reworked attribute calculation (#15)

src/beatmap/attributes.rs

@@ -1,87 +1,250 @@
-use crate::Mods;
-
-/// Summary struct for a [`Beatmap`](crate::Beatmap)'s attributes.
-#[derive(Clone, Debug)]
-pub struct BeatmapAttributes {
-    /// The approach rate.
-    pub ar: f64,
-    /// The overall difficulty.
-    pub od: f64,
-    /// The circle size.
-    pub cs: f64,
-    /// The health drain rate
-    pub hp: f64,
-    /// The clock rate with respect to mods.
-    pub clock_rate: f64,
-}
-
-impl BeatmapAttributes {
-    const AR0_MS: f64 = 1800.0;
-    const AR5_MS: f64 = 1200.0;
-    const AR10_MS: f64 = 450.0;
-    const AR_MS_STEP_1: f64 = (Self::AR0_MS - Self::AR5_MS) / 5.0;
-    const AR_MS_STEP_2: f64 = (Self::AR5_MS - Self::AR10_MS) / 5.0;
-
-    #[inline]
-    pub(crate) fn new(ar: f32, od: f32, cs: f32, hp: f32) -> Self {
-        Self {
-            ar: ar as f64,
-            od: od as f64,
-            cs: cs as f64,
-            hp: hp as f64,
-            clock_rate: 1.0,
-        }
-    }
-
-    /// Adjusts attributes w.r.t. mods.
-    /// AR is further adjusted by its hitwindow.
-    /// OD is __not__ adjusted by its hitwindow.
-    pub fn mods(self, mods: impl Mods) -> Self {
-        if !mods.change_map() {
-            return self;
-        }
-
-        let clock_rate = mods.clock_rate();
-        let multiplier = mods.od_ar_hp_multiplier();
-
-        // AR
-        let mut ar = (self.ar * multiplier) as f64;
-        let mut ar_ms = if ar <= 5.0 {
-            Self::AR0_MS - Self::AR_MS_STEP_1 * ar
-        } else {
-            Self::AR5_MS - Self::AR_MS_STEP_2 * (ar - 5.0)
-        };
-
-        ar_ms = ar_ms.max(Self::AR10_MS).min(Self::AR0_MS);
-        ar_ms /= clock_rate;
-
-        ar = if ar_ms > Self::AR5_MS {
-            (Self::AR0_MS - ar_ms) / Self::AR_MS_STEP_1
-        } else {
-            5.0 + (Self::AR5_MS - ar_ms) / Self::AR_MS_STEP_2
-        };
-
-        // OD
-        let od = (self.od * multiplier).min(10.0);
-
-        // CS
-        let mut cs = self.cs;
-        if mods.hr() {
-            cs *= 1.3;
-        } else if mods.ez() {
-            cs *= 0.5;
-        }
-        cs = cs.min(10.0);
-
-        // HP
-        let hp = (self.hp * multiplier).min(10.0);
-
-        Self {
-            ar,
-            od,
-            cs,
-            hp,
-            clock_rate,
-        }
-    }
-}
+use crate::{Beatmap, GameMode, Mods};
+
+/// Summary struct for a [`Beatmap`]'s attributes.
+#[derive(Clone, Debug, PartialEq)]
+pub struct BeatmapAttributes {
+    /// The approach rate.
+    pub ar: f64,
+    /// The overall difficulty.
+    pub od: f64,
+    /// The circle size.
+    pub cs: f64,
+    /// The health drain rate
+    pub hp: f64,
+    /// The clock rate with respect to mods.
+    pub clock_rate: f64,
+    /// The hit windows for approach rate and overall difficulty.
+    pub hit_windows: BeatmapHitWindows,
+}
+
+#[derive(Copy, Clone, Debug, PartialEq)]
+/// AR and OD hit windows
