IRC log for #brlcad on 20090514

00:22.31 brlcad starseeker: you happen to have a specific nirt/rt script handy that provokes a root convergence error?
00:23.15 brlcad if you get a chance, would like to put that to rest and have a couple things I'd like to check out but need a test case or three
00:49.14 starseeker brlcad: do you mean for the eto?
00:49.35 brlcad for any that fail to converge
00:49.59 starseeker erm. I can probably make one for the default tire - give me a sec
00:55.59 starseeker brlcad: does that error message output suppression you added for the nurbs raytracing work for all of them?
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01:07.28 starseeker brlcad: this rt script will kick up a healthy bunch on one of the ellipses you get with the default tire command (no tread - just run tire tire)
01:07.31 starseeker http://pastebin.bzflag.bz/mb9f9cf3
01:07.40 starseeker you can see the lines in the raytrace
01:08.07 starseeker I'll be back later if you want me to narrow it down further
01:09.10 Mike111 hi all
01:09.53 Mike111 is there help available on dsp (can't see it in Vol. II)
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01:50.17 brlcad Mike111: it's an advanced primitive, best to ask specific questions on how to use it
01:50.43 brlcad you'll need a raw binary data file with unsigned short height values
01:51.00 Mike111 what does it do?
01:52.11 brlcad it's a height field primitive
01:52.29 brlcad a grid of elevation values
01:53.12 Mike111 something like an landscape defined by elevations?
01:53.23 Mike111 something like a landscape defined by elevations?
01:53.24 brlcad I'd use an ARS before using a DSP for your air foil
01:53.28 brlcad yes
01:53.59 brlcad for an air foil, you'd basically use two aligned dsp's unioned together with smoothed values
01:54.48 brlcad but again, not what I'd recommend first
01:54.48 brlcad here is a massive data set dsp: http://brlcad.org/tmp/puget01.png
01:56.11 Mike111 regarding the ars, as I understand the waterlines all start from the same point?
01:58.11 brlcad ?
01:58.37 brlcad not really
01:59.16 brlcad there is a starting reference point, but from there it's whatever you input
01:59.57 Mike111 The webpage says:`In addition to the intermediate polygons a line will be created that begins at the start point, goes through each polygon at its vertex numbered 1, and terminates at the end point. This is repeated for each polygon vertex 2 thru N. The start point, polygons, and end point are each a "waterline"'
02:00.45 Mike111 so with that twisted cube, the start point is the center of the top face and the endpoint if center of the bottom face, right?
02:03.09 brlcad think of it like this: http://www.dans-hobbies.com/wp-content/uploads/2007/11/waterlines.jpg
02:03.36 brlcad there are "loops" at each waterline level -- those are the polygons it refers to
02:04.24 brlcad like if you sliced an apple, http://www.mathcubed.com/images/sliced_apple.jpg
02:04.40 brlcad each polygon is the outline of the apple for that layer
02:05.52 Mike111 so each polygon is a 2D slice?
02:06.21 brlcad yes
02:07.10 Mike111 so if I want to model a wing comprised of airfoil cross-sections, each `polygon' is now an airfoil?
02:07.28 brlcad so in http://brlcad.org/wiki/BRL-CAD_Primitives .. there are four simple slices (layers)
02:07.43 brlcad each layer simply has just four points so it's really boxy
02:07.48 brlcad add more points and it smooths out
02:07.56 brlcad yes
02:08.13 brlcad each cross-section would be described by a simple 2d polygon
02:08.39 Mike111 but for accurate description of the airfoil I'll need tens of points
02:08.56 brlcad probably hundreds
02:09.15 brlcad if you have the equations, that part can be automated
02:09.33 Mike111 the airfoil is defined by a polynomial, so yes
02:10.09 Mike111 I have the coordinates for the airfoil's upper and lower surface (above and below its mean line) in a plain text file
02:17.23 Mike111 for the wing model, the start point will be in root airfoil section (say its centre) and the end point is in the tip airfoil section?
