/**
* @author Richard Davey <rich@photonstorm.com>
* @copyright 2014 Photon Storm Ltd.
* @license {@link https://github.com/photonstorm/phaser/blob/master/license.txt|MIT License}
*/
/**
* A collection of mathematical methods.
*
* @class Phaser.Math
*/
Phaser.Math = {
/**
* = 2 π
* @method Phaser.Math#PI2
*/
PI2: Math.PI * 2,
/**
* Two number are fuzzyEqual if their difference is less than ε.
* @method Phaser.Math#fuzzyEqual
* @param {number} a
* @param {number} b
* @param {number} epsilon
* @return {boolean} True if |a-b|<ε
*/
fuzzyEqual: function (a, b, epsilon) {
if (typeof epsilon === "undefined") { epsilon = 0.0001; }
return Math.abs(a - b) < epsilon;
},
/**
* a is fuzzyLessThan b if it is less than b + ε.
* @method Phaser.Math#fuzzyLessThan
* @param {number} a
* @param {number} b
* @param {number} epsilon
* @return {boolean} True if a<b+ε
*/
fuzzyLessThan: function (a, b, epsilon) {
if (typeof epsilon === "undefined") { epsilon = 0.0001; }
return a < b + epsilon;
},
/**
* a is fuzzyGreaterThan b if it is more than b - ε.
* @method Phaser.Math#fuzzyGreaterThan
* @param {number} a
* @param {number} b
* @param {number} epsilon
* @return {boolean} True if a>b+ε
*/
fuzzyGreaterThan: function (a, b, epsilon) {
if (typeof epsilon === "undefined") { epsilon = 0.0001; }
return a > b - epsilon;
},
/**
* @method Phaser.Math#fuzzyCeil
* @param {number} val
* @param {number} epsilon
* @return {boolean} ceiling(val-ε)
*/
fuzzyCeil: function (val, epsilon) {
if (typeof epsilon === "undefined") { epsilon = 0.0001; }
return Math.ceil(val - epsilon);
},
/**
* @method Phaser.Math#fuzzyFloor
* @param {number} val
* @param {number} epsilon
* @return {boolean} floor(val-ε)
*/
fuzzyFloor: function (val, epsilon) {
if (typeof epsilon === "undefined") { epsilon = 0.0001; }
return Math.floor(val + epsilon);
},
/**
* Averages all values passed to the function and returns the result. You can pass as many parameters as you like.
* @method Phaser.Math#average
* @return {number} The average of all given values.
*/
average: function () {
var args = [];
for (var _i = 0; _i < (arguments.length - 0); _i++) {
args[_i] = arguments[_i + 0];
}
var avg = 0;
for (var i = 0; i < args.length; i++) {
avg += args[i];
}
return avg / args.length;
},
/**
* @method Phaser.Math#truncate
* @param {number} n
* @return {number}
*/
truncate: function (n) {
return (n > 0) ? Math.floor(n) : Math.ceil(n);
},
/**
* @method Phaser.Math#shear
* @param {number} n
* @return {number} n mod 1
*/
shear: function (n) {
return n % 1;
},
/**
* Snap a value to nearest grid slice, using rounding.
*
* Example: if you have an interval gap of 5 and a position of 12... you will snap to 10 whereas 14 will snap to 15.
*
* @method Phaser.Math#snapTo
* @param {number} input - The value to snap.
* @param {number} gap - The interval gap of the grid.
* @param {number} [start] - Optional starting offset for gap.
* @return {number}
*/
snapTo: function (input, gap, start) {
if (typeof start === "undefined") { start = 0; }
if (gap === 0) {
return input;
}
input -= start;
input = gap * Math.round(input / gap);
return start + input;
},
/**
* Snap a value to nearest grid slice, using floor.
*
* Example: if you have an interval gap of 5 and a position of 12... you will snap to 10. As will 14 snap to 10... but 16 will snap to 15
*
* @method Phaser.Math#snapToFloor
* @param {number} input - The value to snap.
* @param {number} gap - The interval gap of the grid.
* @param {number} [start] - Optional starting offset for gap.
* @return {number}
*/
snapToFloor: function (input, gap, start) {
if (typeof start === "undefined") { start = 0; }
if (gap === 0) {
return input;
}
input -= start;
input = gap * Math.floor(input / gap);
return start + input;
},
/**
* Snap a value to nearest grid slice, using ceil.
