BMFont utils

BMFont utilities for WebGL.

yarn add @downpourdigital/bmfont-utils

npm i @downpourdigital/bmfont-utils

LayoutGenerator

import {
	LayoutGenerator,
} from '@downpourdigital/bmfont-utils';

const generator = new LayoutGenerator( font: BMFont );

The generator instance exposes some metrics about the font:

generator.capHeight
generator.xHeight
generator.ascenderHeight
generator.descenderHeight

If you're not familiar with the terminology, Monotype has you covered. All metrics are relative to font-size 1.

LayoutGenerator only has one method:

generator.layout({
	text: string;
	width?: number;
	letterSpacing?: number;
	lineHeight?: number;
	noWrap?: boolean;
	tabWidth?: number;
	xShift?: number;
	align?: 'left' | 'right' | 'center' | 'justify';
	computeLineY?: boolean;
	computeCharUvs?: boolean;
	computeCharIndex?: boolean;
	computeLineIndex?: boolean;
});

width defines the maximum line-width at font-size 1. Most of the other options should be self-explanatory. By setting the computeXXXX options to true, you can compute some additional vertex attributes:

LineY describes the verical position of the vertex between ascender (0) and descender (1).

CharUvs gives you normalized coordinates relative to the current glyph quad.

CharIndex and LineIndex should be self-explanatory.

LayoutGenerator.layout() returns an object, which may be used to construct an indexed buffer geometry:

{
	verts: number[],
	uvs: number[],
	indices: number[],
	lineY?: number[],
	charUvs?: number[],
	charIndices?: number[],
	lineIndices?: number[],
	charCount: number,
	lineCount: number,
}

verts are the actual 2D vertices, indices are the pointer indices for your ELEMENT_ARRAY_BUFFER.

It's important to note that everything here is relative to font-size 1, so some scaling may be necessary on your end.

WordWrapper

WordWrapper is a naïve implementation of a greedy word wrapper. It bases its measurements on the actual glyph widths and takes kernings into account.

import {
	WordWrapper,
} from '@downpourdigital/bmfont-utils';

const wrapper = new WordWrapper({
	font: BMFont;
	breakPoints?: BreakPoint[];
	useKernings?: boolean;
});

breakPoints defines an array of possible line break opportunities. By default, space (\u0020), soft hyphen (\u00AD), en dash (\u2013), em dash (\u2014) and hyphen minus (\u002D) are used.

A BreakPoint consists of a char to look for and its replacement, containing the actual line-break:

{	// en dash
	char: '–'.charCodeAt( 0 ),
	replace: '–\n',
}

Two methods are exported:

wrapper.mesure( text: string );

Returns the width of a given string at font-size 1.

wrapper.wrap(
	text: string;
	width?: number;
	letterSpacing?: number;
	tabWidth?: number;
});

Returns a given string text with inserted line-breaks.

width defines the maximum line-width at font-size 1, letterSpacing and tabWidth should be self-explanatory

License

© 2019 DOWNPOUR DIGITAL, licensed under BSD-4-Clause