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ojsama.js
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// this is free and unencumbered software released into the public
// domain. refer to the attached UNLICENSE or http://unlicense.org/
//
// [](
// https://travis-ci.org/Francesco149/ojsama)
//
// pure javascript implementation of
// https://github.com/Francesco149/oppai-ng intended to be easier
// to use and set up for js developers as well as more portable
// than straight up bindings at the cost of some performance
//
// installation:
// ----------------------------------------------------------------
// since this is a single-file library, you can just drop the file
// into your project:
// ```sh
// cd my/project
// curl https://waa.ai/ojsama > ojsama.js
// ```
//
// or include it directly in a html page:
// ```html
// <script type="text/javascript" src="ojsama.min.js"></script>
// ```
//
// it's also available as a npm package:
// ```sh
// npm install ojsama
// ```
//
// you can find full documentation of the code at
// http://hnng.moe/stuff/ojsama.html or simply read ojsama.js
//
// usage (nodejs):
// ----------------------------------------------------------------
// (change ./ojsama to ojsama if you installed through npm)
//
// ```js
// var readline = require("readline");
// var osu = require("./ojsama");
//
// var parser = new osu.parser();
// readline.createInterface({
// input: process.stdin, terminal: falsei
// })
// .on("line", parser.feed_line.bind(parser))
// .on("close", function() {
// console.log(osu.ppv2({map: parser.map}).toString());
// });
// ```
//
// ```sh
// $ curl https://osu.ppy.sh/osu/67079 | node minexample.js
// 133.24 pp (36.23 aim, 40.61 speed, 54.42 acc)
// ```
//
// advanced usage (nodejs with acc, mods, combo...):
// ----------------------------------------------------------------
// ```js
// var readline = require("readline");
// var osu = require("./ojsama");
//
// var mods = osu.modbits.none;
// var acc_percent;
// var combo;
// var nmiss;
//
// // get mods, acc, combo, misses from command line arguments
// // format: +HDDT 95% 300x 1m
// var argv = process.argv;
//
// for (var i = 2; i < argv.length; ++i)
// {
// if (argv[i].startsWith("+")) {
// mods = osu.modbits.from_string(argv[i].slice(1) || "");
// }
//
// else if (argv[i].endsWith("%")) {
// acc_percent = parseFloat(argv[i]);
// }
//
// else if (argv[i].endsWith("x")) {
// combo = parseInt(argv[i]);
// }
//
// else if (argv[i].endsWith("m")) {
// nmiss = parseInt(argv[i]);
// }
// }
//
// var parser = new osu.parser();
// readline.createInterface({
// input: process.stdin, terminal: false
// })
// .on("line", parser.feed_line.bind(parser))
// .on("close", function() {
// var map = parser.map;
// console.log(map.toString());
//
// if (mods) {
// console.log("+" + osu.modbits.string(mods));
// }
//
// var stars = new osu.diff().calc({map: map, mods: mods});
// console.log(stars.toString());
//
// var pp = osu.ppv2({
// stars: stars,
// combo: combo,
// nmiss: nmiss,
// acc_percent: acc_percent,
// });
//
// var max_combo = map.max_combo();
// combo = combo || max_combo;
//
// console.log(pp.computed_accuracy.toString());
// console.log(combo + "/" + max_combo + "x");
//
// console.log(pp.toString());
// });
// ```
//
// ```sh
// $ curl https://osu.ppy.sh/osu/67079 | node example.js
// TERRA - Tenjou no Hoshi ~Reimeiki~ [BMax] mapped by ouranhshc
//
// AR5 OD8 CS4 HP8
// 262 circles, 69 sliders, 5 spinners
// 469 max combo
//
// 4.33 stars (2.09 aim, 2.19 speed)
// 100.00% 0x100 0x50 0xmiss
// 469/469x
// 133.24 pp (36.23 aim, 40.61 speed, 54.42 acc)
//
// $ curl https://osu.ppy.sh/osu/67079 \
// | node example.js +HDDT 98% 400x 1m
// ...
