IRC log for #brlcad on 20121001

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11:31.34 starseeker hmm... CIA really got clobbered this time
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15:25.40 brlcad starseeker: yeah, critical fail
15:26.16 brlcad been working with the previous maintainer to see if he has access to his mirror from a couple years ago when we were working on sf.net integration
15:26.40 brlcad there are a half-dozen distinct efforts under way to get notifications back online
15:27.15 brlcad one guy got the current code updated for modern django, but still leaves a lot starting from scratch without a dump
15:31.15 brlcad ``Erik: bug is probably that stdint.h isn't included
15:32.10 brlcad looks like other platforms are getting lucky with sys headers that ended up including it
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16:01.13 ``Erik brlcad: put #include <stdint.h> in the .h and it still failed, wrapped it in an extern "C" {} and it still failed *shrug* both fbsd and linux failed the same way
16:01.29 ``Erik prods brlcad.org and sago
16:03.10 brlcad o.O
16:03.34 brlcad found https://issues.apache.org/ooo/show_bug.cgi?id=64762
16:04.07 brlcad testing a clean netbsd and vanilla system at the moment to see if I can reproduce
16:07.10 brlcad I mean, that symbol shouldn't even be conditional as far as I know -- SIZE_MAX is what c99 defines
16:07.21 brlcad found a comment thread indicating freebsd4 even had it
16:07.38 ``Erik if we have a stray stdc=c89, that might force it off?
16:07.57 brlcad hm, yeah, that's possible
16:08.07 brlcad especially in that src/other subdir
16:08.22 ``Erik ah, fbsd's headers explicitely turn it off in c++
16:08.58 brlcad woot, just got it to reproduce
16:09.07 brlcad ahh
16:09.48 ``Erik cstddef has the right stuff, according to this post
16:10.21 brlcad tests
16:11.24 brlcad nfg here, I'll dig some
16:13.19 brlcad looks like c++ doesn't define that c99 symbol (bleh)
16:13.56 brlcad got it, cplusplusy
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16:16.27 brlcad CIA: BRL-CAD: brlcad * r52608 /brlcad/trunk/src/other/step: turns out, c++ doesn't define the SIZE_MAX c99 constant. instead of adding a (size_t)-1 define manually, do it the c++y-way. use numeric_limits.
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16:23.37 ``Erik http://paste.lisp.org/display/132283 alter is screwey
16:27.26 brlcad that verizon's backbone?
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16:28.13 brlcad brl-cad tutorial in portuguese: http://www.scribd.com/doc/107130136/Trabalho-Desenho-Tecnico-aplicado-BRLCAD-1%C2%BA-Bimestre
16:29.02 brlcad notes that carl has fixed no less than 50 spelling mistakes in docs
16:31.10 elf_ Hello, brlcad
16:31.12 ``Erik it's a backbone, verizon and uunet both use it to get to sago... *shrug*
16:31.14 brlcad hi elf_
16:31.42 brlcad ``Erik: going to alter.net jumps to verizon, so looks like it's backbone that they own
16:32.01 ``Erik could be, traceroute from the office fails, too
16:32.03 ``Erik in alter
16:32.27 elf_ Added another patch right now, it fixes the meter/mm problem that I've got when transferring the units from brlcad to bullet, also added that README file with the simulate command workings explained
16:32.34 ``Erik comcrap can still hit sago? O.o
16:32.57 elf_ the mass of the objects is being calculated in the right way now, meaning it doesn't grow during the simulation
16:33.34 ``Erik (yeh, alter.net whois lists verizon contacts)
16:34.43 brlcad ``Erik: yeah, no problems
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16:35.08 elf_ right now I am working on the ray-tracing part of the simulate command, the rt part is not working properly yet, it is done only for the box-box collision, talked with Abhi and he suggested I do a standalone bullet demo, where I will add the custom algorithm for simulation using his implementation just as reference since it hasn't been tested extensively
16:58.00 brlcad elf_: okay -- it'd be good to have a specific goal identified for that
17:00.17 brlcad i'm a bit concerned over how progress has slowed over the past week -- given there's only a few weeks remaining now
17:01.58 brlcad need to plan effort going forward so that we don't end up with you having finally understood what you need to do with bullet and the raytracing portion, yet no useful code written
17:02.23 elf_ brlcad, yes I do have a specific goal for that one, actually there(in the simrt.c file and the registered custom collision algorithm) is where the collision detection for objects it happens, so doing the standalone bullet project and seeing what it works and what doesn't for box-box and spheres then changing the existing code, I hope it will fix the physics for those 2 shapes
17:03.13 elf_ and I am sorry for the slow progress over the last week, I moved a little around, but I totally understand your concerns
17:05.01 brlcad "doing the standalone bullet project and seeing what it works and what doesn't for box-box and spheres then changing the existing code" is not a goal... that's a plan of action, and it sounds rather vague at that
17:05.26 brlcad fixing the physics for "those 2 shapes" might be a goal, but that's not very specific
17:05.40 brlcad what's the goal?