*
* Example: if you have an interval gap of 5 and a position of 12... you will snap to 15. As will 14 will snap to 15... but 16 will snap to 20.
*
* @method Phaser.Math#snapToCeil
* @param {number} input - The value to snap.
* @param {number} gap - The interval gap of the grid.
* @param {number} [start] - Optional starting offset for gap.
* @return {number}
*/
snapToCeil: function (input, gap, start) {
if (typeof start === "undefined") { start = 0; }
if (gap === 0) {
return input;
}
input -= start;
input = gap * Math.ceil(input / gap);
return start + input;
},
/**
* Snaps a value to the nearest value in an array.
* @method Phaser.Math#snapToInArray
* @param {number} input
* @param {array} arr
* @param {boolean} sort - True if the array needs to be sorted.
* @return {number}
*/
snapToInArray: function (input, arr, sort) {
if (typeof sort === "undefined") { sort = true; }
if (sort) {
arr.sort();
}
if (input < arr[0]) {
return arr[0];
}
var i = 1;
while (arr[i] < input) {
i++;
}
var low = arr[i - 1];
var high = (i < arr.length) ? arr[i] : Number.POSITIVE_INFINITY;
return ((high - input) <= (input - low)) ? high : low;
},
/**
* Round to some place comparative to a 'base', default is 10 for decimal place.
*
* 'place' is represented by the power applied to 'base' to get that place
* e.g.
* 2000/7 ~= 285.714285714285714285714 ~= (bin)100011101.1011011011011011
*
* roundTo(2000/7,3) === 0
* roundTo(2000/7,2) == 300
* roundTo(2000/7,1) == 290
* roundTo(2000/7,0) == 286
* roundTo(2000/7,-1) == 285.7
* roundTo(2000/7,-2) == 285.71
* roundTo(2000/7,-3) == 285.714
* roundTo(2000/7,-4) == 285.7143
* roundTo(2000/7,-5) == 285.71429
*
* roundTo(2000/7,3,2) == 288 -- 100100000
* roundTo(2000/7,2,2) == 284 -- 100011100
* roundTo(2000/7,1,2) == 286 -- 100011110
* roundTo(2000/7,0,2) == 286 -- 100011110
* roundTo(2000/7,-1,2) == 285.5 -- 100011101.1
* roundTo(2000/7,-2,2) == 285.75 -- 100011101.11
* roundTo(2000/7,-3,2) == 285.75 -- 100011101.11
* roundTo(2000/7,-4,2) == 285.6875 -- 100011101.1011
* roundTo(2000/7,-5,2) == 285.71875 -- 100011101.10111
*
* Note what occurs when we round to the 3rd space (8ths place), 100100000, this is to be assumed
* because we are rounding 100011.1011011011011011 which rounds up.
*
* @method Phaser.Math#roundTo
* @param {number} value - The value to round.
* @param {number} place - The place to round to.
* @param {number} base - The base to round in... default is 10 for decimal.
* @return {number}
*/
roundTo: function (value, place, base) {
if (typeof place === "undefined") { place = 0; }
if (typeof base === "undefined") { base = 10; }
var p = Math.pow(base, -place);
return Math.round(value * p) / p;
},
/**
* @method Phaser.Math#floorTo
* @param {number} value - The value to round.
* @param {number} place - The place to round to.
* @param {number} base - The base to round in... default is 10 for decimal.
* @return {number}
*/
floorTo: function (value, place, base) {
if (typeof place === "undefined") { place = 0; }
if (typeof base === "undefined") { base = 10; }
var p = Math.pow(base, -place);
return Math.floor(value * p) / p;
},
/**
* @method Phaser.Math#ceilTo
* @param {number} value - The value to round.
* @param {number} place - The place to round to.
* @param {number} base - The base to round in... default is 10 for decimal.
* @return {number}
*/
ceilTo: function (value, place, base) {
if (typeof place === "undefined") { place = 0; }
if (typeof base === "undefined") { base = 10; }
var p = Math.pow(base, -place);
return Math.ceil(value * p) / p;
},
/**
* A one dimensional linear interpolation of a value.
* @method Phaser.Math#interpolateFloat
* @param {number} a
* @param {number} b
* @param {number} weight
* @return {number}
*/
interpolateFloat: function (a, b, weight) {
return (b - a) * weight + a;
},
/**
* Find the angle of a segment from (x1, y1) -> (x2, y2).