// +HDDT
// 6.13 stars (2.92 aim, 3.11 speed)
// 97.92% 9x100 0x50 1xmiss
// 400/469x
// 266.01 pp (99.70 aim, 101.68 speed, 60.41 acc)
// ```
//
// usage (in the browser)
// ----------------------------------------------------------------
// ```html
// <!DOCTYPE html>
// <html>
// <head>
// <meta charset="utf-8" />
// <script type="text/javascript" src="ojsama.min.js"></script>
// <script type="text/javascript">
// function load_file()
// {
// var frame = document.getElementById("osufile");
// var contents = frame.contentWindow
// .document.body.childNodes[0].innerHTML;
//
// var parser = new osu.parser().feed(contents);
// console.log(parser.toString());
//
// var str = parser.map.toString();
// str += osu.ppv2({map: parser.map}).toString();
//
// document.getElementById("result").innerHTML = str;
// }
// </script>
// </head>
// <body>
// <iframe id="osufile" src="test.osu" onload="load_file();"
// style="display: none;">
// </iframe>
// <blockquote><pre id="result">calculating...</pre></blockquote>
// </body>
// </html>
// ```
//
// (this example assumes you have a test.osu beatmap in the same
// directory)
//
// performance
// ----------------------------------------------------------------
// this is around 50-60% slower than the C implementation and uses
// ~10 times more memory.
// ```sh
// $ busybox time -v node --use_strict test.js
// ...
// User time (seconds): 16.58
// System time (seconds): 0.43
// Percent of CPU this job got: 101%
// Elapsed (wall clock) time (h:mm:ss or m:ss): 0m 16.70s
// ...
// Maximum resident set size (kbytes): 314080
// Minor (reclaiming a frame) page faults: 20928
// Voluntary context switches: 72138
// Involuntary context switches: 16689
// ```
// # code documentation
// when used outside of node, a osu namespace will be exposed
// without polluting the global scope
var osu = {};
if (typeof exports !== "undefined") {
osu = exports;
}
(function() {
osu.VERSION_MAJOR = 1;
osu.VERSION_MINOR = 2;
osu.VERSION_PATCH = 1;
// internal utilities
// ----------------------------------------------------------------
// override console with nop when running in a browser
var log = {warn: Function.prototype};
if (typeof exports !== "undefined") {
log = console;
}
var array_toFixed = function(arr, n) {
var res = new Array(arr.length);
for (var i = 0; i < res.length; ++i) {
res[i] = arr[i].toFixed(n);
}
return res;
};
function isUndefined(val) {
return typeof val === "undefined";
}
// timing point
// ----------------------------------------------------------------
// defines parameters such as timing and sampleset for an interval.
// for pp calculation we only need time and ms_per_beat
//
// it can inherit from its preceeding point by having
// change = false and setting ms_per_beat to a negative value which
// represents the bpm multiplier as ```-100 * bpm_multiplier```
function timing(values) {
this.time = values.time || 0.0;
this.ms_per_beat = values.ms_per_beat;
if (this.ms_per_beat === undefined) {
this.ms_per_beat = 600.0;
}
this.change = values.change;
if (this.change === undefined) {
this.change = true;
}
}
timing.prototype.toString = function() {
return "{ time: " + this.time.toFixed(2) + ", "
+ "ms_per_beat: " + this.ms_per_beat.toFixed(2) + " }";
}
// hit objects
// ----------------------------------------------------------------
// partial structure of osu! hitobjects with just enough data for
// pp calculation
// bitmask constants for object types. note that the type can
// contain other flags so you should always check type with
// ```if (type & objtypes.circle) { ... }```
var objtypes = {
circle: 1<<0,
slider: 1<<1,
spinner: 1<<3,
};
// all we need from circles is their position. all positions
// stored in the objects are in playfield coordinates (512*384
// rect)
function circle(values) {
this.pos = values.pos || [0, 0];
}
circle.prototype.toString = function() {
return "pos: [" + array_toFixed(this.pos, 2) + "]";
};
// to calculate max combo we need to compute slider ticks
//
// the beatmap stores the distance travelled in one repetition and
// the number of repetitions. this is enough to calculate distance
// per tick using timing information and slider velocity.
//
// note that 1 repetition means no repeats (1 loop)
function slider(values) {
this.pos = values.pos || [0, 0];
this.distance = values.distance || 0.0;
this.repetitions = values.repetitions || 1;
}
slider.prototype.toString = function() {
return (
"pos: " + array_toFixed(this.pos, 2) + ", " +
"distance: " + this.distance.toFixed(2) + ", " +
"repetitions: " + this.repetitions
);
};
// generic hitobject
//
// the only common property is start time (in millisecond).
