Real-Time Physics Simulation Forum

Re: driving game

2011-12-13T20:35:19+00:00

Hi,

The normals, positions and indices I used came from the collision mesh for my road.

There's a lot of work not really mentioned in my article: you need to implement a btStridingMeshInterface class to provide the normals, implement ray-cast callbacks, and the vehicle ray-caster to override the wheel casts.

I haven't got my original code to refer to any more, and it's been quite a while since I've looked at it, but I've updated the code in my article to indicate the general idea. I haven't tested it though.

The article's here: http://bit.ly/tmC4nG

Cheers,

Kester

Statistics: Posted by kester — Tue Dec 13, 2011 8:35 pm

Re: driving game

2011-11-30T12:53:33+00:00

I am trying to implement "interpolate normals" in my racing game. As per Kester's document of interpolate normals, i am not able to figure out which normals,positions and indices are used in InterpolateMeshNormal method. Please give your valuable suggestions...

Regards
huRRc@ne

Statistics: Posted by hurricane — Wed Nov 30, 2011 12:53 pm

Re: driving game

2010-06-10T01:06:36+00:00

Bullet sets the wheel contact normal in btVehicleRaycaster::castRay.

I derive from btVehicleRaycaster and override that method ...
How do you determine which vertices to use?
I assume the data must be somewhere in either the btRigidBody or the btVehicleRaycasterResult ?
Generally, since the vehicles are heavy & slow-moving, perhaps you'll get better result using rigid body wheels instead of ray cast.
In my own experiments, rigid body wheels have quite big advantages over raycast in terms of being realistic. But since things usually breaks apart physics-wise at high speed (rotations) and require more processing power, raycast usually is better suited for racing-type games... But your choice of vehicles implies that this is not racing

true. But processor power IS a concern. Hence, we're trying raycast vehicles first.

@kester: Thanks! That triangle index is what I was looking for.

Statistics: Posted by dakffyd — Thu Jun 10, 2010 1:06 am

Re: driving game

2010-06-09T09:57:35+00:00

Bullet sets the wheel contact normal in btVehicleRaycaster::castRay.

I derive from btVehicleRaycaster and override that method ...
How do you determine which vertices to use?
I assume the data must be somewhere in either the btRigidBody or the btVehicleRaycasterResult ?

Generally, since the vehicles are heavy & slow-moving, perhaps you'll get better result using rigid body wheels instead of ray cast.
In my own experiments, rigid body wheels have quite big advantages over raycast in terms of being realistic. But since things usually breaks apart physics-wise at high speed (rotations) and require more processing power, raycast usually is better suited for racing-type games... But your choice of vehicles implies that this is not racing

Statistics: Posted by tatsujin — Wed Jun 09, 2010 9:57 am

Re: driving game

2010-06-09T03:30:03+00:00

castRay performs a ray-cast, which returns the triangle index, part id, collision object, and hit position of the end of the ray.

You can use the triangle index to work out which vertices form the hit triangle.

Statistics: Posted by kester — Wed Jun 09, 2010 3:30 am

Re: driving game

2010-06-09T01:19:59+00:00

Bullet sets the wheel contact normal in btVehicleRaycaster::castRay.

I derive from btVehicleRaycaster and override that method ...

How do you determine which vertices to use?
I assume the data must be somewhere in either the btRigidBody or the btVehicleRaycasterResult ?

Statistics: Posted by dakffyd — Wed Jun 09, 2010 1:19 am

Re: driving game

2010-06-08T21:28:00+00:00

I'm trying to create realistic simulations of very large and heavy vehicles - bulldozers, dump trucks, etc. Masses of 35 000 kg or so. I've had to bump up the max suspension force, and I've got a couple questions.
A) are there any repercussion for bumping this limit way higher?
B) are there any other limits I might run into?
thanks.....

Statistics: Posted by dakffyd — Tue Jun 08, 2010 9:28 pm

Re: driving game

2009-12-10T07:05:32+00:00

Btw, I created an enhancement "issue" for having support for normals in the collision shape(s).

Statistics: Posted by tatsujin — Thu Dec 10, 2009 7:05 am

Re: driving game

2009-11-09T08:10:00+00:00

I think you'd only want to add it to the 'mesh' shapes: the bvh tri mesh shape, and the heightfield terrain shape.

Yeah, and it's probably only useful for ray cast vehicle-type things.

Statistics: Posted by tatsujin — Mon Nov 09, 2009 8:10 am

Re: driving game

2009-11-09T05:16:29+00:00

It's good to hear that it's working!

Adding it by default to Bullet probably requires some quite invasive changes. It's quite a bit of work just for vehicle simulation. I think you'd only want to add it to the 'mesh' shapes: the bvh tri mesh shape, and the heightfield terrain shape.

Statistics: Posted by kester — Mon Nov 09, 2009 5:16 am