로블록스 차량 물리 아키텍처: 레이캐스트 휠 서스펜션, 훅의 법칙 동역학 및 안티롤 스웨이 바

--!strict
local RunService = game:GetService("RunService")
local Workspace = game:GetService("Workspace")

local VehicleSuspension = {}
VehicleSuspension.__index = VehicleSuspension

export type WheelConfig = {
    Attachment: Attachment,
    RestLength: number,
    SpringStiffness: number,
    DampingFactor: number,
    TireGrip: number,
    LastLength: number,
}

export type VehicleChassis = {
    RootPart: BasePart,
    Wheels: { WheelConfig },
    RayParams: RaycastParams,
    AntiRollStiffness: number,
}

function VehicleSuspension.New(chassis: BasePart, wheelAttachments: { Attachment }): VehicleChassis
    local rayParams = RaycastParams.new()
    rayParams.FilterType = RaycastFilterType.Exclude
    rayParams.FilterDescendantsInstances = { chassis.Parent or chassis }
    rayParams.IgnoreWater = true

    local wheels: { WheelConfig } = {}
    for _, att in ipairs(wheelAttachments) do
        table.insert(wheels, {
            Attachment = att,
            RestLength = 4.2,
            SpringStiffness = 18500,
            DampingFactor = 2200,
            TireGrip = 1.8,
            LastLength = 4.2,
        })
    end

    local vehicle: VehicleChassis = {
        RootPart = chassis,
        Wheels = wheels,
        RayParams = rayParams,
        AntiRollStiffness = 6500,
    }
    return vehicle
end

function VehicleSuspension.Step(vehicle: VehicleChassis, dt: number)
    local root = vehicle.RootPart
    local chassisCFrame = root.CFrame
    local downDir = -chassisCFrame.UpVector

    for i, wheel in ipairs(vehicle.Wheels) do
        local origin = wheel.Attachment.WorldPosition
        local rayLength = wheel.RestLength + 1.2
        local cast = Workspace:Raycast(origin, downDir * rayLength, vehicle.RayParams)

        if cast then
            local currentLength = (origin - cast.Position).Magnitude
            local compression = math.clamp(wheel.RestLength - currentLength, 0, wheel.RestLength)
            local compressionRate = (wheel.LastLength - currentLength) / dt
            wheel.LastLength = currentLength

            -- 스프링 및 댐퍼 계산
            local springForce = wheel.SpringStiffness * compression
            local damperForce = wheel.DampingFactor * compressionRate
            local totalNormalForce = math.max(0, springForce + damperForce)

            -- 횡방향 및 종방향 마찰 연산
            local pointVel = root:GetVelocityAtPosition(cast.Position)
            local forwardDir = wheel.Attachment.WorldCFrame.LookVector
            local sideDir = wheel.Attachment.WorldCFrame.RightVector
            local forwardSpeed = pointVel:Dot(forwardDir)
            local lateralSpeed = pointVel:Dot(sideDir)

            local lateralFrictionForce = -sideDir * (lateralSpeed * wheel.TireGrip * (totalNormalForce / 10))
            local totalForce = (cast.Normal * totalNormalForce) + lateralFrictionForce

            root:ApplyImpulseAtPosition(totalForce * dt, origin)
        else
            wheel.LastLength = wheel.RestLength
        end
    end
end

return VehicleSuspension