GForce display for each player when sitting in a seat - place this in autorun

gforce.lua

if SERVER then
    hook.Add("PlayerEnteredVehicle", "GForce::EnterVehicle", function(ply, veh)
        ply.gforceLastPos = veh:GetPos()
        ply.gforceLastVel = Vector()
    end)

    hook.Add("PlayerLeaveVehicle", "GForce::ExitVehicle", function(ply, Veh)
        ply.gforceLastPos = nil
        ply.gforceLastVel = nil
    end)

    local gravity = Vector(0, 0, -600)

    hook.Add("InitPostEntity", "GForce::Init", function()
        gravity = physenv.GetGravity() --physenv.GetGravity returns nil if ran too early
    end)

    hook.Add("Tick", "GForce::Tick", function()
        for _, ply in pairs(player.GetHumans()) do
            if ply:GetVehicle() and ply:GetVehicle():IsValid() then
                local veh = ply:GetVehicle()

                if not ply.gforceLastVel or not ply.gforceLastPos then
                    ply.gforceLastVel = Vector()
                    ply.gforceLastPos = veh:GetPos()
                end

                local vel = (veh:GetPos() - ply.gforceLastPos) / engine.TickInterval()
                local gforce = (vel - ply.gforceLastVel) / engine.TickInterval() / gravity[3] - Vector(0, 0, 1)

                --To calculate local acceleration relative to the vehicle, calculate the acceleration in world space,
                --and then dot each axis with each normalized direction vector of the vehicle, for example the up/down gforce
                --would be calculated by gforce:Dot(veh:GetUp())
                --This is used for the clientside HUD below

                ply.gforceLastVel = vel
                ply.gforceLastPos = veh:GetPos()
                ply:SetNWFloat("gx", gforce[1])
                ply:SetNWFloat("gy", gforce[2])
                ply:SetNWFloat("gz", gforce[3])
            end
        end
    end)
else
    local pos = {
        x = ScrW() * 0.01,
        y = ScrH() * 0.5
    }

    local max = 0
    local maxAge = SysTime()

    hook.Add("HUDPaint", "GForce::HUD", function()
        local ply = LocalPlayer()
        if not ply:InVehicle() or not ply:GetVehicle():IsValid() then return end
        local veh = ply:GetVehicle()
        local gforce = Vector(ply:GetNWFloat("gx", 0), ply:GetNWFloat("gy", 0), ply:GetNWFloat("gz", 0))

        if SysTime() - maxAge > 5 then
            max = 0
            maxAge = SysTime()
        end

        if gforce:Length() > max then
            max = gforce:Length()
            maxAge = SysTime()
        end

        surface.SetDrawColor(0, 0, 0, 127)
        surface.DrawRect(pos.x, pos.y - 2, 138, 102)
        draw.DrawText("GForce Statistics", "ChatFont", pos.x + 5, pos.y)
        draw.DrawText("Local X: " .. string.format("%.1f", gforce:Dot(-veh:GetForward())), "ChatFont", pos.x + 5, pos.y + 16)
        draw.DrawText("Local Y: " .. string.format("%.1f", gforce:Dot(veh:GetRight())), "ChatFont", pos.x + 5, pos.y + 32)
        draw.DrawText("Local Z: " .. string.format("%.1f", gforce:Dot(-veh:GetUp())), "ChatFont", pos.x + 5, pos.y + 48)
        draw.DrawText("Overall: " .. string.format("%.1f", gforce:Length()), "ChatFont", pos.x + 5, pos.y + 64)
        draw.DrawText("Max (5s): " .. string.format("%.1f", max), "ChatFont", pos.x + 5, pos.y + 80)
    end)
end