IRC log for #brlcad on 20110711

00:37.19 CIA-62 BRL-CAD: 03Sean 07http://brlcad.org * r2999 10/wiki/Density_functions: initial page on material (density) objects
00:37.29 CIA-62 BRL-CAD: 03Sean 07http://brlcad.org * r3000 10/wiki/ESA_Summer_of_Code_in_Space/Project_Ideas: link to all of the new articles
00:41.24 *** join/#brlcad kunigami (~kunigami@201.53.206.27)
00:46.03 *** join/#brlcad bhinesley (~bhinesley@99.125.86.110)
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00:55.46 *** topic/#brlcad is BRL-CAD Open Source Solid Modeling || http://brlcad.org || http://sf.net/projects/brlcad || #brlcad logs: http://ibot.rikers.org/%23brlcad/ || BRL-CAD release 7.20.2 being tagged today (20110701) || BRL-CAD has applied to participate in the ESA Summer of Code in Space!
02:09.13 CIA-62 BRL-CAD: 03Sean 07http://brlcad.org * r3001 10/wiki/Community_Publication_Portal: initial stub of 7.20.2 release announcement
02:46.34 CIA-62 BRL-CAD: 03Sean 07http://brlcad.org * r3002 10/wiki/Community_Publication_Portal: /* Release 7.20.2 */ restructure
03:47.28 CIA-62 BRL-CAD: 03Sean 07http://brlcad.org * r3003 10/wiki/Community_Publication_Portal: /* Release 7.20.2 */ expand writeup, consolidate contributors
03:52.36 CIA-62 BRL-CAD: 03Sean 07http://brlcad.org * r3004 10/wiki/Community_Publication_Portal: /* Release 7.20.2 */
03:57.38 CIA-62 BRL-CAD: 03brlcad * r45418 10/brlcad/trunk/NEWS: reword the writeup for brevity/clarity
04:15.18 CIA-62 BRL-CAD: 03Sean 07http://brlcad.org * r3005 10/wiki/Community_Publication_Portal: /* Final Editorial Review */ release 7.20.2 posted
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08:05.10 CIA-62 BRL-CAD: 03d_rossberg * r45419 10/brlcad/trunk/CMakeLists.txt: corrected comment on brlcad.dll flag
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13:57.35 CIA-62 BRL-CAD: 03brlcad * r45420 10/brlcad/trunk/src/liboptical/material.c: two found: labels in the same file, bad ju ju
14:20.50 *** join/#brlcad kunigami (~kunigami@loco-gw.ic.unicamp.br)
14:27.34 d_rossberg kunigami: could you solve the refraction issue?
14:29.39 kunigami d_rossberg: nope. I think I'll redo the tests and attach the images in the email. Maybe they give a better idea on what's going on
14:32.13 d_rossberg do you know now whats the difference between pt_inhit and pt_outhit?
14:32.23 CIA-62 BRL-CAD: 03erikgreenwald * r45421 10/brlcad/trunk/src/libgcv/bottess.c: add precomputed face add to avoid fp fuzz on the plane equation
14:45.10 *** join/#brlcad silvap (~silvap@static-96-255-52-7.washdc.fios.verizon.net)
14:53.39 kunigami I'm not sure if I understand them correctly. As far as I understand, the outhit is the intersection of the ray as if I were refracted
15:14.36 d_rossberg the ray-trace gives you a series of hits with solids (regions or primitives)
15:15.36 d_rossberg a hit with a solid is the part of the ray which lies inside the solid
15:16.25 d_rossberg and it is determi
15:16.55 d_rossberg ... sorry, defined by the entry and exit point
15:18.40 d_rossberg i.e. pt_inhit descibes the point where your ray enters a solid (point, distance from the rays origin normal of the solin in this point, ...)
15:19.23 d_rossberg and pt_outhit does the same for the point where the ray leaves the solid
15:20.38 d_rossberg normaly the light goes outside the solids, but in case of refraction you are interested in the lights way inside a solid
16:34.09 brlcad kunigami: make sense?
16:36.02 brlcad if you shot a ray towards a sphere, you'll get an inhit at the point where it hits, then an outhit on the other side of the sphere where it would exit
16:36.34 brlcad remember you're dealing with solid geometry, not just surfaces, so a sphere isn't just the outer surface -- it's solid all the way through
16:42.34 brlcad so the ray tracer gives you sets of inhit/outhit (i.e., partitions)
16:43.34 brlcad you might want to see how our existing phong shader -- src/liboptical/sh_plastic.c -- deals with refraction and transmission, calls rr_render() from refract.c
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17:02.16 kunigami brlcad: but this outhit takes into account the index of refraction, right?
