phaser
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A fast, free and fun HTML5 Game Framework for Desktop and Mobile web browsers from the team at Phaser Studio Inc.
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JavaScript
/**
* @author Richard Davey <rich@phaser.io>
* @copyright 2013-2025 Phaser Studio Inc.
* @license {@link https://opensource.org/licenses/MIT|MIT License}
*/
var Class = require('../../utils/Class');
/**
* @classdesc
* A seeded Random Data Generator.
*
* Access via `Phaser.Math.RND` which is an instance of this class pre-defined
* by Phaser. Or, create your own instance to use as you require.
*
* The `Math.RND` generator is seeded by the Game Config property value `seed`.
* If no such config property exists, a random number is used.
*
* If you create your own instance of this class you should provide a seed for it.
* If no seed is given it will use a 'random' one based on Date.now.
*
* @class RandomDataGenerator
* @memberof Phaser.Math
* @constructor
* @since 3.0.0
*
* @param {(string|string[])} [seeds] - The seeds to use for the random number generator.
*/
var RandomDataGenerator = new Class({
initialize:
function RandomDataGenerator (seeds)
{
if (seeds === undefined) { seeds = [ (Date.now() * Math.random()).toString() ]; }
/**
* Internal var.
*
* @name Phaser.Math.RandomDataGenerator#c
* @type {number}
* @default 1
* @private
* @since 3.0.0
*/
this.c = 1;
/**
* Internal var.
*
* @name Phaser.Math.RandomDataGenerator#s0
* @type {number}
* @default 0
* @private
* @since 3.0.0
*/
this.s0 = 0;
/**
* Internal var.
*
* @name Phaser.Math.RandomDataGenerator#s1
* @type {number}
* @default 0
* @private
* @since 3.0.0
*/
this.s1 = 0;
/**
* Internal var.
*
* @name Phaser.Math.RandomDataGenerator#s2
* @type {number}
* @default 0
* @private
* @since 3.0.0
*/
this.s2 = 0;
/**
* Internal var.
*
* @name Phaser.Math.RandomDataGenerator#n
* @type {number}
* @default 0
* @private
* @since 3.2.0
*/
this.n = 0;
/**
* Signs to choose from.
*
* @name Phaser.Math.RandomDataGenerator#signs
* @type {number[]}
* @since 3.0.0
*/
this.signs = [ -1, 1 ];
if (seeds)
{
this.init(seeds);
}
},
/**
* Private random helper.
*
* @method Phaser.Math.RandomDataGenerator#rnd
* @since 3.0.0
* @private
*
* @return {number} A random number.
*/
rnd: function ()
{
var t = 2091639 * this.s0 + this.c * 2.3283064365386963e-10; // 2^-32
this.c = t | 0;
this.s0 = this.s1;
this.s1 = this.s2;
this.s2 = t - this.c;
return this.s2;
},
/**
* Internal method that creates a seed hash.
*
* @method Phaser.Math.RandomDataGenerator#hash
* @since 3.0.0
* @private
*
* @param {string} data - The value to hash.
*
* @return {number} The hashed value.
*/
hash: function (data)
{
var h;
var n = this.n;
data = data.toString();
for (var i = 0; i < data.length; i++)
{
n += data.charCodeAt(i);
h = 0.02519603282416938 * n;
n = h >>> 0;
h -= n;
h *= n;
n = h >>> 0;
h -= n;
n += h * 0x100000000;// 2^32
}
this.n = n;
return (n >>> 0) * 2.3283064365386963e-10;// 2^-32
},
/**
* Initialize the state of the random data generator.
*
* @method Phaser.Math.RandomDataGenerator#init
* @since 3.0.0
*
* @param {(string|string[])} seeds - The seeds to initialize the random data generator with.
*/
init: function (seeds)
{
if (typeof seeds === 'string')
{
this.state(seeds);
}
else
{
this.sow(seeds);
}
},
/**
* Reset the seed of the random data generator.
