AsciiEffect.js

/**
 * @author zz85 / https://github.com/zz85
 *
 * Ascii generation is based on http://www.nihilogic.dk/labs/jsascii/
 * Maybe more about this later with a blog post at http://lab4games.net/zz85/blog
 *
 * 16 April 2012 - @blurspline
 */



var AsciiEffect = function ( renderer, charSet, options ) {

	// its fun to create one your own!

	charSet = ( charSet === undefined ) ? ' .:-=+*#%@' : charSet;

	// ' .,:;=|iI+hHOE#`$';
	// darker bolder character set from https://github.com/saw/Canvas-ASCII-Art/
	// ' .\'`^",:;Il!i~+_-?][}{1)(|/tfjrxnuvczXYUJCLQ0OZmwqpdbkhao*#MW&8%B@$'.split('');

	if ( ! options ) options = {};

	// Some ASCII settings

	var bResolution = ! options[ 'resolution' ] ? 0.15 : options[ 'resolution' ]; // Higher for more details
	var iScale = ! options[ 'scale' ] ? 1 : options[ 'scale' ];
	var bColor = ! options[ 'color' ] ? false : options[ 'color' ]; // nice but slows down rendering!
	var bAlpha = ! options[ 'alpha' ] ? false : options[ 'alpha' ]; // Transparency
	var bBlock = ! options[ 'block' ] ? false : options[ 'block' ]; // blocked characters. like good O dos
	var bInvert = ! options[ 'invert' ] ? false : options[ 'invert' ]; // black is white, white is black

	var strResolution = 'low';

	var width, height;

	var domElement = document.createElement( 'div' );
	domElement.style.cursor = 'default';

	var oAscii = document.createElement( "table" );
	domElement.appendChild( oAscii );

	var iWidth, iHeight;
	var oImg;

	this.setSize = function ( w, h ) {

		width = w;
		height = h;

		renderer.setSize( w, h );

		initAsciiSize();

	};


	this.render = function ( scene, camera ) {

		renderer.render( scene, camera );
		asciifyImage( renderer, oAscii );

	};

	this.domElement = domElement;


	// Throw in ascii library from http://www.nihilogic.dk/labs/jsascii/jsascii.js

	/*
	* jsAscii 0.1
	* Copyright (c) 2008 Jacob Seidelin, jseidelin@nihilogic.dk, http://blog.nihilogic.dk/
	* MIT License [http://www.nihilogic.dk/licenses/mit-license.txt]
	*/

	function initAsciiSize() {

		iWidth = Math.round( width * fResolution );
		iHeight = Math.round( height * fResolution );

		oCanvas.width = iWidth;
		oCanvas.height = iHeight;
		// oCanvas.style.display = "none";
		// oCanvas.style.width = iWidth;
		// oCanvas.style.height = iHeight;

		oImg = renderer.domElement;

		if ( oImg.style.backgroundColor ) {

			oAscii.rows[ 0 ].cells[ 0 ].style.backgroundColor = oImg.style.backgroundColor;
			oAscii.rows[ 0 ].cells[ 0 ].style.color = oImg.style.color;

		}

		oAscii.cellSpacing = 0;
		oAscii.cellPadding = 0;

		var oStyle = oAscii.style;
		oStyle.display = "inline";
		oStyle.width = Math.round( iWidth / fResolution * iScale ) + "px";
		oStyle.height = Math.round( iHeight / fResolution * iScale ) + "px";
		oStyle.whiteSpace = "pre";
		oStyle.margin = "0px";
		oStyle.padding = "0px";
		oStyle.letterSpacing = fLetterSpacing + "px";
		oStyle.fontFamily = strFont;
		oStyle.fontSize = fFontSize + "px";
		oStyle.lineHeight = fLineHeight + "px";
		oStyle.textAlign = "left";
		oStyle.textDecoration = "none";

	}


	var aDefaultCharList = ( " .,:;i1tfLCG08@" ).split( "" );
	var aDefaultColorCharList = ( " CGO08@" ).split( "" );
	var strFont = "courier new, monospace";

	var oCanvasImg = renderer.domElement;

	var oCanvas = document.createElement( "canvas" );
	if ( ! oCanvas.getContext ) {

		return;