+pub struct BeatmapHitWindows {
+    /// Hit window for approach rate i.e. TimePreempt in milliseconds.
+    pub ar: f64,
+    /// Hit window for overall difficulty i.e. time to hit a 300 ("Great") in milliseconds.
+    pub od: f64,
+}
+
+#[derive(Clone, Debug, Default, PartialEq)]
+/// Specify values for this builder to get [`BeatmapAttributes`] or [`BeatmapHitWindows`] based on
+/// mods & co.
+pub struct BeatmapAttributesBuilder {
+    mode: GameMode,
+    ar: f64,
+    od: f64,
+    cs: f64,
+    hp: f64,
+    mods: Option<u32>,
+    clock_rate: Option<f64>,
+    converted: bool,
+}
+
+impl BeatmapAttributesBuilder {
+    const OSU_MIN: f64 = 80.0;
+    const OSU_AVG: f64 = 50.0;
+    const OSU_MAX: f64 = 20.0;
+
+    const TAIKO_MIN: f64 = 50.0;
+    const TAIKO_AVG: f64 = 35.0;
+    const TAIKO_MAX: f64 = 20.0;
+
+    #[inline]
+    /// Create a new [`BeatmapAttributesBuilder`].
+    pub fn new(map: &Beatmap) -> Self {
+        Self::from(map)
+    }
+
+    #[inline]
+    /// Specify the mode.
+    pub fn mode(&mut self, mode: GameMode) -> &mut Self {
+        self.mode = mode;
+
+        self
+    }
+
+    #[inline]
+    /// Specify the approach rate.
+    pub fn ar(&mut self, ar: f64) -> &mut Self {
+        self.ar = ar;
+
+        self
+    }
+
+    #[inline]
+    /// Specify the overall difficulty.
+    pub fn od(&mut self, od: f64) -> &mut Self {
+        self.od = od;
+
+        self
+    }
+
+    #[inline]
+    /// Specify the circle size.
+    pub fn cs(&mut self, cs: f64) -> &mut Self {
+        self.cs = cs;
+
+        self
+    }
+
+    #[inline]
+    /// Specify the drain rate.
+    pub fn hp(&mut self, hp: f64) -> &mut Self {
+        self.hp = hp;
+
+        self
+    }
+
+    #[inline]
+    /// Specify the mods.
+    pub fn mods(&mut self, mods: u32) -> &mut Self {
+        self.mods = Some(mods);
+
+        self
+    }
+
+    #[inline]
+    /// Specify a custom clock rate.
+    pub fn clock_rate(&mut self, clock_rate: f64) -> &mut Self {
+        self.clock_rate = Some(clock_rate);
+
+        self
+    }
+
+    #[inline]
+    /// Specify whether it's a converted map.
+    /// Only relevant for mania.
+    pub fn converted(&mut self, converted: bool) -> &mut Self {
+        self.converted = converted;
+
+        self
+    }
+
+    #[inline]
+    /// Calculate the AR and OD hit windows.
+    pub fn hit_windows(&self) -> BeatmapHitWindows {
+        let mods = self.mods.unwrap_or(0);
+        let clock_rate = self.clock_rate.unwrap_or_else(|| mods.clock_rate());
+
+        let mod_mult = |val: f64| {
+            if mods.hr() {
+                (val * 1.4).min(10.0)
+            } else if mods.ez() {
+                val * 0.5
+            } else {
+                val
+            }
+        };
+
+        let raw_ar = mod_mult(self.ar);
+        let preempt = difficulty_range(raw_ar, 1800.0, 1200.0, 450.0) / clock_rate;
+
+        // OD
+        let hit_window = match self.mode {
+            GameMode::Osu | GameMode::Catch => {
