Bullet version

Programmers discuss here anything related to FreeOrion programming. Primarily for the developers to discuss.

Moderators: Committer, Committer

Post Reply
Message
Author
cazfi
Space Floater
Posts: 42
Joined: Thu May 28, 2009 10:08 pm

Bullet version

#1 Post by cazfi » Sun Oct 16, 2011 9:18 pm

Before there can be official FreeOrion debian packet, there must be debain packets for all the dependencies. We are lacking only bullet packet at the moment. While I were investigating this, I found out this:
http://lists.debian.org/debian-devel-ga ... 00213.html
different versions of Bullet physics will have (slightly) different simulation behaviour. And once a game or app is tuned, you don't want to upgrade the physics anymore, it would break everything.
This is quite old quote already, so it may not even be true anymore, but I find it quite disturbing anyway. Bullet is not truly backward compatible, so you have to stick with the version you have designed your program against. Using newer bullet without adjusting your program can lead to unwanted results.

Do you think this is relevant to FreeOrion, or does it affect more the kind of games where programmer expects certain result from physics (adventure game where ball hitting a pillar causes something otherwise unreachable from top of the pillar to drop)? Should you list exact Bullet version that should be used instead of minimum version? Should correct version of bullet be included in FreeOrion source tree as suggested?

User avatar
tzlaine
Programming Lead Emeritus
Posts: 1092
Joined: Thu Jun 26, 2003 1:33 pm

Re: Bullet version

#2 Post by tzlaine » Sun Oct 16, 2011 9:29 pm

This is not relevant for FO. We use mainly the really simple bits of Bullet. I use the latest version of Bullet whenever I set up development on a fresh system (which happens a lot for me), with no problems.

User avatar
Geoff the Medio
Programming, Design, Admin
Posts: 12571
Joined: Wed Oct 08, 2003 1:33 am
Location: Munich

Re: Bullet version

#3 Post by Geoff the Medio » Sun Oct 16, 2011 9:34 pm

Bullet isn't actually used for anything yet in playable FreeOrion, so at present it doesn't matter at all what version is used as long as it builds.

As far as I know, in future, the actual outcome of a battle will be determined on the server, and updates sent to clients. Clients may simulate steps between server updates, and this might lead to a slightly inaccurate prediction on clients and a sudden jump to the new situation when the server update arrives. This is not a huge problem, and may not be noticeable at all in practice.

If client prediction vs. server reality differences are noticeable and objectionable to players, we can fix / pick a particular Bullet version at that time. For now, it's not a problem.

Post Reply