17:02.50 kunigami I read the code in refract.c. I borrowed part of that code to implement the refraction callback of sh_osl
17:04.14 brlcad it depends what you mean by taking it into account
17:05.04 brlcad if you rt_shootray an application struct with index of refraction set, then NO .. it won't take it into account for *that* ray being fired
17:05.31 brlcad inhit/outhit will always be along the ray pnt->dir being fired
17:05.46 brlcad the index of refraction controls the next ray being fired
17:10.22 kunigami hmm, interesting. I had the impression that changing the index of refraction did changed the way the glass looked. maybe I had changed something else
17:10.28 kunigami I'll check again
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19:45.21 CIA-62 BRL-CAD: 03bhinesley * r45422 10/brlcad/trunk/src/libged/alter.c: Added a few examples to the scale manual to help work out issues. It is straightforward compared to the rotate command. These examples are probably sufficient.
19:56.48 bhinesley brlcad: I'm starting to work on the argument handler (alter) for translate/rotate/scale.
19:56.48 bhinesley While all 3 commands accept different arguments, the methods of grouping them are all based on the same concepts. I'm building a sort of argument handling system for alter, so that adding another command, or altering an existing one will be easy enough. What I'm implying is that you can check out the mock manuals at your leisure, and just let me know what changes you'd like.
20:32.29 *** part/#brlcad kunigami (~kunigami@loco-gw.ic.unicamp.br)
21:49.33 brlcad bhinesley: okay
21:49.50 brlcad haven't had a chance to read up in detail since you started on rotate, but will this week
21:50.33 brlcad at a glance, would really like scale to accept simple uniform scaling via single arg
21:50.39 brlcad like scale 2.0 foo
21:51.08 brlcad since that's the most common use case, it should be the most brief
21:51.15 bhinesley nods
21:53.58 bhinesley I could make 'scale 2.0' == 'scale 2.0 2.0 2.0' while 'scale -x 2.0' performs a stretch
21:56.28 bhinesley but then, should 'scale 2.0 3.0' == 'scale -x 2.0 -y 3.0'? This would seem weird: 'scale 2.0 3.0' == 'scale 2.0 3.0 3.0'
21:58.11 bhinesley looks like 'sca' would do the prior
22:06.45 CIA-62 BRL-CAD: 03bhinesley * r45423 10/brlcad/trunk/src/libged/alter.c: All 3 FACTOR_TO_POS arguments areset to its first argument, if it is the only one given.
22:07.55 CIA-62 BRL-CAD: 03bhinesley * r45424 10/brlcad/trunk/src/libged/alter.c: accidentally removed a brace in the last commit
23:31.03 ``Erik mebbe scale 2/2/2 ? so'z you can do 2// or whatever?
23:35.56 ``Erik (defmethod scale-x (obj val) (* (x-of obj) val)) (defmethod scale (obj val) (scale-x obj val) (scale-y obj val) (scale-z obj val)) ... :D
23:41.59 bhinesley ``Erik see libged/alter.c for the manuals I've cooked up so far
23:43.12 bhinesley notably: {xyz_factor | {x y [z]}} | {[-x {x | X_OBJ}] [-y {y | Y_OBJ}] [-z {z | Z_OBJ}]}
23:45.18 bhinesley 2// would be a stretch in the x-axis
23:45.29 bhinesley while 2/2/2 would be a uniform scale
23:47.06 bhinesley the slashes would actually work pretty well though, as far as trimming the size of the commands
23:50.37 bhinesley it means we could do things like './sphere.s 1 4 5/7' rather than '-x . -y sphere.s 1 4 5 -z 7'
23:51.48 bhinesley (which means: use the x-coordinate of each argument we're scaling, the y-coordinate of the center of sphere.s offset (1,4,5), and the z-coordinate of 7)
23:53.38 bhinesley not that the '.' makes much sense for that particular usage of 'scale', but it is very useful for translate/rotate, which use a similar syntax
23:59.08 CIA-62 BRL-CAD: 03bhinesley * r45425 10/brlcad/trunk/src/libged/alter.c: expand upon the definition of OFFSET_DIST, to clarify its dissimilarities from *POS arguments

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