/**
* @author Richard Davey <rich@photonstorm.com>
* @copyright 2014 Photon Storm Ltd.
* @license {@link https://github.com/photonstorm/phaser/blob/master/license.txt|MIT License}
*/
/**
* Utility functions for dealing with Arrays.
*
* @class Phaser.ArrayUtils
* @static
*/
Phaser.ArrayUtils = {
/**
* Fetch a random entry from the given array.
* Will return null if random selection is missing, or array has no entries.
*
* @method
* @param {any[]} objects - An array of objects.
* @param {integer} startIndex - Optional offset off the front of the array. Default value is 0, or the beginning of the array.
* @param {integer} length - Optional restriction on the number of values you want to randomly select from.
* @return {object} The random object that was selected.
*/
getRandomItem: function (objects, startIndex, length) {
if (objects == null) { // undefined or null
return null;
}
if (typeof startIndex === 'undefined') { startIndex = 0; }
if (typeof length === 'undefined') { length = objects.length; }
var randomIndex = startIndex + Math.floor(Math.random() * length);
return objects[randomIndex] || 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
* @param {any[]} objects - An array of objects.
* @param {integer} startIndex - Optional offset off the front of the array. Default value is 0, or the beginning of the array.
* @param {integer} length - Optional restriction on the number of values you want to randomly select from.
* @return {object} The random object that was removed.
*/
removeRandomItem: function (objects, startIndex, length) {
if (objects == null) { // undefined or null
return null;
}
if (typeof startIndex === 'undefined') { startIndex = 0; }
if (typeof length === 'undefined') { length = objects.length; }
var randomIndex = startIndex + Math.floor(Math.random() * length);
if (randomIndex < objects.length)
{
var removed = objects.splice(randomIndex, 1);
return removed[0];
}
else
{
return null;
}
},
/**
* A standard Fisher-Yates Array shuffle implementation which modifies the array in place.
*
* @method
* @param {array} array - The array to shuffle.
* @return {array} The original array, now shuffled.
*/
shuffle: 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;
},
/**
* Transposes the elements of the given Array.
*
* @method
* @param {array} array - The array to transpose.
* @return {array} The transposed array.
*/
transposeMatrix: function (array) {
var result = new Array(array[0].length);
for (var i = 0; i < array[0].length; i++)
{
result[i] = new Array(array.length - 1);
for (var j = array.length - 1; j > -1; j--)
{
result[i][j] = array[j][i];
}
}
return result;
},
/**
* Rotates the given array.
* Based on the routine from http://jsfiddle.net/MrPolywhirl/NH42z/
*
* @method
* @param {array} matrix - The array to rotate.
* @param {number|string} direction - The amount to rotate. Either a number: 90, -90, 270, -270, 180 or a string: 'rotateLeft', 'rotateRight' or 'rotate180'
* @return {array} The rotated array
*/
rotateMatrix: function (matrix, direction) {
if (typeof direction !== 'string')
{
direction = ((direction % 360) + 360) % 360;
}
if (direction === 90 || direction === -270 || direction === 'rotateLeft')
{
matrix = Phaser.ArrayUtils.transposeMatrix(matrix);
matrix = matrix.reverse();
}
else if (direction === -90 || direction === 270 || direction === 'rotateRight')
{
matrix = matrix.reverse();
matrix = Phaser.ArrayUtils.transposeMatrix(matrix);
}
else if (Math.abs(direction) === 180 || direction === 'rotate180')
{
for (var i = 0; i < matrix.length; i++)
{
matrix[i].reverse();
}
matrix = matrix.reverse();
}
return matrix;
},
/**
* Snaps a value to the nearest value in an array.
* The result will always be in the range `[first_value, last_value]`.
*
* @method
* @param {number} value - The search value
* @param {number[]} arr - The input array which _must_ be sorted.
* @return {number} The nearest value found.
*/
findClosest: function (value, arr) {
if (!arr.length)
{
return NaN;
}
else if (arr.length === 1 || value < arr[0])
{
return arr[0];
}
var i = 1;
while (arr[i] < value) {
i++;
}
var low = arr[i - 1];
var high = (i < arr.length) ? arr[i] : Number.POSITIVE_INFINITY;
return ((high - value) <= (value - low)) ? high : low;
},
/**
* Moves the element from the start of the array to the end, shifting all items in the process.
* The "rotation" happens to the left.
*
* @method Phaser.ArrayUtils.rotate
* @param {any[]} array - The array to shift/rotate. The array is modified.
* @return {any} The shifted value.
*/
rotate: function (array) {
var s = array.shift();
array.push(s);
return s;
},
/**
* Create an array representing the inclusive range of numbers (usually integers) in `[start, end]`.
* This is equivalent to `numberArrayStep(start, end, 1)`.
*
* @method Phaser.Math#numberArray
* @param {number} start - The minimum value the array starts with.
* @param {number} end - The maximum value the array contains.
* @return {array} The array of number values.
*/
numberArray: function (start, end) {
var result = [];
for (var i = start; i <= end; i++)
{
result.push(i);
}
return result;
},
/**
* Create an array of numbers (positive and/or negative) progressing from `start`
* up to but not including `end` by advancing by `step`.
*
* If `start` is less than `stop` a zero-length range is created unless a negative `step` is specified.
*
* Certain values for `start` and `end` (eg. NaN/undefined/null) are currently coerced to 0;
* for forward compatibility make sure to pass in actual numbers.
*
* @method Phaser.Math#numberArrayStep
* @param {number} start - 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 = Math.max(Phaser.Math.roundAwayFromZero((end - start) / (step || 1)), 0);
var result = new Array(length);
while (++index < length)
{
result[index] = start;
start += step;
}
return result;
}
};