Source: d:/wamp/www/phaser/src/pixi/filters/AsciiFilter.js

/**
 * @author Vico @vicocotea
 * original shader : https://www.shadertoy.com/view/lssGDj by @movAX13h
 */

/**
 * An ASCII filter.
 * 
 * @class AsciiFilter
 * @extends AbstractFilter
 * @constructor
 */
PIXI.AsciiFilter = function()
{
    PIXI.AbstractFilter.call( this );

    this.passes = [this];

    // set the uniforms
    this.uniforms = {
        dimensions: {type: '4fv', value:new PIXI.Float32Array([10000, 100, 10, 10])},
        pixelSize: {type: '1f', value:8}
    };

    this.fragmentSrc = [
        
        'precision mediump float;',
        'uniform vec4 dimensions;',
        'uniform float pixelSize;',
        'uniform sampler2D uSampler;',

        'float character(float n, vec2 p)',
        '{',
        '    p = floor(p*vec2(4.0, -4.0) + 2.5);',
        '    if (clamp(p.x, 0.0, 4.0) == p.x && clamp(p.y, 0.0, 4.0) == p.y)',
        '    {',
        '        if (int(mod(n/exp2(p.x + 5.0*p.y), 2.0)) == 1) return 1.0;',
        '    }',
        '    return 0.0;',
        '}',

        'void main()',
        '{',
        '    vec2 uv = gl_FragCoord.xy;',
        '    vec3 col = texture2D(uSampler, floor( uv / pixelSize ) * pixelSize / dimensions.xy).rgb;',
            
        '    #ifdef HAS_GREENSCREEN',
        '    float gray = (col.r + col.b)/2.0;', 
        '    #else',
        '    float gray = (col.r + col.g + col.b)/3.0;',
        '    #endif',
  
        '    float n =  65536.0;             // .',
        '    if (gray > 0.2) n = 65600.0;    // :',
        '    if (gray > 0.3) n = 332772.0;   // *',
        '    if (gray > 0.4) n = 15255086.0; // o',
        '    if (gray > 0.5) n = 23385164.0; // &',
        '    if (gray > 0.6) n = 15252014.0; // 8',
        '    if (gray > 0.7) n = 13199452.0; // @',
        '    if (gray > 0.8) n = 11512810.0; // #',
            
        '    vec2 p = mod( uv / ( pixelSize * 0.5 ), 2.0) - vec2(1.0);',
        '    col = col * character(n, p);',
            
        '    gl_FragColor = vec4(col, 1.0);',
        '}'
    ];
};

PIXI.AsciiFilter.prototype = Object.create( PIXI.AbstractFilter.prototype );
PIXI.AsciiFilter.prototype.constructor = PIXI.AsciiFilter;

/**
 * The pixel size used by the filter.
 *
 * @property size
 * @type Number
 */
Object.defineProperty(PIXI.AsciiFilter.prototype, 'size', {
    get: function() {
        return this.uniforms.pixelSize.value;
    },
    set: function(value) {
        this.dirty = true;
        this.uniforms.pixelSize.value = value;
    }
});