02:18.22 starseeker brlcad: does that script help any?
02:20.10 brlcad trying to get it to run
02:21.24 brlcad got it!
02:21.25 brlcad thanks!
02:24.12 starseeker np
02:43.46 Mike111 is there a tutorial for scripting brlcad (besides http://brlcad.org/wiki/SGI_Cube)?
02:47.28 brlcad the mged tutorial series covers most of the basic commands, the appendix itemizes the majority of available commands, the quick reference card summarizes the commands (and has another scripting example)
02:48.25 Mike111 brlcad uses tcl programming syntax, right?
02:48.28 brlcad the cube example covers at least three ways to script mged -- if that's not sufficient, then you're probably lacking something else
02:48.46 brlcad no, mged has a tcl interpreter
02:48.59 brlcad but you can script mged using almost any language
02:49.05 brlcad as it's command-driven
02:49.26 brlcad that's specifically what the SGI_Cube explains
02:49.28 Mike111 there was an example in Vol.II for writing a loop and it mentioned it's in tcl format
02:50.05 Mike111 p.107
02:50.10 brlcad it really sounds like you're not understanding something fundamental -- what do/don't you understand about the SGI_Cube tutorial
02:50.27 brlcad yes, and?
02:51.10 Mike111 is there any benefit in learning the tcl syntax, that is, will it help in scripting for brlcad?
02:51.13 brlcad mged's internal interpreter is tcl, so that example is in tcl -- and the SGI_Cube example is a simple posix shell script, not Tcl
02:51.18 Mike111 besides loop, that is
02:52.24 brlcad there's benefits to learning most languages, depends what your goal is
02:52.34 brlcad is it necessary, no
02:52.37 brlcad it it useful, sure
02:53.16 brlcad what language(s) do you know?
02:53.22 Mike111 for the airfoil, I can either generate all the coordinates in octave and output a plain text file with commands for brlcad
02:53.29 Mike111 octave
02:54.02 brlcad eh, anything else?
02:55.43 Mike111 or I can presumably write a function/procedure for brlcad which will cycles over the airfoil points (instead of creating a text file with hundreds of lines)
02:56.24 brlcad it's a means to an end -- it doesn't really matter
02:56.30 Mike111 wondering which is better
02:56.34 brlcad hundreds/thousands of lines would work just fine
02:56.37 brlcad as would a proc
02:57.06 brlcad given your background, writing out mged commands to a text file is probably the easiest
02:57.26 brlcad in ars ars val1 val2 val3 val4 .......
02:57.42 Mike111 yep, I was thinking something like that
02:58.05 Mike111 it's basically a loop which appends text lines to file with printf
02:58.27 Mike111 octave uses the C printf syntax
02:59.07 brlcad octave's syntax is close to csh/tcsh shell scripting syntax
02:59.20 brlcad you might do well to learn/write a tcsh script
02:59.37 Mike111 I've done a bit of bash scripting
03:00.12 brlcad okay, then that
03:00.44 brlcad sgi_cube is a posix/bash/ksh/sh script
03:01.00 Mike111 there's no issue on mged side handling an ars with say 200 points per polygon?
03:01.06 brlcad you should study/understand it -- it shows three specific ways to issue commands
03:01.13 brlcad nope
03:04.45 Mike111 ok. thanks for your help brlcad
03:07.46 brlcad sure
03:12.48 starseeker wonders how workable a tool to generate birail based wings from NACA numbers + wing type (straight, tapered, delta, etc)
03:21.26 Mike111 starseeker: NACA is only one of airfoil parameterization methods. common current methods are PARSEC (11 design variables) and Hicks-Henne (sum of basis functions)
03:21.46 starseeker Is NACA a subset, or different altogether?
03:21.54 Mike111 different
03:22.08 starseeker so, not terribly useful for modern wings?
03:22.18 Mike111 PARSEC are Hicks-Henne are recent
03:22.48 Mike111 Hard to say. I haven't seen many recent studies where people directly used NACA.
