SketchUp Backface default material leak

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  • Hi. I'm glad to see the new video features in the beta releases! I'm working on a video right now and they come in handy.


    I try my best to follow SketchUp modeling best practices, and this includes never applying materials to groups or components, only to faces, and only to front faces, not back faces. This has worked wonderfully with every single render software I've used until now... except Enscape. As you can see in the first image, Enscape is leaking SketchUp's default backface materials through the table's and chair's unsmoothed lines. In the second image, I copied each object's material and applied it at the group level (thus going against SketchUp best practices), and this "solves" the Enscape bug.


    I understand why Enscape works this way: Most users work in a very sloppy way, and this suits them well. However, I wish there was an option for Enscape to not render (aka "cull"), backfaces when they have no material applied to them, that is, when they only have the default SketchUp material. This is the way Lumion works. And I hope Enscape can shave off a few miliseconds per frame by doing so. Why use system resources in something that won't be seen?


    Keep up the good work!

  • You mention that it is a best practice to only paint faces. Where is that advice from?


    Besides Lumion, what other renderer do you use that prefers materials applied to faces?


    That requirement would be inefficient in many cases when working in sketchup.


    I prefer to group before appling materials... and only apply to faces as an override or when refined uvw is needed.


    Seems to work well for Thea, Octane, and Enscape.


    Thanks,


    Chris

  • In general, I apply textures to groups rather than faces. The only exception to this is when I need to rotate/scale a texture - this might be why I have never seen this (Or the times I have seen it in others work I thought it was the artistic architectural thing of outlining.)

  • Yes, I also apply "materials" to group/components, EXCEPTED all the groups/components which have textures, which are in my experience about the 90% of the models I use ^^

    So basically I agree with Arqui3D: I consider the "group mapping" (so-to-say) an exception to my usual workflow.

    I didn't notice this issue, to tell the truth, but if it's confirmed I hope it can be fixed one way or another.

  • Hi. Thanks for your comments. Here's the advice from a legend of the SketchUcation forums. I also use LightUp, and my work method helps me cut down on render time, as I don't need to activate "double sided" mode to compensate for sloppy modeling.

    Quote

    It is always good practice to create your Sketchup forms correctly with all of the faces oriented the proper way, so that the front-face is facing outwards where you might see it and it has any required material/texture applied to it - and conversely the back-face is inside and never has a material applied, as it's not seen or rendered by most renderers.

    https://sketchucation.com/forums/viewtopic.php?f=323&t=30107

  • I agree with the first bit; insides should be inside and outside should be outside. Primarily this is for other software like renders and 3D printing.


    "the back-face is inside and never has a material applied, as it's not seen or rendered by most renders". You would never deliberately colour an inside face; as the quote said it's pointless because it's never seen... but a face being in part of a group that gets a texture applied to the group wrapper - that just happens.


    Personally I think that if I was modeling that scene I would model the chairs as component chair halves, grouping the seat pad as one group and the frame as another group within that component. Then click once to fill each group. If I then see any faces with a miss-aligned texture I go into the group and fill that face with the same texture and rotate it. This saves loads of time having to go round each face and filling them individually. And as a side-effect it renders beautifully ;)

  • I agree that it is "best" to make sure only front faces are showing, as it can cause issues with many renderers.


    Arqui3D I was mainly curious about your comments regarding applying to faces and not groups.... "never applying materials to groups or components, only to faces". Do you still think that is important, and if so why?


    I just want to make sure that the Enscape team gets good feedback from this community.


    Thanks!


    Chris

  • my experience - if i can say my two cents too - is that mapping entire groups often leads to misunderstanding in future phases, when you eventually want to change material to some sub-objects/sub-faces. It is also misleading the fact that you can see a texture applied but you cannot UVmap it, because this operation is only allowed over faces. That's not an issue, it's only a workflow annoyance, to me.

