Multiple directional lights in 3D

This is a READ-ONLY snapshot of the Godot Community Forums when TwistedTwigleg was the owner, which is hosted for archival reasons only. The current Godot Community Forums can be found here.

Some links may point to external websites, including the current Godot Community Forums. These websites are not associated with TwistedTwigleg.

yvan

I made a simple scene to test out some lights and shadows.

Everything works well with an unique directional light.

When I add a second one, with shadows also turned on, I only see the shadows from the first directional light in the scene tree. If I switch from one to the other (only one active at a time) I saw the shadows made by each light.

Is this normal?

PS I searched the documentation but couldn't find any restriction on the number of directional lights.

TwistedTwigleg

Welcome to the forums @yvan!

I think there is a limit of 8 lights for point lights due to shadow map constraints. I’m not sure if there is a limit for directional lights though, but I imagine there is due to each directional light needing a shadow map. I think it probably is possible to have two directional lights with shadows though. Does the issue occur in the Godot editor as well?

cybereality

This is a limitation of Godot 3.x. There can only really be 1 DirectionalLight. It works in 4.0, though. Even so, a directional light is supposed to simulate the sun. So unless you are making some sort of alien world game, it doesn't make much sense to have multiple directional lights. Best to use a single light as the sun (or moon) and then use other lights, such as omni or spot. You can also use emissive materials, but that only really looks good with baked lighting.

yvan

Thanks you for the response. I've already try with omni light but the result is not the same, and i get some weird artifacts from the shadow mapping. BTW, I'm making a procedural universe with possibly multiple suns for one planet, so yes i need to have 2 directional lights, 3 will be perfect ! I'll try it in godot 4

Calinou

For reference, this was cross-posted on the Godot Q&A: https://godotengine.org/qa/133770/have-multiple-directional-lights-with-shadows-together-scene

Using more than 1 DirectionalLight will always have a significant performance impact, especially if shadows are enabled on more than 1 DirectionalLight. Doing so will also worsen shadow quality, as the shadow map texture will have to be shared for multiple DirectionalLights.

Even if it doesn't look physically accurate for your game, I strongly recommend sticking to 1 DirectionalLight for best performance and quality.

I've already try with omni light but the result is not the same, and i get some weird artifacts from the shadow mapping.

OmniLights with shadows are not intended to be used as a replacement for DirectionalLights. You could increase the shadow atlas size (or use a distant SpotLight instead), but it will never look ideal since there is only one shadow "split" to speak of.

cybereality

I tried it in Godot 3.x and using more than 1 DirectionalLight did not work. There is only 1 shadow map and even the direct lighting was non-functional. In any case, it's not a great idea.

yvan

Even if it doesn't look physically accurate for your game, I strongly recommend sticking to 1 DirectionalLight for best performance and quality. I try it under godot 4.0. Seen from space, the rendering of a planet with 3 suns seems quite accurate and really good quality (after some minor adjustments) And on the surface of the planet, it's not bad at all for a first attempt. Different shades depending on the time of day or night (when there are any) I'm not interested, for the moment, in performance, but only in the aesthetic side, and I get the result I had in mind, it's the most important! In any case, it's not a great idea. Even if I hear your advices, I'll stick to my bad idea of using multiple directional lights and switch to godot 4.0, despite it being an alpha version.

Thanks you again for your responses.