Implement distance fade properties in OmniLight3D and SpotLight3D #58512
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Calinou
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This can be used to fade lights and their shadows in the distance, similar to Decal nodes. This can bring significant performance improvements, especially for lights with shadows enabled and when using higher-than-default shadow quality settings. While lights can be smoothly faded out over distance, shadows are currently "all or nothing" since per-light shadow color is no longer customizable in the Vulkan renderer. This may result in noticeable pop-in when leaving the shadow cutoff distance, but depending on the scene, it may not always be that noticeable.
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Looks great!
We have discussed in the past about adding a unified distance fade system for all visual instance types, but I think if this ever happens, it will be a set of properties in VisualInstance that are handled accordingly on each visual type. That means these changes should be reusable mostly unchanged, and the feature is useful on its own.
| @@ -3494,7 +3522,24 @@ void RendererSceneRenderRD::_setup_lights(const PagedArray<RID> &p_lights, const | |||
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| light_data.attenuation = storage->light_get_param(base, RS::LIGHT_PARAM_ATTENUATION); | |||
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| float energy = sign * storage->light_get_param(base, RS::LIGHT_PARAM_ENERGY) * Math_PI; | |||
| // Reuse fade begin, fade length and distance for shadow LOD determination later. | |||
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Is this some reference for a future implementation? I don't see anything related to shadow LOD in this PR.
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Light shadow LOD refers to the shadow cutoff distance, which can be set separately from the light cutoff distance (which is begin + length). I can reword the comment if it's confusing.
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Thanks! |
This can be used to fade lights and their shadows in the distance, similar to Decal nodes. This can bring significant performance improvements, especially for lights with shadows enabled and when using higher-than-default shadow quality settings.
While lights can be smoothly faded out over distance, shadows are currently "all or nothing" since per-light shadow color is no longer customizable in the Vulkan renderer. This may result in noticeable pop-in when leaving the shadow cutoff distance, but depending on the scene, it may not always be that noticeable.
The default values and property hints are identical to #58296. Note that distance fade is still disabled by default (like for Decal), which means the default light rendering behavior is unchanged.
I've tested this PR with VoxelGI, SDFGI and LightmapGI. All techniques still work with distance fade, regardless of the camera position when baking. Lights will still be present in GI rendering even if they are past the distance, but this also helps make light transitions less noticeable, so it's not too bad.
Edit (May 2022): I started working on a
3.xbackport, but didn't manage to get it fully working so far:https://github.com/Calinou/godot/tree/light-add-distance-fade-3.x
This closes godotengine/godot-proposals#2744.
Testing project: test_light_lod.zip
Press L to toggle distance fade for all lights.
Preview
The highest shadow quality settings are used here.
Without distance fade
Lights are never culled regardless of distance. This is the current behavior.
With distance fade
Distant lights are culled, and partially faded lights have their shadows disabled (this is configurable).