+                let raw_od = mod_mult(self.od);
+
+                difficulty_range(raw_od, Self::OSU_MIN, Self::OSU_AVG, Self::OSU_MAX) / clock_rate
+            }
+            GameMode::Taiko => {
+                let raw_od = mod_mult(self.od);
+
+                difficulty_range(raw_od, Self::TAIKO_MIN, Self::TAIKO_AVG, Self::TAIKO_MAX).floor()
+                    / clock_rate
+            }
+            GameMode::Mania => {
+                let mut value = if !self.converted {
+                    34.0 + 3.0 * (10.0 - self.od).clamp(0.0, 10.0)
+                } else if self.od > 4.0 {
+                    34.0
+                } else {
+                    47.0
+                };
+
+                if mods.hr() {
+                    value /= 1.4;
+                } else if mods.ez() {
+                    value *= 1.4;
+                }
+
+                ((value * clock_rate).floor() / clock_rate).ceil()
+            }
+        };
+
+        BeatmapHitWindows {
+            ar: preempt,
+            od: hit_window,
+        }
+    }
+
+    /// Calculate the [`BeatmapAttributes`].
+    pub fn build(&self) -> BeatmapAttributes {
+        let mods = self.mods.unwrap_or(0);
+        let clock_rate = self.clock_rate.unwrap_or_else(|| mods.clock_rate());
+        let multiplier = mods.od_ar_hp_multiplier();
+
+        // HP
+        let hp = (self.hp * multiplier).min(10.0);
+
+        // CS
+        let mut cs = self.cs;
+
+        if mods.hr() {
+            cs = (cs * 1.3).min(10.);
+        } else if mods.ez() {
+            cs *= 0.5;
+        }
+
+        let hit_windows = self.hit_windows();
+        let BeatmapHitWindows { ar, od } = hit_windows;
+
+        // AR
+        let ar = if ar > 1200.0 {
+            (1800.0 - ar) / 120.0
+        } else {
+            (1200.0 - ar) / 150.0 + 5.0
+        };
+
+        // OD
+        let od = match self.mode {
+            GameMode::Osu => (Self::OSU_MIN - od) / (Self::OSU_MIN - Self::OSU_AVG) * 5.0,
+            GameMode::Taiko => (Self::TAIKO_MIN - od) / (Self::TAIKO_MIN - Self::TAIKO_AVG) * 5.0,
+            GameMode::Catch | GameMode::Mania => self.od,
+        };
+
+        BeatmapAttributes {
+            ar,
+            od,
+            cs,
+            hp,
+            clock_rate,
+            hit_windows,
+        }
+    }
+}
+
+impl From<&Beatmap> for BeatmapAttributesBuilder {
+    #[inline]
+    fn from(map: &Beatmap) -> Self {
+        Self {
+            mode: map.mode,
+            ar: map.ar as f64,
+            od: map.od as f64,
+            cs: map.cs as f64,
+            hp: map.hp as f64,
+            mods: None,
+            clock_rate: None,
+            converted: false,
+        }
+    }
+}
+
+fn difficulty_range(difficulty: f64, min: f64, mid: f64, max: f64) -> f64 {
+    if difficulty > 5.0 {
+        mid + (max - mid) * (difficulty - 5.0) / 5.0
+    } else if difficulty < 5.0 {
+        mid - (mid - min) * (5.0 - difficulty) / 5.0
+    } else {
+        mid
+    }
+}

