User:Andrew Linden/Office Hours/2008 02 05
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Transcript of Andrew Linden's office hours:
[11:02] | Arawn Spitteler: | I've an idea for a circular bench, that grows with occupation, but have to figure how to turn people about. |
[11:02] | Teravus Ousley: | Hello everybody :D I'm actually in two meetings unfortunately ;P |
[11:02] | Arawn Spitteler: | I think I just solved it, though. |
[11:02] | Kitto Flora: | Hello Andrew |
[11:02] | Andrew Linden: | Hi everybody. |
[11:02] | Teravus Ousley: | Hello :D |
[11:03] | Anders Falworth: | Hi, Andrew |
[11:03] | Ruud Lathrop: | Hi |
[11:03] | Rex Cronon: | hi |
[11:03] | Arawn Spitteler grovels politely in the discretely general direction of our new arrival | |
[11:03] | Andrew Linden: | I'm in a bad mood today, because I've been trying to fix @#$%^& avatar motion bugs |
[11:03] | Andrew Linden: | that code is going to be the death of me |
[11:04] | Arawn Spitteler hopes he isn't serious, about catching his death of Code: Live by hte sword, and all | |
[11:04] | Rex Cronon: | u should buy a punch bag. helps u releave stress:) |
[11:04] | Kitto Flora: | Whats buggy about avatar motion? |
[11:04] | Ruud Lathrop: | Or grap a gun and go shoot somebody in SL :) |
[11:05] | Teravus Ousley: | yes, or a pillow .. or at least a fax machine that you can bash in the parking lot |
[11:05] | Andrew Linden: | we have a new update, held up by some last minute QA stuff going on right now |
[11:05] | Andrew Linden: | hopefully today |
[11:05] | Rex Cronon: | yes, go to a fighthing sim and create havok:) |
[11:05] | Ruud Lathrop: | new update of server? |
[11:05] | Andrew Linden: | yeah, new Havok4 preview update |
[11:06] | Andrew Linden: | There will also be a viewer update sometime after that, in a few days |
[11:06] | Andrew Linden: | but it is pending some MONO compatibility UI stuff |
[11:06] | Kitto Flora: | Hi Simon |
[11:07] | Simon Linden: | Hi folks |
[11:07] | Ruud Lathrop: | Hi |
[11:07] | Rex Cronon: | hi simon |
[11:07] | Anders Falworth: | Hi, Simon. |
[11:07] | Rex Cronon: | interesting, we have a mole here:) |
[11:07] | Teravus Ousley: | Hello |
[11:07] | Andrew Linden: | the stuff in the next Havok4 update was all stuff that was done last week |
[11:08] | Andrew Linden: | so nothing new to report that will be in the update |
[11:08] | Arawn Spitteler: | STATUS_ROTATE? |
[11:08] | Andrew Linden: | what is NOT in the update are things such as the STATUS_ROTATE fix |
[11:09] | Andrew Linden: | I fixed one of Cubey Terra's planes (the ultralight). NOT in the update |
[11:09] | Andrew Linden: | And while I was at it I convexified the collision proxies for sculpy prims |
[11:10] | Andrew Linden: | they were being proxied by tori |
[11:10] | Rex Cronon: | what does that mean? i am talking about sculpties. |
[11:10] | Andrew Linden: | but will eventully be convex hull's of tori |
[11:10] | Andrew Linden: | Well, at the moment sculpties don't collide anything like their apparent shape |
[11:10] | Rex Cronon: | yes, i know is torus |
[11:10] | Andrew Linden: | the collide and roll around like a regular default torus, with scale |
[11:11] | Andrew Linden: | but the torus uses the Havok "mesh shape" which is kinda CPU expensive |
[11:11] | Andrew Linden: | and sculpties are usually used for their collision properties |
[11:12] | Andrew Linden: | so instead of using the mesh shape I use the "convex vertices shape" (basically a convex hull) |
[11:12] | Andrew Linden: | which is cheaper |
[11:12] | Andrew Linden: | and still kinda rolls around like the torus (but with the hole filled in) |
[11:12] | Arawn Spitteler: | So, Stairs won't need their invisible ramps? |
[11:12] | Rex Cronon: | so now basically sculpties are ovals? |
[11:13] | Andrew Linden: | no, stairs may still need their invisible ramps |
[11:13] | Andrew Linden: | sculpties still won't collide like their apparent shapes |
