How do you control reversed faces?
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i notices that sometimes my model turns purple in some areas. i looked it up and it called reverse faces.
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surely there must be some rule that controls which side of the face will display? usually it has to do with the direction of the lines around the face (clockwise/counterclockwise) but I can't seem to force a consistent behavior from SU. Anyone know?
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You can use the Automatic View-based face reverser plugin by Didier Bur for help you when you have many facets on many objects
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@mirjman said:
surely there must be some rule that controls which side of the face will display? usually it has to do with the direction of the lines around the face (clockwise/counterclockwise) but I can't seem to force a consistent behavior from SU. Anyone know?
Here is a thread about the subject.
http://www.sketchucation.com/forums/scf/viewtopic.php?f=79&t=6018&st=0&sk=t&sd=a&hilit=wo3dan+simon&start=15
Somewhere halfway the second page you will find a post by Wo3Dan with an attachment called FaceOrient.skp
In here you'll find some sort of explanation on how SU decides to create either front or back as visible face. But more important: after checking out and understanding it better don't waste to much time on the subject. (I did!) It's easier to repair (reverse) then remembering the details.
(b.t.w clockwise/counter clockwise has nothing to do with how a face is created)Wo3Dan
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I've gotten tot he point where i will reverse a backwards face just out of habit. Purple is bad and white is good!! Its very easy to reverse a face, and its even easier to reverse a group of selected face as well. Although i do think its kind of a pain, its gotten to the point where I just do it out of habit, and I love the functionality of faces and materials in sketchup, so i guess i never really thought of it as a problem.
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Wo3Dan-
I have to disagree with you about the line direction- at least in any vertical plane. The faces seem to follow the "right hand rule", ie, if you draw the face counterclockwise you will see the white/front/normal side. (this is similar to other 3d programs) The exception is drawing faces on the ground plane for some reason- which as you pointed out in that other thread does not seem very rational.
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SketchUp tries a best guess based on what you've already drawn...but it really needs two adjacent faces to ensure that it gets things right (most of the time).
In the attached file, if you start to draw in more diagonals in the same direction as the ones I've already done, things ought to be ok.In the single gap between the two filled in parts...because it has a correct adjacent face either side..it ought to fill-in correctly whatever direction the diagonal. If however you draw the diagonal the other way in some of the spaces on the left, they'll probably be wrong (even the space next to the leftmost correct one.
If you reinstate the base of the truncated cone, however, the next one on the left ought to fill correctly whatever the direction, because it now has two adjacent faces....the side and the base
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If you have lots of faces to reverse try the free ReverseFaces.rb plugin from Smustard. (http://www.smustard.com)
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