src/beatmap/mod.rs

@@ -3,7 +3,7 @@ use std::{borrow::Cow, cmp::Ordering};
 use crate::parse::HitObject;
 
 pub use self::{
-    attributes::BeatmapAttributes,
+    attributes::{BeatmapAttributes, BeatmapAttributesBuilder, BeatmapHitWindows},
     breaks::Break,
     control_points::{ControlPoint, ControlPointIter, DifficultyPoint, TimingPoint},
     mode::GameMode,
@@ -66,8 +66,8 @@ pub struct Beatmap {
 impl Beatmap {
     /// Extract a beatmap's attributes into their own type.
     #[inline]
-    pub fn attributes(&self) -> BeatmapAttributes {
-        BeatmapAttributes::new(self.ar, self.od, self.cs, self.hp)
+    pub fn attributes(&self) -> BeatmapAttributesBuilder {
+        BeatmapAttributesBuilder::new(self)
     }
 
     /// The beats per minute of the map.

src/catch/gradual_difficulty.rs

@@ -66,8 +66,8 @@ pub struct CatchGradualDifficultyAttributes<'map> {
 
 impl<'map> CatchGradualDifficultyAttributes<'map> {
     /// Create a new difficulty attributes iterator for osu!catch maps.
-    pub fn new(map: &'map Beatmap, mods: impl Mods) -> Self {
-        let map_attributes = map.attributes().mods(mods);
+    pub fn new(map: &'map Beatmap, mods: u32) -> Self {
+        let map_attributes = map.attributes().mods(mods).build();
 
         let attributes = CatchDifficultyAttributes {
             ar: map_attributes.ar,

src/catch/mod.rs

@@ -147,8 +147,8 @@ fn calculate_movement(params: CatchStars<'_>) -> (Movement, CatchDifficultyAttri
     } = params;
 
     let take = passed_objects.unwrap_or(usize::MAX);
-    let map_attributes = map.attributes().mods(mods);
-    let clock_rate = clock_rate.unwrap_or(map_attributes.clock_rate);
+    let clock_rate = clock_rate.unwrap_or_else(|| mods.clock_rate());
+    let map_attributes = map.attributes().mods(mods).clock_rate(clock_rate).build();
 
     let attributes = CatchDifficultyAttributes {
         ar: map_attributes.ar,

src/gradual.rs

@@ -3,7 +3,7 @@ use crate::{
     mania::{ManiaGradualDifficultyAttributes, ManiaGradualPerformanceAttributes},
     osu::{OsuGradualDifficultyAttributes, OsuGradualPerformanceAttributes, OsuScoreState},
     taiko::{TaikoGradualDifficultyAttributes, TaikoGradualPerformanceAttributes, TaikoScoreState},
-    Beatmap, DifficultyAttributes, GameMode, Mods, PerformanceAttributes,
+    Beatmap, DifficultyAttributes, GameMode, PerformanceAttributes,
 };
 
 /// Gradually calculate the difficulty attributes on maps of any mode.
@@ -51,7 +51,7 @@ pub enum GradualDifficultyAttributes<'map> {
 
 impl<'map> GradualDifficultyAttributes<'map> {
     /// Create a new gradual difficulty calculator for maps of any mode.
-    pub fn new(map: &'map Beatmap, mods: impl Mods) -> Self {
+    pub fn new(map: &'map Beatmap, mods: u32) -> Self {
         match map.mode {
             GameMode::Osu => Self::Osu(OsuGradualDifficultyAttributes::new(map, mods)),
             GameMode::Taiko => Self::Taiko(TaikoGradualDifficultyAttributes::new(map, mods)),

src/lib.rs

@@ -242,7 +242,7 @@ pub trait BeatmapExt {
     /// Return an iterator that gives you the [`DifficultyAttributes`] after each hit object.
     ///
     /// Suitable to efficiently get the map's star rating after multiple different locations.
-    fn gradual_difficulty(&self, mods: impl Mods) -> GradualDifficultyAttributes<'_>;
+    fn gradual_difficulty(&self, mods: u32) -> GradualDifficultyAttributes<'_>;
 
     /// Return a struct that gives you the [`PerformanceAttributes`] after every (few) hit object(s).
     ///
@@ -294,7 +294,7 @@ impl BeatmapExt for Beatmap {
     }
 
     #[inline]
-    fn gradual_difficulty(&self, mods: impl Mods) -> GradualDifficultyAttributes<'_> {
+    fn gradual_difficulty(&self, mods: u32) -> GradualDifficultyAttributes<'_> {
         GradualDifficultyAttributes::new(self, mods)
     }
 
@@ -511,16 +511,5 @@ impl From<taiko::TaikoPerformanceAttributes> for PerformanceAttributes {
     }
 }
 
