Babylon.js/postProcessLibrary/src/asciiArt/babylon.asciiArtPostProcess.ts

/// <reference path="../../../dist/preview release/babylon.d.ts"/>

module BABYLON {

    /**
     * AsciiArtFontTexture is the helper class used to easily create your ascii art font texture.
     * 
     * It basically takes care rendering the font front the given font size to a texture.
     * This is used later on in the postprocess.
     */
    export class AsciiArtFontTexture extends BaseTexture {
        
        @serialize("font")
        private _font: string;

        @serialize("text")
        private _text: string;

        private _charSize: number;

        /**
         * Gets the size of one char in the texture (each char fits in size * size space in the texture). 
         */
        public get charSize(): number {
            return this._charSize;
        }

        /**
         * Create a new instance of the Ascii Art FontTexture class
         * @param name the name of the texture
         * @param font the font to use, use the W3C CSS notation
         * @param text the caracter set to use in the rendering.
         * @param scene the scene that owns the texture
         */
        constructor(name: string, font: string, text: string, scene: Nullable<Scene> = null) {
            super(scene);

            scene = this.getScene();

            if (!scene) {
                return;
            }

            this.name = name;
            this._text == text;
            this._font == font;

            this.wrapU = Texture.CLAMP_ADDRESSMODE;
            this.wrapV = Texture.CLAMP_ADDRESSMODE;
            //this.anisotropicFilteringLevel = 1;

            // Get the font specific info.
            var maxCharHeight = this.getFontHeight(font);
            var maxCharWidth = this.getFontWidth(font); 

            this._charSize = Math.max(maxCharHeight.height, maxCharWidth);

            // This is an approximate size, but should always be able to fit at least the maxCharCount.
            var textureWidth = Math.ceil(this._charSize * text.length);
            var textureHeight = this._charSize;

            // Create the texture that will store the font characters.
            this._texture = scene.getEngine().createDynamicTexture(textureWidth, textureHeight, false, Texture.NEAREST_SAMPLINGMODE);
            //scene.getEngine().setclamp
            var textureSize = this.getSize();

            // Create a canvas with the final size: the one matching the texture.
            var canvas = document.createElement("canvas");
            canvas.width = textureSize.width;
            canvas.height = textureSize.height;
            var context = <CanvasRenderingContext2D>canvas.getContext("2d");
            context.textBaseline = "top";
            context.font = font;
            context.fillStyle = "white";
            context.imageSmoothingEnabled = false;

            // Sets the text in the texture.
            for (var i = 0; i < text.length; i++) {
                context.fillText(text[i], i * this._charSize, -maxCharHeight.offset);
            }        

            // Flush the text in the dynamic texture.
          
            scene.getEngine().updateDynamicTexture(this._texture, canvas, false, true);
        }

        /**
         * Gets the max char width of a font.
         * @param font the font to use, use the W3C CSS notation
         * @return the max char width
         */
        private getFontWidth(font: string): number {
            var fontDraw = document.createElement("canvas");
            var ctx = <CanvasRenderingContext2D>fontDraw.getContext('2d');
            ctx.fillStyle = 'white';
            ctx.font = font;

            return ctx.measureText("W").width;
        }

        // More info here: https://videlais.com/2014/03/16/the-many-and-varied-problems-with-measuring-font-height-for-html5-canvas/
        /**
         * Gets the max char height of a font.
         * @param font the font to use, use the W3C CSS notation
         * @return the max char height
         */
        private getFontHeight(font: string): {height: number, offset: number} {
            var fontDraw = document.createElement("canvas");
            var ctx = <CanvasRenderingContext2D>fontDraw.getContext('2d');
            ctx.fillRect(0, 0, fontDraw.width, fontDraw.height);
            ctx.textBaseline = 'top';
            ctx.fillStyle = 'white';
            ctx.font = font;
            ctx.fillText('jH|', 0, 0);
            var pixels = ctx.getImageData(0, 0, fontDraw.width, fontDraw.height).data;
            var start = -1;
            var end = -1;
            for (var row = 0; row < fontDraw.height; row++) {
                for (var column = 0; column < fontDraw.width; column++) {
                    var index = (row * fontDraw.width + column) * 4;
                    if (pixels[index] === 0) {
                        if (column === fontDraw.width - 1 && start !== -1) {
                            end = row;
                            row = fontDraw.height;
                            break;
                        }
                        continue;
                    }
                    else {
                        if (start === -1) {
                            start = row;
                        }
                        break;
                    }
                }
            }
            return { height: (end - start)+1, offset: start-1}
        }