// object-specific properties are stored in data, which can be
// an instance of circle, slider, or null
function hitobject(values) {
this.time = values.time || 0.0;
this.type = values.type || 0;
if (!isUndefined(values.data)) this.data = values.data;
}
hitobject.prototype.typestr = function() {
var res = "";
if (this.type & objtypes.circle) res += "circle | ";
if (this.type & objtypes.slider) res += "slider | ";
if (this.type & objtypes.spinner) res += "spinner | ";
return res.substring(0, Math.max(0, res.length - 3));
};
hitobject.prototype.toString = function() {
return (
"{ time: " + this.time.toFixed(2) + ", " +
"type: " + this.typestr() +
(this.data ? ", " + this.data.toString() : "") +
" }"
);
};
// beatmap
// ----------------------------------------------------------------
// gamemode constants
var modes = {
std: 0,
};
// partial beatmap structure with just enough data for pp
// calculation
function beatmap() {
this.reset();
}
beatmap.prototype.reset = function() {
this.format_version = 1;
this.mode = modes.std;
this.title = this.title_unicode = "";
this.artist = this.artist_unicode = "";
this.creator = "";
this.version = "";
this.ar = undefined;
this.cs = this.od = this.hp = 5.0;
this.sv = this.tick_rate = 1.0;
this.ncircles = this.nsliders = this.nspinners = 0;
if (!this.objects) {
this.objects = [];
} else {
this.objects.length = 0;
}
if (!this.timing_points) {
this.timing_points = [];
} else {
this.timing_points.length = 0;
}
return this;
};
// max combo calculation
//
// this is given by ncircles + nspinners + nsliders * 2
// (heads and tails) + nsliderticks
//
// we approximate slider ticks by calculating the
// playfield pixels per beat for the current section
// and dividing the total distance travelled by
// pixels per beat. this gives us the number of beats,
// which multiplied by the tick rate gives use the
// tick count.
beatmap.prototype.max_combo = function() {
var res = this.ncircles + this.nspinners;
var tindex = -1;
var tnext = Number.NEGATIVE_INFINITY;
var px_per_beat = 0.0;
for (var i = 0; i < this.objects.length; ++i) {
var obj = this.objects[i];
if (!(obj.type & objtypes.slider)) {
continue;
}
// keep track of the current timing point without
// looping through all of them for every object
while (obj.time >= tnext) {
++tindex;
if (this.timing_points.length > tindex + 1) {
tnext = this.timing_points[tindex + 1].time;
} else {
tnext = Number.POSITIVE_INFINITY;
}
var t = this.timing_points[tindex];
var sv_multiplier = 1.0;
if (!t.change && t.ms_per_beat < 0) {
sv_multiplier = -100.0 / t.ms_per_beat;
}
// beatmaps older than format v8 don't apply
// the bpm multiplier to slider ticks
if (this.format_version < 8) {
px_per_beat = this.sv * 100.0;
} else {
px_per_beat = this.sv * 100.0 * sv_multiplier;
}
}
var sl = obj.data;
var num_beats = (sl.distance * sl.repetitions) / px_per_beat;
// subtract an epsilon to prevent accidental
// ceiling of whole values such as 2.00....1 -> 3 due
// to rounding errors
var ticks = Math.ceil(
(num_beats - 0.1) / sl.repetitions
* this.tick_rate
);
--ticks;
ticks *= sl.repetitions;
ticks += sl.repetitions + 1;
res += Math.max(0, ticks);
}
return res;
};
beatmap.prototype.toString = function() {
var res = this.artist + " - " + this.title + " [";
if (this.title_unicode || this.artist_unicode) {
res += "(" + this.artist_unicode + " - "
+ this.title_unicode + ")";
}
res += (
this.version + "] mapped by " + this.creator + "\n"
+ "\n"
+ "AR" + parseFloat(this.ar.toFixed(2)) + " "
+ "OD" + parseFloat(this.od.toFixed(2)) + " "
+ "CS" + parseFloat(this.cs.toFixed(2)) + " "
+ "HP" + parseFloat(this.hp.toFixed(2)) + "\n"
+ this.ncircles + " circles, "
+ this.nsliders + " sliders, "
+ this.nspinners + " spinners" + "\n"
+ this.max_combo() + " max combo" + "\n"
);
return res;
};
// beatmap parser
// ----------------------------------------------------------------
// partial .osu file parser built around pp calculation
function parser() {
// once you're done feeding data to the parser, you will find
// the parsed beatmap in this object
