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I'm trying to replicate what this user was after, but without using particles. (I know the particles will work easier, it's just not what I want for this.) Glowing Light Trail in Eevee

I've got an emission shader on my curve object, and a path for it to follow. It's animated along the path, and what I want to do is fade out the tail end (the Bevel Start) as the curve animates, to create a simple light trail using geometry.

I was trying to do this with mixing a transparency shader and an emission shader with a color ramp between them, but that only gives me a smooth transition across the entire object, instead of fading it along the path.

Here's the scene I'm working with: light trail testing geometry

and a couple screencaps of what I have, what I'm after (just an image edit) and my current shaders enter image description here enter image description here enter image description here

Eric Schamer
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    Please place a screen snapshot in your question. Some readers have no need to download your file. – atomicbezierslinger Dec 10 '20 at 06:32
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    You could do similar to https://blender.stackexchange.com/a/94976/29586 but create the path manually if you really need to avoid particles (although in that example the particles are only used to create the path, not for the final result). – Rich Sedman Dec 10 '20 at 09:26

1 Answers1

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You can use a mix between an Emission and a Transparent node and use a Gradient along the axis, with the Texture Coordinate UV socket.

If you're using Eevee you can use Bloom to make it look like a ray (the Emission Strength needs to be pushed high enough), if you're using Cycles you'll need to do it in the Compositor.

enter image description here

moonboots
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