-#[inline]
-fn difficulty_range(val: f64, max: f64, avg: f64, min: f64) -> f64 {
-    if val > 5.0 {
-        avg + (max - avg) * (val - 5.0) / 5.0
-    } else if val < 5.0 {
-        avg - (avg - min) * (5.0 - val) / 5.0
-    } else {
-        avg
-    }
-}
-
 #[cfg(all(feature = "async_tokio", feature = "async_std"))]
 compile_error!("Only one of the features `async_tokio` and `async_std` should be enabled");

src/mania/pp.rs

@@ -1,7 +1,10 @@
 use std::borrow::Cow;
 
 use super::{ManiaDifficultyAttributes, ManiaPerformanceAttributes, ManiaStars};
-use crate::{Beatmap, DifficultyAttributes, GameMode, Mods, OsuPP, PerformanceAttributes};
+use crate::{
+    beatmap::BeatmapHitWindows, Beatmap, DifficultyAttributes, GameMode, Mods, OsuPP,
+    PerformanceAttributes,
+};
 
 /// Performance calculator on osu!mania maps.
 ///
@@ -142,9 +145,16 @@ impl<'map> ManiaPP<'map> {
             scaled_score /= percent_passed;
         }
 
-        let mut od = 34.0 + 3.0 * (10.0 - self.map.od as f64).max(0.0).min(10.0);
         let clock_rate = self.clock_rate.unwrap_or_else(|| self.mods.clock_rate());
 
+        let BeatmapHitWindows { od: hit_window, .. } = self
+            .map
+            .attributes()
+            .mods(self.mods)
+            .clock_rate(clock_rate)
+            .converted(matches!(self.map, Cow::Owned(_)))
+            .hit_windows();
+
         let mut multiplier = 0.8;
 
         if nf {
@@ -153,23 +163,8 @@ impl<'map> ManiaPP<'map> {
 
         if ez {
             multiplier *= 0.5;
-            od *= 1.4;
         }
 
-        let hit_window = {
-            let not_converted = matches!(self.map, Cow::Borrowed(_));
-
-            let value = if not_converted {
-                od
-            } else if self.map.od > 4.0 {
-                34.0
-            } else {
-                47.0
-            };
-
-            ((value * clock_rate).floor() / clock_rate).ceil()
-        };
-
         let strain_value = self.compute_strain(scaled_score, stars);
         let acc_value = self.compute_accuracy_value(scaled_score, strain_value, hit_window);
 

src/osu/gradual_difficulty.rs

@@ -5,7 +5,7 @@ use crate::{
 };
 
 use super::{
-    calculate_star_rating, difficulty_range_ar, difficulty_range_od, old_stacking,
+    calculate_star_rating, old_stacking,
     osu_object::{ObjectParameters, OsuObject, OsuObjectKind},
     scaling_factor::ScalingFactor,
     skill::{Skill, Skills},
@@ -58,27 +58,17 @@ pub struct OsuGradualDifficultyAttributes {
 
 impl OsuGradualDifficultyAttributes {
     /// Create a new difficulty attributes iterator for osu!standard maps.
-    pub fn new(map: &Beatmap, mods: impl Mods) -> Self {
-        let map_attributes = map.attributes().mods(mods);
-        let hit_window = difficulty_range_od(map_attributes.od) / map_attributes.clock_rate;
-        let od = (80.0 - hit_window) / 6.0;
-
-        let mut raw_ar = map.ar as f64;
+    pub fn new(map: &Beatmap, mods: u32) -> Self {
+        let map_attributes = map.attributes().mods(mods).build();
+        let hit_window = map_attributes.hit_windows.od;
+        let time_preempt = map_attributes.hit_windows.ar;
         let hr = mods.hr();
-
-        if hr {
-            raw_ar = (raw_ar * 1.4).min(10.0);
-        } else if mods.ez() {
-            raw_ar *= 0.5;
-        }
-
-        let time_preempt = difficulty_range_ar(raw_ar);
         let scaling_factor = ScalingFactor::new(map_attributes.cs);
 
         let mut attributes = OsuDifficultyAttributes {
             ar: map_attributes.ar,
             hp: map_attributes.hp,
-            od,
+            od: map_attributes.od,
             ..Default::default()
         };
 

src/osu/mod.rs

@@ -265,26 +265,16 @@ fn calculate_skills(params: OsuStars<'_>) -> (Skills, OsuDifficultyAttributes) {
     let take = passed_objects.unwrap_or(map.hit_objects.len());
     let clock_rate = clock_rate.unwrap_or_else(|| mods.clock_rate());
 