03:22.59 starseeker hrm
03:23.12 starseeker any references available on PARSEC and Hicks-Henne online?
03:23.29 Mike111 It will probably be sufficient if brlcad can smoothly blend two arbitrary cross-sections
03:23.42 Mike111 the user will need to provide the cross-sections (airfoils)
03:24.19 starseeker oh, sure - I'm more curious about the possibility of generating "standard" wing shapes based on some standard specification - be it NACA numbers, PARSEC, what have you
03:25.38 starseeker procedural wings, if you prefer
03:26.12 Mike111 it can be an issue since there are quite a few methods out there and they're all different
03:26.32 Mike111 also, people are experimenting with new methods, like orthogonal polynomials
03:26.38 starseeker nods
03:26.45 starseeker understood
03:27.05 starseeker but for most "standard" wing designs already in use, it's likely they're characterized by some existing method
03:27.24 starseeker I need some XXXXXXX wings for commercial plane XXXXXX
03:28.00 Mike111 what engineers do is optimze the wing for a performance profile
03:28.19 Mike111 cruise speed, altitude, take-off weight etc.
03:28.25 Mike111 either wind-tunnel or CFD
03:28.48 starseeker once they've optimized it, how do they tell someone else what to build?
03:29.24 Mike111 airfoil cross-sections, sweep (backward tilt of the wing), twist of airfoil sections etc.
03:30.18 starseeker ok, so airfoil cross sections, sweep (is that an angle, or something more complex?), twist of sections (is that from one cross section to the next?)
03:30.57 Mike111 sweep=angle of wing w.r.t to hull, twist=between airfoils
03:31.42 Mike111 I hope brlcad will have nurbs capabilities soon (including scripting support) :)
03:32.51 starseeker I realize no one specification is going to encompass all the experimental wing designs out there - what I'm after is some sort of "ISO or ANSI wing specification" standard that outlines a way to geometrically describe most standard wing shapes
03:38.09 starseeker for example, for tires it would be something like this: http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=36320
03:47.22 Mike111 not sure if this exists for wings
03:58.02 Mike111 need to go now. have a good one
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11:37.36 brlcad d-lo: so they're already working on migration scripts for the forums
11:37.42 brlcad couple weeks
11:38.13 brlcad they'll be getting rid of the old forums, the task manager, the doc manager, and the diary/notes sections
11:40.52 brlcad yay, indianlarry is in
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12:38.52 brlcad indianlarry: heh welcome!
12:38.58 brlcad see you figured it out :)
12:39.24 indianlarry partly
12:40.09 brlcad cheers
13:01.28 d-lo brlcad excellent!
13:01.36 d-lo waves @ indianlarry
13:01.52 indianlarry hey d
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13:49.13 d_rossberg why is the color in struct mater_info float?
13:49.37 d_rossberg in struct rt_comb_internal it is unsigned char
15:24.15 brlcad d_rossberg: libmultispectral and other portions of the code use floating point values for color information
15:24.57 brlcad for increased color range/depth and to avoid quantization and aliasing effects
15:26.35 brlcad rt_comb_internal's are structures that predate by quite a bit
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15:30.43 Briggs does brlcade use doubles or floats to represent positions internally?
15:31.44 brlcad Briggs: compile-time toggleable, but doubles
15:32.09 brlcad nobody has tried a float compile in over a decade too.. so might not even be possible to drop it down :)
15:32.12 Briggs brlcad: thank you.
15:32.26 Briggs brlcad: just curious what other packages are doing since I have been having some precision problems with floats lately.
15:32.37 brlcad ah yeah
15:33.03 Briggs especially at extreme scales...
15:33.07 brlcad we hit precision problems a *long* time ago..
15:33.29 brlcad pre ieee floating point was notoriously unstable
15:33.52 Briggs sorting 7kmx7km of map data to find things like intersections and collinear edges just wasnt behaving nice with floats in the picture...