    • Official Post

    Hey Arqui3D, just to make sure I got you right - you'd prefer if any back faces that have the default material applied were culled?

    Please confirm, and I can file this as feature request.


  • Arqui3D I was mainly curious about your comments regarding applying to faces and not groups.... "never applying materials to groups or components, only to faces". Do you still think that is important, and if so why?

    Hi, renderwiz. What pibuz said: Because you need to work directly on faces, not on groups, if you want to correctly map wood, concrete, TVscreens, etc. And yeah, it's also confusing when materials are applied to groups and components. You end up looking all over the place until you find on which level the material was applied.

  • Arqui3D thanks for the clarification.


    Hopefully in addressing your issue Enscape does not require users to apply materials directly to faces. Perhaps there could be an option in the settings for not rendering backfaces?


    I just look at it the other way around... 1st apply to group/component containers, 2nd apply to subgroups as overrides, 3rd apply to faces for elements that are not handled well by #1 and #2. Base geometry remains default material and default uv unless a specific override is needed.


    I can say from experience applying directly to faces comes with its own problems and is not as efficient for my workflow in architectural modeling. For any newbies reading this, I would test both and use whichever seems best for you.


    pibuz If you ever accidentally apply to groups and want it on the faces instead... when you explode the group, all that material and uv information should get passed directly to the faces.


    Chris

  • I've tons of objects with material applied directly on front face (none on back) but not grouped.

    (this has no effect on TheaRender that no considers backface)


    In Enscape I've big problems with transparent objects. Default material in backface results visible and often ugly.


    I can re-open all of my objects, group them by material and re-save them. But it is an hard work and I hope it will not necessarely


    My +1 to "no rendering" on back faces with default material


    :)

    • Official Post

    Thanks happymilk , your feedback has been filed

  • in principle I support the workflow and the wish of Arqui3D - Of course, I often also click a material onto a group, but I only do this where I use a simple pure color, never a textured material - especially with more complex geometry the result is often unreflected and somehow randomly bad. Assigning material to a group also always means that it is then materialized throughout the entire group, also the backface. This circumstance can actually cause problems - e.g. RenderIn reacts to it very allergically as well (while Shaderlight or others don't care about that at all)

    Since each modeled thing has its own thickness, even a sheet of paper would be a cube in the model, and so the backface would remain hidden. - We all know that we rarely keep up with this effort down to the last detail.

    So "trimming" the backface material as an option within Enscape would be great - so we would be able to use our models on our mostly multiple render platforms without any further effort at least ...

  • happymilk ... are you familiar with the plugin UV Toolkit 2 ? It will automatically apply "frontface material to backface" etc.... to selected objects. From your description, this may be useful to you.


    Also, just curious... If Enscape provided a global option to "Ignore Backfaces with Default Material", would this satisfy your needs?

  • If Enscape provided a global option to "Ignore Backfaces with Default Material", would this satisfy your needs?

    I think I would prefer "Fill Default Material faces with the reverse face." : I would be concerned that simply ignoring the face would result in more problems; leaving gaps or the odd 'invisible' face unintentionally... And if it's done behind the scenes then (as a user) I wouldn't have to do anything or even be aware that there was ever an issue.


    (If the reverse face is already a default, then it's just 'white')


    {Edit:} Feature request idea - can there be a special 'enscape default material' that could be substituted/changed in the model? So that every face in your model that was filled with the Default material could be tweaked by simply changing that one dummy material.

  • happymilk ... are you familiar with the plugin UV Toolkit 2 ? It will automatically apply "frontface material to backface" etc.... to selected objects. From your description, this may be useful to you.


    Also, just curious... If Enscape provided a global option to "Ignore Backfaces with Default Material", would this satisfy your needs?

    Hi renderwiz

    Yes. I heard about UV toolkit, but for now i never used it. Your advice is interesting. I will investigate on it.


    And, about your second question: YES! Definitely! :thumbsup: