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amaviztime

"Trace" around a mess of points in a flat plane

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Dear Forumers,

 

I have a FLIP mesh and long story short I need to cut the silhouette of it out of a big cuboid.

 

Currently (tell me if I'm doing it wrong from the start, I tried about 3 completely different workflows but I think this one is best) I am using a transform matrix in an attribute VOP to flatten all the points into one plane (the silhouette) so what I need at some point is to Boolean this out of the cuboid.

 

How can I trace an edge around the outside of this 2D "blob" of points? Then I will extrude and hey presto can do some Boolean action.

 

Cheers in advance for any help

 

5D

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Posted (edited)

A screenshot/diagram or especially an example scene would help visualize what you are trying to do that's not working.  There is a Trace SOP you can use on an image if you render a frame of the FLIP sim from your desired projection angle and use to cut out a dense grid, but if you've got a FLIP mesh, converting it to polygons would give you the fairly precise geo to boolean with? 

Edited by ryew

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My scene file has so much huge caching it wouldn't be practical? I thought I gave quite a precise description of what I wanted to achieve?

 

I think your idea with the Trace SOP might work. I'll try and do that.

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Here's a couple of approaches. Neither are perfect but should get the job done.

Method 1: Triangulate 2d, then delete long edges to hopefully cull the exterior polys from the silhouette.

Method 2: Attibute transfer from the flattened points onto a subdivided plane in order to cut out the silhouette. Higher subdivs give a more accurate result.

Squab_bool.hipnc

squab_bool.png

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You could also try the Geometry COP, which does a sort of projection along a specified axis and extracts alpha. Then pass that into a Trace SOP to polygonize the result.

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