IRC log for #brlcad on 20080404

01:33.57 *** join/#brlcad Twingy (n=justin@74.92.144.217)
02:04.46 *** join/#brlcad Daytona (n=jra@c-68-55-36-65.hsd1.md.comcast.net)
02:06.33 Daytona prasad_: Hey, how's it going?
02:28.01 *** join/#brlcad pacman87 (n=Timothy@resnet-45-192.dorm.utexas.edu)
02:41.13 poolio yikes. I accidentally just removed my brlcad folder because the box I was ssh'd into has the same PS1 :'(
02:56.02 yukonbob :P
02:57.42 poolio hopes he backed up everything
03:14.19 poolio So I passed configure and when I went to building it failed because it could not find zlib.h. I installed zlib, but shouldn't configure have caught this?
03:15.53 poolio (it correctly detects that I do not have a working zlib though, maybe it should be pointed to brlcad's zlib.h?)
03:20.10 poolio so the problem appears to be that I had working zlib runtime and not the development headers...
04:18.34 brlcad hello Harriss
04:18.41 brlcad and howdy poolio
04:20.14 *** join/#brlcad wuxia (n=wuxia@unaffiliated/wuxia)
04:20.15 brlcad yeah, the test is technically for both libs and (separately) for headers and (separately) for run-time functionality .. at least usually those three have to pass for a given lib
04:20.28 brlcad otherwise it doesn't have what it needs
04:20.33 brlcad hello wuxia
04:21.00 wuxia can anyone expain what the brlcad rendering algorithm does? i.e. does it only require that the geometry support a 'does this ray intersect with this shape' query? [I'm trying to find something similar to 'generative modeling language' or synder's 'genmod' ]
04:22.35 brlcad depends what the "it" is in your sentence
04:23.32 brlcad in terms of implementing or adding new primitives, they basically just have to answer the "does this ray intersect with this shape"
04:23.36 wuxia hey, that's a good bot
04:23.42 wuxia what algorithm? alice? elizra ?
04:23.54 brlcad ~fishslap wuxia
04:23.54 ibot ACTION slaps wuxia up side the head with a wet fish.
04:24.42 wuxia a human would have kicked me
04:25.18 brlcad so comparing against all primitives, it ends up with lots of "segments" -- those are weaved together per the CSG rules
04:25.40 wuxia gotcha :-)
04:25.54 wuxia is there any good interfaces between pbrt and brlcad?
04:26.04 wuxia I feel that pbrt does ray tracing better, but brlcad is better at modeling
04:26.48 brlcad pbrt does a lot of things fundamentally differently
04:28.15 wuxia is there any good bridge for taking a gbrlcad model
04:28.20 wuxia and rendering it in pbrt?
04:28.31 brlcad if generating pretty pictures is your goal, they certainly have a better global illum model integrated -- but then iirc they are almost exclusively explicit geometry models and not a shotline-capable solid geometry ray-tracer (evaluating all the way along through materials)
04:28.48 brlcad i'm not aware of any "good" bridge yet
04:29.01 brlcad mostly because of that implicit vs explicit geometry issue
04:29.02 wuxia what is 'shotline-capable solid geometry ray-tracer' ?
04:30.17 brlcad it's a fair bit to explain, but basically a ray-trace engine that takes solidity into account -- not just surface-based or (the most common) first-hit based ray-trace interfaces
04:30.43 wuxia for a surface-based
04:30.47 wuxia I need only provide "does this ray intersect"
04:30.57 brlcad brl-cad's librt ray-trace engine is a full-path shotliner that will either report first-hit or all segments along the ray
04:31.04 wuxia what more complicated thing does "shotline-capable solid geometry ray-tracer' require me?
04:31.10 wuxia ah
04:31.14 wuxia and one way to do csg
04:31.19 wuxia is to report all semgnets along the ray?
04:31.25 wuxia and then do the csg operations
04:31.29 wuxia to decide which one it actually hit?
