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So i am in the process of finishing a successor to AChassis. ive been using really Hi polygonal spheres to use at collision for the wheels. this also includes the vehicle traction being calculated on that sphere. but to optimize the poly count i wanted to put a tire around the wheel. so with a lower polygon count as well.
On the left you see what i did in regards of wrapping the wheel with a low poly tyre.
on the right you see what i have originally. The left one doesnt get up to speed and the wheels are bumpy as hell. luckily suspension is done right to compensate but it gets worse IF you could reach high speeds up to 300km/u as that is the speed barrier i set.
So why is there such a big difference in traction? does someone have a wrap for my wheels that have a good grip etc? I tried rubber too., but i use a 1,1,1,1,1 custom properties for the grip and stuff. not rubber as it makes the car a bit toooo… hm… shaky i guess.
First off you should change your post title, it could get reported and taken down.
Don’t use MeshParts for wheels, use transparent Roblox Cylinders and weld your wheel meshes to them.
I’m pretty sure I read in really old posts that Roblox’s Cylinders and Balls have a very good physical round shape that works well for wheels.
Meshparts are physically flat faceted cylinders so they bounce around.
For my wheels I usually make the CustomPhysicalProperties Density about 1.5 and the Friction about 1.5. You’ll have to tune it to your car’s handling properties though. You could reduce the Elasticity of the wheel as well so it doesn’t bounce against other surfaces.
This is a bit hard to visualize for me. If you make the mesh a high enough resolution and make the collisions accurate, wouldn’t it be less flat than a Roblox primitive?
Roblox cylinders are already pretty low resolution, so I don’t understand how making it a part solves the problem. Is poly count just part of the story?
In terms of collision, what you see is not what you get. Same applies for default parts too. The sphere and cylinder may look very low-poly, but since they’re embedded to the engine, they have perfect collision.
I meant Grip* sorry i was just blown away. im about to read this discussion. for me it also is a theoretical problem which i find important. maybe you can give me leads on a better title? anyone, really… Engine Geometry theories.
also. youre right. but im testing this and im blown away really because it wont make sense. why are roblox’s spheres actual spheres? what makes the infinity possible to calculate? isnt there a resolution on any geometry?
and as the last. i use the same density but i use less friction. just 1 seems fine. youre even using them over the value of rubber roblox material, which i find really clunky and feels unsatifying. im playing a game after all.
This seems reasonable. honestly. but what makes something perfectly circular? in any dimension it seems it will still have to be measured by unit. which means something rather then nothing. if nothingness would be infinite. yes you could say infinite geomtry is impossible. but on the other hand. what does math say? because it cannot be less then 0.000…to the infinite 1… where the tire is practically useless unless you increase friction a whole lot. and the hi res sphere was working pretty good as base value. but has to many triangles. what would be ideal?
And if i visualize a flat sided cylinder i can say that if mass is high enough , that makes the wheel touch the ground. and the geomtry will follow. maybe a few more or less bumps. but as soon as we drive fast enough and are also in proportion to the physical world really big and will not notice these bumps.
so i increase mass then?
Edit: Im sorry i see i gave myself reason. i know what to do. but i will continue to think about it and post here.
PS. I was tripping my eyes out. so uhm ignore some 8head stuff im writing. sorry and thanks
Like I said, I’m sure I read that the physical shape of cylinders and balls were calculated as round. There’s probably a tipping point of how many faces a cylinder has before it’ll bounce while rolling at a certain speed.
The Part Shape documentation states why Balls can be used as wheels. I’ve never had an issue with Cylinders as wheels, but I generally don’t build high speed vehicles, more suspension related slower vehicles. I do know that using Unions or MeshParts for wheels gives a real bumpy vehicle (although treaded MeshPart wheels are great for rock crawler type vehicles because they have rougher surfaces for better traction over rough terrain or parts.
I jusat tested them both in multiple situation, having cylinders is a stupid idea if you want the car to be able to drive onto higher platforms in an angle. round speheres then. using primitive i get like 5x less effect on what properties the tire sphere has. so the car will slide while turning and stuff. it looks like Achassis uses primitives and i feel the same way when i use that rig. so then i tested it all with the high fidellity spheres (i have no clue what the resolution is tho, its high. maybe like 500.)and they just offer the most realistic driving mechanics. '(also a cylinder makes the the car be unstable all the time while turning at 1m/h, it will jiggle because turning on a flat face is stupid if you could have a sphere where 1 point only touches the groundm, but still it acts more like real life). So my decision was to keep the spheres i had.
Even with tweaking the whole rig (with primitive cylinders) as in torque and grip and stuff was just not doing what i wanted. or it glitched out or it simply was jiggling all the time even with high spring stiffness in suspension.
I recommend a high fidelity sphere. in ROBLOX at least.
Thanks for helping me think about it and stuff. nicely done!
One last thing, collision is done on the server. i think its really important to have as little as possible active collision handling. so using a cylinder, as i said will use flat faces (big data compared) to detect collision. the debugger in roblox was simply showing me red boxes (this means its heavy for the server) but with the high fidelity sphers. this went from red to grean and yellow at most. the server was really responsive even if there were like 25 cars spread out over the map that had to be calculated for collisions to not break reality. so i guess we figured it all out. even what is most optimzed
Sorry that i debunked the story about the primitives. if you want. you can request me to make a video about it and ill explain and show what is happening. theres a choice you must make. because primitives are performant. but not really with collisions, then high poly spheres give better realistic results. however they have lots of polygons, but are more performant in collisions. which i think you must do because if you minimize what the server does. your game runs smooth
No worries.
I’d never had much of an issue with cylinders, but then again I’m not running higher speeds.
Instead of high poly spheres could you use a more tire shaped cylinder by slicing the sphere into 1/4 it’s total width (or whatever works)?
Basically make it only a few tris wide, but lots in the circumference.
It might help out with collision calculations of each tire.
very smart, however i really have no clue how to handle vertices. Im bad at modelling and I have no clue what buttons to use in blender. if you do this tho, I would love to sample it too.
Since its a sphere in my case. maybe having 1 hi poly line, would be enough to have the same effect. in theory the sphere only touched on the middle " line"
That’s what I was thinking with lots of tris just in the center circumference.
Cutting a high poly sphere (ICO I think) is like a map of the earth which has loops of parallel edges (latitude) and loops of edges between the poles (longitude).
You could create a sphere with hundreds of latitude edges, but only 4 or 8 longitude edges. Then you could delete the outer pole end face loops then select the ring of edges that are open and click F to make them a single face.
The other option would be to create a torus with the same type of structure and then delete all the interior faces and make a face with the edges that are open.
You get exactly what i want, if you would, could you maybe make those, with different stats, so more or less round ones? if this works. that deletes a lot of issues for me like using a cylinder as wheels also happens to not give you enough manouvrability when it comes to ledges and rocks. In theory this 1d model might fix this and still give me enough traction.
I actually made higher traction wheels for slow moving vehicles using deep grooved MeshPart wheels.
You can see the actual shapes of Meshes and Unions by clicking on the ShowDecompostionGeometry tool in the Studio Settings.
I make my wheels heavier than the rest of the vehicle, with more Friction to get better traction.