        /**
         * Clones the current AsciiArtTexture.
         * @return the clone of the texture.
         */
        public clone(): AsciiArtFontTexture {
            return new AsciiArtFontTexture(this.name, this._font, this._text, this.getScene());
        }

        /**
         * Parses a json object representing the texture and returns an instance of it.
         * @param source the source JSON representation
         * @param scene the scene to create the texture for
         * @return the parsed texture
         */
        public static Parse(source: any, scene: Scene): AsciiArtFontTexture {
            var texture = SerializationHelper.Parse(() => new AsciiArtFontTexture(source.name, source.font, source.text, scene), 
                source, scene, null);

            return texture;
        }
    }

    /**
     * Option available in the Ascii Art Post Process.
     */
    export interface IAsciiArtPostProcessOptions {

        /**
         * The font to use following the w3c font definition.
         */
        font?: string;

        /**
         * The character set to use in the postprocess.
         */
        characterSet?: string;

        /**
         * This defines the amount you want to mix the "tile" or caracter space colored in the ascii art.
         * This number is defined between 0 and 1;
         */
        mixToTile?:number;

        /**
         * This defines the amount you want to mix the normal rendering pass in the ascii art.
         * This number is defined between 0 and 1;
         */
        mixToNormal?:number;
    }

    /**
     * AsciiArtPostProcess helps rendering everithing in Ascii Art.
     * 
     * Simmply add it to your scene and let the nerd that lives in you have fun.
     * Example usage: var pp = new AsciiArtPostProcess("myAscii", "20px Monospace", camera);
     */
    export class AsciiArtPostProcess extends PostProcess {

        /**
         * The font texture used to render the char in the post process.
         */
        private _asciiArtFontTexture: AsciiArtFontTexture;

        /**
         * This defines the amount you want to mix the "tile" or caracter space colored in the ascii art.
         * This number is defined between 0 and 1;
         */
        public mixToTile:number = 0;

        /**
         * This defines the amount you want to mix the normal rendering pass in the ascii art.
         * This number is defined between 0 and 1;
         */
        public mixToNormal:number = 0;

        /**
         * Instantiates a new Ascii Art Post Process.
         * @param name the name to give to the postprocess
         * @camera the camera to apply the post process to.
         * @param options can either be the font name or an option object following the IAsciiArtPostProcessOptions format
         */
        constructor(name: string, camera: Camera, options?: string | IAsciiArtPostProcessOptions) {
            super(name, 
                'asciiart', 
                ['asciiArtFontInfos', 'asciiArtOptions'], 
                ['asciiArtFont'],
                { 
                    width: camera.getEngine().getRenderWidth(), 
                    height: camera.getEngine().getRenderHeight()
                }, 
                camera, 
                Texture.TRILINEAR_SAMPLINGMODE, 
                camera.getEngine(), 
                true);

            // Default values.
            var font = "40px Monospace";
            var characterSet =  " `-.'_:,\"=^;<+!*?/cL\\zrs7TivJtC{3F)Il(xZfY5S2eajo14[nuyE]P6V9kXpKwGhqAUbOd8#HRDB0$mgMW&Q%N@";

            // Use options.
            if (options) {
                if (typeof(options) === "string") {
                    font = <string>options;
                }   
                else {
                    font = (<IAsciiArtPostProcessOptions>options).font || font;
                    characterSet = (<IAsciiArtPostProcessOptions>options).characterSet || characterSet;
                    this.mixToTile = (<IAsciiArtPostProcessOptions>options).mixToTile || this.mixToTile;
                    this.mixToNormal = (<IAsciiArtPostProcessOptions>options).mixToNormal || this.mixToNormal;
                } 
            }

            this._asciiArtFontTexture = new AsciiArtFontTexture(name, font, characterSet, camera.getScene());
            var textureSize = this._asciiArtFontTexture.getSize();

            this.onApply = (effect: Effect) => {
                effect.setTexture("asciiArtFont", this._asciiArtFontTexture);
				
                effect.setFloat4("asciiArtFontInfos", 
                    this._asciiArtFontTexture.charSize, 
                    characterSet.length, 
                    textureSize.width, 
                    textureSize.height);

                effect.setFloat4("asciiArtOptions",
                    this.width, 
                    this.height,
                    this.mixToNormal, 
                    this.mixToTile);
            };
        }
    }
}