04:32.07 brlcad actually you can evaluate the csg with just first hit or with all segments
04:32.18 brlcad that's not really different
04:32.31 brlcad i'm talking about other purposes of ray-tracing, not just generating pictures
04:32.41 wuxia oh
04:32.45 wuxia like firing a bullet into a tank?
04:32.57 brlcad sure
04:33.13 brlcad or simply answering the question of "how much of this material is on this shotline"
04:34.09 brlcad with an explicit ray-engine, you end up with all sorts of analytic/analysis questions that are harder to guarantee without solid geometry
04:34.48 wuxia why is that
04:34.51 wuxia given a boundary
04:34.54 brlcad if you assertively have "crack-free" geometry, and aren't inside things when you start a ray
04:35.03 wuxia why can't I get the 'solid geometry' by looking at entry and exit points?
04:36.27 brlcad mostly because of numerics -- if your geometry isn't actually cracked (i.e. non-solid), there is a higher probability of numerical cracks due to floating point issues on the seams on the boundaries
04:36.50 brlcad solid geometry entails a *guarantee* that there is no crack, numeric or otherwise
04:37.23 brlcad implicit geometry implicitly guarantees this, other CAD systems provide the guarantee through "crack-free" BREP implementations
04:37.38 brlcad something that only generates pictures doesn't really have to care
04:37.57 brlcad anyway, why you ask? :)
04:38.38 brlcad there are ways to extract an explicit geometry model from brl-cad geometry that you could undoubtedly feed to pbrt via one of their importers
04:39.06 wuxia i want to render procedural sci-fi cities
04:39.07 brlcad it conceivably wouldn't be that hard to write an exporter if you have their file format (especially if they support primitive descriptions)
04:39.16 wuxia brl-cad looks awesome for geometry modeling; pbrt for rendering
04:41.35 brlcad wuxia: for what it's worth, pbrt looks great because most of their shots have global illumination calcs turned on (which librt doesn't implement, though it is a gsoc topic)
04:42.21 brlcad there's only two screenshots that use the global illum renderer we do have: http://brlcad.org/gallery/s/renderings/humvee.png.html and http://brlcad.org/gallery/s/renderings/stryker_slat.jpg.html
04:42.57 brlcad brute force solutions
04:43.10 brlcad and required conversion to brep polygonal format
04:43.21 wuxia why brep first?
04:43.27 wuxia why can't global illumination be done on csg's ?
04:47.19 brlcad there's no reason it can't
04:47.41 brlcad it just hasn't been done yet, that's why it's a gsoc suggested task
04:50.10 *** join/#brlcad hippieindamakin8 (n=hippiein@203.200.95.130)
04:55.01 poolio brlcad: wait, so then why did it fail compiling but pass configure? in config output it says it's using system zlib, but I fail the tests
05:01.04 poolio basically, I was just upset to see the build die :)
05:04.27 brlcad as you should be, build failures indicate something is probably wrong in configure :)
05:07.39 brlcad that third test -- the functionality test -- is either weak or non-existent for zlib
05:10.59 poolio bah. I want configure to stop and print in big bold letters that I should not continue :) I ran configure and looked away, and the summary looked all fine and dandy
05:13.58 brlcad that's what I mean -- it's probably missing a test
05:14.02 brlcad it normally does halt
05:14.44 poolio ah Ok
05:14.49 poolio thanks and sorry for the whining :)
05:15.10 brlcad hum, was just looking
05:15.15 brlcad there is a functionality test
05:15.26 brlcad so "something else" is wrong
05:15.39 poolio errr, I also just realized the build failed again later
05:16.17 brlcad can you post your build log and config.log files?