*
* _Note_: the seed array is only processed up to the first `undefined` (or `null`) value, should such be present.
*
* @method Phaser.Math.RandomDataGenerator#sow
* @since 3.0.0
*
* @param {string[]} seeds - The array of seeds: the `toString()` of each value is used.
*/
sow: function (seeds)
{
// Always reset to default seed
this.n = 0xefc8249d;
this.s0 = this.hash(' ');
this.s1 = this.hash(' ');
this.s2 = this.hash(' ');
this.c = 1;
if (!seeds)
{
return;
}
// Apply any seeds
for (var i = 0; i < seeds.length && (seeds[i] != null); i++)
{
var seed = seeds[i];
this.s0 -= this.hash(seed);
this.s0 += ~~(this.s0 < 0);
this.s1 -= this.hash(seed);
this.s1 += ~~(this.s1 < 0);
this.s2 -= this.hash(seed);
this.s2 += ~~(this.s2 < 0);
}
},
/**
* Returns a random integer between 0 and 2^32.
*
* @method Phaser.Math.RandomDataGenerator#integer
* @since 3.0.0
*
* @return {number} A random integer between 0 and 2^32.
*/
integer: function ()
{
// 2^32
return this.rnd() * 0x100000000;
},
/**
* Returns a random real number between 0 and 1.
*
* @method Phaser.Math.RandomDataGenerator#frac
* @since 3.0.0
*
* @return {number} A random real number between 0 and 1.
*/
frac: function ()
{
// 2^-53
return this.rnd() + (this.rnd() * 0x200000 | 0) * 1.1102230246251565e-16;
},
/**
* Returns a random real number between 0 and 2^32.
*
* @method Phaser.Math.RandomDataGenerator#real
* @since 3.0.0
*
* @return {number} A random real number between 0 and 2^32.
*/
real: function ()
{
return this.integer() + this.frac();
},
/**
* Returns a random integer between and including min and max.
*
* @method Phaser.Math.RandomDataGenerator#integerInRange
* @since 3.0.0
*
* @param {number} min - The minimum value in the range.
* @param {number} max - The maximum value in the range.
*
* @return {number} A random number between min and max.
*/
integerInRange: function (min, max)
{
return Math.floor(this.realInRange(0, max - min + 1) + min);
},
/**
* Returns a random integer between and including min and max.
* This method is an alias for RandomDataGenerator.integerInRange.
*
* @method Phaser.Math.RandomDataGenerator#between
* @since 3.0.0
*
* @param {number} min - The minimum value in the range.
* @param {number} max - The maximum value in the range.
*
* @return {number} A random number between min and max.
*/
between: function (min, max)
{
return Math.floor(this.realInRange(0, max - min + 1) + min);
},
/**
* Returns a random real number between min and max.
*
* @method Phaser.Math.RandomDataGenerator#realInRange
* @since 3.0.0
*
* @param {number} min - The minimum value in the range.
* @param {number} max - The maximum value in the range.
*
* @return {number} A random number between min and max.
*/
realInRange: function (min, max)
{
return this.frac() * (max - min) + min;
},
/**
* Returns a random real number between -1 and 1.
*
* @method Phaser.Math.RandomDataGenerator#normal
* @since 3.0.0
*
* @return {number} A random real number between -1 and 1.
*/
normal: function ()
{
return 1 - (2 * this.frac());
},
/**
* Returns a valid RFC4122 version4 ID hex string from https://gist.github.com/1308368
*
* @method Phaser.Math.RandomDataGenerator#uuid
* @since 3.0.0
*
* @return {string} A valid RFC4122 version4 ID hex string
*/
uuid: function ()
{
var a = '';
var b = '';
for (b = a = ''; a++ < 36; b += ~a % 5 | a * 3 & 4 ? (a ^ 15 ? 8 ^ this.frac() * (a ^ 20 ? 16 : 4) : 4).toString(16) : '-')
{
// eslint-disable-next-line no-empty
}
return b;
},
/**
* Returns a random element from within the given array.