[11:13] | Andrew Linden: | but the shape the DO use will cause less lag |
[11:13] | Nitram Wei: | Script run-time error |
[11:13] | Nitram Wei: | Too Many Listens |
[11:13] | Teravus Ousley: | always a positive :D |
[11:13] | Andrew Linden: | yeah, they are kinda egg shaped... but symmetrical, no fat end |
[11:14] | Rex Cronon: | elyptical? |
[11:14] | Arawn Spitteler thinks the lack of a fat end is why we can't open them | |
[11:14] | Rex Cronon: | hi nitram |
[11:14] | Andrew Linden: | I had some subject that I was going to raise for discussion... but I've forgotten what it is. |
[11:14] | Nitram Wei: | hi |
[11:14] | Andrew Linden: | Hello Nitram, welcome. |
[11:14] | Nitram Wei: | thnx |
[11:15] | Andrew Linden: | oh yeah, I remember one thing... |
[11:15] | Teravus Ousley: | Kind of like that.. ---> Points to the prim on the table |
[11:16] | Andrew Linden: | A Resident named Areth Gall contacted me because he had been measuring the moments of inertia of hollow boxes |
[11:16] | Andrew Linden: | and was coming up with numbers that did not match the theoretical values |
[11:16] | Andrew Linden: | so when I looked into it... sure enough there was a bug |
[11:16] | Andrew Linden: | so I fixed it (NOT in the update, but few would notice anyway) |
[11:17] | Andrew Linden: | and was pleased that I've got such intrepid Residents out there testing stuff. |
[11:17] | Rex Cronon: | they had too much mass? |
[11:17] | Andrew Linden: | well... too much angular mass |
[11:18] | Andrew Linden: | all of the diagonal elements of the inertia tensor were too large by 0.01 |
[11:18] | Arawn Spitteler: | That sounds rather precise |
[11:18] | Andrew Linden: | really not very noticable... maybe 16% too big for a default cube |
[11:19] | Andrew Linden: | yes, it was very precise. Turns out the default inertia was set to the identity before adding up the parts |
[11:19] | Andrew Linden: | and there is a mysterious factor of 1/100 related to the discrepancies between the new "real" mass and the "legacy" Havok1 mass that you get when you call llGetMass() |
[11:20] | Arawn Spitteler: | How do you measure "real" mass? |
[11:20] | Andrew Linden: | well, you can multiply the legacy mass by 100 |
[11:21] | Andrew Linden: | but it is only used internally (in the physics engine) at the moment |
[11:21] | Andrew Linden: | I'm not interested in adding a llGetRealMass() |
[11:21] | Arawn Spitteler wonders how the measurement was done. | |
[11:21] | Andrew Linden: | but maybe someday when we have LSL3 or whatever we can move toward more realistic masses |
[11:22] | Arawn Spitteler: | So GetRealMass()= llGetMass()*100; |
[11:22] | Andrew Linden: | How would you measure the moments of inertia of an object in SL? Anyone know? |
[11:22] | Rex Cronon: | i thought that lsl will be replaced by mono |
[11:22] | Andrew Linden: | MONO will initially have the same LSL interface... you'll still write in LSL |
[11:22] | Andrew Linden: | but the execution under the hood is different |
[11:23] | Arawn Spitteler: | I know that Rotational Inertia is the sum of mass* radius squared |
[11:23] | Andrew Linden: | but what if someone were to write LLPython that uses different syntax |
[11:23] | Rex Cronon: | but eventually u should be able to use c#, c++, java, or other languages |
[11:23] | Andrew Linden: | and maybe different callback structure |
[11:23] | Andrew Linden: | Yes Arawn, it is the integration of mass * radius^2, over the object's volume |
[11:24] | Domchi Underwood: | Hi everyobdy... |
[11:24] | Ruud Lathrop: | Hi |
[11:24] | Rex Cronon: | hi domchi |
[11:24] | Andrew Linden: | so for complicated objects the integral is messy |
[11:24] | Andrew Linden: | it is often easier to just measure it |
[11:24] | Rex Cronon: | . |
[11:25] | Arawn Spitteler: | I think there's something about adding the Moments of Inertia, of each prim, as factored somehow by the square of that prim's radius. Generally, you'd llGetTargetOmega before and affter llApplyRotationalImpulse |
