> On 10/12/2010 10:23 AM, Warp wrote:
>> I don't understand how it could work ok with a bicubic patch, because
>> a bicubic patch has no well-defined interior.
>>
>
> That is my understanding too but I did a couple of tests before posting.
> In the cases I tried it gave me the results I expected. (Assuming that a
> patch can be used in a difference or intersection.)
>
>> (Meshes don't have one either, by default, but an interior calculation
>> for closed meshes can be turned on with the 'inside_vector' feature.
>> IIRC discs work like planes in that they divide the space into two parts:
>> the outside and the inside. However, because the visible surface does not
>> cover the entire partition, they will cause odd behavior when used in
>> CSG.)
>>
>
> That is true, discs do cause odd behavior when used in CSG.

You may difference FROM a patch. It will only cut the parts of the patch 
that are not inside the solid object.
An intersection should give the same result: Only the part of the patch 
that intersects the solid object if the patch is the first object.

The message is mostly a warning as the result may not be what you expect.


Alain

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