*
* @method Phaser.Math.RandomDataGenerator#pick
* @since 3.0.0
*
* @generic T
* @genericUse {T[]} - [array]
* @genericUse {T} - [$return]
*
* @param {T[]} array - The array to pick a random element from.
*
* @return {T} A random member of the array.
*/
pick: function (array)
{
return array[this.integerInRange(0, array.length - 1)];
},
/**
* Returns a sign to be used with multiplication operator.
*
* @method Phaser.Math.RandomDataGenerator#sign
* @since 3.0.0
*
* @return {number} -1 or +1.
*/
sign: function ()
{
return this.pick(this.signs);
},
/**
* Returns a random element from within the given array, favoring the earlier entries.
*
* @method Phaser.Math.RandomDataGenerator#weightedPick
* @since 3.0.0
*
* @generic T
* @genericUse {T[]} - [array]
* @genericUse {T} - [$return]
*
* @param {T[]} array - The array to pick a random element from.
*
* @return {T} A random member of the array.
*/
weightedPick: function (array)
{
return array[~~(Math.pow(this.frac(), 2) * (array.length - 0.5) + 0.5)];
},
/**
* Returns a random timestamp between min and max, or between the beginning of 2000 and the end of 2020 if min and max aren't specified.
*
* @method Phaser.Math.RandomDataGenerator#timestamp
* @since 3.0.0
*
* @param {number} min - The minimum value in the range.
* @param {number} max - The maximum value in the range.
*
* @return {number} A random timestamp between min and max.
*/
timestamp: function (min, max)
{
return this.realInRange(min || 946684800000, max || 1577862000000);
},
/**
* Returns a random angle between -180 and 180.
*
* @method Phaser.Math.RandomDataGenerator#angle
* @since 3.0.0
*
* @return {number} A random number between -180 and 180.
*/
angle: function ()
{
return this.integerInRange(-180, 180);
},
/**
* Returns a random rotation in radians, between -3.141 and 3.141
*
* @method Phaser.Math.RandomDataGenerator#rotation
* @since 3.0.0
*
* @return {number} A random number between -3.141 and 3.141
*/
rotation: function ()
{
return this.realInRange(-3.1415926, 3.1415926);
},
/**
* Gets or Sets the state of the generator. This allows you to retain the values
* that the generator is using between games, i.e. in a game save file.
*
* To seed this generator with a previously saved state you can pass it as the
* `seed` value in your game config, or call this method directly after Phaser has booted.
*
* Call this method with no parameters to return the current state.
*
* If providing a state it should match the same format that this method
* returns, which is a string with a header `!rnd` followed by the `c`,
* `s0`, `s1` and `s2` values respectively, each comma-delimited.
*
* @method Phaser.Math.RandomDataGenerator#state
* @since 3.0.0
*
* @param {string} [state] - Generator state to be set.
*
* @return {string} The current state of the generator.
*/
state: function (state)
{
if (typeof state === 'string' && state.match(/^!rnd/))
{
state = state.split(',');
this.c = parseFloat(state[1]);
this.s0 = parseFloat(state[2]);
this.s1 = parseFloat(state[3]);
this.s2 = parseFloat(state[4]);
}
return [ '!rnd', this.c, this.s0, this.s1, this.s2 ].join(',');
},
/**
* Shuffles the given array, using the current seed.
*
* @method Phaser.Math.RandomDataGenerator#shuffle
* @since 3.7.0
*
* @generic T
* @genericUse {T[]} - [array,$return]
*
* @param {T[]} [array] - The array to be shuffled.
*
* @return {T[]} The shuffled array.
*/
shuffle: function (array)
{
var len = array.length - 1;
for (var i = len; i > 0; i--)
{
var randomIndex = Math.floor(this.frac() * (i + 1));
var itemAtIndex = array[randomIndex];
array[randomIndex] = array[i];
array[i] = itemAtIndex;
}
return array;
}
});
module.exports = RandomDataGenerator;