[11:25] | Andrew Linden: | that is right Arawn |
[11:26] | Andrew Linden: | In SL you can give the object hover so that it doesn't hit anything |
[11:26] | Andrew Linden: | then apply angular impulses and measure the angular acceleration |
[11:26] | Andrew Linden: | F = ma is the linear equation |
[11:27] | Andrew Linden: | torque = inertia * angular_velocity is the angular equivalent |
[11:27] | Andrew Linden: | however, the inertia is actually a tensor, but if you're spinning about one cardinal axis then it collapses into a scalar equation |
[11:27] | Arawn Spitteler: | Angular Acceleration could get complicated |
[11:27] | Andrew Linden: | and you can just measure each axis by itself |
[11:28] | Andrew Linden: | The legendary Xylor Bayslef was the first person I knew of to measure the inertia tensors in that way. |
[11:29] | Ruud Lathrop: | What are the major bug fixes in this release? |
[11:29] | Andrew Linden: | lemme look them up... |
[11:29] | Arawn Spitteler: | So, if this table were set Physical Hover, it would gain speed, each time one of us dismounted? |
[11:30] | Kitto Flora: | It has no rotational speed |
[11:30] | Kitto Flora: | cchange the sizze - still no r-speed |
[11:31] | Andrew Linden: | first of all, the next update will bring Havok4 up to par with the recently released 1.19.0 server |
[11:31] | Simon Linden: | The hover calculations use the current mass and are applied in each timestep, so changing the mass won't make it rise or fall |
[11:31] | Andrew Linden: | There were a few small performance optimizations... I expect them to be measureable in a few content scenarios, but not very big. |
[11:32] | Andrew Linden: | There was a duplication of selection not lining up bug that as fixed |
[11:33] | Andrew Linden: | I tried to fix SVC-1089 and failed |
[11:34] | Andrew Linden: | SVC-1239 is fixed (llSetLinkPrimitiveParams() on avatar) was breaking some boats and other things |
[11:34] | Andrew Linden: | I'm hoping SVC-1272 (boats too low in water) is actually fixed |
[11:34] | Domchi Underwood: | Andrew, I read your plan on megaprims... but can you comment on microprims? Will some action be taken regarding them? |
[11:34] | Andrew Linden: | oops... I take that back |
[11:35] | Andrew Linden: | I wasn't watching the revision numbers carefully and looked over where we stopped for this update |
[11:36] | Andrew Linden: | sigh... which means everything since SVC-1089 is NOT fixed in this update |
[11:36] | Gaius Goodliffe: | Hmm... Andrew, is SVC-1089 possibly related to other "dropping like a rock" issues, like, for example, how when flying at 640m, if you press forward, you drop like a rock? |
[11:36] | Andrew Linden: | the dropping like a rock issue is fixed |
[11:36] | Andrew Linden: | and is not related |
[11:36] | Gaius Goodliffe: | oh cool. |
[11:37] | XerxesTiny.LITTLE BEE.Head: | Touched. |
[11:37] | Ruud Lathrop: | If a bug is 'fix pending' will that mean they are being released in next server/client update? |
[11:38] | Andrew Linden: | sigh... I'm just not in the mood to read the logs and figure out where one update started and another ended |
[11:38] | Andrew Linden: | do you remember anything Simon? |
[11:38] | Simon Linden: | Ruud - it may not be the immediate next update. It depends on when it was fixed vs. when we built and start testing the update |
[11:38] | Andrew Linden: | most of the stuff we announced as in the next update on Thursday is in this one |
[11:39] | Simon Linden: | I'm not sure of the cutoff either ... I think most of what's about to go out was discussed Thursday |
[11:39] | Ruud Lathrop: | Ok |
[11:39] | Sascha Vandyke: | is an update version scheduled already ? |
[11:40] | Arawn Spitteler: | So, how soon is a certain Cabriole ready for a test drive? |
