[ODE] AI steering behaviors using ODE

[STenyaK (Bruno Gonzalez)]

I'm not an expert in physics nor in maths, but assuming your force-related  
code is right, and since torques are the equivalent to forces when it  
comes to rotations, the code should be pretty similar: just replace  
position with angle, velocity with rotational velocity, force with  
torque... i think that should work.

<offtopic>así que un juego de naves espaciales en 3d... será de  
estrategia? O:-)</offtopic>

On Mon, 15 May 2006 17:50:37 +0200, Raul Chaparro  
<raul.chaparro at pyrostudios.com> wrote:

> Hello. I'm new with ODE, just trying to use it to physics needed for a  
> 3D spaceship game. I have a problem about calculating torque of enemy  
> ships. Perhaps my question is more about physics than ODE, but i have  
> this problem since many weeks ago, any help would be appreciated. Thanks.
> The enemy spaceships moves with steering behavior forces. Once force is  
> calculated, physics are updated and ship moves. The problem is that  
> resulting force is applied linearly to the Center of Mass (translation).  
> I don't know if it is possible obtain torque from this initial force,  
> because there is no rotation at CM.
>
> Just now i'm not using rocket engines to get the propulsion of the  
> ships. For example, to calculate force when ship is going towards an  
> enemy, i do:
>
> current velocity = ship.velocity
> desired velocity = target.position - ship.position
> Force = desired velocity - current velocity
>
> I would need to find how to calculate torque based on that Force. If i  
> imagine one engine thrust at the center bottom of the ship, applying
>
> Torque = (CM - point of force application) X Force         (X = cross  
> product)
>
> then i obtain one torque vector that sometimes points in wrong  
> direction, which makes ship's rotation faces away target and not towards  
> target. I am trying that ship's heading always points to right direction  
> while it moves. How can i solve that?
>
> Other solution I've thought is create many thrusters at backwards ship,  
> all controlling torque and lineal force (for example one for each vertex  
> of the bounding box backwards), or one controlling lineal force and the  
> rest controlling only torque, but then, how to calculate the force to  
> apply to each thruster based on Force value?
>
> Again, thanks for your time.
> R.



-- 
Saludos,
     STenyaK

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