Function ncollide2d::query::time_of_impact_ball_ball

pub fn time_of_impact_ball_ball<N: RealField>(
    center1: &Point<N>, 
    vel1: &Vector<N>, 
    b1: &Ball<N>, 
    center2: &Point<N>, 
    vel2: &Vector<N>, 
    b2: &Ball<N>, 
    max_toi: N, 
    target_distance: N
) -> Option<TOI<N>>

Time Of Impact of two balls under translational movement.