05:16.22 poolio this is a trunk checkout by the way
05:16.38 poolio yeah, do I uninstalled the zlib1g-dev package and am going to regenerate the broken zlib.h error
05:21.19 poolio brlcad: build is gonna take a little while, I'm on my shiny new, not that fast, x300 :P
05:23.15 brlcad heh
05:29.20 poolio brlcad: config.log: http://poolio.org/files/config.log and build: http://poolio.org/files/zlib_error.txt
05:38.37 brlcad poolio: try editing src/other/tkimg/png/Makefile.am and add: ${LIBZ_CPPFLAGS} \ after the PNG_CPPFLAGS line
05:39.13 poolio brlcad: alright, I'm waiting for the build to finish with zlib-dev installed, so gimme a few minutes.
05:39.30 poolio is feeling the grind of the 1.2ghz for the first time
05:41.01 CIA-33 BRL-CAD: 03brlcad * r30625 10/brlcad/trunk/src/other/tkimg/png/Makefile.am: missing LIBZ_CPPFLAGS
05:41.35 brlcad yeah, I'm betting that was the problem -- tkimg's png module's build rules didn't have the header search path
05:41.50 brlcad the configure tests worked, failed and was set to build
05:43.21 poolio alrighty
05:47.38 poolio brlcad: http://poolio.org/files/htester_error.txt is what I'm getting with zlib working
05:58.10 brlcad didn't realize you're on ubuntu/debian?
05:59.14 brlcad they have a busted libtool, it incorrectly strips out linkage paths
05:59.46 poolio sorry :(
06:00.00 poolio is there an easy fix?
06:00.26 brlcad other than installing an unmodified libtool from gnu?
06:00.37 brlcad unmodified works without a hitch
06:01.58 brlcad otherwise, I haven't completed debugging the libtool script itself to see if there's a good way to trick it or work around it
06:22.18 poolio that's weird, because when I was working on brlcad last summer I was using debian
06:24.28 brlcad yeah, the build options have changed to not be excessively redundant -- there was a recursive redundant declaration of libraries pushed down to the binary LD line instead of relying on libtool's usual dependency tracking
06:25.03 brlcad pushed down to the binary ld option, debian's mods don't come into play
06:25.27 brlcad but that's a bear to keep -- libraries listed dozens of times over per binary
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07:07.38 poolio brlcad: sounds like a good dev choice, but having a source install not function on a very popular distro is a bad decision :)
07:10.28 brlcad of course
07:12.13 brlcad someone(tm) really needs to see if there's some way to work around the problem
07:13.43 brlcad being popular isn't a good excuse for being wrong too, the problem has been reported by others to debian devs and they refuse to fix it
07:15.25 brlcad we make workarounds for a lot of platform-specific stupidities, that one just isn't in the frequent testing rotation as nobody has stepped up to maintain the port
07:17.44 brlcad so feel free to be that someone(tm) and fix it :)
07:18.08 brlcad shouldn't be too hard to find a work-around
07:22.28 poolio brlcad: in a month or so I'll give it a shot :)
08:20.28 *** join/#brlcad Axman6 (n=Axman6@pdpc/supporter/student/Axman6)
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09:53.20 *** join/#brlcad mafm (n=mafm@elnet-111.lip.pt)
09:54.40 mafm hallo
10:19.16 *** join/#brlcad MinuteElectron (i=5207211c@silentflame/member/pdpc.base.minuteelectron)
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13:04.08 brlcad howdy mafm
13:05.17 mafm :)
13:05.52 ``Erik no love for twingy's photon mapping, I see O.o
13:38.36 mafm hmm, I have a linguistic question totally unrelated to the topic of the channel, may I?
13:39.43 brlcad go for it
13:41.38 mafm if I'm studying a degree, say CS, what's the name of the individual parts composing it, as in Programming I, Networks, Distributed Systems, AI, etc, comprising typically one semester or a year, one hour per day or so? it's "courses"?
13:48.13 brlcad yeah, those are your courses
13:48.51 mafm hmm, and you're from USA right?
