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boolean - Strange behavior

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kurisutofu
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Hello,

I'm trying to use booleans to create a geometry but it is not behaving as I expected.

I have a normal grid that I'll call A and a cross-shaped grid that I'll call B.
I'd like to do a boolean operation A-B so a cross-shaped “hole” would result in the object A.
Then I'd extrude the result where the hole would be more distinguishable.

However, the boolean creates a strange shape for the cross-shaped hole … Is boolean not working for grids? Should I extrude first before?
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kurisutofu
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Here are some screenshots.

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all.jpg (182.6 KB)

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EigenAlex
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cookie (boolean) operation can yield some pretty nasty result, though it does has its place… Perhaps try extruding the cross prior to boolean operation? I don't think a flat surface boolean against another flat surface will do well…
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kurisutofu
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TheUsualAlex
cookie (boolean) operation can yield some pretty nasty result, though it does has its place… Perhaps try extruding the cross prior to boolean operation? I don't think a flat surface boolean against another flat surface will do well…

I will try that, thank you.
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kurisutofu
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I've tried to extrude before and that didn't change anything. Then, I thought anyway it would be better to use box and tubes instead of grid and circle that I would extrude anyway.
At the end, I could get close to what I expected but still not there …
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fsimerey
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I think your problem comes from your object A. In your capture, we can see the circle seems not be fused with the other part. The normal of circle is in his center and not in the middle of the half circle…

Like for all 3D software, booleans operations need some very clean objects.

If you attache a file, we could be help you.
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kurisutofu
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fsimerey
I think your problem comes from your object A. In your capture, we can see the circle seems not be fused with the other part. The normal of circle is in his center and not in the middle of the half circle…

Like for all 3D software, booleans operations need some very clean objects.

If you attache a file, we could be help you.

I merged the grid and the circle with the merge node, should I use something else? I try to use a cookie but was not cleaner …

Once back home, I will put the file if it's not too big.
Thank you!
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fsimerey
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Merge isn't fuse your geometry. So you need have for both, A and B, clean geo.
You can do that either by a cookie SOP (boolean) to create A and B or create your geometry like it could be before merge them together.
For example, use an closed arc circle and not a closed circle and merge + fuse them.

Remember Fuse SOP proceed on points, so your grid used for A must have equals points on his edge than the closed arc. SO simplify your grid by setup row and columns by 3.
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fsimerey
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Something like the attached capture.

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Form_A.png (19.6 KB)

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fsimerey
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Like said TheUsualAlex, operate cookie SOP on flat surface isn't works fine. It's what for i put a PolyExtrude SOP on form B before cookie SOP.

Attachments:
cookie1_A-B.png (20.0 KB)
cookie_net.png (22.7 KB)
cookie1.png (23.2 KB)

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kurisutofu
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Wow! Thank you!!
I didn't know for the arc … I will try and let you know if how it went ^^
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kurisutofu
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I tried to replicate the same as you fsimerey but I didn't get the same result …
I'm attaching the file, if you could take a look at it, I'd appreciate it.

Thank you.

Attachments:
bar2.hipnc (46.4 KB)

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fsimerey
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Your problem is simple. You didn't setup a translate in Y axis in Global Tab of polyextrude (your form B is still a flat form but with coplanars polygons).

See attached file.

Attachments:
bar2_FS.hipnc (98.2 KB)

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kurisutofu
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Thank you very much fsimerey!! You taught me a lot!
I now understand the importance to fuse (I thought a merge was doing that … ^_^ and how to polyextrude properly.

Thank you!!
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fsimerey
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You're welcome kurisutofu. I hope you will appreciate more and more Houdini. The most difficult is the beginning, but when you will understand the philosophy, you can't return on another package
And the last but not least, Houdini's community is a great one.
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kurisutofu
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fsimerey
You're welcome kurisutofu. I hope you will appreciate more and more Houdini. The most difficult is the beginning, but when you will understand the philosophy, you can't return on another package
And the last but not least, Houdini's community is a great one.

I almost gave up but then it's free so I tried a little harder … and I find it good for beginner who can change things quickly thanks to the procedural design.
Plus, I'm a programmer so I find it easy to understand.

It's just that I need to check all the nodes like the circle for example, which I didn't know we could set as open/close arc … Thanks to you, I know that now ;-)
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