* @method Phaser.Math#angleBetween
* @param {number} x1
* @param {number} y1
* @param {number} x2
* @param {number} y2
* @return {number}
*/
angleBetween: function (x1, y1, x2, y2) {
return Math.atan2(y2 - y1, x2 - x1);
},
/**
* Find the angle of a segment from (x1, y1) -> (x2, y2).
* Note that the difference between this method and Math.angleBetween is that this assumes the y coordinate travels
* down the screen.
*
* @method Phaser.Math#angleBetweenY
* @param {number} x1
* @param {number} y1
* @param {number} x2
* @param {number} y2
* @return {number}
*/
angleBetweenY: function (x1, y1, x2, y2) {
return Math.atan2(x2 - x1, y2 - y1);
},
/**
* Find the angle of a segment from (point1.x, point1.y) -> (point2.x, point2.y).
* @method Phaser.Math#angleBetweenPoints
* @param {Phaser.Point} point1
* @param {Phaser.Point} point2
* @return {number}
*/
angleBetweenPoints: function (point1, point2) {
return Math.atan2(point2.y - point1.y, point2.x - point1.x);
},
/**
* Find the angle of a segment from (point1.x, point1.y) -> (point2.x, point2.y).
* @method Phaser.Math#angleBetweenPointsY
* @param {Phaser.Point} point1
* @param {Phaser.Point} point2
* @return {number}
*/
angleBetweenPointsY: function (point1, point2) {
return Math.atan2(point2.x - point1.x, point2.y - point1.y);
},
/**
* Reverses an angle.
* @method Phaser.Math#reverseAngle
* @param {number} angleRad - The angle to reverse, in radians.
* @return {number} Returns the reverse angle, in radians.
*/
reverseAngle: function (angleRad) {
return this.normalizeAngle(angleRad + Math.PI, true);
},
/**
* Normalizes an angle to the [0,2pi) range.
* @method Phaser.Math#normalizeAngle
* @param {number} angleRad - The angle to normalize, in radians.
* @return {number} Returns the angle, fit within the [0,2pi] range, in radians.
*/
normalizeAngle: function (angleRad) {
angleRad = angleRad % (2 * Math.PI);
return angleRad >= 0 ? angleRad : angleRad + 2 * Math.PI;
},
/**
* Normalizes a latitude to the [-90,90] range. Latitudes above 90 or below -90 are capped, not wrapped.
* @method Phaser.Math#normalizeLatitude
* @param {number} lat - The latitude to normalize, in degrees.
* @return {number} Returns the latitude, fit within the [-90,90] range.
*/
normalizeLatitude: function (lat) {
return Math.max(-90, Math.min(90, lat));
},
/**
* Normalizes a longitude to the [-180,180] range. Longitudes above 180 or below -180 are wrapped.
* @method Phaser.Math#normalizeLongitude
* @param {number} lng - The longitude to normalize, in degrees.
* @return {number} Returns the longitude, fit within the [-180,180] range.
*/
normalizeLongitude: function (lng) {
if (lng % 360 == 180)
{
return 180;
}
lng = lng % 360;
return lng < -180 ? lng + 360 : lng > 180 ? lng - 360 : lng;
},
/**
* Generate a random bool result based on the chance value.
* <p>
* Returns true or false based on the chance value (default 50%). For example if you wanted a player to have a 30% chance
* of getting a bonus, call chanceRoll(30) - true means the chance passed, false means it failed.
* </p>
* @method Phaser.Math#chanceRoll
* @param {number} chance - The chance of receiving the value. A number between 0 and 100 (effectively 0% to 100%).
* @return {boolean} True if the roll passed, or false otherwise.
*/
chanceRoll: function (chance) {
if (typeof chance === "undefined") { chance = 50; }
if (chance <= 0)
{
return false;
}
else if (chance >= 100)
{
return true;
}
else
{
if (Math.random() * 100 >= chance)
{
return false;
}
else
{
return true;
}
}
},
/**
* Returns an Array containing the numbers from min to max and inclusive of both values.
* If you need exclusive of max then see Phaser.Math.numberArrayEx.
*
* @method Phaser.Math#numberArray
* @param {number} min - The minimum value the array starts with.
* @param {number} max - The maximum value the array contains.
* @return {array} The array of number values.
