| name | roblox-physics |
| description | Constraints, VehicleSeat, ragdoll, projectiles, Attachment patterns, network ownership. |
| last_reviewed | "2026-05-27T00:00:00.000Z" |
| sources | ["https://github.com/Roblox/creator-docs/blob/main/content/en-us/physics/mechanical-constraints.md","https://github.com/Roblox/creator-docs/blob/main/content/en-us/physics/mover-constraints.md"] |
When to Load
Use this skill when building physics-driven gameplay: vehicles, ragdolls, projectiles, mechanical contraptions, elevators, swinging platforms, or anything using constraints and forces.
Quick Reference
Constraint Types
Mechanical: HingeConstraint (doors/wheels), PrismaticConstraint (elevators/pistons), CylindricalConstraint (telescoping), BallSocketConstraint (ragdoll/chains), UniversalConstraint (steering), WeldConstraint/RigidConstraint (rigid attach)
Motion: AlignPosition, AlignOrientation, LinearVelocity, AngularVelocity, VectorForce, Torque
Spring/Rope: SpringConstraint (suspension/trampolines), RopeConstraint (grapple, slack), RodConstraint (rigid link)
Attachment Pattern
All constraints connect via Attachment objects, not Parts directly. Create Attachment on each part, set constraint.Attachment0/Attachment1, parent constraint to part0. Actuator types: None, Motor (constant velocity), Servo (target position/angle).
Vehicles
Wheel = HingeConstraint (ActuatorType.Motor) + SpringConstraint for suspension. Steer = Hinge with ActuatorType.Servo. Rear wheels get throttle AngularVelocity, front wheels get servo TargetAngle. Use CustomPhysicalProperties on wheels for friction tuning.
Ragdoll
Replace Motor6Ds with BallSocketConstraint: create Attachments from motor.C0/C1, set LimitsEnabled=true, UpperAngle=45. Keep Root Motor6D for HRP. Set humanoid state to Physics. Re-enable motors to recover.
Network Ownership
Default: nearest player owns unanchored physics (exploitable!). part:SetNetworkOwner(nil) = server-owned (secure, laggy). part:SetNetworkOwner(player) = player-owned (responsive). Rule: NPCs/world objects → server. Vehicles → driver player. Always set explicitly on important physics objects.
Common Gotchas
- Constraints do nothing on Anchored parts
- Both Attachment0 AND Attachment1 required (missing one = silent fail)
- Over-constraining = jitter. Tune mass with
CustomPhysicalProperties
- Use Raycast for hitscan,
Touched only for slow physics projectiles
- Always set lifetime on physics projectiles (forgotten ones kill perf)
Need more detail? Load
references/full.md for the complete reference with code examples, API tables, and edge cases.
