Two questions

[Knobi der Rechnerschrat]

Hallo,

  I have two (unrelated) questions. I hope somebody can give me some
peace of information on them.

1) In the makefile for MOLCAD we use the following construct to pass
   the CFLAGS to a lower-level makefile

   (cd some_directory; make "CFLAGS = $(CFLAGS)")

   This worked fine up to Rev 3.2.2 of IRIX. Last week I had the chance
   to try out a 220/VGX with some kind of pre 3.3 IRIX and the makefile
   in some_directory didn't see the CFLAGS. It seems that somebody
   changed the way make processes it's arguments. Is it a bug, a feature
   or the expected behaviour? Is there a way around (we will at some
   time get 3.3 in Germany !!!) this problem?

2) This is a more fundamental question. The molecular surfaces used by
   MOLCAD are constructed from triangles, which are generated from a set
   of arbitrary - non-analytically defined - dots, which are numbered from
   0-n. For each triangle we know the numbers (and from that the 3-D
   coordinates, of cource) of the three vertices (dots). The triangles are
   read from a file and then analyzed "for that we can display them as meshes
   to please the lords of the pipeline". We have two sources of dots and
   two algorithms to generate the triangles. The first combination generates
   a good (in terms of tmeshes) ratio between new-meshes, continuation-
   vertices and swap-vertices. Within the 256-vertex limit of the gl, we
   get a pretty good performance. Unfortunately the second combination
   of dots and algorithm (which is really fast in generating the triangles)
   does generate very poor meshes. Over 90% of the triangles are singles, and
   the remaining meshes are rather short. This still gives excellent graphics
   performance on the GT and GTX, but we would like to get the best possible
   results of course (having in mind the VGX, which is told to be tuned for
   meshes). After this rather long introduction: does anybody know of
   algorithm that can be used to rearrange a given set of more or less single
   triangles into meshes? The algorithm has to be fast, as we want to use it
   on surfaces with several 100.000 triangles. Any code examples, any
   published material?


Regards and many thanks in advance
Martin Knoblauch

TH-Darmstadt
Physical Chemistry 1
Petersenstrasse 20
D-6100 Darmstadt, FRG

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