*/
numberArray: function (min, max) {
var result = [];
for (var i = min; i <= max; i++)
{
result.push(i);
}
return result;
},
/**
* Creates an array of numbers (positive and/or negative) progressing from
* `start` up to but not including `end`. If `start` is less than `stop` a
* zero-length range is created unless a negative `step` is specified.
*
* @static
* @method Phaser.Math#numberArrayStep
* @param {number} [start=0] - The start of the range.
* @param {number} end - The end of the range.
* @param {number} [step=1] - The value to increment or decrement by.
* @returns {Array} Returns the new array of numbers.
* @example
*
* Phaser.Math.numberArrayStep(4);
* // => [0, 1, 2, 3]
*
* Phaser.Math.numberArrayStep(1, 5);
* // => [1, 2, 3, 4]
*
* Phaser.Math.numberArrayStep(0, 20, 5);
* // => [0, 5, 10, 15]
*
* Phaser.Math.numberArrayStep(0, -4, -1);
* // => [0, -1, -2, -3]
*
* Phaser.Math.numberArrayStep(1, 4, 0);
* // => [1, 1, 1]
*
* Phaser.Math.numberArrayStep(0);
* // => []
*/
numberArrayStep: function(start, end, step) {
start = +start || 0;
// enables use as a callback for functions like `_.map`
var type = typeof end;
if ((type === 'number' || type === 'string') && step && step[end] === start)
{
end = step = null;
}
step = step == null ? 1 : (+step || 0);
if (end === null)
{
end = start;
start = 0;
}
else
{
end = +end || 0;
}
// use `Array(length)` so engines like Chakra and V8 avoid slower modes
// http://youtu.be/XAqIpGU8ZZk#t=17m25s
var index = -1;
var length = Phaser.Math.max(Phaser.Math.ceil((end - start) / (step || 1)), 0);
var result = new Array(length);
while (++index < length)
{
result[index] = start;
start += step;
}
return result;
},
/**
* Adds the given amount to the value, but never lets the value go over the specified maximum.
*
* @method Phaser.Math#maxAdd
* @param {number} value - The value to add the amount to.
* @param {number} amount - The amount to add to the value.
* @param {number} max- The maximum the value is allowed to be.
* @return {number}
*/
maxAdd: function (value, amount, max) {
value += amount;
if (value > max)
{
value = max;
}
return value;
},
/**
* Subtracts the given amount from the value, but never lets the value go below the specified minimum.
*
* @method Phaser.Math#minSub
* @param {number} value - The base value.
* @param {number} amount - The amount to subtract from the base value.
* @param {number} min - The minimum the value is allowed to be.
* @return {number} The new value.
*/
minSub: function (value, amount, min) {
value -= amount;
if (value < min)
{
value = min;
}
return value;
},
/**
* Ensures that the value always stays between min and max, by wrapping the value around.
* max should be larger than min, or the function will return 0.
*
* @method Phaser.Math#wrap
* @param {number} value - The value to wrap.
* @param {number} min - The minimum the value is allowed to be.
* @param {number} max - The maximum the value is allowed to be.
* @return {number} The wrapped value.
*/
wrap: function (value, min, max) {
var range = max - min;
if (range <= 0)
{
return 0;
}
var result = (value - min) % range;
if (result < 0)
{
result += range;
}
return result + min;
},
/**
* Adds value to amount and ensures that the result always stays between 0 and max, by wrapping the value around.
* Values must be positive integers, and are passed through Math.abs.
*
* @method Phaser.Math#wrapValue
* @param {number} value - The value to add the amount to.
* @param {number} amount - The amount to add to the value.
* @param {number} max - The maximum the value is allowed to be.
* @return {number} The wrapped value.
*/
wrapValue: function (value, amount, max) {
var diff;
value = Math.abs(value);
amount = Math.abs(amount);
max = Math.abs(max);
diff = (value + amount) % max;
return diff;
},
/**
* Ensures the given value is between min and max inclusive.
*
* @method Phaser.Math#limitValue
* @param {number} value - The value to limit.
* @param {number} min - The minimum the value can be.
* @param {number} max - The maximum the value can be.
* @return {number} The limited value.
*/
limitValue: function(value, min, max) {
return value < min ? min : value > max ? max : value;
},
/**
* Randomly returns either a 1 or -1.
