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Entropy

[SOLVED] Silhouette edges

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Hello
is it possible to extract the silhouette of a flatten object?
after flattening the object to the camera plane and inverse the object's transform matrix
i have all the faces rest on the xy plane

how to union - boolean all the intersected faces on the xy plane
and extract the silhouette edges

are there any 2d boolean operations on polygons - shapes ?

thanks in advance

ioannis. 
  

 

silhouette_edges.hipnc

Edited by Entropy

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I haven't looked at the scene file, but perhaps this could be done in compositing in the Image Network?

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Hi miles

thank you yes it could be done in that way 
but what i am asking is do we have 2d boolean operations in houdini ?
is there a way to do this with vex?

best regards
ioannis

Edited by Entropy

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With some Triangulate 2D and Divide you can extract outlines like this:

extract_sillhouette_edges.png.8052bebe98ce1f220b3c85a9a6fe2af8.pngsilhouette_edges_no_transform.png.f9684bd7d3b22c3a29e99a4f7faaa1f0.png

No need to do inverse transform, if you don't need it further, since Triangulate 2D will find best plane.

silhouette_edges.hipnc

Edited by f1480187
  • Thanks 1

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Thank you this is so great!
i did some test with
VDB from polygons -> VDB Topology to SDF -> Convert to polygons ->  Clip
but my results were not as accurate
your solution is perfect
 

much appreciated
ioannis
 

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wait for me !!!

here's my "hillbilly can't VEX my way out of a wet paperbag" approach...

(errr...bit rough around the edges...but that's just how hillbillies like it...)

silhouette_edges_approx.hipnc

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Haha pixel perfect!!!

even with 1000x1000 subdivisions its... rough
at least these hillbillies are fast
as long as you have some spare grid to divide...

 

Edited by Entropy

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