[UE5] [Lumen] Should `Source Length` affect shadows?

Hi! I’m tring to make a long neon light with soft dynamic shadows. But when I setup point light’s length, shadows do not change. While source radius and even area lights work as expected, I cannot make a point light’s length to cast soft shadows.

Same thing with Spot Light.

So, is this a bug and should be reported, or Lumen does not support long lights at all by design?

Here are my project settings:

Shadow maps are only rendered from a single point, so no, it’s not a bug. You need to adjust the source radius to get plausible soft shadows. Virtual Shadow Maps | Unreal Engine Documentation

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So the only way to make long light sources with proper penumbra is to use Area Lights?

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If I’m not mistaken, area/rect lights render from the center only, too, so you still need to adjust the source radius. But if you bake the lights (static or stationary), then the area light shadows will render from the entire area, but that’s only for baking.

@midgunner66 No, Area lights cast proper shadows. That’s why I thought Spot and Point lights should also work, as there is no sense to make this work and other don’t.

UE5LongShadows

Oh, good to know. I guess you’ll have to use area light, then. When I tested it in EA, I don’t remember it working like that, but I could be remembering wrong.

Edit: Oh, it’s because you’re using raytraced shadows, so it’ll cast proper shadows. I don’t have a raytracing GPU, so for me, it’ll render using shadow maps.

So yeah, strange it doesn’t work for point & spot lights. Maybe it’s a bug or just something they haven’t implemented yet.