MetaFun - Pragma ADE

Here the & glues strings together, while the decimal operator converts a number into a string.
The result has no typographic beauty —keep in mind that here we use METAPOST to typeset the
text—but the result serves its purpose.
redpart: 0.625
greenpart: 0
bluepart: 0
We can also ask for the path itself (pathpart), the pen (penpart) and the dashpattern (dashpart),
but these can only be assigned to variables of the corresponding type.
A path can be stroked or filled, in which case it is a cyclic path. It can have a non natural bounding
box, be a clip path, consist of line segments or contain text. All these characteristics can be tested.
label.rt("filled: " & condition filled p, (4cm,+1.25cm)) ;
label.rt("stroked: " & condition stroked p, (4cm,+0.75cm)) ;
label.rt("textual: " & condition textual p, (4cm,+0.25cm)) ;
label.rt("clipped: " & condition clipped p, (4cm,-0.25cm)) ;
label.rt("bounded: " & condition bounded p, (4cm,-0.75cm)) ;
label.rt("cycle: " & condition cycle pathpart p, (4cm,-1.25cm)) ;
filled: false
stroked: true
textual: false
clipped: false
bounded: false
cycle: true
In this code snippet, condition is a macro that takes care of translating a boolean value into a
string (like decimal does with a numeric value).
def condition primary b =
if b : "true" else : "false" fi
enddef ;
Clip paths and bounding boxes are kind of special in the sense that they can obscure components.
The following examples demonstrate this. In case of a clip path or bounding box, the pathpart
operator returns this path. In any case that asking for a value does not make sense —a clipping
path for instance has no color— a zero (null) value is returned.
draw fullcircle withpen pencircle scaled 3mm ;
clip currentpicture to fullcircle ;
setbounds currentpicture to fullcircle ;
n: 1 / length: 1 / stroked: false / clipped: true / bounded: false
Analyzing pictures A few more details
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