Real-Time Physics Simulation Forum

Physics of Plant

2005-11-17T17:57:25+00:00

I would definitely go with a verlet-based integrator coupled with a simple relaxation solver using distance constraints... i.e. jakobsen style physics.

http://www.teknikus.dk/tj/gdc2001.htm

stable and fast, but not that accurate, but a truly accurate model of a tree isn't going to be anywhere near fast enough for real-time.

There was a talk at Game Developer Conference on extending the relaxation solver to handle orientation constraints, but I can't remember it's name. It used interpolations of quaternions.

- Michael Alexander Ewert

Statistics: Posted by mewert — Thu Nov 17, 2005 5:57 pm

Physics of Plant

2005-11-17T13:32:43+00:00

Hi,

I've made a small mistake writing point to point constraint connecting branches and it caused constraints to oscillate ... at the moment whole simulation is stable even at 5 fps. I still didn't manage to implement rotational constraint blocking twists at the joint.

I will try to research information on implicit integration any suggestion where to start ?

thanks Janusz Klaptocz

Hi Janusz,

I recommend you read the course paper written by David Baraff:

http://www.cs.cmu.edu/~baraff/sigcourse/notese.pdf

Feel free to ask on the subject if you need in depth explanations.

Best Regards,

Carlo Lanzotti

Statistics: Posted by clanzotti — Thu Nov 17, 2005 1:32 pm

Physics of Plant

2005-11-15T14:55:51+00:00

Hi,

I've made a small mistake writing point to point constraint connecting branches and it caused constraints to oscillate ... at the moment whole simulation is stable even at 5 fps. I still didn't manage to implement rotational constraint blocking twists at the joint.

I will try to research information on implicit integration any suggestion where to start ?

thanks Janusz Klaptocz

Statistics: Posted by Janusz — Tue Nov 15, 2005 2:55 pm

Re: Physics of Plant

2005-11-15T13:17:19+00:00

Hi,

I'm trying to simulate a tree my first idea was to use spring/mass system to create soft body of the plant, problem with that approach was how to connect branches together without 1000's of springs

Secound attempt was to build system from rigid bodies , costraints + springs to give elsticity to joints... at the moment I've finished my litle construction,but it becomes unstable when frame rate drops to 40 fps and I haven't yet implemented springs into it...

any sugestions how to simulate complex plant like tree with 4 levels and 100 branches ?

thx

Hi,

Depend on the quality you want to achieve, stiff springs mean stiff equations and you better try implicit integration.

1000 springs are easily handled by an implicit solver even using time steps on the order of 1/50.

You can use rotational springs instead of simple linear springs for your constraints.

BTW: You say that no springs are included in your simulator, so what you mean by 'it becomes unstable when frame rate drops to 40 fps'?

Regards,

Carlo Lanzotti

Statistics: Posted by clanzotti — Tue Nov 15, 2005 1:17 pm

Physics of Plant

2005-11-10T22:32:02+00:00

Hi,

I'm trying to simulate a tree my first idea was to use spring/mass system to create soft body of the plant, problem with that approach was how to connect branches together without 1000's of springs

Secound attempt was to build system from rigid bodies , costraints + springs to give elsticity to joints... at the moment I've finished my litle construction,but it becomes unstable when frame rate drops to 40 fps and I haven't yet implemented springs into it...

any sugestions how to simulate complex plant like tree with 4 levels and 100 branches ?

thx

Statistics: Posted by Janusz — Thu Nov 10, 2005 10:32 pm