68 lines
2 KiB
JavaScript
68 lines
2 KiB
JavaScript
'use strict';
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/*global require, module*/
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/************************************************************************
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### Drone.rand() method
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rand takes either an array (if each blockid has the same chance of occurring) or an object where each property is a blockid and the value is it's weight (an integer)
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#### Example
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place random blocks stone, mossy stone and cracked stone (each block has the same chance of being picked)
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rand( [blocks.brick.stone, blocks.brick.mossy, blocks.brick.cracked ],w,d,h)
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to place random blocks stone has a 50% chance of being picked,
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var distribution = {};
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distribution[ blocks.brick.stone ] = 5;
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distribution[ blocks.brick.mossy ] = 3;
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distribution[ blocks.brick.cracked ] = 2;
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rand( distribution, width, height, depth)
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regular stone has a 50% chance, mossy stone has a 30% chance and cracked stone has just a 20% chance of being picked.
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***/
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//
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// standard fisher-yates shuffle algorithm
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//
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function fisherYates( myArray ) {
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var i = myArray.length;
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if ( i == 0 ) return false;
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while ( --i ) {
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var j = Math.floor( Math.random( ) * ( i + 1 ) );
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var tempi = myArray[i];
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var tempj = myArray[j];
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myArray[i] = tempj;
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myArray[j] = tempi;
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}
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}
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function _rand( blockDistribution ) {
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if ( !(blockDistribution.constructor == Array ) ) {
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var a = [];
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for ( var p in blockDistribution ) {
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var n = blockDistribution[p];
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for ( var i = 0;i < n;i++ ) {
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a.push(p );
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}
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}
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blockDistribution = a;
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}
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while ( blockDistribution.length < 1000 ) {
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// make array bigger so that it's more random
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blockDistribution = blockDistribution.concat(blockDistribution );
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}
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fisherYates(blockDistribution );
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return blockDistribution;
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}
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function rand( dist, width, height, depth, overwrite ) {
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if ( typeof overwrite == 'undefined' ) {
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overwrite = true;
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}
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var randomized = _rand( dist );
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this.boxa( randomized, width, height, depth, overwrite);
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}
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module.exports = function(Drone){
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Drone.extend( rand );
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};
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