// 0 and 1 which can be used to model lower friction with wet runways.
bool get_agl(double t, const SGVec3d& pt, SGVec3d& contact,
SGVec3d& normal, SGVec3d& linearVel, SGVec3d& angularVel,
// 0 and 1 which can be used to model lower friction with wet runways.
bool get_agl(double t, const SGVec3d& pt, SGVec3d& contact,
SGVec3d& normal, SGVec3d& linearVel, SGVec3d& angularVel,