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Old 28th December 2006, 05:54 PM   #1
Slipknot
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Default Problem with boolean operations...

i am still on my trial with ac3d and i am quite loving it (expecting to buy) and currently im making some low poly guns and whatnot, when making the barrel of the gun, i make a cylinder then make a smaller cylinder inside in and do the object-> boolean-> subtract method to somewhat hollow out the barrel for better detail. naturally this would work, but i keep getting faces of the cylender left over and more faces than necisary takin away. i have tried other boolean operations but others lead to the same result. i have tried reloading it. no other objects are touching it. is there a fix?
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Old 30th December 2006, 01:06 AM   #2
brvids
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Default Re: Problem with boolean operations...

That new boolean feature is great! I was messing around with it. Why don't you just use a sphere instead for the barrel. Cut away a sphere like I did in these pictures. Not sure if this is what you were looking for. But maybe this would work for you. After you cut away the sphere move its left over vertices to the back of the barrel and flatten it. Well good luck anyway.

http://www.beteogames.com/barrel1.jpg
http://www.beteogames.com/barrel2.jpg
http://www.beteogames.com/barrel3.jpg
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Old 31st December 2006, 05:14 PM   #3
Slipknot
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Default Re: Problem with boolean operations...

intresting... thanks. say why would the boolean for cylinders - in - cylinders produce a messed up result?
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Old 31st December 2006, 09:36 PM   #4
brvids
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Default Re: Problem with boolean operations...

I'm not sure. Honestly I didn't even try the cylinder. Must just be some kind of glitch or something.
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Old 31st December 2006, 11:45 PM   #5
mconn1
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Default Re: Problem with boolean operations...

Slipknot,

I just tried your method of creating a "gun barrel".

It worked splendidly for me. No left over surfaces or vertices. No messy boolean leftovers either. All this from 2-10 sided cylinders.

I did have to make the final object 2-sided in order for all of the surface lines to show up properly in wireframe.

Things I did to make sure there are no artifacts:
1. Made the inside cylinder longer than the outside cylinder.
2. Made sure all of the end caps of the cylinders matched according to the end cap surface lines.
3. I think the outside cylinder was first in the hierarchy.

Not sure if this actually helps...Just trying to replicate what you did.

Just tried to use the Boolean subtract on another set of cylinders. I combined each end cap of the cylinders. I ended up with a lot of Boolean artifacts on the end caps. I hope you didn't combine your end caps because you are not dealing with simple triangles. The complex surfaces are not handled very well with the Boolean commands.

Just tried another strange set of objects. I made 1 large triangular cylinder and placed 3 10 sided cylinders inside. Boolean subtracted each of the 10 sided cylinders from the triangular cylinder, not as a group...but one at a time. No Boolean artifacts showed up. It was actually a nice looking object after all was said and done.
Attached Files
File Type: ac gunbarrel.ac (4.4 KB, 239 views)

Last edited by mconn1; 1st January 2007 at 01:50 AM.
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Old 4th March 2007, 11:29 AM   #6
Terry Capps
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Question Re: Problem with boolean operations...

I am also having trouble with the boolean operation involving a cylinder inside a larger cylinder to create a hollow cylinder. The surface normals of the cylinders all appear to be outward facing, but the boolean result has extra surfaces and some missing surfaces. Is this a bug or what?
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Old 4th March 2007, 11:56 AM   #7
Andy
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Default Re: Problem with boolean operations...

If your model is very small (or very large), you may get errors. The booleans rely on floating point precision and are configured for average use. Very small sizes can cause errors.

Try pressing the 200% button (Toolbar) a few times before the boolean and then 50% (the same number of times) after, to restore the original size/scale.
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Old 4th March 2007, 02:51 PM   #8
Terry Capps
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Default Re: Problem with boolean operations...

I was using one cylinder that was 1x1x1 and a smaller one that was .8x1.5x.8. I tried your suggestion and it worked. Thanks.
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