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timfagan

Inset with PolyExtrude - overlapping polygons

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I'm wondering if anyone has figured out how to solve this problem with the extrude sop?

 

 

I have a trace of the letter C, and I would like to add an inset with the extrusion. However the result has overlapping polygons. Is there a way to correct this? I thought it might be to do with the normals but they're all in the same direction...

 

 

Edit: What I'm trying to get is the extrusion meeting in the middle of the letter....

post-12939-0-26079500-1449806454_thumb.j

post-12939-0-34398000-1449806463_thumb.j

Edited by kayman

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...A resample node before the extrusion cleans it up a bit. I'm still not sure how to clean up the edges.

 

 

post-12939-0-09126000-1449814041_thumb.j

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I dont think there is a problem with the extrude SOP. an extrusion is just moving new points along normals regardless of intersections.

 

what you are probably looking for is a solution for creating "straight skeletons".

http://forums.odforce.net/topic/14151-roof-generator/

https://en.wikipedia.org/wiki/Straight_skeleton

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Also with the polyextrude, what you say makes sense, but anytime an inset is applied with a high angle between adjacent edges, it seems there's going to be overlapping polygons, as in the ends of the 'c' above. Is that right? I'm sure there's a way to correct for it, I don't know what it is right now...

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in order to avoid overlappings you should keep the number of edges low (this is especially true for corner regions). a refine SOP can get you there.

 

you can also convert the extruded polygons group to a point group and snap those inner points together. that way you should be able to approximate the requested middle line for the letter C.

C.hipnc

Edited by konstantin magnus

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If I wanted to smooth that middle line/edge, can I resample just that line somehow?

 

I've managed to isolate the line through either a group SOP, but can't seem to resample it. Or I can delete everything except those middle line points and resample them, but I'm not sure how to reinsert them back to the mesh... (The resample node has that option to treat polygons as Interpolating Curves, which smooths out the line as it inserts points.)

 

I've fiddled around with the connect adjacent pieces and using that to try to form a polygon mesh. I also tried converting them to NURBS curves, and skinning them together, but they don't connect correctly. 

C_smooth.hipnc

post-12939-0-52379800-1449898833_thumb.j

Edited by kayman

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while i still dont quite get what youre after in a broader sense, i would suggest to start with a clean center line and extrude from that. reducing complexity in a meaningful manner is often times harder than increasing it.

C2.hipnc

Edited by konstantin magnus

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There is rough asset (still at subnet stage, actually) based on the Poly Expand 2D node which is that straight skeleton stuff added in H15. Not very usable currently due to lot of segfaults and infinite cooks on my 15.0.273 build, but the basic setup maybe will work for you.

zhOpzEP.png

offset_extrude.hipnc

  • Like 1

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Thanks guys, yeah I found the polyexpand2D to be pretty useful as it avoids the overlapping when extruding in a flat plane.

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