Java-Gaming.org Hi !
Featured games (81)
games approved by the League of Dukes
Games in Showcase (513)
Games in Android Showcase (119)
games submitted by our members
Games in WIP (576)
games currently in development
News: Read the Java Gaming Resources, or peek at the official Java tutorials
 
    Home     Help   Search   Login   Register   
Pages: [1]
  ignore  |  Print  
  Rotational Physics advice needed  (Read 2532 times)
0 Members and 1 Guest are viewing this topic.
Offline blahblahblahh

JGO Coder


Medals: 1


http://t-machine.org


« Posted 2003-04-15 20:13:50 »

Does anyone have any advice on rot physics? I've got various objects which have multiple moments acting on them dynamically from different points, and need to accurately rotate the objects under the action of the moments.

Main problems which spring to mind:

- What's the centre-of-rotation when acted on by multiple moments?
- What's the rotational acceleration about that centre? (I suspect I can work this out by getting the A at a point, and assuming it is rotating the edge of a circle whose radius is the distance of that point from the centre, and then calculate the angular/rotational acceleration from there).

Unfortunately, it has been a very very long time since I covered circular/spherical physics, and I can't seem to find any good resources (my books are long since vanished, and there appear to be no good resources online for this particular branch. Several days of google searches currently fruitless)

malloc will be first against the wall when the revolution comes...
Offline swpalmer

JGO Coder


Exp: 12 years


Where's the Kaboom?


« Reply #1 - Posted 2003-04-16 00:08:06 »

Rotations are usually about the center of mass..  I think you would be able to merge things to rotations in a few planes centered on that point.

Offline lilspikey

Senior Newbie




Computers Stole My Social Skills


« Reply #2 - Posted 2003-04-20 11:04:19 »

Check out:

http://www.d6.com/users/checker/dynamics.htm

There are some pretty good articles there on rotational phsyics.  

The biggest trouble (if you are gonna do 3D) is picking a representation for your orientation.  Hecker uses 3x3 matrices, but I quite like quarternions.


Games published by our own members! Check 'em out!
Legends of Yore - The Casual Retro Roguelike
Offline blahblahblahh

JGO Coder


Medals: 1


http://t-machine.org


« Reply #3 - Posted 2003-04-22 16:53:53 »

Quote
Does anyone have any advice on rot physics? I've got various objects which have multiple moments acting on them dynamically from different points, and need to accurately rotate the objects under the action of the moments.

Main problems which spring to mind:

- What's the centre-of-rotation when acted on by multiple moments?


Well, duh! After thinking about this a bit more, I realised that by definition the centre-of-rot has to be the centre-of-mass. I'm dealing with multiple differently-defined centres-of-mass for the same body (e.g. centre-of-buoyancy for floating objects) and was being very thick, and worrying about something I shouldn't have bothered with!

Sadly, I've also discovered that Java2D is horrifically slow once you start using complex CAG operations Sad(. It wasn't my physics engine that was slow, it was Java2D that was painting slowly!

malloc will be first against the wall when the revolution comes...
Offline blahblahblahh

JGO Coder


Medals: 1


http://t-machine.org


« Reply #4 - Posted 2003-04-22 16:57:31 »

Quote
Check out:

http://www.d6.com/users/checker/dynamics.htm

There are some pretty good articles there on rotational phsyics.  

The biggest trouble (if you are gonna do 3D) is picking a representation for your orientation.  Hecker uses 3x3 matrices, but I quite like quarternions.


Hmm. I've looked at Chris's site for physics info before, and although I just checked again, I couldn't find anything particular to rotational physics - although I didn't bother looking closely at the books (I don't have access to a library - online online resources, sadly).

Sorry if I'm being thick (again) but which resources in particular did you spot on Chris's pages?

P.S. Yeees, 3x3 matrices are rather crap if you're doing anything interesting. I'm using J2D as a zero-maintenance display technology (very useful to not have to debug graphics AND physics in parallel), so happy to use the actually-rather-well-designed AffineTransform class for all matrices.

malloc will be first against the wall when the revolution comes...
Offline lilspikey

Senior Newbie




Computers Stole My Social Skills


« Reply #5 - Posted 2003-04-27 08:58:36 »

There are some PDF articles there (written for Game Developer) that are a very good starting point.  Plus there is some sample C code too:

http://www.d6.com/users/checker/dynamics.htm#articles

http://www.d6.com/users/checker/dynamics.htm#samples


Pages: [1]
  ignore  |  Print  
 
 
You cannot reply to this message, because it is very, very old.

 

Add your game by posting it in the WIP section,
or publish it in Showcase.

The first screenshot will be displayed as a thumbnail.

Longarmx (38 views)
2014-10-17 03:59:02

Norakomi (29 views)
2014-10-16 15:22:06

Norakomi (24 views)
2014-10-16 15:20:20

lcass (28 views)
2014-10-15 16:18:58

TehJavaDev (57 views)
2014-10-14 00:39:48

TehJavaDev (56 views)
2014-10-14 00:35:47

TehJavaDev (47 views)
2014-10-14 00:32:37

BurntPizza (64 views)
2014-10-11 23:24:42

BurntPizza (36 views)
2014-10-11 23:10:45

BurntPizza (78 views)
2014-10-11 22:30:10
Understanding relations between setOrigin, setScale and setPosition in libGdx
by mbabuskov
2014-10-09 22:35:00

Definite guide to supporting multiple device resolutions on Android (2014)
by mbabuskov
2014-10-02 22:36:02

List of Learning Resources
by Longor1996
2014-08-16 10:40:00

List of Learning Resources
by SilverTiger
2014-08-05 19:33:27

Resources for WIP games
by CogWheelz
2014-08-01 16:20:17

Resources for WIP games
by CogWheelz
2014-08-01 16:19:50

List of Learning Resources
by SilverTiger
2014-07-31 16:29:50

List of Learning Resources
by SilverTiger
2014-07-31 16:26:06
java-gaming.org is not responsible for the content posted by its members, including references to external websites, and other references that may or may not have a relation with our primarily gaming and game production oriented community. inquiries and complaints can be sent via email to the info‑account of the company managing the website of java‑gaming.org
Powered by MySQL Powered by PHP Powered by SMF 1.1.18 | SMF © 2013, Simple Machines | Managed by Enhanced Four Valid XHTML 1.0! Valid CSS!