*
* @method Phaser.Math#randomSign
* @return {number} 1 or -1
*/
randomSign: function () {
return (Math.random() > 0.5) ? 1 : -1;
},
/**
* Returns true if the number given is odd.
*
* @method Phaser.Math#isOdd
* @param {number} n - The number to check.
* @return {boolean} True if the given number is odd. False if the given number is even.
*/
isOdd: function (n) {
return (n & 1);
},
/**
* Returns true if the number given is even.
*
* @method Phaser.Math#isEven
* @param {number} n - The number to check.
* @return {boolean} True if the given number is even. False if the given number is odd.
*/
isEven: function (n) {
if (n & 1)
{
return false;
}
else
{
return true;
}
},
/**
* Updated version of Math.min that can be passed either an array of numbers or the numbers as parameters.
* See http://jsperf.com/math-s-min-max-vs-homemade/5
*
* @method Phaser.Math#min
* @return {number} The lowest value from those given.
*/
min: function () {
if (arguments.length === 1 && typeof arguments[0] === 'object')
{
var data = arguments[0];
}
else
{
var data = arguments;
}
for (var i = 1, min = 0, len = data.length; i < len; i++)
{
if (data[i] < data[min])
{
min = i;
}
}
return data[min];
},
/**
* Updated version of Math.max that can be passed either an array of numbers or the numbers as parameters.
*
* @method Phaser.Math#max
* @return {number} The largest value from those given.
*/
max: function () {
if (arguments.length === 1 && typeof arguments[0] === 'object')
{
var data = arguments[0];
}
else
{
var data = arguments;
}
for (var i = 1, max = 0, len = data.length; i < len; i++)
{
if (data[i] > data[max])
{
max = i;
}
}
return data[max];
},
/**
* Updated version of Math.min that can be passed a property and either an array of objects or the objects as parameters.
* It will find the lowest matching property value from the given objects.
*
* @method Phaser.Math#minProperty
* @return {number} The lowest value from those given.
*/
minProperty: function (property) {
if (arguments.length === 2 && typeof arguments[1] === 'object')
{
var data = arguments[1];
}
else
{
var data = arguments.slice(1);
}
for (var i = 1, min = 0, len = data.length; i < len; i++)
{
if (data[i][property] < data[min][property])
{
min = i;
}
}
return data[min][property];
},
/**
* Updated version of Math.max that can be passed a property and either an array of objects or the objects as parameters.
* It will find the largest matching property value from the given objects.
*
* @method Phaser.Math#maxProperty
* @return {number} The largest value from those given.
*/
maxProperty: function (property) {
if (arguments.length === 2 && typeof arguments[1] === 'object')
{
var data = arguments[1];
}
else
{
var data = arguments.slice(1);
}
for (var i = 1, max = 0, len = data.length; i < len; i++)
{
if (data[i][property] > data[max][property])
{
max = i;
}
}
return data[max][property];
},
/**
* Keeps an angle value between -180 and +180.
*
* @method Phaser.Math#wrapAngle
* @param {number} angle - The angle value to check
* @param {boolean} radians - Set to `true` if the angle is given in radians, otherwise degrees is expected.
* @return {number} The new angle value, returns the same as the input angle if it was within bounds.
*/
wrapAngle: function (angle, radians) {
var radianFactor = (radians) ? Math.PI / 180 : 1;
return this.wrap(angle, -180 * radianFactor, 180 * radianFactor);
},
/**
* Keeps an angle value between the given min and max values.
*
* @method Phaser.Math#angleLimit
* @param {number} angle - The angle value to check. Must be between -180 and +180.
* @param {number} min - The minimum angle that is allowed (must be -180 or greater).
* @param {number} max - The maximum angle that is allowed (must be 180 or less).
* @return {number} The new angle value, returns the same as the input angle if it was within bounds
*/
angleLimit: function (angle, min, max) {
var result = angle;
if (angle > max)
{
result = max;
}
else if (angle < min)
{
result = min;
}
return result;
},
/**
* A Linear Interpolation Method, mostly used by Phaser.Tween.
* @method Phaser.Math#linearInterpolation
* @param {Array} v
* @param {number} k
* @return {number}
*/
linearInterpolation: function (v, k) {
var m = v.length - 1;
var f = m * k;
var i = Math.floor(f);
if (k < 0)
{
return this.linear(v[0], v[1], f);
}
if (k > 1)
{
return this.linear(v[m], v[m - 1], m - f);
}
return this.linear(v[i], v[i + 1 > m ? m : i + 1], f - i);
},
/**
* A Bezier Interpolation Method, mostly used by Phaser.Tween.
