POV-Ray : Newsgroups : povray.newusers : Is it possible to extrude a 3D shape? Server Time
23 Dec 2024 15:20:44 EST (-0500)
  Is it possible to extrude a 3D shape? (Message 1 to 2 of 2)  
From: Timwi
Subject: Is it possible to extrude a 3D shape?
Date: 18 Mar 2009 14:45:50
Message: <49c1415e$1@news.povray.org>
Generally, is there a built-in feature in POV Ray to create a solid 
object from sweeping an existing solid object along a path?

If not, is it at least possible to sweep it along a straight line?

If still not possible, maybe my special case is possible some other way. 
I actually want to extrude a planar sphere-sweep. So supopose I have a 
spline on the y plane, and I use sphere-sweep to turn this into a tube 
lying on the y plane. Now I want to turn that tube into a "sheet" with 
round edges by extruding it along the y axis. Is this possible?

Perhaps is there a way to construct an equivalent shape by using 
something other than sphere-sweep?

Thanks
Timwi


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From: Mike Williams
Subject: Re: Is it possible to extrude a 3D shape?
Date: 18 Mar 2009 17:43:08
Message: <p$rM5GBprWwJFwZN@econym.demon.co.uk>
Wasn't it Timwi who wrote:
>
>Generally, is there a built-in feature in POV Ray to create a solid 
>object from sweeping an existing solid object along a path?
>
>If not, is it at least possible to sweep it along a straight line?
>
>If still not possible, maybe my special case is possible some other 
>way. I actually want to extrude a planar sphere-sweep. So supopose I 
>have a spline on the y plane, and I use sphere-sweep to turn this into 
>a tube lying on the y plane. Now I want to turn that tube into a 
>"sheet" with round edges by extruding it along the y axis. Is this 
>possible?
>
>Perhaps is there a way to construct an equivalent shape by using 
>something other than sphere-sweep?

In this particular case you could make three copies of the sphere sweep.

Place one copy at y=0

Translate one copy in the y direction

Scale the third copy by a huge amount in the y direction and intersect 
it with the y=0 and y=1 planes. [If it were possible to scale it by 
infinity in the y direction, it would fit perfectly, but scaling by, say 
1e12, will create a shape that's off by less than a millionth of a pixel 
unless your original shape is huge.]

#declare D=10;

union {
   object {Sweep}
   object {Sweep translate y*D}
   intersection {
     object {Sweep scale <1,1e12,1> translate y*D/2 }
     plane {-y,0}
     plane {y,10}
   }
   pigment {rgb 1}
}


-- 
Mike Williams
Gentleman of Leisure


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