MetaFun - Pragma ADE

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We can view this file in a POSTSCRIPT viewer like GHOSTVIEW or convert the graphic to PDF (using
mptopdf) and view the result in a suitable PDF viewer like ACROBAT. Of course, you can embed
such a file in a CONTEXT document, using a command like:
\externalfigure[yourfile.7]
We will go in more detail about embedding graphics in chapter 3.
If you have installed CONTEXT, somewhere on your system there resides a file mp-tool.mp. If you
make a stand--alone graphic, it's best to put the following line at the top of your file:
input mp-tool ; % or input metafun ;
By loading this file, the resulting graphic will provide a high resolution bounding box, which enables
more accurate placement. The file also sets the prologues := 1 so that viewers like GHOST-
VIEW can refresh the file when it is changed.
Next we will introduce some more METAPOST commands. From now on, we will omit the encapsulating
beginfig and endfig macros. If you want to process these examples yourself, you should
add those commands yourself, or if you use CONTEXT you don't need them at all.
pickup pencircle scaled .5cm ;
draw unitsquare xscaled 8cm yscaled 1cm withcolor .625white ;
draw origin withcolor .625yellow ;
pickup pencircle scaled 1pt ;
draw bbox currentpicture withcolor .625red ;
In this example we see a mixture of so called primitives as well as macros. A primitive is something
hard coded, a built--in command, while a macro is a collection of such primitives, packaged in a
way that they can be recalled easily. Where scaled is a primitive and draw a macro, unitsquare
is a path variable, an abbreviation for:
unitsquare = (0,0) -- (1,0) -- (1,1) -- (0,1) -- cycle ;
The double dash (--) is also a macro, used to connect two points with a straight line segment.
However, cycle is a primitive, which connects the last point of the unitsquare to the first on unitsquare's
path. Path variables must first be declared, as in:
path unitsquare ;
A large collection of such macros is available when you launch METAPOST. Consult the METAPOST
manual for details.
In the first line of our example, we set the drawing pen to .5cm. You can also specify such a
dimension in other units, like points (pt). When no unit is provided, METAPOST will use a big point
(bp) , the POSTSCRIPT approximation of a point.
A few more details Making graphics