251 lines
7.1 KiB
JavaScript
251 lines
7.1 KiB
JavaScript
/**
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* Renders a given map
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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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* Renders a map to a canvas
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*/
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ltjs.MapRender = Class( 'MapRender',
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{
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/**
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* Property to hold lock bit on canvas element
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* @type {string}
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*/
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'private const _LOCK': '__$$MapRenderLock$$',
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/**
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* 2d context to which map should be drawn
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* @type {CanvasRenderingContext2d}
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*/
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'private _ctx': null,
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/**
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* 2d context to which masked game objects should be drawn
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* @type {CanvasRenderingContext2d}
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*/
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'private _ctxObj': null,
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/**
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* Tile set to be rendered
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* @type {Object}
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*/
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'private _tiles': {},
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/**
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* Initialize renderer with a canvas context and a tile set
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*
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* An additional canvas of equal dimensions will be created and laid atop of
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* the provided canvas to render masked game objects.
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*
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* @param {CanvasRenderingContext2d} ctx canvas 2d context
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* @param {Object} tiles tile set to render
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*/
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__construct: function( ctx, tiles )
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{
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this._ctx = ctx;
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this._tiles = tiles;
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// ensure that we are exclusively rendering to this canvas (no other
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// MapRenders)
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this._lockCanvas();
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this._ctxObj = this._getObjCanvas();
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},
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/**
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* Lock the canvas to prevent other MapRender instances from rendering to it
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*
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* The purpose of this is to provide feedback to the user/developer in the
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* event that multiple MapRender instances are attempting to render to the
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* same canvas, which would certainly cause display issues and confusion.
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*
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* @return {undefined}
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*/
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'private _lockCanvas': function()
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{
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var o = this._ctx,
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l = this.__self.$( '_LOCK' );
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// simple one-line check to both set the lock and fail if the lock is
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// already set (implying that something else is already rendering to the
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// canvas)
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if ( ( o[ l ] ^= 1 ) !== 1 )
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{
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// reset the lock
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o[ l ] = 1;
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throw Error(
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'Could not set exclusive lock on canvas (in use by another ' +
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'MapRender instance)'
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);
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}
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},
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/**
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* Remove exclusive lock on canvas to permit other MapRender instances to
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* render to it
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*
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* This will also destroy the overlay canvas that the masked objects were
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* rendered to. The remaining canvas will not be cleared.
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*
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* @return {MapRender} self
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*/
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'public freeCanvas': function()
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{
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var c = this._ctxObj.canvas;
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// destroy the overlay canvas
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c.parentNode.removeChild( c );
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// free the lock
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this._ctx[ this.__self.$( '_LOCK' ) ] = 0;
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return this;
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},
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/**
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* Create the overlaying canvas for masked elements and return a 2d context
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*
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* @return {CanvasRenderingContext2d} 2d context for new canvas element
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*/
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'private _getObjCanvas': function()
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{
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var canvas = this._ctx.canvas,
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canvas_obj = document.createElement( 'canvas' );
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// mimic the dimensions and positions of the original canvas
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canvas_obj.style.position = 'absolute';
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canvas_obj.width = canvas.width;
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canvas_obj.height = canvas.height;
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canvas_obj.style.left = ( canvas.offsetLeft + 'px' );
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canvas_obj.style.top = ( canvas.offsetTop + 'px' );
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// append the new canvas to the DOM under the same parent
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canvas.parentNode.appendChild( canvas_obj );
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return canvas_obj.getContext( '2d' );
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},
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/**
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* Render the provided map
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*
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* @param {Map} map map to render
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*
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* @return {MapRender} self
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*/
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'public render': function( map )
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{
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if ( !( Class.isA( ltjs.Map, map ) ) )
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{
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throw TypeError( 'Invalid Map provided' );
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}
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var objs = map.getObjects(),
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size = map.getDimensions(),
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omap = map.getObjectTileMap(),
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sizex = size[ 0 ],
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sizey = size[ 1 ],
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i = objs.length,
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// get the width and height from one of the tiles
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t = this._tiles.dirt.data,
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w = t.width,
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h = t.height;
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// render each object (remember, we're dealing with columns, not rows;
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// see Map.getObjects())
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while ( i-- )
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{
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var oid = objs[ i ],
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tid = omap[ oid ],
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x = ( Math.floor( i / sizex ) * w ),
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y = ( ( i % sizey ) * h );
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// tunnels are handled a bit differently than other objects
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if ( map.isObjectTunnel( oid ) )
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{
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this._renderTunnel( x, y, map.getTunnelColor( oid ) );
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continue;
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}
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this._drawTile( tid, x, y );
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}
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return this;
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},
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/**
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* Draw the tile identified by the given id
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*
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* The tile will be drawn to the appropriate canvas depending on whether or
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* not it has been masked. If it does have a mask, it will be drawn to the
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* overlaying canvas and the dirt tile will be drawn underneath it.
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*
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* @param {string} tid tile id
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* @param {number} x left position
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* @param {number} y top position
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*
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* @return {undefined}
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*/
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'private _drawTile': function( tid, x, y )
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{
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var tile = this._tiles[ tid ],
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ctx = ( tile.masked ) ? this._ctxObj : this._ctx;
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ctx.putImageData( this._tiles[ tid ].first.data, x, y );
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if ( tile.masked )
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{
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this._ctx.putImageData( this._tiles.dirt.data, x, y );
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}
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},
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/**
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* Render the given tunnel
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*
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* The tunnel background color (which will peek through the mask) is
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* rendered to the base canvas, whereas the tunnel tile itself is rendered
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* on the overlaying canvas.
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*
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* @param {number} x left position
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* @param {number} y top position
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* @param {string} color tunnel color (CSS value)
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*
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* @return {undefined}
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*/
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'private _renderTunnel': function( x, y, color )
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{
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var tdata = this._tiles.tunnel.data;
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// fill tile with the appropriate background color for this tile
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this._ctx.fillStyle = color;
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this._ctx.fillRect( x, y, tdata.width, tdata.height );
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// render the tile to the overlay canvas
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this._ctxObj.putImageData( tdata, x, y );
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}
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} );
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