17:08.14 elf_ the standalone bullet it is actually related to the simrt.c file, everything that takes place in that standalone demo file should take place in the brlcad world too, the nearphase, broadphase callbacks for bullet should be integrated in both brlcad and the standalone bullet world
17:08.38 elf_ the goal is to be able to detect and resolve more than just box-box collision
17:09.20 elf_ the current custom algorithm registered with bullet it's for box-box but it can be extended to more than that, sphere collision for example
17:10.11 elf_ for box-box there are 4 rays shoot to detect collision, for sphere-box it will only have to be one ray to shoot to detect the collision, it will be like one contact point between the 2 geometry shapes
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17:44.19 brlcad elf_: that still sounds ill-defined to me
17:44.32 brlcad to be able to detect and resolve more than just box-box collision is a great high-level goal
17:45.12 brlcad it's more of an objective even
17:45.16 brlcad I'm looking for smaller measurable goals that get you towards that high-level objective
17:45.42 brlcad implementing a nearphase callback in brl-cad and demonstrating it would be two near-term goals
17:46.00 brlcad what's the difference between a nearphase and broadphase callback?
17:47.05 elf_ for bullet the broadphase callback is there when objects can collide, like they are really close to each other, the AABB are almost intersecting or they will intersect in the next few iterations
17:47.17 elf_ after that the nearphase callback it takes place
17:47.25 elf_ when the AABB actually collide
17:47.49 elf_ and the code it is actually there, brlcad, for both of them, it is just ill-working
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17:48.02 elf_ for the moment it is all commented out
17:49.13 brlcad I was aware of a "preliminary" collision detection using the aabb's to tell you when two objects are "close" and a secondary more precise collision detection that should tell the exact points
17:49.46 brlcad is that your broad/nearphase callbacks or is that something else, because it doesn't match your description of a callback prior to the AABBs even overlapping (the broadphase)
17:50.10 elf_ that's it, the broadphase - when objects are close and there's the possibility of them to collide and the nearphase when they actually collide, the nearphase returns the actual collision points
17:50.32 elf_ the callback is not working as it is supposed to
17:50.46 brlcad which, the broad or near?
17:51.23 brlcad by general understanding was that broad has been working for some time
17:54.46 elf_ it has yes, for box-box, the nearphase is not
17:55.42 brlcad so that gets back to my previous point about needing a specific goal
17:56.13 elf_ okay, then the specific goal it is to make the nearphase work
17:56.40 brlcad for what inputs?
17:56.51 brlcad and what does work mean?
17:57.13 brlcad what's your output -- how will you demonstrate the goal being achieved?
17:58.05 elf_ box-box for now, then test the broadphase for box-sphere and adding nearphase for box-spere too
17:58.37 elf_ work = collision points should be detected, that should be verified with shooting rays
17:59.27 brlcad woah, so hold on again
17:59.38 brlcad broadphase is either working for all object or it's not, no?
