Search found 41 matches

by crashlander
Wed Dec 19, 2007 11:57 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Character Simulation
Replies: 6
Views: 3356

Re: Character Simulation

Check the first paper here... not sure you could make it work for games but you may still find it interesging.

http://www.cs.ubc.ca/~van/papers/index.html
by crashlander
Wed Oct 03, 2007 10:37 am
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: Farseer Physics Engine For XNA and Silverlight 1.1
Replies: 0
Views: 2822

Farseer Physics Engine For XNA and Silverlight 1.1

I just released a new version of my 2D physics engine. This engine is a c# engine derived from Erin Catto's Box2D Lite engine. Description The Farseer Physics Engine is an easy to use 2D physics engine designed for Microsoft’s XNA and Silverlight platforms. The Farseer Physics Engine focuses on simp...
by crashlander
Thu Sep 13, 2007 11:30 am
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: Box2D Open Source Project
Replies: 4
Views: 3389

Re: Box2D Open Source Project

There has already been some talk(started by me. :-) of porting this engine to a c#/managed code so that it can be used with XNA: http://forums.xna.com/thread/24356.aspx
by crashlander
Tue Sep 11, 2007 11:44 am
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: Box2D Open Source Project
Replies: 4
Views: 3389

Re: Box2D Open Source Project

This is very impressive. Big step up from your original engine. I have a feeling this engine will be quite popular amoung the indie game developers!
by crashlander
Tue Aug 21, 2007 4:40 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Box2D plus elastic collisions
Replies: 4
Views: 3884

There is a good example of it in this open source engine:

http://wiki.slembcke.net/main/published/Chipmunk
by crashlander
Mon Aug 20, 2007 4:47 pm
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: MetaPhysics (2D PBD-based rigid bodies)
Replies: 8
Views: 5090

I don't have a good answer, but it seems like something that could be pre-computed (an estimate anyway) using the vertex points and the assumption that mass is evenly distributted.
by crashlander
Mon Aug 20, 2007 11:29 am
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: MetaPhysics (2D PBD-based rigid bodies)
Replies: 8
Views: 5090

Very nice. I've been reading thru these papers. Interesting stuff. One piece I'm not clear on for rigid bodies is how moment of intertia is handled when everything is basically just a bunch of connected points that get re-positioned every frame. I'm not done with the papers yet so maybe it's in ther...
by crashlander
Thu Aug 16, 2007 6:33 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Baumgarte and Softness for 2D Joints
Replies: 6
Views: 14385

Thanks a million for that Erin. At first glance, I think I follow. I'll chew on it for a while and see where I get.
by crashlander
Thu Aug 16, 2007 1:54 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Baumgarte and Softness for 2D Joints
Replies: 6
Views: 14385

Thanks Dirk. I'm not really concerned with the values of ERP and CFM (BiasFactor and Softness) I'm just interested in implementing softness into my angle joint class. (I'll worry about good values later) What you show helps me alot. My only question now I guess is the specifics of how to apply this ...
by crashlander
Thu Aug 16, 2007 11:12 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Baumgarte and Softness for 2D Joints
Replies: 6
Views: 14385

I'm still trying to get my head around the implementation of softeness. In particular, I have a 2D Angle Joint with upper and lower limits. I used Erin's description here http://www.continuousphysics.com/Bullet/phpBB2/viewtopic.php?t=517 to create the joint. The joint works fine and I mostly underst...
by crashlander
Fri Aug 10, 2007 6:25 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Baumgarte and Softness for 2D Joints
Replies: 6
Views: 14385

Baumgarte and Softness for 2D Joints

On Erin's blog, in a comment is the following statement: "Relaxation is an indirect way to soften the joints. In the GDC07 version of the bridge I directly use softness and the Baumgarte parameter to achieve a specified joint stiffness and damping. Unlike a true spring and damper, the SI algorithm c...
by crashlander
Fri Aug 10, 2007 5:32 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: 2D Joint Motor For Angle Joint
Replies: 2
Views: 2474

Thanks Erin. Exactly what I was looking for.

My timesteps are constant so I don't think I need to tie by Baumgarte factor to the timestep.
by crashlander
Tue Aug 07, 2007 7:35 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: 2D Joint Motor For Angle Joint
Replies: 2
Views: 2474

2D Joint Motor For Angle Joint

In my 2D physics engine I have a 'FixedAngleJoint'. This joint constrains two bodies to remain at some fixed angle. This joint is implemented using a Baumgarte factor and the ideas in Box2D. I want to dynamically modify the target angle in order to allow the user to control objects in my app. So far...
by crashlander
Tue Aug 07, 2007 5:50 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: 2D Angle Joint Limits (Box2D-Style)
Replies: 4
Views: 3164

I thought this had been discussed before:

http://www.continuousphysics.com/Bullet ... .php?t=517

Looks like I'm missing the clamping!
by crashlander
Tue Aug 07, 2007 11:34 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: 2D Angle Joint Limits (Box2D-Style)
Replies: 4
Views: 3164

Thanks Dirk, that helped. I have my angle limits working (sort of). They work fine for certain configurations, but are very unstable in others. Things seem to become more unstable the further the anchor is from the involved bodies. I'm wondering if this is just the nature of the beast or if I have s...