* @method Phaser.Math#bezierInterpolation
* @param {Array} v
* @param {number} k
* @return {number}
*/
bezierInterpolation: function (v, k) {
var b = 0;
var n = v.length - 1;
for (var i = 0; i <= n; i++)
{
b += Math.pow(1 - k, n - i) * Math.pow(k, i) * v[i] * this.bernstein(n, i);
}
return b;
},
/**
* A Catmull Rom Interpolation Method, mostly used by Phaser.Tween.
* @method Phaser.Math#catmullRomInterpolation
* @param {Array} v
* @param {number} k
* @return {number}
*/
catmullRomInterpolation: function (v, k) {
var m = v.length - 1;
var f = m * k;
var i = Math.floor(f);
if (v[0] === v[m])
{
if (k < 0)
{
i = Math.floor(f = m * (1 + k));
}
return this.catmullRom(v[(i - 1 + m) % m], v[i], v[(i + 1) % m], v[(i + 2) % m], f - i);
}
else
{
if (k < 0)
{
return v[0] - (this.catmullRom(v[0], v[0], v[1], v[1], -f) - v[0]);
}
if (k > 1)
{
return v[m] - (this.catmullRom(v[m], v[m], v[m - 1], v[m - 1], f - m) - v[m]);
}
return this.catmullRom(v[i ? i - 1 : 0], v[i], v[m < i + 1 ? m : i + 1], v[m < i + 2 ? m : i + 2], f - i);
}
},
/**
* Calculates a linear value over t.
*
* @method Phaser.Math#Linear
* @param {number} p0
* @param {number} p1
* @param {number} t
* @return {number}
*/
linear: function (p0, p1, t) {
return (p1 - p0) * t + p0;
},
/**
* @method Phaser.Math#bernstein
* @param {number} n
* @param {number} i
* @return {number}
*/
bernstein: function (n, i) {
return this.factorial(n) / this.factorial(i) / this.factorial(n - i);
},
/**
* @method Phaser.Math#factorial
* @param {number} value - the number you want to evaluate
* @return {number}
*/
factorial : function( value ){
if(value === 0)
{
return 1;
}
var res = value;
while( --value )
{
res *= value;
}
return res;
},
/**
* Calculates a callmum rom value.
*
* @method Phaser.Math#catmullRom
* @param {number} p0
* @param {number} p1
* @param {number} p2
* @param {number} p3
* @param {number} t
* @return {number}
*/
catmullRom: function (p0, p1, p2, p3, t) {
var v0 = (p2 - p0) * 0.5, v1 = (p3 - p1) * 0.5, t2 = t * t, t3 = t * t2;
return (2 * p1 - 2 * p2 + v0 + v1) * t3 + (-3 * p1 + 3 * p2 - 2 * v0 - v1) * t2 + v0 * t + p1;
},
/**
* @method Phaser.Math#difference
* @param {number} a
* @param {number} b
* @return {number}
*/
difference: function (a, b) {
return Math.abs(a - b);
},
/**
* Fetch a random entry from the given array.
* Will return null if random selection is missing, or array has no entries.
*
* @method Phaser.Math#getRandom
* @param {array} objects - An array of objects.
* @param {number} startIndex - Optional offset off the front of the array. Default value is 0, or the beginning of the array.
* @param {number} length - Optional restriction on the number of values you want to randomly select from.
* @return {object} The random object that was selected.
*/
getRandom: function (objects, startIndex, length) {
if (typeof startIndex === "undefined") { startIndex = 0; }
if (typeof length === "undefined") { length = 0; }
if (objects != null) {
var l = length;
if ((l === 0) || (l > objects.length - startIndex))
{
l = objects.length - startIndex;
}
if (l > 0)
{
return objects[startIndex + Math.floor(Math.random() * l)];
}
}
return null;
},
/**
* Removes a random object from the given array and returns it.
* Will return null if random selection is missing, or array has no entries.
*
* @method Phaser.Math#removeRandom
* @param {array} objects - An array of objects.
* @param {number} startIndex - Optional offset off the front of the array. Default value is 0, or the beginning of the array.
* @param {number} length - Optional restriction on the number of values you want to randomly select from.