17:59.56 brlcad if it's not working, that should be the focus of attention before getting into nearphase work
18:00.12 elf_ right, but it hasn't been tested, it should be working, at least in theory, abhi hasn't tested it
18:00.38 brlcad testing that should take all of a few minutes, no?
18:00.54 brlcad you just wrote up a tutorial, replace the box with a sphere
18:01.22 brlcad that is central to planning your next course of action
18:02.45 brlcad in fact, you should be able to also test something complex, like the m35 truck model, to tell you if broadphase is working
18:03.02 elf_ yes, testing it shouldn't take more than a few minutes, so that's why I didn't dwell on it
18:03.26 elf_ okay, about the m35 truck model how do one gets those models inside mged?
18:03.42 brlcad except your plan of action involved testing broadphase for box-sphere later
18:03.58 brlcad the point of testing it is that there's a chance it doesn't work, you don't know
18:04.06 elf_ you are right
18:04.08 brlcad IF it doesn't work, that completely changes your plan
18:04.18 brlcad that's not a minor detail
18:04.29 elf_ true
18:04.48 brlcad that's something you could spend a week investigating and fixing, so it has to come before any nearphase work
18:05.30 brlcad so there's a specific goal
18:06.30 elf_ okay, so for now the goal is to test and make sure the broadphase it is working for all kinds of arbitrary shapes
18:06.37 brlcad TEST broadphase AABB collision detection with aa-box (done), rotated box (not done), ellipsoid (not done), combination (not done)
18:06.55 brlcad not arbitrary, a carefully selected set that gives you confidence it's working
18:07.22 brlcad testing shouldn't take more than an hour or two, but is a good goal
18:07.39 elf_ okay, so rotated box, ellipsoid and combination
18:07.47 brlcad on a related note, I presume with the tolerance work that you were able to get a better animation of the box falling down to the ground in your tutorial?
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18:09.41 elf_ right now the box is not penetrating the plane anymore, ran it for 300 steps and it stopped on the ground plane
18:09.49 elf_ there is a pic on the log page
18:10.20 elf_ http://imageshack.us/a/img18/2438/simulate300.png
18:10.24 brlcad I believe your tutorial created a really small box, right, like 1-2mm big?
18:10.43 elf_ same simulation, geometry in meters this time
18:11.13 brlcad okay, so if it's 1-2mm then it still sinks into the ground?
18:11.23 elf_ yeah, that is not possible 1-2mm big, bullet has the 0.04m tolerance and it can be set lower, but it will have unexpected behaviour
18:11.45 elf_ yes, for geometry that small it is not working
18:12.39 brlcad you should mention that in the tutorial... :)
18:12.42 brlcad after the If you want to see when the cube touches the ground plane then you only have to increase the simulate step numbers to 190. You should see something like the image to the right :
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18:13.29 elf_ okay will do
18:13.43 brlcad after that image, you can say something like "notice how the box goes into the ground and rolls over .. it's too small! we can scale it up simply with this: ... and the re-simulate/re-render looks like this: ...
18:15.29 elf_ will modify it :)
18:16.03 brlcad it's likely to be a common point of confusion, so it's good to say something about the limitation
18:18.48 brlcad quick scale instructions: e cube gp ; sed cube ; sca 1000 ; accept ; sed gp ; sca 1000 ; accept ; d cube gp
18:19.11 brlcad or something like that, test it yourself
18:19.45 brlcad use 'draw' instead of 'e' to be consistent
18:28.59 abhi2011 hallo brlcad :)
18:29.31 brlcad howdy abhi
18:31.20 abhi2011 is BRL-CAD moving to use Qt for the Archer GUI ?
18:31.56 abhi2011 I saw some mails related to DisplayManager
19:15.26 brlcad abhi2011: it might not make it into archer, but Qt is on the mid-term development roadmap
19:15.35 brlcad which is cool, used to be long-term
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19:20.18 abhi2011 yeah and Qt is awesome, I think even Maya uses Qt now :)
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