Everything related to Maxwell Render and general stuff that doesn't fit in other categories.
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By seghier
#397171
PA3K wrote:
Tue May 22, 2018 10:53 pm
I came to the problem with selecting part of surface with different dielectric material few years ago, when i tried to simulate glass plate with rough edges illuminated by small (LED) emitters. This is usual situation these days in furniture designs and also used in car industry to illuminate hands on instrument panels or speedometer. Rough surface is such a delicate (0,00x mm), that it can not be modeled as a geometry with depth. I tried some workarounds back then (1. selecting just edge with rough glass, 2. duplicate edge and offset inside with inverted normals, 3. same as 2. without inverted normals, 4. extruded edge (0,001 mm) to make it closed volume with rough glass, and glass plate (closed volume) with zero roughness, 5. SSS material on edge, 6. SSSS material on edge, and after all not very good and real results i made 7. emitter on extruded edge ).
I had reference in the front of me and also on photos, but I really can not replicate it. Here is small rendered image. If someone have some good solution ... will be welcome :wink: .
Patrik
Image
did you tried with material layers ( glass and emitter with mask )?
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By Mihai
#397182
I can't help but ask, all these solutions with copying edges, duplicating geometry etc. Wouldn't it just be easier/faster to do a quick UV mapping for these objects, in most cases? @PA3K, why don't you just do a quick cubic UV map on those shelves, create a mask which would basically just be a white rectangle in a map, and add another material layer with the same glass material but different roughness for that layer?
By PA3K
#397183
Hello Mihai,

You are right with UM map, but these edges were chamfered and it was easier for me to just select part of geometry in Rhinoceros. In Rhinoceros it is always easier working with geometry than with mapping because of surfaces instead of mesh.
I wrote my response not only because of it is related to subject of this topic, but also because i did`t find any realistic looking solution in my case. Only "edge emitter" just works (workaround). Maybe it is more for challenge topic and about level of realism of frosted (rough) glass than for this, but i asked ... 8)

Patrik
#397196
Hi Mihai, I agree that making uv's is currently the quickest option for simpler shapes.

For a simple glass shelf, you can just flat-map a rectangular mask to define the clear area of glass (the map being slightly smaller than the shelf so it doesn't cover the sides).

For a scene with shattering glass vase there is no solution, even though I already have the poly selections :(
User avatar
By Mihai
#397201
I'm not sure how C4D does it, but usually you get specific UVs automatically for the newly created "inside" parts of a shattered object? Precisely in order to be able to map a textured material to those inside faces. Maybe it's possible to be able to manipulate those newly created UVs...
#397204
I have many Arch-viz projects archived, containing hundreds of props and buldings, every pane of glass has selections for the glass edges, every mirror has selections, sss-food-items,etc etc. For NL to treat its users like that, just dropping a working feature, breaking compatibility to old scenes, and not even saying it will be fixed at anytime, is pretty arrogant.
#397207
Hello Eric,

It's not arrogance, but honesty. Sometimes it's not easy to make some decisions.
Previously, situations like this were not solved correctly either:

two materials in one geometry.png
But we had really complicated situations like the geometry of liquids that flow over a glass which are solved now.
Maybe we didn't make the correct choice; maybe it was better to have an equally incorrect but better-looking solution in some situations without the benefit of the nested dielectrics.
It's nothing that any other render engine has solved; the same situation is still undetermined when using other render engines; maybe it's better looking in some cases (and worse in others), but there's nothing awfully broken. We just tried to make things better, although it may not be better for every situation.

Anyway, maybe in the future we can come up with a better solution. I hope so.

Best wishes,
Fernando
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#397208
But it did work correctly when following the rules, for same nd, within the same mxm structure. (a bit fiddly but it worked)

I can't find the link, but it was expressed clearly that compatibility for existing scenes would be maintained. (which is obviously critical for any 3d artist)

This render seems apt.
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#397229
Ok, I've calmed down.
I'm starting to think there weren't many people that used/ knew how to use, the old technique, so I can see that the decision to drop it (quietly) was not arrogant, I shouldn't of said that.
I also assumed before that other unbiased renders could handle transparent polyselections, but now I'm not sure they can (tried to google it).

For Archviz, for glass facades, esp wonky shaped facades, it really is needed. Most archviz artists won't be able to uv map a rhino cad file of a modern wonky building.

For flat glass panels, my preferred option is to map a channel from the side, which passes through the front face of the glass. The map is a blank white rectangle with tiling off

Here is an example for a bump map, To get a coating on just the front face i can filter out this channel with a backface material (of clear glass)
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