-    let map_attributes = map.attributes().mods(mods);
-    let hit_window = difficulty_range_od(map_attributes.od) / clock_rate;
-    let od = (80.0 - hit_window) / 6.0;
-
-    let mut raw_ar = map.ar as f64;
-    let hr = mods.hr();
-
-    if hr {
-        raw_ar = (raw_ar * 1.4).min(10.0);
-    } else if mods.ez() {
-        raw_ar *= 0.5;
-    }
-
-    let time_preempt = difficulty_range_ar(raw_ar);
+    let map_attributes = map.attributes().mods(mods).clock_rate(clock_rate).build();
     let scaling_factor = ScalingFactor::new(map_attributes.cs);
+    let hr = mods.hr();
+    let time_preempt = map_attributes.hit_windows.ar;
+    let hit_window = map_attributes.hit_windows.od;
 
     let mut attributes = OsuDifficultyAttributes {
         ar: map_attributes.ar,
         hp: map_attributes.hp,
-        od,
+        od: map_attributes.od,
         ..Default::default()
     };
 
@@ -521,11 +511,6 @@ fn old_stacking(hit_objects: &mut [OsuObject], stack_threshold: f64) {
     }
 }
 
-#[inline]
-fn difficulty_range_ar(ar: f64) -> f64 {
-    crate::difficulty_range(ar, 450.0, 1200.0, 1800.0)
-}
-
 fn lerp(start: f64, end: f64, percent: f64) -> f64 {
     start + (end - start) * percent
 }
@@ -610,8 +595,3 @@ impl From<OsuPerformanceAttributes> for OsuDifficultyAttributes {
         attributes.difficulty
     }
 }
-
-#[inline]
-fn difficulty_range_od(od: f64) -> f64 {
-    super::difficulty_range(od, 20.0, 50.0, 80.0)
-}

src/taiko/pp.rs

@@ -1,7 +1,10 @@
 use std::borrow::Cow;
 
 use super::{TaikoDifficultyAttributes, TaikoPerformanceAttributes, TaikoScoreState, TaikoStars};
-use crate::{Beatmap, DifficultyAttributes, GameMode, Mods, OsuPP, PerformanceAttributes};
+use crate::{
+    beatmap::BeatmapHitWindows, Beatmap, DifficultyAttributes, GameMode, Mods, OsuPP,
+    PerformanceAttributes,
+};
 
 /// Performance calculator on osu!taiko maps.
 ///
@@ -281,15 +284,13 @@ impl<'map> TaikoPPInner<'map> {
 
     #[inline]
     fn compute_accuracy_value(&self) -> f64 {
-        let mut od = self.map.od as f64;
+        let BeatmapHitWindows { od: hit_window, .. } = self
+            .map
+            .attributes()
+            .mods(self.mods)
+            .clock_rate(self.clock_rate)
+            .hit_windows();
 
-        if self.mods.hr() {
-            od *= 1.4;
-        } else if self.mods.ez() {
-            od *= 0.5;
-        }
-
-        let hit_window = difficulty_range_od(od).floor() / self.clock_rate;
         let max_combo = self.attributes.max_combo;
 
         (150.0 / hit_window).powf(1.1)
@@ -299,11 +300,6 @@ impl<'map> TaikoPPInner<'map> {
     }
 }
 
-#[inline]
-fn difficulty_range_od(od: f64) -> f64 {
-    crate::difficulty_range(od, 20.0, 35.0, 50.0)
-}
-
 impl<'map> From<OsuPP<'map>> for TaikoPP<'map> {
     #[inline]
     fn from(osu: OsuPP<'map>) -> Self {