13:49.19 brlcad i've lived in a number of places, and the usa is one of them
13:50.23 mafm it's only to ask if you know if it's named the same across english-speaking languages
13:50.55 brlcad tries to think what else you might call them
13:51.06 mafm for some reason I was calling it "subjects", but I don't know where I took it :D
13:51.18 brlcad courses, classes, seminars
13:51.36 mafm maybe it's that I directly translate from portuguese or something like that
13:51.37 prasad_ hey is daytona == jra?
13:51.41 brlcad usually "seminar courses" are a specific type
13:51.44 brlcad prasad_: yup
13:51.49 prasad_ ah missed him
13:52.14 brlcad mafm: yeah, I think courses/classes are pretty much the terms
13:53.14 mafm good, thank you very much
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14:32.40 mafm svn: URL 'https://brlcad.svn.sourceforge.net/svnroot/brlcad/trunk' doesn't exist
14:32.44 mafm what do you use as trunk?
14:38.00 poolio /svnroot/brlcad/brlcad/trunk
14:44.35 mafm oh thanks
15:01.29 brlcad ~cadsvn
15:01.29 ibot To obtain BRL-CAD from Subversion: svn checkout https://brlcad.svn.sourceforge.net/svnroot/brlcad/brlcad/trunk brlcad
15:04.43 mafm not a light download, it seems :)
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16:00.22 mafm hmm, the things using C++ in brl-cad are related to 3rd party tools?
16:03.56 mafm and is it all in other/ 3rd party tools it seems?
16:04.16 *** join/#brlcad Axman6 (n=Axman6@pdpc/supporter/student/Axman6)
16:06.49 mafm brlcad: I have a problem compiling
16:11.21 poolio mafm: are you by any chance running a debian-based distro?
16:11.49 mafm nope, I don't run degenerates
16:11.59 mafm I use Debian itself :)
16:12.01 poolio debian is debian-based, no?
16:12.20 mafm just kidding :)
16:12.30 mafm so what's the problem with debian then?
16:12.42 poolio mafm: So I just had the same problem earlier... brlcad says debian uses a broken libtool, and there's no easy fix other than installing a clean libtool
16:12.56 mafm :S
16:13.34 mafm what's a clean libtool? different versions, vanilla without possible distro patches?
16:13.53 poolio vanilla I would guess
16:14.48 mafm /usr/bin/ld: warning: libtcl8.5.so, needed by ./.libs/libbu.so, not found (try using -rpath or -rpath-link)
16:14.48 mafm ./.libs/libbu.so: undefined reference to `Tcl_ResetResult'
16:14.48 mafm ./.libs/libbu.so: undefined reference to `Tcl_SetObjResult'
16:14.49 mafm ...
16:14.55 mafm is this your error too?
16:23.57 poolio Yep.
16:25.40 mafm :S
16:25.44 mafm version?
16:26.00 mafm ii libtool 1.5.26-1 Generic library support script
16:40.28 poolio 1.5.26-2 here. It's more than just libtool, I tried out a vanilla libtool and that didn't fix it
16:41.27 mafm :S
16:43.23 poolio mafm: Just softlink libtcl8.5.so.0 to libtcl8.5.so for now
16:45.40 mafm what vanilla libtool did you try? I installed the one from 'stable' distro, which is .22, and it just seems to work
16:46.02 mafm or maybe it didn't reach the part failing yet, not sure :D
16:46.49 poolio mafm: haven't tried vanilla, sorry
16:47.24 mafm ok
16:47.30 mafm but this .22 one seems to fix it, yuep
16:47.32 mafm :)
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17:37.26 mafm does anybody know if it's worth patching the 3rd party tools for compiler warnings/errors?
17:42.04 ``Erik yes, debian modifies libtool to "optimize" the link line
17:42.17 ``Erik the effect is that they strip out critical information needed to compile BRL-CAD
17:43.26 ``Erik mafm: don't worry too much about language barriers, both brlcad and I have lived in non-english speaking countries for several years, we will ask if we don't think we understand what you intend to say...
