pub fn marsshine_irradiance_lux(mars_phase_fraction: f64) -> f64 {
0.3 + 2.0 * mars_phase_fraction.clamp(0.0, 1.0)
}
pub fn dark_side_visibility_index(mars_phase_fraction: f64, terrain_albedo: f64) -> f64 {
marsshine_irradiance_lux(mars_phase_fraction) * terrain_albedo.clamp(0.0, 1.0)
}