[11:40] | Simon Linden: | I do know I'm currently working on a vehicle bug, where it's going wildly out of control. I'm not sure how many vechicles it affects |
[11:40] | Andrew Linden: | the update should happen today if all goes well |
[11:40] | Sascha Vandyke: | ahh ok |
[11:41] | Sascha Vandyke: | is there any blog to find the time or announcement |
[11:41] | Andrew Linden: | no the blog announcement would go out after the update has happened and the beta is open |
[11:41] | Sascha Vandyke: | ahh ok thx |
[11:41] | Andrew Linden: | so you can tell when it is happening when the beta grid goes down |
[11:42] | Andrew Linden: | but this update will also go out to any regions on the main grid that are using Havok4 |
[11:42] | Andrew Linden: | hrm... I wonder if they'll do that tomorrow or today |
[11:42] | Andrew Linden: | Sidewinder knows. |
[11:42] | Kitto Flora: | This is 1.18.6.78103 |
[11:42] | Sascha Vandyke: | thx |
[11:43] | Kitto Flora: | so when he 78103 is a larger number, then you are on a new h4 server version |
[11:44] | Domchi Underwood: | Andrew, I have a question re your megaprim genocide plan. ;) |
[11:44] | Andrew Linden: | ok ask |
[11:45] | Domchi Underwood: | What about microprims... any plans about them? |
[11:45] | Andrew Linden: | No microprims for a while. |
[11:45] | Andrew Linden: | Er... no plans. |
[11:45] | Andrew Linden: | The physics engine has a "collision tolerance" of 0.1 meter |
[11:45] | Sascha Vandyke: | will also the 256x256 be gone? lol that would interest me personally |
[11:45] | Brookston Holiday: | Megaprim genocide plan? |
[11:45] | Domchi Underwood: | :) But eventually, will they have to go as well? |
[11:45] | Domchi Underwood: | The plan to get rid of megaprims. :) |
[11:46] | Andrew Linden: | objects smaller than that,or on that scale, will not collide very accurately |
[11:46] | Andrew Linden: | There is no Megaprim genocide plan |
[11:46] | Andrew Linden: | however... that reminds me... |
[11:46] | Andrew Linden: | I think Kelly fixed a megaprim link bug with a hack to the linkability rules |
[11:46] | Gaius Goodliffe: | w00t! |
[11:46] | Andrew Linden: | so someone here had a blimp that did not link |
[11:46] | Andrew Linden: | I believe that has been fixed |
[11:47] | Simon Linden: | Yes, that was fixed ... I confirmed it |
[11:47] | Gaius Goodliffe: | That was me. :D |
[11:47] | Andrew Linden: | Here is the plan for megaprims... |
[11:47] | Rex Cronon: | so any prim that is within 10m can be linked? |
[11:47] | Andrew Linden: | (1) make it so parcel owners can return (or maybe just move?) objects that are overlapping their parcels |
[11:48] | Andrew Linden: | (2) provide some UI feedback to builders when their objects extend outside of their allowed building boundaries |
[11:48] | Gaius Goodliffe: | (I don't know if "just move" would work -- what if the megaprim is bigger than the owner's parcel? (thinking of First Land plots (and dating myself, I guess lol))) |
[11:48] | Andrew Linden: | (3) give parcel owners some more options for automatic enforcement of their boundaries (off by default) |
[11:49] | Ruud Lathrop: | That can also be applied to normal prims? |
[11:49] | Andrew Linden: | (4) allow builders to build any size (and sometimes only as large as can fit on their parcel) AKA "megaprim liberation" |
[11:49] | Gaius Goodliffe: | That would be very nice. :D |
[11:50] | Andrew Linden: | yes, steps (1) throuth (3) are just about normal prims |
[11:50] | Andrew Linden: | after that, Megaprims can be considered normal prims |
[11:50] | Andrew Linden: | there are a few details in there... |
[11:50] | Andrew Linden: | sculpties are difficult to query for parcel overlap |
[11:50] | Andrew Linden: | so that is it own kinda big project |
[11:50] | Sascha Vandyke: | ok what about a private estate with some parcels and i want a megaprim going over them |
[11:51] | Andrew Linden: | btw... that is NOT the official LL plan on megaprims |
