[ODE] I´m totally unhappy with ODE ... Please Help me

arturapps arturapps at gmail.com
Fri Dec 15 13:47:25 MST 2006

Hi people: 

I´m working on a game that doesn´t need Real time physics  but needs
Trimesh-Trimesh colision Detection . 

The game is a kind  of spaceship race that takes place on a  quite large
enviromment composed of trimeshes.

I´m  experiencing all kind of problems with my collisions : Since false
collisions , until  missed collisions. Sometimes  the near callback is not
triggered even if two trimeshes visually collide.

I examined ODE´s documentation and figured out that  it´s possible to use
just the colision detection capabilitys of ODE.  So my sojtware does not
create the "word"  and any body   for physics  processing. The ODE´s "step"
of simulation is not called.  The software just create the colision space 
and associate   geoms ( trimeshes ) to  the game entitys . 

That´s the way the game works: 

Create collision space
Create Entytys and associated geoms ( trimeshes) 

Call Entity´s IA  // Each entity decide about its next movement and then
modify it´s position and  orientation
modify entity´s geoms // based on entity´s  position and orientation
call colision detection (dSpaceCollide) 

 call dcollide  to get contact points between the colision pair
iinform the entitys associated with the colision geoms , about the colision
//In the next loop the Entity´s IA will do something as colision response

Well ... first of all , I´d like to know if is that aproach correct. IS
there any problem using just colilision detection system  of ode ?

By the way : I´m using  the version of ODE , that uses GIMPACT instead of
OPCODE. I downloaded  this version at :

In second place : I´d like to describe some tests I made to be sure that my
trimeshes and trimesh creation process are correct: 

I  changed the test_moving_trimesh example that comes with the  ODE-Gimpact
project, in order to create the trimeshes from my model file format ,
instead of creating the "bunnys" on the code.  I didn´t changed the way it
does trimesh creation because it was the same way I do it . So I could
notice that my trimesh models work very well . they are displayed correctly
and collyde very well.  So I discarded problems about vertex order or normal

In my software I don´t call dGeomTriMeshSetLastTransform in order to update
temporal coerence for the Geoms. 
I removed all calls of  dGeomTriMeshSetLastTransform from the
test_moving_trimesh example  and than I noticed that it does not afect
colisions , but only the quality of physics simulation. 

So I don´t know what I can do next  in order to understand my problem ? 

Help me please !!!

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