shaku/src/gfx/draw_batches/text_batch.js

A simple and effective JavaScript game development framework that knows its place!

/**
 * Implement the gfx text sprite batch renderer.
 * 
 * |-- copyright and license --|
 * @module     Shaku
 * @file       shaku\src\gfx\draw_batches\text_batch.js
 * @author     Ronen Ness (ronenness@gmail.com | http://ronenness.com)
 * @copyright  (c) 2021 Ronen Ness
 * @license    MIT
 * |-- end copyright and license --|
 * 
 */
'use strict';
const FontTextureAsset = require('../../assets/font_texture_asset');
const MsdfFontTextureAsset = require('../../assets/msdf_font_texture_asset');
const { Color } = require('../../utils');
const SpritesGroup = require('../sprites_group');
const DrawBatch = require('./draw_batch');
const SpriteBatch = require('./sprite_batch');
const SpriteBatchBase = require('./sprite_batch_base');
const _logger = require('../../logger.js').getLogger('gfx-effect');


/**
 * Text sprite batch renderer.
 * Responsible to drawing a batch of characters sprites.
 */
class TextSpriteBatch extends SpriteBatchBase
{
    /**
     * Create the text sprites batch.
     * @param {Number=} batchSpritesCount Internal buffers size, in sprites count (sprite = 4 vertices). Bigger value = faster rendering but more RAM.
     */
    constructor(batchSpritesCount)
    {
        super(batchSpritesCount, true);

        /**
         * If true, will render as Msdf Fonts.
         * @type {Boolean}
         * @name TextSpriteBatch#msdfFont
         */
        this.msdfFont = false;

        /**
         * If bigger than 0, will draw outline.
         * Currently not supported with msdf fonts.
         * Must be set before begin() is called.
         * @type {Number}
         * @name TextSpriteBatch#outlineWeight
         */
        this.outlineWeight = 0;

        /**
         * Outline color, when outlineWeight is set.
         * Must be set before begin() is called.
         * @type {Color}
         * @name TextSpriteBatch#outlineColor
         */
        this.outlineColor = Color.black;
    }

    /**
     * Get the gfx manager.
     * @private
     */
    get #_gfx()
    {
        return DrawBatch._gfx;
    }

    /**
     * Get the web gl instance.
     * @private
     */
    get #_gl()
    {
        return DrawBatch._gfx._internal.gl;
    }

    /**
     * @inheritdoc
     */
    get defaultEffect()
    {
        return this.msdfFont ? 
                this.#_gfx.builtinEffects.MsdfFont : 
                (this.outlineWeight ? this.#_gfx.builtinEffects.SpritesWithOutline : this.#_gfx.builtinEffects.Sprites);
    }

    /**
     * Add text sprites group to batch.
     * @param {SpritesGroup} textGroup Text sprite group to draw.
     * @param {Boolean} cullOutOfScreen If true, will cull out sprites that are not visible in screen.
     */
    drawText(textGroup, cullOutOfScreen)
    {
        let transform = textGroup.getTransform();
        this.drawSprite(textGroup._sprites, transform, cullOutOfScreen);
    }

    /**
     * @inheritdoc
     * @private
     */
    _drawBatch()
    {
        // extract texture
        let texture = this.__currDrawingParams.texture;

        // sanity for msdf font
        if (this.msdfFont && !(texture.isMsdfFontTextureAsset)) {
            _logger.warn("Trying to render an MSDF font but using an asset that isn't an instance of 'MsdfFontTextureAsset'!");
        }

        // sanity for none msdf font
        if (!this.msdfFont && !(texture.isFontTextureAsset)) {
            _logger.warn("Trying to render text sprites but using an asset that isn't an instance of 'FontTextureAsset'!");
        }

        // set default effect and blend mode
        let effect = this.__currDrawingParams.effect || this.defaultEffect;

        // setup outline
        if (this.outlineWeight) {
            effect.setOutline(this.outlineWeight, this.outlineColor);
        }

        // extract font texture and set in sprite batch before calling internal draw
        let prevFontTexture = this.__currDrawingParams.texture;
        this.__currDrawingParams.texture = texture.texture;
        super._drawBatch();
        this.__currDrawingParams.texture = prevFontTexture;
    }
}


// export the text sprite batch class
module.exports = TextSpriteBatch;