# Question about Force

I am working on a car and I am testing it on a terrain with mountains “To test how it moves on upper and lower hills you know like a normal car”.

However the car when on the terrain will begin to jitter like if it was driving on a bunch of small rocks.

Any one know whats happening?

is the car set to cube bounds, and the terrain set to triangle mesh?

Things you could try:

-Under the physics tab of the car, set Form Factor to 0.

-Under the World tab, under Physics Steps, set Sub-steps to 3 or 4 (5 is usually more than enough)

The BGE physics often acts unstable under default settings. There are a lot of different settings that affect physics – play around with them until you get the results you want.

If you’re still stuck, post your blend file and one of us can look into it in more depth.

I don’t know if it is still present but in bullet physics there was a but with triangle <> triangle collisions that caused the objects to constantly collide and drift.
Have you tried changing the car collision to something else like box?

Sadly none of the advice work and the first question everything was set to defaults.

Im kinda losing hope on Force when it comes to making a car mechanic movement based what is the best way to do this aside from Force?

ok, I use rays from each corner, and apply impulse based on the rays and Dampening on Z axis etc,

I’ll try and make a physics car again…

One issue, is if your moving very fast, shapes will clip through meshes if they hit them,

so ‘Ray riding’ means you lock the cars position using raycasts, one issue is the raycast should really come from above the car, through the car and into the terrain, (in case you fall through)…

To fix this, they use “Decompose”= (breaking triangle meshes into many convex hulls or solid bounds)

it’s in the more recent builds of bullet, but we are on a old version of bullet in the BGE.

after about 30 minutes of tinkering and thinking

Edit: work so far is now in a thread in resources - Ray Rider

### Attachments

RayRider3.blend (597 KB)

Hello and thank you for the demo I saw what you did with your car and there were some similarities to mine the way you used the shape and placed it.

Your tutorial is very interesting I learned a few things the thing you did with the wheels is something I actually animated on my car along with landing and the way the cars body bounces but animations in some cases can be tricky.

I did manage to fix the cars problem with force so it works but still buggy however your tutorial did show me some new tricks.

Thank you Blue your great and you did not have to put so much effort on your tutorial but I appreciate it so much dude.