[NTG-context] update

[Hans Hagen <j.hagen@xs4all.nl>]

Hi,

Todays update has a fix for the compact mode slant interference (as 
explained by Wolfgang a few days ago). Hopefully that works out well.

We (MS and HH) also managed to make curve detection more accurate (the 
decision routine that is responsible for straight lines in the MP 
output) so that extreme paths with control points way beyond reasonable 
still produce the right output (before we could get a wrong bbox due to 
clipping the curve in the backend). One can actually also force "always 
curve" with "withcurvature 1" (more variants might follow) but that is 
more or us to have a test option. Curvature detection is mostly a pdf 
efficiency feature and normally users should rely on the default to work 
okay.

Other new mp features are relative and absolute points which makes it 
possible to define paths in a turtle graphics way (a bit like hlineto 
and vline in postscript), a native "--" operator (equivalent but 
somewehat more efficient on huge generated paths). The luametafun manual 
has a chapter on paths that describes some of this.

Yet another new feature is "firstcontrol" and "secondcontrol" that is an 
addendum to controls that makes both control points the same when only 
one is given.

Finally there is a fix in mp where some directions, think { dir 120 }, 
gave the wrong result due to sign swapping (so it was seen as { dir 200} 
or { dir -60 }) as side effect of negative zeros fed into tan2. This 
became obvious when MS reprocessed a graphic, as last year we switched 
from scsled (no bug) to double (long time bug exposed). (The bug is also 
present in LuaTeX double/binary mode but it will be fixed there too.)

The rest is not (yet) worth mentioning,

Hans

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                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
        tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
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