Light and rays questions

Hi there. Is that possible to emit rays from a rectangle light?
Even if I pick a rectangle area light, the rays are emitted only from a point…
I’d like a Neon to be the source… Any tip?

Unfortunately, no. Long time request.

The best you can do is put your light really, really far back in z-pace.

Thx. I’ve cheated quite a lot taking a gradient, and using a replica node to rotate it 16 times by 2 degrees sur it kind of emits light in one direction, then comped it using screen mode and it almost does what I was looking for. Cheap solution for today…

So , just to be sure. The Rectangle area light is just for a reflexion purpose. not really for lighting. Correct?

Rectangle and elliptical lighting can do much more than reflections. But for light rays, no matter what type of light you use, the rays only come from a point light. Unfortunately.

I use Action rays all the time and both love and hate them.

It’s a feature that was introduced with fanfare, then abandoned and not readdressed. Like many, many features.

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Well, not an area light but I used the replica node with a frame of white at 99% transparency to create volumetric rays.
Numbers: 100
Position Z: 100
Scale : 102
this gives me a nice but stepping ray. Add another replica at
Numbers : 10
Position Z: 10
Scale : 100.2
to fill in the gaps and you got a nice volumetric ray. You can also add a texture and create a volumetric pattern


You can emit light from a cube.

and add rays from all the cube surface?

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I don’t have that result at all… :frowning: Must be missing something.

Some tips:
Turn z-buffer off. Replica doesn’t compute well with Z-buffer
Main axis should be the parent in the hierarchy, replicas are children.

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Much much better result, thank you. The stepping is a bit too visible for me (probably depending on the size of the comp of course) . But nice tip. Thx

You can adjust the stepping with the z position values. My sample has 100 x 10 = 1000 samples for the ray.

Yes sure. And for me, 1000 samples is already quite sticky, even in HD

I did it a long time ago. Add a geometry. Make it a Substance PBR Glass material. Then you crank the Emissive Intensity to whatever. Like 10.

Then add a Rays Matchbox to the Camera.


Tried that and it’s interesting but if I x scale my geometry to the width of the image, I still don’t have ray on the hole width. But it’s wider than just a light, and definitely closer to what I was expecting…

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