* @return {object} The random object that was removed.
*/
removeRandom: function (objects, startIndex, length) {
if (typeof startIndex === "undefined") { startIndex = 0; }
if (typeof length === "undefined") { length = 0; }
if (objects != null) {
var l = length;
if ((l === 0) || (l > objects.length - startIndex))
{
l = objects.length - startIndex;
}
if (l > 0)
{
var idx = startIndex + Math.floor(Math.random() * l);
var removed = objects.splice(idx, 1);
return removed[0];
}
}
return null;
},
/**
* Round down to the next whole number. E.g. floor(1.7) == 1, and floor(-2.7) == -2.
*
* @method Phaser.Math#floor
* @param {number} Value Any number.
* @return {number} The rounded value of that number.
*/
floor: function (value) {
var n = value | 0;
return (value > 0) ? (n) : ((n != value) ? (n - 1) : (n));
},
/**
* Round up to the next whole number. E.g. ceil(1.3) == 2, and ceil(-2.3) == -3.
*
* @method Phaser.Math#ceil
* @param {number} value - Any number.
* @return {number} The rounded value of that number.
*/
ceil: function (value) {
var n = value | 0;
return (value > 0) ? ((n != value) ? (n + 1) : (n)) : (n);
},
/**
* Generate a sine and cosine table simultaneously and extremely quickly. Based on research by Franky of scene.at
* <p>
* The parameters allow you to specify the length, amplitude and frequency of the wave. Once you have called this function
* you should get the results via getSinTable() and getCosTable(). This generator is fast enough to be used in real-time.
* </p>
* @method Phaser.Math#sinCosGenerator
* @param {number} length - The length of the wave
* @param {number} sinAmplitude - The amplitude to apply to the sine table (default 1.0) if you need values between say -+ 125 then give 125 as the value
* @param {number} cosAmplitude - The amplitude to apply to the cosine table (default 1.0) if you need values between say -+ 125 then give 125 as the value
* @param {number} frequency - The frequency of the sine and cosine table data
* @return {Array} Returns the sine table
*/
sinCosGenerator: function (length, sinAmplitude, cosAmplitude, frequency) {
if (typeof sinAmplitude === "undefined") { sinAmplitude = 1.0; }
if (typeof cosAmplitude === "undefined") { cosAmplitude = 1.0; }
if (typeof frequency === "undefined") { frequency = 1.0; }
var sin = sinAmplitude;
var cos = cosAmplitude;
var frq = frequency * Math.PI / length;
var cosTable = [];
var sinTable = [];
for (var c = 0; c < length; c++) {
cos -= sin * frq;
sin += cos * frq;
cosTable[c] = cos;
sinTable[c] = sin;
}
return { sin: sinTable, cos: cosTable, length: length };
},
/**
* Removes the top element from the stack and re-inserts it onto the bottom, then returns it.
* The original stack is modified in the process. This effectively moves the position of the data from the start to the end of the table.
*
* @method Phaser.Math#shift
* @param {array} stack - The array to shift.
* @return {any} The shifted value.
*/
shift: function (stack) {
var s = stack.shift();
stack.push(s);
return s;
},
/**
* Shuffles the data in the given array into a new order
* @method Phaser.Math#shuffleArray
* @param {array} array - The array to shuffle
* @return {array} The array
*/
shuffleArray: function (array) {
for (var i = array.length - 1; i > 0; i--) {
var j = Math.floor(Math.random() * (i + 1));
var temp = array[i];
array[i] = array[j];
array[j] = temp;
}
return array;
},
/**
* Returns the distance between the two given set of coordinates.
*
* @method Phaser.Math#distance
* @param {number} x1
* @param {number} y1
* @param {number} x2
* @param {number} y2
* @return {number} The distance between the two sets of coordinates.
*/
distance: function (x1, y1, x2, y2) {
var dx = x1 - x2;
var dy = y1 - y2;
return Math.sqrt(dx * dx + dy * dy);
},
/**
* Returns the distance between the two given set of coordinates at the power given.
*
* @method Phaser.Math#distancePow
* @param {number} x1
* @param {number} y1
* @param {number} x2
* @param {number} y2
* @param {number} [pow=2]
* @return {number} The distance between the two sets of coordinates.