[11:51] | Andrew Linden: | that is MY plan |
[11:51] | Sascha Vandyke: | ahh ok lol |
[11:51] | Andrew Linden: | I'm the only one with a plan on megaprims |
[11:51] | Andrew Linden: | unfortunatly, I'm trying to finish Havok4 first |
[11:51] | Rex Cronon: | don't sculpties have a bounding box? |
[11:52] | Andrew Linden: | yes sculpties do have a bounding box, but it is not accurate |
[11:52] | Teravus Ousley: | up to twice the radius that the sim currently knows about |
[11:52] | Teravus Ousley: | and that's radius in terms of an ellipsis |
[11:52] | Andrew Linden: | so as soon as you start trying to enforce prim encroachment then sculpties will be one of those corners of the possibility space that do not follow the expected rules |
[11:52] | Teravus Ousley: | :D |
[11:53] | Andrew Linden: | also... there is the problem of prims overlapping into neighboring regions |
[11:53] | Andrew Linden: | that is harder to solve for the encroachment problem |
[11:53] | Andrew Linden: | so that is its own kinda big project |
[11:54] | Andrew Linden: | I describe my megaprim plan every other week in office hours nowadays |
[11:54] | Ruud Lathrop: | :) |
[11:54] | LuckySweet Kondor: | o.o walked in on somthing i see |
[11:54] | Domchi Underwood: | And you also did on forums and blog... :) |
[11:55] | Arawn Spitteler: | Mega-Sculpties will be nice, but their appearence shouldn't be allowed to damage their repute |
[11:55] | Gaius Goodliffe: | prims of ill-repute? o.O |
[11:55] | Andrew Linden: | I was thinking I'd like to work on making better collision approximations for sculpties |
[11:56] | Domchi Underwood: | Ah, forums are working again... here's the link to original post Andrew wrote: |
[11:56] | Domchi Underwood: | http://forums.secondlife.com/showpost.php?p=1667877&postcount=33 |
[11:56] | Andrew Linden: | however recently I ventured into the simulator side code for sculpties (for the convexification project I was mentioning earlier today) |
[11:56] | Andrew Linden: | and now I don't want to touch the sculptie code with a 10-foot pole |
[11:57] | Teravus Ousley: | heh |
[11:57] | Arawn Spitteler: | A ten foot pole wouldn't be Sculpty or Maga |
[11:57] | Andrew Linden: | I might even rather fix vehicle and avatar motion bugs than try to work on sculpties |
[11:57] | Teravus Ousley: | hehe |
[11:58] | Gaius Goodliffe: | lol |
[11:58] | Sascha Vandyke: | is better yes, i have found a lot of av bugs lately lol |
[11:58] | Teravus Ousley: | the texture would be a property of the sculptie that would have to be 'stored with' the sculptie instead of requested on demand.. and you'd have to decode the image and generate a convex mesh from it. |
[11:58] | Rex Cronon: | what did u find there that scared u so much:) |
[11:59] | Teravus Ousley: | a scary proposition.. with lots of math |
[11:59] | Andrew Linden: | it turns out the simulator doesn't know much about sculpties |
[11:59] | Harleen Gretzky: | Then there is also animated sculpties to worry about |
[12:00] | Andrew Linden: | but prims have a general purpose container for holding some "extra data" |
[12:00] | Teravus Ousley: | lol, the idea of a body having to be rebuilt with an animation is @.@ |
[12:00] | Andrew Linden: | it is currently used for flexi, sculptie, and something else that I can't remember |
[12:00] | Gaius Goodliffe: | I've always had the impression that sculpties were pretty much spheres with some interesting client-side drawing behavior... |
[12:00] | Andrew Linden: | the interface to that extra data container is terrible (a mix of bad C and bad C++) |
[12:00] | Teravus Ousley: | knowing what a change does to a physical body that interpenetrates something.. essentially 'explode kaboom' |
[12:01] | Teravus Ousley: | like what happens when you unlink physical prim |
[12:01] | Teravus Ousley: | :D |
[12:01] | Andrew Linden: | right Gaius, so atm the simulator doesn't know much about the sculptie status |
