt or wulff are called.

size choice lower [upper]

size is included for backward compatibility. The prefered command is pointsize. size changes the size of the symbols for the command choice. Lower and upper are numbers and the units are 1/33 of an inch from the outdated Stanford vplot plotting programs. The default size is 3 except for the title which is 10. So to make the poles plot larger you might give the command "size pole 6". Note the default for title is 10 The short name is sz.

symbol choice lower [upper]

symbol changes the symbols used to plot the command choice. The values for lower and upper can be any single ascii character in which case that character is used or they can be one of the following words in order to plot a geometric symbol. The geometric symbols are plotted in the current color for the choice and outlined in black with the current pen width for the choice. Possible geometric symbols are circle, cross (not outlined in black), diamond, hexagon, itriangle (an inverted triangle), square, star (a five pointed star), and triangle. The circles have a diameter equal to the current point size for the choice and all other geometric symbols are inscribed into this size circle (don't ask why, that's how the GMT subroutine library does it). An attempt has been made to get the ascii characters to center properly and it works well for the default font (courier). If you need very accurately centered symbols test them by plotting a cross and the symbol at the same spot. Defaults are pole 'o' (all on lower hemisphere), line 'x' and 's', and rake '+' and '*'. The short name is sy.

through

causes all information on the upper hemisphere to be plotted as if you were above the sphere and were looking down onto the lower hemisphere. The viewing type may be changed at ANY line at the file after the title, although it is rare you will want to, so it will probably be given once (if it all) near the top.

wulff

causes the Wulff equal-angle projection to be used for all items after it is called. The projection can be changed at any time, but it is rare that you will want to, so either schmidt or wulff should be specified once at the top, if at all. The only time you might want to change within a file is if you are trying to demonstrate the effects of the two projections.

Commands