Today (12 Dec 2024) a lightmap shadowmasking feature , created by BlueCube3310 , was merged to the Godot’s upstream. It means that Godot 4.4 release will bring this feature for everyone. Check Godot blog for upcoming annoucements!

Lightmap shadowmasking

Lightmap Shadowmasking is a technique used in real-time rendering engines (like Unity , Unreal Engine , and now Godot ) to combine baked lighting with real-time shadows for efficient lighting calculations. It helps balance performance and visual fidelity by minimizing the number of real-time light calculations required during gameplay.