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IDProjectCategoryView StatusDate SubmittedLast Update
0008507opensim[REGION] Physics Enginespublic2019-03-24 00:022019-03-25 05:27
Assigned ToBillBlight 
StatusresolvedResolutionwon't fix 
PlatformOSOS Version
Product Version0.9.0.1 
Target VersionFixed in Version 
Summary0008507: UbODE and Bulletsim are not compatible.
DescriptionForwarded from GitHub (reporter: Ana Green):

UbODE (UBit's customized version of Open Dynamics Engine) and Bulletsim are not compatible I just found out in certain ways, besides with Bulletsim I can walk up a ramp with UbODE I have to jump, If a woman put her shoes on, on a region where Bulletsim is activated it looks ok, however, if that woman HG Teleport or local Teleport to a region with Bulletsim activated the shoes do not fit anymore she has to re-adjust it with the ALPHA HUD what comes with the Mesh Body. Ubit things this remark or issue is:: [01:27:02] Ubit Umarov: wrong meshes, [01:27:24] Ubit Umarov: learn how to make them, and about physics shape type convex. However, I tested it with over 12 different shoes myself or "use what you like" so he said and "plz stop bothering me with nonsense" walk up a ramp with UbODE I have to jump with BulletSim I can just walk up the ramp, that is not a mesh issue (wrong Meshes) but clearly a compatibility problem between the two Physics Engines. I don't see what a Physics Engine has to do with Hypergrid? I just observed the difference between UbODE and BulletSim, both Physics engines are not WhiteCoreSim specific thus they are used on a wide range of OpenSimulators, and therefore I forwarded Ana her post indeed I should post this issue to the OpenSimulator Mantis.

With respect,
Ana Green
Steps To ReproduceLog in to a Grid outside OSGrid, be sure they have BulletSim activated, now walk with your avatar up a ramp or something similar, then buy some (Mesh) shoes or boots (some footwear) remember the outcome due to the walk/or jumps, wear the footwear and be sure it fits nicely now HG Teleport to OSGrid or a local Region but be sure this local region or remote region has UbODE activated. Now look at your footwear does it still fits nicely? Can you still walk up a ramp? Or do you have to jump? Observe and compare.

Ana Green
Forwarded on her request by Xantis
TagsNo tags attached.
Git Revision or version number309
Run Mode Grid (Multiple Regions per Sim)
Physics EngineODE
Script Engine
Environment.NET / Windows64
Mono VersionNone
Attached Files

- Relationships

-  Notes
BillBlight (developer)
2019-03-24 00:07
edited on: 2019-03-24 00:30

First off they are DIFFERENT physics engines, if they were the same, would be no reason to have more than one ..

The physics engines affect many things other than RAMPS, and unless the mesh was uploaded with a proper physics model, which seems to be rare using bullet, bullet creates a physics mesh from the visual mesh, ubODE requires an actual physics mesh.

So of course they are not "compatible" they are not the same really.

ubODE is 3 years old, and actually this issue with mesh is well known.

The issue you have with the ramp, is because the collision shape is different between ubODE and Bullet, if you did not upload the bullet one with the same physics shape that ubODE one has, bullet will create/fake one from the visual mesh , therefore not equal to each other.

Xantis (reporter)
2019-03-24 01:33

I agree fully that they are both DIFFERENT. And your explanation sounds logical where you type "The issue you have with the ramp, is because the collision shape is different between ubODE and Bullet, if you did not upload the bullet one with the same physical shape that ubODE one has, bullet will create/fake one from the visual mesh, therefore not equal to each other." But if they are not compatible then I rather like to see one Physics Engine what does the job right, and one with no mesh issues, why so many Physics engines if one does it differently then the other that can create a mess among grid - regions servers that run all different physics engines is that not correct? Like if all had different script engines, that would be fun, if one would write a dance script on Region A it would not work on region B without correction if possible to correct it at all, I did learn that compatibility is the most fundamental basic, that was the case in the past with Chuck Forsberg his ZModem Protocol and today with the TCP and UDP Protocols if they would be different in each country then internet did not travel far, and as for Physics I think if Isaac Newton would turn around in his grave about incompatible Physics.
BillBlight (developer)
2019-03-24 01:42

I'm just going to quote MisterBlue from the dev irc a couple of months ago ..

