[ODE] move body and encapsulated objects in ODE

rosa777 rana_m_75 at hotmail.com
Tue Apr 17 01:48:45 MST 2007


Hallo,
i have the same problem:-( i want to make Y-Up so i set the gravity like you
said   0,-9.82,0 but nothing chang Z still Up and every thing gravate to
Y-axis....what should i do to change the ODE 's world to right haned so that
i can bind it with opensg!

thanks in advance
Rosa

Jon Watte (ODE) wrote:
> 
> 
> 
> Sharad Gupta wrote:
> 
>> 1) Cordinate system. Do i need to interchange my coordinates. I reason i 
> 
> The coordinate system in ODE is whatever you want it to be. If you set 
> gravity to 0,-9.82,0, then it's Y up, with earth gravity, assuming SI
> units.
> 
>> 2) Since i am using triangulated meshes, do i need to use 
>> boxes/cylinders/spheres etc to build corresponding shape in ODE. My 
> 
> Proxy objects will always perform better (use less CPU) and be more 
> stable. This is true for all physics APIs. Arbitrary, concave, triangle 
> mesh geometries are typically only used for static objects so that you 
> don't get trimesh/trimesh tests, only proxy/trimesh tests.
> 
> This means you probably have to model a separate representation of your 
> objects using proxy objects, and store that in the .X file, or a 
> parallel data file. That's what most games do.
> 
>> 3) How to do setposition of body and its many geoms's? Initially at the 
> 
> Anything that moves with relation to something else is its own body. You 
> connect bodies with joints. The body is always positioned at the center 
> of gravity for that component of the object. Geoms are positioned 
> relative to a body, either using the new geom position functionality, or 
> using the geomtransform geom.
> 
> If a body moves, then the geoms that are attached to the body will move. 
> However, you should not setposition on bodies, as that will introduce 
> instability in the simulation (especially if there are joints or 
> collisions involved). Instead, let ODE run the simulation, and get the 
> position out of ODE.
> 
>> 4) In the ODE text_boxstack example, i could not understand this bit for 
>> composite objects under case 'x';
> 
> The "offset" part of dMass is ignored by bodies; the body-local origin 
> is always the center of gravity.
> 
> Cheers,
> 
> 			/ h+
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> 
> 

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