this.map = new beatmap();
this.reset();
}
parser.prototype.reset = function() {
this.map.reset();
// parser state: number of lines fed, last touched line,
// last touched substring and the current section name
//
// these can be used to debug syntax errors
this.nline = 0;
this.curline = "";
this.lastpos = "";
this.section = "";
return this;
};
// you can feed a single line or a whole block of text which
// will be split into lines. partial lines are not allowed
//
// both feed functions return the parser instance for easy
// chaining
parser.prototype.feed_line = function(line) {
this.curline = this.lastpos = line;
++this.nline;
// comments
if (line.startsWith(" ") || line.startsWith("_")) {
return this;
}
// now that we've handled space comments we can trim space
line = this.curline = line.trim();
if (line.length <= 0) {
return this;
}
// c++ style comments
if (line.startsWith("//")) {
return this;
}
// [SectionName]
if (line.startsWith("[")) {
// on old maps there's no ar and ar = od
if (this.section == "Difficulty" && isUndefined(this.map.ar)) {
this.map.ar = this.map.od;
}
this.section = line.substring(1, line.length - 1);
return this;
}
if (!line) {
return this;
}
switch (this.section) {
case "Metadata": this._metadata(); break;
case "General": this._general(); break;
case "Difficulty": this._difficulty(); break;
case "TimingPoints": this._timing_points(); break;
case "HitObjects": this._objects(); break;
default:
var fmtpos = line.indexOf("file format v");
if (fmtpos< 0) {
break;
}
this.map.format_version = parseInt(line.substring(fmtpos + 13));
break;
}
return this;
};
parser.prototype.feed = function(str) {
var lines = lines = str.split("\n");
for (var i = 0; i < lines.length; ++i) {
this.feed_line(lines[i]);
}
return this;
};
// returns the parser state formatted into a string. useful
// for debugging syntax errors
parser.prototype.toString = function() {
return (
"at line " + this.nline + "\n" +
this.curline + "\n" +
"-> " + this.lastpos + " <-"
);
};
// _(internal)_ parser utilities
parser.prototype._setpos = function(str) {
this.lastpos = str.trim();
return this.lastpos;
};
parser.prototype._warn = function() {
log.warn.apply(null, Array.prototype.slice.call(arguments));
log.warn(this.toString());
};
parser.prototype._property = function() {
var s = this.curline.split(":", 2);
s[0] = this._setpos(s[0]);
s[1] = this._setpos(s[1]);
return s;
};
// _(internal)_ line parsers for each section
parser.prototype._metadata = function() {
var p = this._property();
switch (p[0]) {
case "Title":
this.map.title = p[1];
break;
case "TitleUnicode":
this.map.title_unicode = p[1];
break;
case "Artist":
this.map.artist = p[1];
break;
case "ArtistUnicode":
this.map.artist_unicode = p[1];
break;
case "Creator":
this.map.creator = p[1];
break;
case "Version":
this.map.version = p[1];
break;
}
};
parser.prototype._general = function() {
var p = this._property();
if (p[0] !== "Mode") {
return;
}
this.map.mode = parseInt(this._setpos(p[1]));
};
parser.prototype._difficulty = function() {
var p = this._property();
switch (p[0]) {
case "CircleSize":
this.map.cs = parseFloat(this._setpos(p[1]));
break;
case "OverallDifficulty":
this.map.od = parseFloat(this._setpos(p[1]));
break;
case "ApproachRate":
this.map.ar = parseFloat(this._setpos(p[1]));
break;
case "HPDrainRate":
this.map.hp = parseFloat(this._setpos(p[1]));
break;
case "SliderMultiplier":
this.map.sv = parseFloat(this._setpos(p[1]));
break;
case "SliderTickRate":
this.map.tick_rate = parseFloat(this._setpos(p[1]));
break;
}
};
parser.prototype._timing_points = function() {
var s = this.curline.split(",");
if (s.length > 8) {
this._warn("timing point with trailing values");
} else if (s.length < 2) {
this._warn("ignoring malformed timing point");
return;
}
var t = new timing({
time: parseFloat(this._setpos(s[0])),
ms_per_beat: parseFloat(this._setpos(s[1])),
});
if (s.length >= 7) {
t.change = s[6].trim() !== "0";
}
this.map.timing_points.push(t);
};
parser.prototype._objects = function() {
var s = this.curline.split(",");