[12:01] | Andrew Linden: | it doesn't yet download the textures itself |
[12:01] | Gaius Goodliffe nods. | |
[12:01] | Andrew Linden: | but it would have to in order to generate the collision mesh |
[12:02] | Andrew Linden: | or else we'd have to provide the collision mesh in some other way |
[12:02] | Andrew Linden: | in fact, there is very little sculptie specific code in the simulator |
[12:02] | Andrew Linden: | since it goes through a general purpose container |
[12:03] | Andrew Linden: | but that general purpose container is just poorly implemented and I phear it |
[12:03] | Roxanne Hynes: | Are there plans on completely removing some of the Megaprims, for example prims that are equal or go above 256x256? Or will nothing change for now with that? |
[12:03] | Gaius Goodliffe: | hehe |
[12:03] | Andrew Linden: | sorry, yes Roxanne. megaprims with sides > 256 will have their sides clamped to 256 |
[12:03] | Gaius Goodliffe: | Awww |
[12:03] | Sascha Vandyke: | ahh then is fine |
[12:03] | Roxanne Hynes: | ok thanks |
[12:04] | Andrew Linden: | not exactly megaprim genocide, but definitely targeted murder |
[12:04] | Teravus Ousley: | yeah, at this point, there's not a lot of good uses for megaprim beyond that size |
[12:04] | Sascha Vandyke: | is there anything you noticed from havok 4 playing together with the new server code? |
[12:04] | Arawn Spitteler: | I think it depends on whether you've more than one sim |
[12:04] | Simon Linden: | Sascha - you mean moving from one sim to another? |
[12:04] | Gaius Goodliffe: | Extropia Core has a good use for them -- check out their "low earth orbit" stuff if you're ever there. I think they use a 1024x1024x100 one to make it happen, though. |
[12:05] | Sascha Vandyke: | yes, and some more lag now, think it has become worse after introducing 1.19 to the main |
[12:05] | Sascha Vandyke: | i have avs coming to my sim and they just don't load sometimes |
[12:06] | Simon Linden: | I haven't heard of any specific problems, but the next version we push out will be based on 1.19 |
[12:06] | Sascha Vandyke: | ahh ok |
[12:06] | Simon Linden: | ... meaning up-to-date; we try to pick up any bug fixes that are pushed with the normal server so we don't fall behind |
[12:07] | Kitto Flora gusses: If you have an island sim and you put a 1024x1024 megaprim on it, and plaint it, you can make ground or sky scenery that extends further than the edge of the sim... effectivly to the horizon. | |
[12:07] | Sascha Vandyke: | ok thx. I also have the problem to report some bugs, jira is not so nice to find bugs for havok4, i already reported twice a double one |
[12:08] | Andrew Linden: | Yeah, the bugs are piling up there. |
[12:08] | Gaius Goodliffe: | Kitto: right. In Extropia they use one up high so you see a curved earth beneath you while you're in orbit. |
[12:08] | Andrew Linden: | I'm going to try to make a pass and close some of the Havok4 bugs in the public jira |
[12:08] | Harleen Gretzky: | How do you gus? as in [12:07] Kitto Flora gusses: If... |
[12:08] | Sascha Vandyke: | would be nice |
[12:09] | Kitto Flora: | SVC-1093 was fixed a while back, still shows open |
[12:09] | Kitto Flora does /me guesses | |
[12:09] | Gaius Goodliffe guesses you should use /me. :) | |
[12:09] | Harleen Gretzky: | ahh |
[12:09] | Andrew Linden: | I've got to go now, so we'll have to wrap up. |
[12:10] | Sascha Vandyke: | have a nice day |
[12:10] | Ruud Lathrop: | Ok |
[12:10] | Teravus Ousley: | Good luck with the avatar movement, sir |
[12:10] | Arawn Spitteler has heard some debate, on whether Megaprims lag the sims | |
[12:10] | Ruud Lathrop: | All have a nice night :) |
[12:10] | Teravus Ousley: | :D |
[12:10] | Kitto Flora: | We await the update with baited bugtraps. |
[12:10] | Rex Cronon: | bye everybody, i have to go to |
[12:11] | Simon Linden: | Thanks everyone |
[12:11] | Teravus Ousley: | take care :D |