Skip to content

Latest commit

 

History

History
63 lines (51 loc) · 3.29 KB

README.md

File metadata and controls

63 lines (51 loc) · 3.29 KB

Bitmap font generation with msdf-bmfont-xml and Gimp

This is the previous method that was used for generating font, which isn't as straightforward as the new method since there are a few steps that must be done manually and more things have to be installed. I recommended using the small utility I made instead to simplify the process.

If you still want to use this method, you'll need the following:

  • msdf-bmfont-xml, a npm package for generating MSDF font texture atlas and .fnt file. This requires npm installed, then running npm install msdf-bmfont-xml -g will install the package globally.
  • Gimp or any image editing tool that can manipulate channels and PNG. This tutorial uses Gimp.
  • The python script to convert the XML .fnt file into the format that LibGDX's BitmapFont uses. The script requires Python 3.

Here's the steps to generate the files from a font.ttf font file.

  1. Generate the SDF font with the command below. You can change the glyph size -s, the distance range -r (the range in px to encode the distance field) and the charset -i file. Here's a great charset to use for complete coverage in over 30 languages (latin-9).

    msdf-bmfont -f xml -i charset.txt -s 32 -r 5 -t sdf --pot --smart-size font.ttf

    If you're planning on using the outer shadow effect, adding a few pixels of padding on the border and between glyph is a good idea. You can do this with the -p (padding) and -b (border) arguments. Because the shadow has some offset, neighboring glyphs in the atlas may appear if padding is too small.

  2. Rename the generated PNG file to font-sdf.png

  3. Generate the MSDF font just like the SDF font but changing the -t parameter. It is important to keep the same parameters used for the MSDF font since they will be merged afterwards.

    msdf-bmfont -f xml -i charset.txt -s 32 -r 5 -t msdf --pot --smart-size font.ttf

  4. Run the python script to convert the generated font.fnt file to LibGDX's format.

    python bmfont_converter.py font.fnt

  5. Use Gimp to merge both distance fields:

    • Open the MSDF png file.
    • Add a new layer and copy the SDF png file there.
    • Select SDF layer and click Layer > Transparency > Alpha to Selection.
    • Select MSDF layer and click Layer > Mask > Add layer mask...
    • Initialize layer mask to "Selection" and click Add.
    • Remove the SDF layer.
    • Export image to PNG under font.png.
      • "Save color values from transparent pixels" option must be checked.
      • Reduce size by unchecking options like "Save thumbnail" and increasing compression level.

  6. Make sure the font atlas file name in .fnt file is correct. (The file=... attribute)

  7. For some reason, the font.fnt base=... attribute will be too small, so increment it by a few pixels until it looks good. I added about 5px for a 32px font for reference.

The result should look like this:

MSDFA Roboto font

The library can also render normal MSDF and SDF but shadows won't work.