HarfBuzz Slug Support with WebGL

HarfBuzz Slug Support with WebGL(harfbuzz.github.io)

29 points by mcraiha 45 days ago | 8 comments

HarfBuzz = text shaping engine, https://github.com/harfbuzz/harfbuzz

Slug = Formely patented font rendering algorithm for GPUs, freed 2 weeks ago https://terathon.com/blog/decade-slug.html

tikimcfee 45 days ago |

Very cool. I've noticed slug popping up more often on HN and I've been thinking of finding a way to incorporate it into my project as well.

Is this yours? What's your rendering system like - anything novel or fun you run into when working with text and GPU parallelism?

mcraiha 44 days ago | |

Not mine. I noticed that Aras was mentioning it https://mastodon.gamedev.place/@aras/116335267839588454

jasonjmcghee 44 days ago |

Note to author: the WebGL has great zoom settings, but WebGPU has different ones that feel very low-sensitivity (at least on trackpad on macos)

eviks 44 days ago |

Are there good explanations/demos comparing this to msdf?

amitp 36 days ago | |

Slug preserves the vector shapes. MSDF first converts to a texture, which can lose small details. How much depends on the size of your texture and the complexity of the font. I expect MSDF will never look better than Slug.

However, MSDF can handle lots of distance-based effects (glow, shadow, outline, gradient, etc.)[1], and I don't think Slug does that. And MSDF is constant time whereas (I think) Slug is going to vary depending on the complexity of the font.

The Slug paper [2] says:

  All of the techniques that store data in a texture atlas are inherently using a discrete
  sampling of what is actually an infinitely precise description of a glyph outline. This
  inescapably leads to limitations that can be mitigated by increasing the resolution of
  the texture atlas, but that can never be completely removed. For applications that
  need to render a wide range of characters at potentially large font sizes, a texture atlas
  capable of producing glyphs at an acceptable level of quality may have prohibitively
  large storage requirements.

[1] https://www.redblobgames.com/articles/sdf-fonts/#demo

[2] https://jcgt.org/published/0006/02/02/

behdad 41 days ago | |

msdf still suffers from detail loss at large sizes, which this method doesn't have.

eviks 41 days ago | | |

Thanks, how large of a size? And at lower sizes, what's the performance/quality like? Is this the silver bullet?

All of the techniques that store data in a texture atlas are inherently using a discrete sampling of what is actually an infinitely precise description of a glyph outline. This inescapably leads to limitations that can be mitigated by increasing the resolution of the texture atlas, but that can never be completely removed. For applications that need to render a wide range of characters at potentially large font sizes, a texture atlas capable of producing glyphs at an acceptable level of quality may have prohibitively large storage requirements.