"Might be time to make ubODE the default physics engine"

And since he wrote bullet , that says a lot ..
BillBlight (developer)
2019-03-24 01:46

The reason there are still more than one physics engine is simple, people don't like change, even if that change is for the better, and I guess options keep the crying down ..
paela argus (reporter)
2019-03-24 13:59

Ask your friend(s) from Linden Lab Xantis, as I see you are very friends with uh lol; Second life is also the first to use different versions of states in their simulators ...
I especially think that you do not understand many things,
Mantis is made to declare real bugs and not record your disagreement or your ideas
Xantis (reporter)
2019-03-25 00:14
edited on: 2019-03-25 00:26

Well paela argus, for one they do not use these Physics Engines and two it is either a bug or the way it has been written in case they acting differently on the same situation. Then "Ask your friend(s) from Linden Lab Xantis, that's not a bug Argus! Mantis is made to declare real bugs and not record your disagreement with me or SL". As for SL nobody from them may tell me anything because they have a Non Disclosure Agreement is a document contract which lays out what they can and cannot disclose. Usually, LL will not permit anyone who is an employee of Linden Labs to disclose new features in their development pipeline, information about the protocol in the grid architecture that could be considered a means or tool others outside of the lindens could use to exploit the infrastructure, etc. Are you still sure I do not understand many things?

Xantis (reporter)
2019-03-25 00:20
edited on: 2019-03-25 00:30

Bill: On MisterBlue well It was actually Robert Adams that wrote BulletSim originally as far as I am aware. Robert Adams's 5 research works with 40 citations and 413 reads, including... and is also the developer of the BulletSim physics engine for OpenSimulator.

BillBlight (developer)
2019-03-25 01:03

Robert Adams is MisterBlue, so yeah now that is something you know ...
BillBlight (developer)
2019-03-25 01:24

I think everyone here knows what an NDA is, most likely more about NDA's than you know about opensimulator ...

But regardless that did not stop you from making this comment on another mantis ..

"well, I am going to talk with Oscar Linden (SL) about how they doing that with Presence because I think it can't be that complicated unless the Grids code is a mess ... "

I really think Paela hit it right on the head, you have no clue what you are talking about most of the time ... The mantis is not for you to attempt to show how smart you think you are, and NOT a place for you to voice your misconceptions about Opensimulator .. So just STOP ....
BillBlight (developer)
2019-03-25 01:30

This is an education issue, it is simply the difference in mesh physics methods between the two physics engines, and has been discussed many times previously, and I do believe there is even a page on the wiki about it ..

This page has a section about the differences in MESH .. [^]

- Issue History
Date Modified Username Field Change
2019-03-24 00:02 Xantis New Issue
2019-03-24 00:07 BillBlight Note Added: 0034970
2019-03-24 00:30 BillBlight Note Edited: 0034970 View Revisions
2019-03-24 01:33 Xantis Note Added: 0034973
2019-03-24 01:42 BillBlight Note Added: 0034974
2019-03-24 01:46 BillBlight Note Added: 0034975
2019-03-24 13:59 paela argus Note Added: 0034981
2019-03-25 00:14 Xantis Note Added: 0034982
2019-03-25 00:20 Xantis Note Added: 0034983
2019-03-25 00:24 Xantis Note Edited: 0034983 View Revisions
2019-03-25 00:26 Xantis Note Edited: 0034982 View Revisions
2019-03-25 00:30 Xantis Note Edited: 0034983 View Revisions
2019-03-25 01:03 BillBlight Note Added: 0034984
2019-03-25 01:24 BillBlight Note Added: 0034986
2019-03-25 01:30 BillBlight Note Added: 0034987
2019-03-25 01:30 BillBlight Status new => resolved
2019-03-25 01:30 BillBlight Resolution open => won't fix
2019-03-25 01:30 BillBlight Assigned To => BillBlight

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