I found an interesting truck simulator called rigs of rods, in which the chassis for the trucks flex in what looks like a realistic (with some tweeks perhaps), manner, and I was wondering if the following approach might be of some help, seeing as lots of people want karts and they're dependant on decent chassis flex.

here are the source urls:

post by pricorde:

http://www.ogre3d.org/phpBB2/v ... 50b33838bd1fa145b88f62854

rigs of rods:

http://rigsofrods.blogspot.com/

"Yes, a spring array is a good way to model a vehicle, but the springs must be very, very strong so the integrator must run on very small time steps to avoid instabilities. This version uses a simple Euler integrator, with 100 integration steps per frame, and a capping at 20fps (below 20fps, the simulation is not realtime), so the integration steps are never below 1/2000th second (with several hundred nodes to compute)!!! And even with that, the chassis is not as rigid as I would want.

I hope that with a Runge Kutta intergrator it will require less steps per second.

The good news is that the model is extremely simple : I simulate monodimensional beams connected by ball-joint. The consequence is that I do not have to compute anything that has to do with angles (rotational speeds and moments, ...). I just compute nodes movements, and nodes are dimension-less objects. Also I do not compute anything central (center of inertia) and in fact if you split the truck in two, the two parts move independentely and realistically (I have seen impressive wheels run-offs)...

Yet the simulation is realistic : all the rigid body "laws" emerge from the interaction of nodes. You observe that the truck has a center of inertia, moments of intertia, you name it, but it is never explicitely computed.

Since everything is ball-joint, you must triangulate everything, and you can always obtain other joints by contruction (many extra triangulation beams are masked in trucks).

The Beam engine is not opensource, the main reason are that it is a horrible programming mess, and it does not uses a good integrator yet.

It is not vehicule engineering research : it would be too resource consuming to really simulate chassis parts. I intend to add some game logic someday.

I chosed trucks because everybody does cars The initial objective was to do a "truck trial" game :

http://www.europatruck-trial.c ... rie/bildergallerie_l1.php

with an extremely precise terrain map (~10cm resolution) that deforms under the wheels! But I am afraid the polygon count would be tremendeous...

Meshes are deformed manually. Skeletal would be better since it would allow more complex meshes, but it has the wrong topology for a truck (tree vs mesh)."

here are the source urls:

post by pricorde:

http://www.ogre3d.org/phpBB2/v ... 50b33838bd1fa145b88f62854

rigs of rods:

http://rigsofrods.blogspot.com/

"Yes, a spring array is a good way to model a vehicle, but the springs must be very, very strong so the integrator must run on very small time steps to avoid instabilities. This version uses a simple Euler integrator, with 100 integration steps per frame, and a capping at 20fps (below 20fps, the simulation is not realtime), so the integration steps are never below 1/2000th second (with several hundred nodes to compute)!!! And even with that, the chassis is not as rigid as I would want.

I hope that with a Runge Kutta intergrator it will require less steps per second.

The good news is that the model is extremely simple : I simulate monodimensional beams connected by ball-joint. The consequence is that I do not have to compute anything that has to do with angles (rotational speeds and moments, ...). I just compute nodes movements, and nodes are dimension-less objects. Also I do not compute anything central (center of inertia) and in fact if you split the truck in two, the two parts move independentely and realistically (I have seen impressive wheels run-offs)...

Yet the simulation is realistic : all the rigid body "laws" emerge from the interaction of nodes. You observe that the truck has a center of inertia, moments of intertia, you name it, but it is never explicitely computed.

Since everything is ball-joint, you must triangulate everything, and you can always obtain other joints by contruction (many extra triangulation beams are masked in trucks).

The Beam engine is not opensource, the main reason are that it is a horrible programming mess, and it does not uses a good integrator yet.

It is not vehicule engineering research : it would be too resource consuming to really simulate chassis parts. I intend to add some game logic someday.

I chosed trucks because everybody does cars The initial objective was to do a "truck trial" game :

http://www.europatruck-trial.c ... rie/bildergallerie_l1.php

with an extremely precise terrain map (~10cm resolution) that deforms under the wheels! But I am afraid the polygon count would be tremendeous...

Meshes are deformed manually. Skeletal would be better since it would allow more complex meshes, but it has the wrong topology for a truck (tree vs mesh)."