DeleD Community Edition

kholder · DeleD PRO user Joined: 10 Feb 2007 Posts: 2

First off, I am new to the 3D modeling world. I am confident that I am simply not using the tool correctly when creating/altering polys to be used for subtraction but the tutorials and documents I have read do not clear up the issue for me so I am posing the question here.

With simple cubes, I have no problem using subtraction to create holes in other polys. Anything more complex than a simple cube, however, when I create them anyway, does not seem to actually be a solid poly. When it is used for subtraction, I get bits and pieces cut out rather than the whole poly shape.

For example, I am even having trouble cutting out a window hole for a square window with an arched top. The object I create to be the subject of the subtraction does not actually cut all of the space out.

What am I doing wrong? Please keep my ignorance of the subject in mind. hehe.

Thanks.

Jeroen · Posted: Wed Feb 14, 2007 1:17 pm Post subject:

You might not be doing anything wrong. I'm not trying to make up excuses, but it's very hard to create CSG routines that produce the correct result 100% of the time. Even the big applications have troubles with that.

Having said that, maybe your geometry isn't 100% correct. What does your object look like? Are you sure all polygons in the object are flat? Take a look at this thread here:

http://www.delgine.com/forum/viewtopic.php?t=2044

It explains why, in some cases, the CSG routines fail because of bad geometry. If your geometry is good, something is wrong with the CSG routines. In that case, I'd very much like to get my hands on that geometry so I can possibly improve the CSG routines. Smile

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Mr.Fletcher · Posted: Wed Feb 14, 2007 2:27 pm Post subject:

Even if your geometry is correct, it might very well result in a non correct object. The following image is just a 16x16 torus subtracted from a cube. There are holes in it, as you see on the background color:

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Jeroen · Posted: Wed Feb 14, 2007 2:50 pm Post subject:

Yes, that is correct. My own tests have shown that the torus object can indeed cause issues like this. That's why I mentioned that 100% error-free CSG routines are hard to find. Wink

Anyway, as soon as I have some time, I will spend it on fixing CSG errors like this.

Note: most of these errors are easily fixed by using Fill, for example.
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