[NTG-context] Labels in MetaPost (MetaObj)
Stefan Müller
warrence.stm at gmx.de
Tue Jan 18 13:17:45 CET 2011
Hi list,
I'm having some trouble with MetaPost in general and MetaObj in
particular. I hope someone on this list can assist me here. I'm trying
to run the appended ConTeXt file with a quite simple object "Segment"
(from the manual [1], section 2.1). This script works fine as it is. I
wanted to add a simple TeX label ("\tt \overbar{E}") to the drawing
macro, but failed.
When including the line marked with "% 1" the TeX run fails. I don't
understand why.
The line with "% 2" is taken frome the metaobj manual (section 5.8) [1],
but including this doesn't work either.
It would be great if someone could tell me what's wrong with the mp-code
below and explain how to place a (TeX) label inside a metaobj object.
Thanks in advance,
Stefan.
[1] http://tex.loria.fr/prod-graph/momanual.pdf
PS: Both variants fail with mp error messages like this:
"mplib > mp terminal: ! Inconsistent equation (off by 1).
<to be read again>
;
assignObj->(SUFFIX0)=incr(nObj_);
iname_[(SUFFIX0)]=str(SUFFIX0);addclass_((S...
newSegment->...roup.assignObj((SUFFIX2),"Segment")
;ObjPoint.a,b;ObjCode"@##b...
<to be read again>
;
<*> ...ar {E}") shifted n.a; enddef; newSegment.s;
s.a=origin;
drawObj(s); ;
! Redundant equation.
<to be read again>
;
assignObj->...bj_);iname_[(SUFFIX0)]=str(SUFFIX0);
addclass_((SUFFIX0),(EXPR1...
newSegment->...roup.assignObj((SUFFIX2),"Segment")
;ObjPoint.a,b;ObjCode"@##b..."
<=======================================>
\startMPinclusions
input metaobj;
\stopMPinclusions
\startMPpage
vardef newSegment@#=
assignObj(@#,"Segment");
ObjPoint a,b;
ObjCode "@#b-@#a=(1cm,2cm)";
enddef;
def drawSegment(suffix n)=
draw n.a--n.b;
% draw btex \tt \overbar{E} etex shifted n.a; % 1
enddef;
newSegment.s;
% ObjLabel.s(btex hello! etex) "labpoint(a)"; % 2
s.a=origin;
drawObj(s);
\stopMPpage
<=======================================>
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