15:34.52 brlcad :)
15:36.04 brlcad we also use tuned data structures for certain primitives, integer indexing where it makes sense for example
15:36.08 brlcad gridded data
15:36.13 ChiGai hello everyone, my question seem to be a little bit stupid but I still want to ask
15:36.39 brlcad like our height fields (dsps), their raw data is unsigned short integer ranged data that is positioned in 3space
15:36.45 brlcad ChiGai: ask away
15:37.07 Briggs brlcad: right, I'm doing similar things.
15:37.11 brlcad there are no stupid questions, just stupid people ;)
15:37.20 ChiGai I am a mechanic student living in a third world country where a commerical CAD program cost is several times larger than GDP
15:37.41 ChiGai so I am interested in finding a free CAD program, and found about brl-cad
15:37.53 brlcad okay, cool
15:37.54 ChiGai I don't know if it is suited for education?
15:38.17 ChiGai most people here are using pirated version of Catia, SolidWork etc...
15:38.26 ChiGai and I want to change that
15:38.44 _clock_ use pirated version of brl-cad!
15:38.56 ChiGai _clock_: how to pirate brl-cad anyway? :D
15:39.01 _clock_ not possible :)
15:39.07 _clock_ function not implemented :)
15:39.16 ChiGai :P
15:39.18 brlcad it involves wearing a pirate hat and ending a lot of sentances with arrrrrrrr....
15:39.52 brlcad there's a parrot invovled too, but you don't want to know what you do with it
15:40.01 ChiGai :))
15:40.22 ChiGai I am building brl-cad at the moment and eager to try it
15:40.43 ChiGai oh, done already
15:41.12 brlcad ChiGai: we're chocked full of features and in use in production environments, but for very specific usage domains with a lot of experts
15:41.27 brlcad so you'll find there to be a pretty steep learning curve and lacking usability
15:41.40 brlcad things we're working on improving of course, but it takes a lot of time and effort
15:42.15 brlcad particularly if/when compared with the usability and features in the products of multibillion dollar companies like those you mentioned ;)
15:42.26 ChiGai hmm, I don't intend to do anything advanced so it shouldn't be too hard
15:42.32 brlcad we still hold our own very well though, and pretty much are the best out there (as open source)
15:42.37 brlcad if I do say so myself
15:42.52 ChiGai and beside I like banging my head on the wall, doing hard thing
15:43.13 brlcad there are pretty extensive tutorials on the website
15:43.58 ChiGai I see
15:44.17 ChiGai thank you for your answer then :)
15:44.30 brlcad np
15:44.33 ChiGai I hope the situation here will be improved soon
15:44.43 brlcad and if you have questions, someone is almost always on here or will eventually answer
15:44.45 ChiGai and thank again for your work on brl-cad
15:45.02 brlcad though the answer is often "contributions welcome" ;)
15:45.10 ChiGai :)
15:45.18 brlcad we need developers more than new users (unfortunately) ;)
15:45.26 brlcad demand is much greater than supply
15:45.31 brlcad several orders..
15:45.41 ChiGai I can understand that
15:46.30 ChiGai writing CAD software is pretty hard and need a good, solid team, that also explain why there aren't many oopen source cad software out there :(
15:47.02 CIA-28 BRL-CAD: 03brlcad * r34526 10/brlcad/trunk/src/tclscripts/mged/ (Makefile.am bots.tcl tclIndex):
15:47.03 CIA-28 BRL-CAD: add the 'bots' command (along with 'per_line') to mged for finding specific
15:47.03 CIA-28 BRL-CAD: kinds of bots in an open database as a short term replacement until 'search' can
15:47.03 CIA-28 BRL-CAD: do it better. make the commands already deprecated so they can be removed at
15:47.03 CIA-28 BRL-CAD: will when search is enhanced.
15:47.13 brlcad yep, that's part of it
15:50.33 brlcad the magnitude of work involved to even have basic features is pretty huge
15:53.19 CIA-28 BRL-CAD: 03brlcad * r34527 10/brlcad/trunk/TODO: search needs some sort of -param option to inquire about specific (internal) properties of objects, like finding dsp with given dimensions, spheres of certain sizes, bots with a given orientation, etc
15:53.38 CIA-28 BRL-CAD: 03brlcad * r34528 10/brlcad/trunk/doc/deprecation.txt: bots and per_line are new and already deprecated.