var d;
if (s.length > 11) {
this._warn("object with trailing values");
} else if (s.length < 4) {
this._warn("ignoring malformed hitobject");
return;
}
var obj = new hitobject({
time: parseFloat(this._setpos(s[2])),
type: parseInt(this._setpos(s[3])),
});
if (isNaN(obj.time) || isNaN(obj.type)) {
this._warn("ignoring malformed hitobject");
return;
}
if ((obj.type & objtypes.circle) != 0) {
++this.map.ncircles;
d = obj.data = new circle({
pos: [
parseFloat(this._setpos(s[0])),
parseFloat(this._setpos(s[1])),
]
});
if (isNaN(d.pos[0]) || isNaN(d.pos[1])) {
this._warn("ignoring malformed circle");
return;
}
} else if ((obj.type & osu.objtypes.spinner) != 0) {
++this.map.nspinners;
} else if ((obj.type & osu.objtypes.slider) != 0) {
if (s.length < 8) {
this._warn("ignoring malformed slider");
return;
}
++this.map.nsliders;
d = obj.data = new slider({
pos: [
parseFloat(this._setpos(s[0])),
parseFloat(this._setpos(s[1])),
],
repetitions: parseInt(this._setpos(s[6])),
distance: parseFloat(this._setpos(s[7])),
});
if (isNaN(d.pos[0]) || isNaN(d.pos[1]) ||
isNaN(d.repetitions) || isNaN(d.distance))
{
this._warn("ignoring malformed slider");
return;
}
}
this.map.objects.push(obj);
}
// difficulty calculation
// ----------------------------------------------------------------
// mods bitmask constants
// NOTE: td is touch device, but it's also the value for the
// legacy no video mod
var modbits = {
nomod: 0,
nf: 1<<0,
ez: 1<<1,
td: 1<<2,
hd: 1<<3,
hr: 1<<4,
dt: 1<<6,
ht: 1<<8,
nc: 1<<9,
fl: 1<<10,
so: 1<<12,
};
// construct the mods bitmask from a string such as "HDHR"
modbits.from_string = function(str) {
var mask = 0;
str = str.toLowerCase();
while (str != "") {
var nchars = 1;
for (var property in modbits) {
if (property.length != 2) {
continue;
}
if (!modbits.hasOwnProperty(property)) {
continue;
}
if (str.startsWith(property)) {
mask |= modbits[property];
nchars = 2;
break;
}
}
str = str.slice(nchars);
}
return mask;
};
// convert mods bitmask into a string, such as "HDHR"
modbits.string = function(mods) {
var res = "";
for (var property in modbits) {
if (property.length != 2) {
continue;
}
if (!modbits.hasOwnProperty(property)) {
continue;
}
if (mods & modbits[property]) {
res += property.toUpperCase();
}
}
if (res.indexOf("DT") >= 0 && res.indexOf("NC") >= 0) {
res = res.replace("DT", "");
}
return res;
};
modbits.speed_changing = modbits.dt | modbits.ht | modbits.nc;
modbits.map_changing = modbits.hr | modbits.ez | modbits.speed_changing;
// _(internal)_
// osu!standard stats constants
var OD0_MS = 80;
var OD10_MS = 20;
var AR0_MS = 1800.0;
var AR5_MS = 1200.0;
var AR10_MS = 450.0;
var OD_MS_STEP = (OD0_MS - OD10_MS) / 10.0;
var AR_MS_STEP1 = (AR0_MS - AR5_MS) / 5.0;
var AR_MS_STEP2 = (AR5_MS - AR10_MS) / 5.0;
// _(internal)_
// utility functions to apply speed and flat multipliers to
// stats where speed changes apply (ar and od)
function modify_ar(base_ar, speed_mul, multiplier) {
var ar = base_ar;
ar *= multiplier;
// convert AR into milliseconds window
var arms = (
ar < 5.0 ?
AR0_MS - AR_MS_STEP1 * ar
: AR5_MS - AR_MS_STEP2 * (ar - 5.0)
);
// stats must be capped to 0-10 before HT/DT which
// brings them to a range of -4.42->11.08 for OD and
// -5->11 for AR
arms = Math.min(AR0_MS, Math.max(AR10_MS, arms));
arms /= speed_mul;
ar = (
arms > AR5_MS ?
(AR0_MS - arms) / AR_MS_STEP1
: 5.0 + (AR5_MS - arms) / AR_MS_STEP2
);
return ar;
}
function modify_od(base_od, speed_mul, multiplier) {
var od = base_od;
od *= multiplier;
var odms = OD0_MS - Math.ceil(OD_MS_STEP * od);
odms = Math.min(OD0_MS, Math.max(OD10_MS, odms));
odms /= speed_mul;
od = (OD0_MS - odms) / OD_MS_STEP;
return od;
}
// stores osu!standard beatmap stats
function std_beatmap_stats(values) {
this.ar = values.ar;
this.od = values.od;
this.hp = values.hp;
this.cs = values.cs;
this.speed_mul = 1.0;
// previously calculated mod combinations are cached in a map
this._mods_cache = {};
}
// applies difficulty modifiers to a map's ar, od, cs, hp and
// returns the modified stats and the speed multiplier.
