120 lines
3.3 KiB
JavaScript
120 lines
3.3 KiB
JavaScript
/**
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* Handles the loading of LVL files
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*
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* Copyright (C) 2012 Mike Gerwitz
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*
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* Maps (the term "level" is used in the game) are stored in a fixed-width LVL
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* file.
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*/
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/**
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* Handles delegation of LVL data
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*
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* This acts as a Map factory, leaving all processing responsibilities to the
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* Map instance. Consequently, any custom map format would be supported,
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* provided that the appropriate Map is handling it.
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*/
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ltjs.MapSet = Class( 'MapSet',
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{
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/**
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* Raw level set data (binary)
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* @type {string}
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*/
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'private _data': '',
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/**
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* Constructor used to create new map instances
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* @type {Function}
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*/
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'private _mapCtor': null,
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/**
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* Number of maps in the given LVL data
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* @type {number}
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*/
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'private _mapCount': 0,
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/**
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* Initialize map set with LVL data and a Map constructor
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*
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* The Map constructor is used in place of a separate Map factory.
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*
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* @param {string} data binary LVL data
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* @param {ltjs.Map} map_ctor Map constructor
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*/
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__construct: function( data, map_ctor )
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{
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this._data = ''+( data );
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this._mapCtor = map_ctor;
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// perform a simple integrity check on the provided data
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this._mapDataCheck();
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},
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/**
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* Perform a simple map data integrity check
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*
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* This is intended to throw an error if we believe the LVL data to be
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* invalid, or if the LVL data is invalid for the given Map constructor.
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* The check will simply ensure that the map size (in bytes) divides into
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* the total LVL size (in bytes) without any remainder.
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*
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* This is by no means fool-proof, but it should catch most.
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*
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* @return {undefined}
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*/
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'private _mapDataCheck': function()
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{
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var n = ( this._data.length / this._mapCtor.getMapSize() );
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// if the result is not an integer, then it is either not an LVL, the
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// file is corrupt, or we were given the wrong Map constructor
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if ( n % 1 )
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{
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throw Error( 'Invalid or corrupt LVL data' );
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}
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// we already calculated it, so we may as well store it
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this._mapCount = n;
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},
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/**
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* Load a level by the given number (e.g. level 1)
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*
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* @param {number} id number of level to load, 1-indexed
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*/
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'public getMapByNumber': function( id )
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{
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return this._mapCtor( this._data, id );
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},
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/**
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* Retrieve the number of maps in the LVL file
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*
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* @return {number} number of maps
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*/
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'public getMapCount': function()
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{
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return this._mapCount;
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},
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} );
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