*/
distancePow: function (x1, y1, x2, y2, pow) {
if (typeof pow === 'undefined') { pow = 2; }
return Math.sqrt(Math.pow(x2 - x1, pow) + Math.pow(y2 - y1, pow));
},
/**
* Returns the rounded distance between the two given set of coordinates.
*
* @method Phaser.Math#distanceRounded
* @param {number} x1
* @param {number} y1
* @param {number} x2
* @param {number} y2
* @return {number} The distance between this Point object and the destination Point object.
*/
distanceRounded: function (x1, y1, x2, y2) {
return Math.round(Phaser.Math.distance(x1, y1, x2, y2));
},
/**
* Force a value within the boundaries of two values.
* Clamp value to range <a, b>
*
* @method Phaser.Math#clamp
* @param {number} x
* @param {number} a
* @param {number} b
* @return {number}
*/
clamp: function ( x, a, b ) {
return ( x < a ) ? a : ( ( x > b ) ? b : x );
},
/**
* Clamp value to range <a, inf).
*
* @method Phaser.Math#clampBottom
* @param {number} x
* @param {number} a
* @return {number}
*/
clampBottom: function ( x, a ) {
return x < a ? a : x;
},
/**
* Checks if two values are within the given tolerance of each other.
*
* @method Phaser.Math#within
* @param {number} a - The first number to check
* @param {number} b - The second number to check
* @param {number} tolerance - The tolerance. Anything equal to or less than this is considered within the range.
* @return {boolean} True if a is <= tolerance of b.
*/
within: function ( a, b, tolerance ) {
return (Math.abs(a - b) <= tolerance);
},
/**
* Linear mapping from range <a1, a2> to range <b1, b2>
*
* @method Phaser.Math#mapLinear
* @param {number} x the value to map
* @param {number} a1 first endpoint of the range <a1, a2>
* @param {number} a2 final endpoint of the range <a1, a2>
* @param {number} b1 first endpoint of the range <b1, b2>
* @param {number} b2 final endpoint of the range <b1, b2>
* @return {number}
*/
mapLinear: function ( x, a1, a2, b1, b2 ) {
return b1 + ( x - a1 ) * ( b2 - b1 ) / ( a2 - a1 );
},
/**
* Smoothstep function as detailed at http://en.wikipedia.org/wiki/Smoothstep
*
* @method Phaser.Math#smoothstep
* @param {number} x
* @param {number} min
* @param {number} max
* @return {number}
*/
smoothstep: function ( x, min, max ) {
x = Math.max(0, Math.min(1, (x - min) / (max - min)));
return x * x * (3 - 2 * x);
},
/**
* Smootherstep function as detailed at http://en.wikipedia.org/wiki/Smoothstep
*
* @method Phaser.Math#smootherstep
* @param {number} x
* @param {number} min
* @param {number} max
* @return {number}
*/
smootherstep: function ( x, min, max ) {
x = Math.max(0, Math.min(1, (x - min) / (max - min)));
return x * x * x * (x * (x * 6 - 15) + 10);
},
/**
* A value representing the sign of the value.
* -1 for negative, +1 for positive, 0 if value is 0
*
* @method Phaser.Math#sign
* @param {number} x
* @return {number}
*/
sign: function ( x ) {
return ( x < 0 ) ? -1 : ( ( x > 0 ) ? 1 : 0 );
},
/**
* Work out what percentage value a is of value b using the given base.
*
* @method Phaser.Math#percent
* @param {number} a - The value to work out the percentage for.
* @param {number} b - The value you wish to get the percentage of.
* @param {number} [base=0] - The base value.
* @return {number} The percentage a is of b, between 0 and 1.
*/
percent: function (a, b, base) {
if (typeof base === 'undefined') { base = 0; }
if (a > b || base > b)
{
return 1;
}
else if (a < base || base > a)
{
return 0;
}
else
{
return (a - base) / b;
}
},
/**
* Convert degrees to radians.
*
* @method Phaser.Math#degToRad
* @return {function}
*/
degToRad: (function() {
var degreeToRadiansFactor = Math.PI / 180;
return function ( degrees ) {
return degrees * degreeToRadiansFactor;
};
}()),
/**
* Convert degrees to radians.
*
* @method Phaser.Math#radToDeg
* @return {function}
*/
radToDeg: (function() {
var radianToDegreesFactor = 180 / Math.PI;
return function ( radians ) {
return radians * radianToDegreesFactor;
};
}())
};