[Solved] problem with the wheels

[MysticCat]

Please help me! It's my first conversion and I just need to fix this, the front wheels of my vehicle are skidding and it's very difficult to drive, it feels like it's sliding, in addition to the suspension being very low on the rear wheels.

[MysticCat]

https://youtu.be/issCxSaRR7o

[Oleg]

it looks like you have bad physics data on a model. Make sure to assign some-what real "Mass" values on COL objects. Also, the local axes of every COL object is the center of mass - you might need to move axes lower for chassis and slightly toward the front part. It looks like center of mass is right above the rear wheels or even behind them.

[MysticCat]

it looks like you have bad physics data on a model. Make sure to assign some-what real "Mass" values on COL objects. Also, the local axes of every COL object is the center of mass - you might need to move axes lower for chassis and slightly toward the front part. It looks like center of mass is right above the rear wheels or even behind them.

thank you for your attention! but can you tell me where I can change the center of mass? and in which pieces exactly should I change the center of mass?

[Oleg]

attach a screenshot of Left viewport with "COL" state toggled on (and L0/L1... togged off), so only collision objects are visible in viewport.

object's axes are moved with "Move" tool. You need to toggle an option "Move axes only" before moving.

[MysticCat]

attach a screenshot of Left viewport with "COL" state toggled on (and L0/L1... togged off), so only collision objects are visible in viewport.

object's axes are moved with "Move" tool. You need to toggle an option "Move axes only" before moving.

Here

[Oleg]

Move entire scene (geometry, collisions and dummies) to the right and a bit up. You can move just root dummy node with Move tool and "Affect children" option toggled on. You can select this node in hierarchy view with Alt+click on visibility icon. To move "pre-selected" objects, disable automatic selection ("Auto" button in the bottom of ZM window) and enable "Selected" button so the "Move" tool will act on selected element rather than on hovered element.

Once you move entire scene this use "Display\local axes\Reset to world" tool on main scene dummy node (hide everything except this dummy to be able to click on it); and apply to "chassis" object too.

Then use Move tool in "Move axes only" to move chassis' collision local axes to green/blue point like on this scheme:

[MysticCat]

Move entire scene (geometry, collisions and dummies) to the right and a bit up. You can move just root dummy node with Move tool and "Affect children" option toggled on. You can select this node in hierarchy view with Alt+click on visibility icon. To move "pre-selected" objects, disable automatic selection ("Auto" button in the bottom of ZM window) and enable "Selected" button so the "Move" tool will act on selected element rather than on hovered element.

Once you move entire scene this use "Display\local axes\Reset to world" tool on main scene dummy node (hide everything except this dummy to be able to click on it); and apply to "chassis" object too.

Then use Move tool in "Move axes only" to move chassis' collision local axes to green/blue point like on this scheme:
Screenshot 2023-11-21 011258.png

like this?

[MysticCat]

Move entire scene (geometry, collisions and dummies) to the right and a bit up. You can move just root dummy node with Move tool and "Affect children" option toggled on. You can select this node in hierarchy view with Alt+click on visibility icon. To move "pre-selected" objects, disable automatic selection ("Auto" button in the bottom of ZM window) and enable "Selected" button so the "Move" tool will act on selected element rather than on hovered element.

Once you move entire scene this use "Display\local axes\Reset to world" tool on main scene dummy node (hide everything except this dummy to be able to click on it); and apply to "chassis" object too.

Then use Move tool in "Move axes only" to move chassis' collision local axes to green/blue point like on this scheme:
Screenshot 2023-11-21 011258.png

or this

[Oleg]

none of that. entire scene (L0 models and collisions, everything) should be moved. then "reset axes" on main dummy node and chassis object.

[MysticCat]

none of that. entire scene (L0 models and collisions, everything) should be moved. then "reset axes" on main dummy node and chassis object.

The dummy would be the chassis_dummy, right?

[Oleg]

no. the hierarchy's topmost element. it should have a model's name (or model's name with "_hi" on the end). "chassis" is a child of this node. So, this root node and "chassis" should have local axes at 0,0,0 point ("Reset to world" tool does this).

The object shown as primitive (has no geometry) is called a "dummy node" in ZModeler. By default, it is a blue box shape, but can have different shape/size/color (adjusted in properties).

[MysticCat]

no. the hierarchy's topmost element. it should have a model's name (or model's name with "_hi" on the end). "chassis" is a child of this node. So, this root node and "chassis" should have local axes at 0,0,0 point ("Reset to world" tool does this).

The object shown as primitive (has no geometry) is called a "dummy node" in ZModeler. By default, it is a blue box shape, but can have different shape/size/color (adjusted in properties).

Okay, I've already moved the entire scene and reset the node and the chassis, so what can I do?

I even went to test it after that, and the wheel error was reversed, the front is now normal and the rear is bugged lmao

[Oleg]

Hmmm... may be you've moved way too far.
Also, what is the Mass value in user-defined options on chassis[COL] object?

[MysticCat]

Hmmm... may be you've moved way too far.
Also, what is the Mass value in user-defined options on chassis[COL] object?

[MysticCat]

Hmmm... may be you've moved way too far.
Also, what is the Mass value in user-defined options on chassis[COL] object?

here

and it wasn't because I moved it too far, I think, I tried to fix it by moving it a little down and forward but it still looked like this

[Oleg]

have you tried to load original bus model to compare scene position to yours? and to compare physics values (Mass, E) ?

[MysticCat]

have you tried to load original bus model to compare scene position to yours? and to compare physics values (Mass, E) ?

Bro, when I went to convert my bus, I simply dragged what I wanted to convert to the same position as the bus in the original game, because what I was going to convert was in a higher position

[Oleg]

I think your converted bus should be somewhat similar in position relative to original bus. Vertical position of entire scene could have impact on physics in game. That is why following the guideline of original bus is suggested.

[MysticCat]

I think your converted bus should be somewhat similar in position relative to original bus. Vertical position of entire scene could have impact on physics in game. That is why following the guideline of original bus is suggested.

But I did that, but it's giving me this error that I can't fix

[Oleg]

I don't have any exact solution for this issue, it's all up to trial and error. I think you should start from loading and exporting original bus with no changes to see whether it's physics/handling behaves properly or has the same issue as your own model.

If everything is fine, start porting your model into the game based on original bus model by replacing individual parts. Do not reposition objects and don't touch anything in [COL] objects at all. Once you port geometry, adjust collisions to match your new bus model.

[Oleg]

the issue might be related to some collision bumping out of the bus to the ground, so bus "skids" on road with this collision object instead of riding on wheels. in particular, you can make some light poles and road signs to fall onto the ground and try to push them with some vehicle under the bus to see whether these objects pass through or stuck.

[MysticCat]

I think your converted bus should be somewhat similar in position relative to original bus. Vertical position of entire scene could have impact on physics in game. That is why following the guideline of original bus is suggested.

Update: the bus has now stopped skidding, after I moved it a little further forward, now I just need to lower the suspension at the front a little because it looks strange on this type of bus, and I couldn't figure out how to solve it at all, but the physics is good

[MysticCat]

the issue might be related to some collision bumping out of the bus to the ground, so bus "skids" on road with this collision object instead of riding on wheels. in particular, you can make some light poles and road signs to fall onto the ground and try to push them with some vehicle under the bus to see whether these objects pass through or stuck.

Thanks for all your help and patience brother! the physics are now good. I just want to see how I can lower this suspension a little

[Oleg]

it might be some axes issue too. as a temporary fix, you can move front wheels (and their collisions) a bit up.