Spring RTS Engine

New to lua here. Is there a quick way to detect whether or not a non-flying unit is touching the ground or not? I.E. whether it's on the ground like it should be or if it's being tossed around. I'm currently working on a Unit Cannon for Zero-K, which picks up units (only ground units) and flings them accross the map, but I need my script to detect wether a unit is touching the ground or not.

Is there a quick Spring.XXXXXX() function for this?

Maybe this can help:
http://answers.springlobby.info/questio ... e-airborne

local function isTouchingGround(unitID)

local xu,yu,zu=Spring.GetUnitPosition(unitID)
local yg = Spring.GetGroundHeight(xu,zu)

return yu<yg+3

end

-- I used +3 because often units don't exactly stick to the ground,
-- so it's better to have a tolerance.