Add a glow to a boolean modifier boundary

Hi everyone
I was trying to make a material that highlights edges on the boolean intersection. I need a hard glowing line.
I’ve found an answer here https://blender.stackexchange.com/questions/111714/add-a-glow-to-a-boolean-modifier-boundary which is pretty close to what I’m looking for. But in my case it looks completely different. It reacts to a boolean mesh tho.
any thoughts?
I’ve attached a blender file just in case.
glowing_edge.blend (801.9 KB)
Also, there’s a screenshot of another try. I tried different numbers and positions for empty . the line doesn’t hit the boolean intersection at all but itself looks exactly as I need.

may be this thread here

happy bl

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One of the ways to do this is through Dynamic Paint (on Physics tab).

You use the Cube as Canvas and a second object as Proximity Brush.

In the Cube Canvas, change the format to Image Sequence. It has a Dry field active by default, then decrease the time to 1 for instant drying.

In the Brush of the second object, you choose the Proximity paint and see which distance and color ramp is the most ideal for you.

Then use the Image Sequence generated in your Shading Node.

Check the file I uploaded! :grin:

PaintProximityBoolean.7z (910.4 KB)

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thanks for the answer)
It works. But if I understand correctly, it’s not dynamic.
Sorry I should had specified it in my previous message -____-

I’m not very familiar with dynamic paint-- sounds like it sure should be dynamic!-- but RickyBlender’s link is definitely dynamic. (Oh hay I wrote that SE answer.)

But if you can get it working, dynamic paint is probably better than vertex group tricks, as vertex groups/UV are vertex properties, interpolated across faces rather being per-texel.

Either way is fine.
But:
-the solution with proximity doesn’t look as it should (apparently I’m doing something wrong, but can’t find out what exactly). You can check the attached scene.
-and the solution with paint doesn’t work for me because I need to bake the map each time I change something. And I need that effect being dynamic because I use animated object. But again, maybe I’m doing something wrong here too.

Did you mean to attach a file?

Yep, this one glowing_edge.blend

It certainly looks dynamic to me:

However, you have it set up to be emitting from everything except the booleaned edges.

If you want to do it exactly like that SE answer, re-read it. Notice especially:

and

Should all be demonstrated in the SE picture.

Thanks for the answer.
For some reason there wasn’t vertexweightedit modifier. I’ve added it but still same result.
I started again and did everything exactly as it was in that answer.
But I’ve got the same result again. If I understand correctly I still did something wrong with the uv.

I don’t really understand what does this mean
“…where all verts have been mapped to 0,0”
Do I need to do something else with uv? Could you maybe share your scene?

I don’t have a scene. I just looked at your file and saw the obvious things that were screwed up.

If you didn’t map UV to 0,0 for all verts, you didn’t do everything exactly as it was in that answer.

Here’s how to map your UV to 0,0:

Enter edit mode. Select all verts. u->unwrap. Open a UV editor window. Check that the cursor is at 0,0 (default) or else set it there manually using sidebar/view/2D cursor. Select all verts in UV editor. Change pivot point to cursor. Scale to 0. (Or, snap selection to cursor.)

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Here is my attempt with vertex color based dynamic paint:

glowing_edge-dp.blend (838.4 KB)

It’s dynamic, but still geometry resolution dependent. It works fine on rectangles, but if you want to use it on heavier meshes, it might not be ideal.

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Feel so stupid right now))
I didn’t know that I literally need to scale the UV to 0.
Now it looks perfect and works as it should.
Thank you!

Also, thanks everyone for other solutions. They could be very handy in other cases!