Hello! Using a CSG-difference to build an object produces often sharp
edges (for example if you cut off a cylinder out of a sphere). Whats the
best way to get smooth, round edges there?

Martin

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In article <3C190FEC.78BD6D39@radiok2r.de> , Martin <mar### [at] radiok2rde>  
wrote:

> Hello! Using a CSG-difference to build an object produces often sharp
> edges (for example if you cut off a cylinder out of a sphere). Whats the
> best way to get smooth, round edges there?

You could use a CSG of three tori and two cylinders.  Basically you do what
you do now, but then you create an inset with two of the tori and the
cylinder.  I don't have time to create a scene, but this ASCII art should
explain it a bit better, I hope:


    ****oo ------- oo****
  *****oooo ----- oooo*****
 ******oooo ----- oooo******
 *******oo$ ----- $oo*******
********$$$ ----- $$$********
********$$$ ----- $$$********
********$$$ ----- $$$********
 *******oo$ ----- $oo*******
 ******oooo ----- oooo******
  *****oooo ----- oooo*****
    ****oo ------- oo****

* = the outer torus, with the part already cut away with one cylinder
o = the two inner tori
$ = the inner cylinder (needs to be open and/or inverted)


    Thorsten

____________________________________________________
Thorsten Froehlich
e-mail: mac### [at] povrayorg

I am a member of the POV-Ray Team.
Visit POV-Ray on the web: http://mac.povray.org

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Wasn't it Martin who wrote:
>Hello! Using a CSG-difference to build an object produces often sharp
>edges (for example if you cut off a cylinder out of a sphere). Whats the
>best way to get smooth, round edges there?

As it happens, Tor Olav Kristensen has very recently posted in
povray.general:-

Subject: Iso-blobbing made easier
http://news.povray.org/3C1816A0.6D6B72C@hotmail.com

-- 
Mike Williams
Gentleman of Leisure

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Martin wrote:
> 
> Hello! Using a CSG-difference to build an object produces often sharp
> edges (for example if you cut off a cylinder out of a sphere). Whats the
> best way to get smooth, round edges there?

Martin,

as William suggested, you can use the method I
described in my last post to achieve such round
edges (by the help of iso-surfaces in POV-Ray v3.5).

But it is also possible to do it by macros that
does all the necessary transformations and CSG
operations to the object(s) for you.

I have earlier posted several images to the
povray.binaries.images group, where such macros
has been used.

Here's one example image; "Inside it" 17. jan. 2001:

http://news.povray.org/povray.binaries.images/13478/
news://news.povray.org/3A6620ED.E32CE364%40online.no


Tor Olav

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