CGAL users discussion list

["Max" <>]

Hello Peter,

>> I'm curious on these questions:
>> 
>> - is there a nef_1 representation of a nef in 1 dimension?
>>   (yes, it's just a combinition of any open or close ranges. What I mean 
>> is 
>>   a universal representation as nef_3)
>
>We don't have that in CGAL and it does not seem interesting to have.

I also agree that this may be of no use in practice. I'm just interested
in the completeness of the module. Sorry for the naive question.

>
>> - is there a function to elevate the number of dimensions to higher 
>> dimension,
>>   e.g., convert a nef_2 into a nef_3?
>
>Not yet.

Is this on your todo list or would it be?

>
>> - is there a convenient way to perform some well-know geometric operation, 
>> such as
>>   glide, extrude, etc., with an existing nef_X?
>
>Sorry to say, but I don't know glide and extrude.

What I mean by glide is as you understood as below. That by extrude is 
similar, 
except these 2 aspects:
1. the 'gliding' path of extrude op is a line segment rather than a polyline;
2. the extrude op make d+1 dimensional obj from dD obj.

>
>> - is there a function to glide a nef_3 to get the swept nef_3?
>
>if glide means to compute the area swept by a nef_3 moved along a
>polygonal line, then you can do that with the Minkowski_sum_3 package
>that hopefully will be in the next CGAL release.

That's a good news, thank you.
Is there a scheduled time for the next release?

>
>> - is there a machanism to shift the kernel types of one nef_3 (and any 
>> other 
>>   CGAL data structure) at runtime?
>
>No.

That's a bad news. Is there a plan to let us have this? :-)
I think it will be useful in promoting the efficiency of our code.

>> - is there a function to incrementally build a (not necessarily 
>> 2-manifold) nef_3?
>
>No, I neither have an idea how it might work, nor the manpower to do
>realize that at the moment.

... ...

>
>Peter

Thank you so much for you reply.

B/Rgds
Max