Godot New Global Illumination System – HDDAGI

Godot lead developer Juan Linietsky recently tweeted several tweets about a new global illumination system for Godot, HDDAGI, or Hierarhcial Digital Differential Analyzer Global Illumination. This is meant to be a drop in replacement for SDFGI (Signed Distance Fields Global Illumination) released in Godot 4.

Details of Godot HDDAGI:

This is a new global illumination system meant to supersede SDFGI.
Key advantages are:

  • Much, much faster. Significantly lower frame time, orders of magnitude faster cascad
  • Generally higher quality (less arctifacting).
  • Much better occclusion (a lot less light leaked).
  • Less memory usage.

It is meant as a drop-in replacement. Should work as a replacement for SDFGI.

Known issues:

  •  For some reason gets DEVICE LOST on Intel GPUs. No idea why.
  •  Sharp Reflections not always play good with TAA (wobbly).
  •  Darkening (occlusion) on some corners, just like SDFGI. I tried different techniques to see if any worked better. DDGI Octahedral VSM gets rid of them, but also leaks a lot more light, so I am unconvinced. Have other ideas to try, but I don’t have infinite time 🙁
  •  SDFGI spherical harmonics turned out to be buggy and not energy conserving. This makes GI look more saturated and have more light than in HDDAGI (which some people may appreciate more), but It’s a bug 😢. Wondering how this can be compensated.
  •  Still some further pending optimizations.


  •  Dynamic object support.
  •  High density mode (sub-probes).

Key Links

Project Pull Request on GitHub

HDDA Development Branch

Assets Used in This Video (Bundle Ends Dec 15th!)

HDDA Dreamworks PDF

You can learn more about HDDAGI or Hierarchical Digital Differential Analyzer Global Illumination in Godot 4.3 in the video below.

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