vehicles

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Re: vehicles

Postby Julio Jerez » Tue Oct 30, 2018 1:53 pm

Oh very good point Dave.
so the file format is free but the software is not. and I need to be able to distribute the library, so much for FBX.
I se that engine like Unreal do distribute it, but the probable has permission form Autodesk, with the animosity about the Newton Engine I can not take that chance, therefore I deleting all references to FBX.
I guess that the only option left is the GLFP, I will take a look.

about the car on a Terrain I just place in the simple height field, It seems the tire think a little on eh retrain by I belie this is just visual, when I drive around I do not see the tire load flipping when is goes over edges, but I did not drive much.

I do see bumps but I believe is the chassis hit the ground because the vehicle is really low, for this test is better to use the monster truck which ha more clearance over the ground.

which bring me back to the file format, at the point we nee a way to try different mesh so I will check out that GLFP thong and see if is a good, I am no longer using any proprietary files like the NGD because it make the demos harder to use for people, and is also harder to try different assets.

can you try the demo again on the terrain Dave? see if you find flaw that need to be fix before moving on to add the Drive Train, remember the vehicle is for driving on smooth surfaces, so body will bump the ground.
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Re: vehicles

Postby Dave Gravel » Tue Oct 30, 2018 2:02 pm

I can test it more yes, and start to add it in my project too.
I let's you know later how it going.
I have take some days brake for install water cooling on my pc and I have take times to test it hehe... :D

Edited:
I have test the new demo with terrain and it seen to work very good.
If the problem is present it don't seen to affect the vehicle so much.
The terrain mesh is not perfect and the tire seen to roll over very good.

I start to add it in my project and I see later how it going over mesh like loop or jump.

Thanks.
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Re: vehicles

Postby Julio Jerez » Tue Oct 30, 2018 2:48 pm

easy, easy, my friend. :mrgreen: :mrgreen:

this is just the beginning, the vehicle now is just costing,
wait until we start plugin the vehicle dynamics other forces:
Downforce, and drive train :mrgreen: :roll: 8) :D :lol:
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Re: vehicles

Postby Julio Jerez » Tue Oct 30, 2018 3:52 pm

wow Dave, you are right and I drove a little and is feel really nice to drive, even if it goer slow
but you can see that is does all eh thong that vehicle do when driving this kind of terrains.

and there are no cheat of any kind, the only hack I am adding is that I am applying a fix speed to the rear wheel because there is not engine yet. but if anything this will work against the realism,
this is giving me high hopes. :mrgreen: :twisted: 8) :D :shock: :P :idea:

Melting Plastic if you are following this please try it out and tell me what you think so far.
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Re: vehicles

Postby arpio » Tue Oct 30, 2018 7:02 pm

This vehicle is why I stopped at ND now. And if you decide for GLTF would be even better. At least for me. :D
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Re: vehicles

Postby Julio Jerez » Tue Oct 30, 2018 8:07 pm

Yes the file format is important to deal with the coordinate system more easy.
Is there some open source loader for GLFT?
I went to the site and what the have is a specification no code, or anything, or at least is not clear how to get code for a basic loader.
https://github.com/KhronosGroup/glTF
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Re: vehicles

Postby arpio » Tue Oct 30, 2018 9:11 pm

https://github.com/syoyo/tinygltf
And here a nice example https://github.com/SaschaWillems/Vulkan-glTF-PBR
Well, it's for vulkan but that's what I'm looking for.
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Re: vehicles

Postby MeltingPlastic » Wed Oct 31, 2018 12:09 am

I just tried the Vehicle Demo - I didn't see any jumps on the terrain! I also love seeing how you start to spin out when going up a large hill.
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Re: vehicles

Postby Julio Jerez » Wed Oct 31, 2018 11:25 am

wait until we add the four wheel drive differentials with wheel lock.
imagine an off road vehicle, set to rear wheel drive, for more maneubrability, but in a situation like that engage the front differential and bandabing badaboom....
differentials will also have configurable slip control too.
for now my bigger concern is handling without cheats, everything I expect to emerge from the physical model.

one such behavior, is the well known fact that, car with rear wheel traction are more maneuverable than front wheel drive cars given everything equal.
this is why race car are all, as far as I know rear wheel cars, but in video games, in particular physics engine vehicle model are so bad that it is the opposite, they are either front or four wheel drive.
and I do not accept that.
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Re: vehicles

Postby MeltingPlastic » Wed Oct 31, 2018 3:26 pm

I'm Getting some weird behavior with the tires. I am making a chassis and adding onetire somewhere in the bounds of the chassis.

https://www.youtube.com/watch?v=Ma_fzu0iFww&feature=youtu.be

im using these values for tireInfo:
Code: Select all
        tireInfo_->m_mass = 40.0f;
        tireInfo_->m_radio = 0.5f;
        tireInfo_->m_width = 0.25f;

        tireInfo_->m_pivotOffset = 0.01f;
        tireInfo_->m_steerRate = 0.5f * dPi;
        tireInfo_->m_frictionCoefficient = 0.8f;
        tireInfo_->m_maxSteeringAngle = 20.0f * dDegreeToRad;

        tireInfo_->m_suspensionLength = 0.22f;
        tireInfo_->m_dampingRatio = 15.0f * 100.0f/*vehicleMass*/;
        tireInfo_->m_springStiffness = dAbs(100.0f/*vehicleMass*/ * -9.81f * 8.0f / tireInfo_->m_suspensionLength);

        tireInfo_->m_corneringStiffness = dAbs(100.0f/*vehicleMass*/ * -9.81f * 1.0f);
        tireInfo_->m_longitudinalStiffness = dAbs(100.0f/*vehicleMass*/ * -9.81f * 1.0f);


BTW - It might be nice if tireInfo was instantiated with some generic values from a API simplification/ ease of integration point of view.
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Re: vehicles

Postby Julio Jerez » Wed Oct 31, 2018 4:03 pm

the tire location is global space.

in the info, do you mean initializing it to some default values instead of zero?
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Re: vehicles

Postby MeltingPlastic » Wed Oct 31, 2018 4:22 pm

Yes - I add the tire in global space.

in the info, do you mean initializing it to some default values instead of zero?

yes
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Re: vehicles

Postby Julio Jerez » Wed Oct 31, 2018 5:15 pm

ok that's a good idea yes,

what is the mass of the vehicle? in the demo is 1000.00
also the gravity is -10.0
that's -9.8 but for simplify debugging I use a round number
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Re: vehicles

Postby MeltingPlastic » Wed Oct 31, 2018 5:43 pm

Aha! Yes the body mass was only like 1-2.. setting it to 100ish stabalizes it and I am seeing some suspension action!
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Re: vehicles

Postby MeltingPlastic » Wed Oct 31, 2018 5:51 pm

Is this function:
Code: Select all
dVehicleTireInterface* dVehicleChassis::AddTire (const dMatrix& locationInGlobalSpace, const dVehicleTireInterface::dTireInfo& tireInfo)


Is location the only thing used from locationInGlobalSpace or is the rotation component used for something like suspension angle?

I'm assuming its just position as it says.

Edit: looks like rotation is used for tire orientation
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