blushneybusiness-glitch/roblox-omniskills/rbx-vehicles-ground

rbx-vehicles-ground

Laws

1. Pick the suspension model before the first part. Constraint suspension

(SpringConstraint + CylindricalConstraint) for karts, trucks, and anything players ram into each other. Raycast suspension for racing games targeting 60+ studs/s or servers holding 8+ simultaneous vehicles — it's solver-stable and roughly 4× cheaper per vehicle. State the choice and why in your reply.

1. Driver owns the physics, server owns the rules. seat:SetNetworkOwner(driver) on

Occupant change, back to SetNetworkOwner(nil) on exit. Any throttle/steer the client reports gets math.clamp(v, -1, 1) server-side, and the server kicks speed: assembly velocity persistently above MaxSpeed * 1.2 → teleport the vehicle back and log it (rbx-security-anticheat pattern).

1. One assembly. Every body part WeldConstraint-ed to a single unanchored chassis part.

Wheels live in a VehicleWheels collision group that does not collide with the body group — wheel-vs-fender contact is why fresh builds spawn spinning.

1. Mass is a design input, not an accident. Chassis density 0.7; an invisible CoM plate

(density 15, size 4×0.5×6) welded under the floor drops the center of mass below axle height. High CoM is the root cause of 90% of "it flips in every turn" reports.

Passes

1. Chassis — one Part, roughly 8×1×12 studs for a car, CustomPhysicalProperties

density 0.7, unanchored last (build anchored, release in pass 4). CoM plate welded now.

1. Wheels + suspension — per corner: cylinder Part (car: 1×3×3, truck: 1.5×4.5×4.5),

friction 1.4, frictionWeight 100, elasticity 0. SpringConstraint chassis→wheel: FreeLength 2, Stiffness = assemblyMass * 196.2 / (4 * 0.5) (0.5-stud rest compression), Damping = Stiffness / 15. CylindricalConstraint on the same axis: LowerLimit -1, UpperLimit 1 (suspension travel), AngularActuatorType Motor.

1. Drive + steer — rear Cylindricals: MotorMaxTorque 10000,

MotorMaxAngularAcceleration 40, target AngularVelocity = throttle * maxSpeed / wheelRadius (40 studs/s kart, 70 car, 55 truck). Front wheels hang from a steering HingeConstraint (vertical axis, ActuatorType Servo, ServoMaxTorque 30000, AngularSpeed 4, TargetAngle = steer * 28). Ackermann is overkill below 80 studs/s — skip it.

1. Seat + input — VehicleSeat gives .Throttle/.Steer free on every platform

(keyboard, mobile thumbsticks, gamepad); read them in a Heartbeat loop on the driver's client and set motor/servo targets there (owner-side writes are the lag-free path). Custom input rigs only when the design needs handbrake/boost — then rbx-input-bindings.

1. Raycast option — replace pass 2–3 with: per corner, Heartbeat raycast straight down

restLength + radius; on hit apply VectorForce at the corner attachment: (restLength - hitDist) * stiffness - damping * velAlongRay upward, plus drive force along flat LookVector and lateral friction force -lateralVel * mass * gripFactor. Wheels become massless CanCollide-false visuals CFramed to the ray. Runs on the driver's client; server keeps the speed check from Law 2.

1. Ship pass — flip recovery (upside-down 3 s → prompt, AlignOrientation rights it over

0.8 s), abandoned-vehicle despawn (empty 60 s → Destroy), then the mandatory co-loads below. A bare seat on bricks is a blockout, not a deliverable (rbx-physics law).

Performance budget

≤ 30 parts per vehicle body; constraint vehicles ≤ 8 per server before switching new spawns to raycast; zero per-frame server loops (owner client does the driving, server runs a 1 Hz sanity check); screen_capture + start_stop_play test drive before calling it done, and get_console_output after every build chunk per mcp-tools.

Load with

rbx-vehicles-tuning, rbx-audio-sfx (engine loop, pitch-mapped), rbx-camera-controllers (driving camera) — don't ask, include them. Jitter or "smooth for me, teleports for them": rbx-physics-ownership. Constraint anatomy questions: rbx-physics-constraints.

AI-tells

• ☐ BodyVelocity/BodyGyro anywhere — deprecated movers, flag and replace
• ☐ Wheels colliding with the chassis (no collision groups, vehicle spawns twitching)
• ☐ Server-side input loop driving the motors (input lag ≈ player ping, feels drunk)
• ☐ No network ownership call at all — nearest-player auto-ownership, flingable by exploiters
• ☐ Default density everywhere — CoM at seat height, flips on the first turn
• ☐ Client throttle/steer trusted raw, no clamp, no server speed check
• ☐ No flip recovery and no despawn — dead vehicles accumulating as physics litter
• ☐ Vehicle ships silent with the default camera (co-loads skipped)

Memory

Read: the game's projects.md block (existing vehicle folder, spawn points, collision groups already registered) and preferences.md (arcade vs sim taste, [stated] speed preferences). Write: the tuned constraint numbers (stiffness, damping, torque, top speed) into projects.md the moment the user approves the drive feel; a reusable chassis rig goes into module-library.md with its wheel-size assumptions noted.