XBR2D96D@DDATHD21.BITNET (Knobi der Rechnerschrat) (06/06/90)
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 BITNET: <XBR2D96D@DDATHD21>
kurt@cashew.sgi.com (Kurt Akeley) (06/07/90)
In article <9006060619.aa20941@VGR.BRL.MIL>, XBR2D96D@DDATHD21.BITNET (Knobi der Rechnerschrat) writes: > 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? i have code that generates reasonable meshes from independent triangle data. further optimized code can be had from Paul Haeberli. my attempt to include the code in a reply to the newsgroup crashed xrn, so i'l simply publish my mail address and let those interested get in touch with me. kurt@cashew.asd.sgi.com -- kurt