// functions for calculating steering values.
@lazyglobal off.

function GetPitch {
  parameter v is SHIP:FACING:FOREVECTOR.
  return 90 - vectorangle(SHIP:UP:FOREVECTOR, v).
}

function GetAscentVector {
  parameter minPitch.
  // face prograde, but hold a solid eastern heading and don't
  // rotate the ship
  local newHeading is lookdirup(SHIP:SRFPROGRADE:FOREVECTOR,
    heading(90, 0, 270):TOPVECTOR).
  if GetPitch(newHeading:FOREVECTOR) < minPitch {
    set newHeading to heading(90, minPitch, 270).
  }
  return newHeading.
}

function CreateCircularizationNode {
  parameter nodeAtPeriapsis is false.

  local dt is choose SHIP:ORBIT:ETA:PERIAPSIS if nodeAtPeriapsis else SHIP:ORBIT:ETA:APOAPSIS.
  local t is TIME + dt.

  local Vc is sqrt(SHIP:BODY:MU/(SHIP:BODY:RADIUS + SHIP:ORBIT:APOAPSIS)).
  local dV is Vc - VelocityAt(SHIP, t):ORBIT:MAG.
  local n is Node(t, 0, 0, dV).

  return n.
}