Function column_interpolated_density 

pub(crate) fn column_interpolated_density<N: DimensionNoises>(
    cache: &mut N::ColumnCache,
    noises: &N,
    x: i32,
    y: i32,
    z: i32,
    cell_w: i32,
    cell_h: i32,
) -> f64

Single-point getInterpolatedDensity. Exposed for GenerationContext.