	}

	var oCtx = oCanvas.getContext( "2d" );
	if ( ! oCtx.getImageData ) {

		return;

	}

	var aCharList = ( bColor ? aDefaultColorCharList : aDefaultCharList );

	if ( charSet ) aCharList = charSet;

	var fResolution = 0.5;

	switch ( strResolution ) {

		case "low" : 	fResolution = 0.25; break;
		case "medium" : fResolution = 0.5; break;
		case "high" : 	fResolution = 1; break;

	}

	if ( bResolution ) fResolution = bResolution;

	// Setup dom

	var fFontSize = ( 2 / fResolution ) * iScale;
	var fLineHeight = ( 2 / fResolution ) * iScale;

	// adjust letter-spacing for all combinations of scale and resolution to get it to fit the image width.

	var fLetterSpacing = 0;

	if ( strResolution == "low" ) {

		switch ( iScale ) {

			case 1 : fLetterSpacing = - 1; break;
			case 2 :
			case 3 : fLetterSpacing = - 2.1; break;
			case 4 : fLetterSpacing = - 3.1; break;
			case 5 : fLetterSpacing = - 4.15; break;

		}

	}

	if ( strResolution == "medium" ) {

		switch ( iScale ) {

			case 1 : fLetterSpacing = 0; break;
			case 2 : fLetterSpacing = - 1; break;
			case 3 : fLetterSpacing = - 1.04; break;
			case 4 :
			case 5 : fLetterSpacing = - 2.1; break;

		}

	}

	if ( strResolution == "high" ) {

		switch ( iScale ) {

			case 1 :
			case 2 : fLetterSpacing = 0; break;
			case 3 :
			case 4 :
			case 5 : fLetterSpacing = - 1; break;

		}

	}


	// can't get a span or div to flow like an img element, but a table works?


	// convert img element to ascii

	function asciifyImage( canvasRenderer, oAscii ) {

		oCtx.clearRect( 0, 0, iWidth, iHeight );
		oCtx.drawImage( oCanvasImg, 0, 0, iWidth, iHeight );
		var oImgData = oCtx.getImageData( 0, 0, iWidth, iHeight ).data;

		// Coloring loop starts now
		var strChars = "";

		// console.time('rendering');

		for ( var y = 0; y < iHeight; y += 2 ) {

			for ( var x = 0; x < iWidth; x ++ ) {

				var iOffset = ( y * iWidth + x ) * 4;

				var iRed = oImgData[ iOffset ];
				var iGreen = oImgData[ iOffset + 1 ];
				var iBlue = oImgData[ iOffset + 2 ];
				var iAlpha = oImgData[ iOffset + 3 ];
				var iCharIdx;

				var fBrightness;

				fBrightness = ( 0.3 * iRed + 0.59 * iGreen + 0.11 * iBlue ) / 255;
				// fBrightness = (0.3*iRed + 0.5*iGreen + 0.3*iBlue) / 255;

				if ( iAlpha == 0 ) {

					// should calculate alpha instead, but quick hack :)
					//fBrightness *= (iAlpha / 255);
					fBrightness = 1;

				}

				iCharIdx = Math.floor( ( 1 - fBrightness ) * ( aCharList.length - 1 ) );

				if ( bInvert ) {

					iCharIdx = aCharList.length - iCharIdx - 1;

				}

				// good for debugging
				//fBrightness = Math.floor(fBrightness * 10);
				//strThisChar = fBrightness;

				var strThisChar = aCharList[ iCharIdx ];

				if ( strThisChar === undefined || strThisChar == " " )
					strThisChar = "&nbsp;";

				if ( bColor ) {

					strChars += "<span style='"
						+ "color:rgb(" + iRed + "," + iGreen + "," + iBlue + ");"
						+ ( bBlock ? "background-color:rgb(" + iRed + "," + iGreen + "," + iBlue + ");" : "" )
						+ ( bAlpha ? "opacity:" + ( iAlpha / 255 ) + ";" : "" )
						+ "'>" + strThisChar + "</span>";

				} else {

					strChars += strThisChar;

				}

			}
			strChars += "<br/>";

		}

		oAscii.innerHTML = "<tr><td>" + strChars + "</td></tr>";

		// console.timeEnd('rendering');

		// return oAscii;

	}

	// end modified asciifyImage block

};

export { AsciiEffect };