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Maxime Durand avatar image
Maxime Durand asked ·

How to vary light intensity and color of a mesh light tag linked to x particles spline mesher?

Hi,

Hope you're all doing well :)

Got a pretty urgent question here.

I've created a complex set up with x particles to represent aeration and airways of a product. I've obviously created some trails to show the air flows. Now, I want each trail to be a light, and each light with a different intensity. I can use the utility node in arnold and I can have all my trails of a different color/intensity. BUT, the render time are definitely too long cause of the emission property of the shader.

The idea is then to speed up render time with a mesh light tag applied to the trails.

As the mesh light tag doesn't work natively with x particles trails, I've created some capsules with a spline wrap deformer linked to the trails to get a polygon object. I've created my mesh light tag on the capsule and everything turned on, great. But, at this stage, how can I get a different intensity for each wrapped capsule?

Then I linked the mesh light tag to an arnold shader to see if I can get some unique ID's and map them on a ramp shader.

I tried all the presets of the utility node, but I can't get back the unique id information of the trails as I'm dealing with capsules "clones" now and not trails directly.

After that, I tried to replace my wrapped capsules by an x particles spline mesher (best result so far for the render time), but again, no chance to have some unique ID :(

I also tried to use the xparticle node of the shader network linked to the mesh light, but no luck too...

If someone know how to properly attach a mesh light tag to an x particles trail - dealing with unique ID's to vary the intensity factor of each "trail" - that would be more than welcome.

Thanks guys :)

lightcolorx-particlestrailsindex
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Peter Horvath avatar image
Peter Horvath answered ·

The mesh light works only with a polymesh, so you have to convert the trails to a mesh. Both solutions (spline wrap deformer and spline mesher) has the same problem, that the trail ids are lost. If you could store that information in a vertex map, you would be able to read it in a shader network, but I guess it's not possible. I don't see any solution, I'm afraid. Maybe someone has an idea.

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