@LAZYGLOBAL OFF.

function int {
    //
    // Truncate or round towards zero.
    //
    parameter n.
    
    if n < 0 return ceiling(n).
    return floor(n).
}


function atmosphere_exit_eta {
    //
    // Return the number of seconds until the vessel exists the atmosphere.
    //
    // the vdot gives us the magnitude of the orbital velocity vector in the UP direction because UP is a unit vector
    return (BODY:atm:height - ALTITUDE) / vdot(velocity:orbit, UP:vector).
}