alex/beta-minecraft-rust

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use crate::math;
use std::f32::consts::PI;

pub const TICKS_PER_DAY: i64 = 24_000;

/// Port of `WorldProvider.calculateCelestialAngle`.
pub fn celestial_angle(time: i64, partial_ticks: f32) -> f32 {
    let mut angle = ((time % TICKS_PER_DAY) as f32 + partial_ticks) / TICKS_PER_DAY as f32 - 0.25;
    if angle < 0.0 {
        angle += 1.0;
    }
    if angle > 1.0 {
        angle -= 1.0;
    }
    let eased = 1.0 - (((f64::from(angle) * std::f64::consts::PI).cos() + 1.0) / 2.0) as f32;
    angle + (eased - angle) / 3.0
}

/// Port of `World.calculateSkylightSubtracted`: night, rain and thunder darken the sky.
pub fn sky_darkness(angle: f32, rain: f32, thunder: f32) -> u32 {
    let light = 1.0 - (math::cos(angle * PI * 2.0) * 2.0 + 0.5);
    let mut light = 1.0 - light.clamp(0.0, 1.0);
    light = (f64::from(light) * (1.0 - f64::from(rain * 5.0) / 16.0)) as f32;
    light = (f64::from(light) * (1.0 - f64::from(thunder * 5.0) / 16.0)) as f32;
    ((1.0 - light) * 11.0) as u32
}