16:06.04 d_rossberg brlcad: i'm using floting point variables for color values in my programs too
16:06.26 d_rossberg but region and rt_comb_internal are closely connected
16:06.40 d_rossberg and have diferent representations for color values
16:07.24 d_rossberg therefore there is somebody else who writes something into mater_info?
16:07.57 d_rossberg eg libmultispectral
16:13.44 CIA-28 BRL-CAD: 03d_rossberg * r34529 10/rt^3/trunk/ (2 files in 2 dirs):
16:13.44 CIA-28 BRL-CAD: a ray-trace hit now gives you some extra data
16:13.44 CIA-28 BRL-CAD: ...to be continued...
17:44.23 brlcad iinteresting, http://www.mail-archive.com/emc-users@lists.sourceforge.net/msg14339.html
17:44.41 brlcad wonders if michael is on irc
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18:02.14 starseeker brlcad: do we need to up the version number to 7.14.9 now?
18:02.35 starseeker oh, nevermind
18:02.37 starseeker I see it now
18:03.51 brlcad version number should always be bumped immediately after tag (or at *least* immediately after the upload
18:04.17 starseeker nods. Yeah, I just missed it being updated in the commits - my bad
18:05.13 brlcad Elrohir: do you know michael buesch?
18:06.37 CIA-28 BRL-CAD: 03bob1961 * r34530 10/brlcad/trunk/ (11 files in 3 dirs): Add editing for EPA and Particle to libged and Archer.
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18:31.20 Elrohir brlcad: no ... never heard of that name
18:37.05 brlcad okay, thanks :)
18:42.10 CIA-28 BRL-CAD: 03brlcad * r34531 10/brlcad/trunk/BUGS:
18:42.10 CIA-28 BRL-CAD: fastgen plate mode bots seem to be busted for shotlines. they render just fine,
18:42.10 CIA-28 BRL-CAD: but are nirting and rtchecking wrong. have a good sample case with attached
18:42.10 CIA-28 BRL-CAD: detail added as sf bug 2791866 (plate mode bots shotline incorrectly)
18:43.02 CIA-28 BRL-CAD: 03brlcad * r34532 10/brlcad/trunk/NEWS: bob continues to add interactive editing support to archer, now for epa and part objects.
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19:01.28 CIA-28 BRL-CAD: 03brlcad * r34533 10/jbrlcad/trunk/src/org/brlcad/ (11 files in 7 dirs):
19:01.28 CIA-28 BRL-CAD: Accept and apply sf patch 2787632 from dave brosius ([patch] minor cleanup in
19:01.29 CIA-28 BRL-CAD: jbrlcad) which applies a lot of lint-style cleanup throughout the code to mark
19:01.29 CIA-28 BRL-CAD: things final, declare overrides, sort imports, cleanup casts, and more.
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21:48.31 pacman87 here's my tetris pics: https://webspace.utexas.edu/trv82/www/6811%20Tetris/index.html
21:54.22 brlcad hehe, pacman87 how do you distinguish an M from an N ? :)
21:54.48 pacman87 M only has one dot in the middle, just above the center
21:54.49 brlcad thinks maybe need 4x6 glyphs or 4x5 :)
21:54.58 pacman87 H has the center dot
21:55.03 pacman87 W has the lower dot
21:55.05 brlcad funny ;)
21:55.10 pacman87 and U has the bottom dot
21:56.30 pacman87 but the way the LCD works, it's a lot easier to code for 4 px wide letters (including spaces)
21:57.54 pacman87 http://pastebin.bzflag.bz/m3a178dbb
21:58.20 brlcad heh, neat
21:58.21 pacman87 that's the font in 4x6
21:58.32 pacman87 including the spacing top and right
21:59.22 pacman87 i want to write a quine with it, but haven't had time with finals

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