17:45.37 ``Erik now if I recall the issues with the debian libtool correctly from last time I chased that down, a system installed tcl85 will still work... and I THINK debian just picked up 85 into testing, d'no if that's floated to ubuntu or other derivatives just yet
17:45.57 ``Erik may have to redo the debian script in BRL-CAD to use the system one
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17:55.52 mafm the language doubts were not meant to clear up misunderstandings, it's because I was updating my CV :)
17:56.29 mafm well, to avoid the hassle I just put that tcl8.5 dir in the ld.so.conf file
17:58.56 mafm bah, a new related error :S
18:05.11 ``Erik oh?
18:05.51 mafm before that ... in libbu you use a temp.c to make temporary files... why not use mktemp calls instead? aren't they portable enough?
18:06.36 mafm ``Erik: the new error is: http://rafb.net/p/YDu6XN14.html
18:37.01 poolio mafm: I got there with the system libtool, linking libtcl8.5.so.0 to .so
18:41.18 mafm but it's not working for me
18:41.35 mafm maybe I'm missing some additional library or something
18:55.20 ``Erik looks like libXi.so isn't being picked up for some reason :/
18:59.24 mafm ``Erik: in libbu you use a temp.c to make temporary files... why not use mktemp calls instead? aren't they portable enough?
19:00.07 ``Erik mktemp is actually bad, mkstemp is better
19:00.54 ``Erik mktemp also doesn't work on all platforms, like old obscure ones (crayos? vms?) or stupid ones (windows?) iirc
19:01.37 ``Erik *looklooklook*
19:01.44 alex_joni heh, stupid :)
19:02.07 mafm doesn't work in windows?
19:02.09 mafm hmm
19:02.23 mafm there was a similar issue with Aqsis
19:02.28 ``Erik ah, looks like it's a "safe" wrapper for mkstemp() with file marshalling
19:02.50 mafm I think that they used in there a relatively clean workaround, not so huge as in libbu
19:02.54 ``Erik and a very low level last ditch attempt
19:03.02 ``Erik huge as bu? temp.c is tiny
19:03.18 ``Erik and works pretty much everywhere O.o :D
19:03.23 mafm well, I'm talking about 10 lines or so
19:03.34 ``Erik notes that aqsis does not work on as many platforms as BRL-CAD
19:03.36 mafm not in the hundreds of lines
19:04.35 ``Erik most of temp.c is error checking of some form or another *shrug*
19:04.40 mafm well, that's the question... it's in the ToDo or Buglist to remove that code, so I thought about that... but if it's not portable enough... :)
19:04.55 ``Erik a lot of the portability isn't NEEDED anymore
19:05.05 ``Erik we've stripped out some vax gould and crayos code already
19:05.21 ``Erik because no one uses 70's or 80's computers anymore
19:05.33 mafm :)
19:06.00 ``Erik also; few os's leave dangling file handles when an app is closed anymore
19:06.07 mafm In the TODO: * libbu routine to make a temp file reliably/consistently
19:06.31 ``Erik hrm, probably means brlcad spotted a place where mkstemp failed
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19:08.09 CIA-33 BRL-CAD: 03brlcad * r30627 10/brlcad/trunk/AUTHORS: add gillich to the contributors list for his g-sat importer
19:08.28 mafm I see
19:08.40 mafm well, I already produced a patch, even if not very useful
19:09.53 mafm if I have time maybe I'll do something better during the selection process :)
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19:11.40 yukonbob waves in
19:12.30 mafm hallo yukonbob
19:16.58 mafm have to go now
19:17.25 mafm bye
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20:58.07 CIA-33 BRL-CAD: 03bob1961 * r30629 10/brlcad/trunk/src/mged/mged.bat: Mods to get rid of complaints about nul.
20:58.07 CIA-33 BRL-CAD: 03bob1961 * r30630 10/brlcad/trunk/src/archer/archer.bat: Move "ECHO OFF" up in the file.
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