msdf-bmfont

Converts a .ttf font file into multichannel signed distance fields, then outputs packed spritesheets and a json representation of an AngelCode BMfont.

Signed distance fields are a method of reproducing vector shapes from a texture representation, popularized in this paper by Valve. This tool uses Chlumsky/msdfgen to generate multichannel signed distance fields to preserve corners. The distance fields are created from vector fonts, then rendered into texture pages. A BMFont object is provided for character layout.

Install

$ npm install msdf-bmfont

Unless previously installed you'll need Cairo, since node-canvas depends on it. For system-specific installation view the node-canvas wiki.

You can quickly install the dependencies by using the command for your OS:

El Capitan users: If you have recently updated to El Capitan and are experiencing trouble when compiling, run the following command: xcode-select --install. Read more about the problem on Stack Overflow.

Examples

Writing the distance fields and font data to disk:

const generateBMFont = require('msdf-bmfont');
const fs = require('fs');

generateBMFont('Some-Font.ttf', (error, textures, font) => {
  if (error) throw error;
  textures.forEach((sheet, index) => {
    font.pages.push(`sheet${index}.png`);
    fs.writeFile(`sheet${index}.png`, sheet, (err) => {
      if (err) throw err;
    });
  });
  fs.writeFile('font.json', JSON.stringify(font), (err) => {
    if (err) throw err;
  });
});

Generating a single channel signed distance field with a custom character set:

const generateBMFont = require('msdf-bmfont');

const opt = {
  charset: 'ABC.ez_as-123!',
  fieldType: 'sdf'
};
generateBMFont('Some-Font.ttf', opt, (error, textures, font) => {
	...
});

Usage

generateBMFont(fontPath, [opt], callback)

Renders a bitmap font from the font at fontPath with optional opt settings, triggering callback on complete.

Options:

• charset (String|Array)
  • the characters to include in the bitmap font. Defaults to all ASCII printable characters.
• fontSize (Number)
  • the font size at which to generate the distance field. Defaults to 42
• textureWidth, textureHeight (Number)
  • the dimensions of an output texture sheet, normally power-of-2 for GPU usage. Both dimensions default to 512
• texturePadding (Number)
  • pixels between each glyph in the texture. Defaults to 2
• transparent (Boolean)
  • generate texture atlases with a transparent background, instead of white
• fieldType (String)
  • what kind of distance field to generate. Defaults to msdf. Must be one of:
    • msdf Multi-channel signed distance field
    • sdf Monochrome signed distance field
    • psdf monochrome signed pseudo-distance field
• distanceRange (Number)
  • the width of the range around the shape between the minimum and maximum representable signed distance in pixels, defaults to 3

The callback is called with the arguments (error, textures, font)

• error on success will be null/undefined
• textures an array of Buffers, each containing the PNG data of one texture sheet
• font an object containing the BMFont data, to be used to render the font

Since opt is optional, you can specify callback as the second argument.

License

MIT, see LICENSE.md for details.