//
// unspecified stats are ignored and not returned
std_beatmap_stats.prototype.with_mods = function(mods) {
if (this._mods_cache[mods]) {
return this._mods_cache[mods];
}
var stats = this._mods_cache[mods] = new std_beatmap_stats(this);
if (!(mods & modbits.map_changing)) {
return stats;
}
if (mods & (modbits.dt|modbits.nc)) {
stats.speed_mul = 1.5;
}
if (mods & modbits.ht) {
stats.speed_mul *= 0.75;
}
var od_ar_hp_multiplier = 1.0;
if (mods & modbits.hr) od_ar_hp_multiplier = 1.4;
if (mods & modbits.ez) od_ar_hp_multiplier *= 0.5;
if (stats.ar) {
stats.ar = modify_ar(stats.ar, stats.speed_mul, od_ar_hp_multiplier);
}
if (stats.od) {
stats.od = modify_od(stats.od, stats.speed_mul, od_ar_hp_multiplier);
}
if (stats.cs) {
if (mods & modbits.hr) stats.cs *= 1.3;
if (mods & modbits.ez) stats.cs *= 0.5;
stats.cs = Math.min(10.0, stats.cs);
}
if (stats.hp) {
stats.hp *= od_ar_hp_multiplier;
stats.hp = Math.min(10.0, stats.hp);
}
return stats;
};
// osu! standard hit object with difficulty calculation values
// obj is the underlying hitobject
function std_diff_hitobject(obj) {
this.obj = obj;
this.reset();
}
std_diff_hitobject.prototype.reset = function() {
this.strains = [ 0.0, 0.0 ];
this.normpos = [ 0.0, 0.0 ];
this.angle = 0.0;
this.is_single = false;
this.delta_time = 0.0;
this.d_distance = 0.0;
return this;
};
std_diff_hitobject.prototype.toString = function() {
return (
"{ strains: [" + array_toFixed(this.strains, 2)
+ "], normpos: [" + array_toFixed(this.normpos, 2)
+ "], is_single: " + this.is_single + " }"
);
};
// _(internal)_
// 2D point operations
function vec_sub(a, b) { return [a[0] - b[0], a[1] - b[1]]; }
function vec_mul(a, b) { return [a[0] * b[0], a[1] * b[1]]; }
function vec_len(v) { return Math.sqrt(v[0] * v[0] + v[1] * v[1]); }
function vec_dot(a, b) { return a[0] * b[0] + a[1] * b[1]; }
// _(internal)_
// difficulty calculation constants
var DIFF_SPEED = 0;
var DIFF_AIM = 1;
var SINGLE_SPACING = 125.0;
var DECAY_BASE = [ 0.3, 0.15 ];
var WEIGHT_SCALING = [ 1400.0, 26.25 ];
var DECAY_WEIGHT = 0.9;
var STRAIN_STEP = 400.0;
var CIRCLESIZE_BUFF_THRESHOLD = 30.0;
var STAR_SCALING_FACTOR = 0.0675;
var PLAYFIELD_SIZE = [512.0, 384.0];
var PLAYFIELD_CENTER = vec_mul(PLAYFIELD_SIZE, [0.5, 0.5]);
var EXTREME_SCALING_FACTOR = 0.5;
// osu!standard difficulty calculator
//
// does not account for sliders because slider calculations are
// expensive and not worth the small accuracy increase
function std_diff() {
this.objects = [];
this.reset();
// make some parameters persist so they can be
// re-used in subsequent calls if no new value is specified
this.map = undefined;
this.mods = modbits.nomod;
this.singletap_threshold = 125.0;
}
std_diff.prototype.reset = function() {
// star rating
this.total = 0.0;
this.aim = 0.0;
this.aim_difficulty = 0.0;
this.aim_length_bonus = 0.0;
this.speed = 0.0;
this.speed_difficulty = 0.0;
this.speed_length_bonus = 0.0;
// number of notes that are seen as singletaps by the
// difficulty calculator
this.nsingles = 0;
// number of notes that are faster than the interval given
// in calc(). these singletap statistic are not required in
// star rating, but they are a free byproduct of the
// calculation which could be useful
this.nsingles_threshold = 0;