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LucaScheller

Mantra Light Path Expressions(LPE) Exclude Coat

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Hi guys,

I'm trying to write a light path expression that excludes the default custom bsdf label "coat" 

To have only the coat layer is: 

 lpe:C<...'coat'>.*

To have all reflections but the coat I would expect it to be:

lpe:C<RG[^...'coat']>.*

This gives a syntax error and doesn't seem to  work.

Has anyone tried this before and knows the correct syntax or is this a bug?

Cheers,

Luca 

Edited by LucaScheller

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try this for all but coat

lpe:C<...[^'coat']>.*

or all glossy reflections but coat

lpe:C<RG.[^'coat']>.*

 

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4 hours ago, LucaScheller said:

Is it possible to have a lpe for caustics only?

something like this

lpe:C<RD>G+L

 

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Mh doesn't seem to work in Mantra. I've also tried

RenderMan lpe:CD[S]+<L.>   --> Mantra  lpe:CD[G]+<L.>

as described here. Also doesn't seem to work.

I guess it's because caustics are not part of the path tracing process? So we can't access them via lpe?

"Soft caustics" (enabling "Allowable paths" on your mantra node) works with

lpe:C<RD>G+L or  lpe:CD[G]+<L.>

though, since it is then path traced. 

Or is there a custom lpe type we can access for caustics?

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7 hours ago, LucaScheller said:

... (enabling "Allowable paths" on your mantra node) works with


lpe:C<RD>G+L or  lpe:CD[G]+<L.>

though, since it is then path traced. ..

correct, that LPE is for true, pathtraced caustics

if you are talking about biased pointcloud caustic light, then I'd assume it would be accessible as direct lighting pass from specifically labeled caustic lights

like adding LPE Tag to your caustic light and name it somehow, like: 'caustics' and then something like 

lpe:CD+<L.'caustics'>

but it doesn't seem to work, neither does more broad lpe Beauty (lpe:C.*) that should capture everything, so I'd assume it's not straightforward to isolate those using LPE currently

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Has there been any development on this? I'd love to pull the caustic light with an lpe.....

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