Carl nous apporta ses lumieres en ce 09-04-2007 15:31:
> Hello,

>    I had a quick question.  I've made this logo seen here:

> http://www.wwwmwww.com/images/MyLogo.png

> It's a simple prism and starts something like this:

>   #declare wwwmwww = prism {
>     linear_sweep
>     bezier_spline
>     0, // sweep the following shape from here ...
>     10, // ... up through here
>     348, // the number of points making up the shape ...

> However instead of cutting this logo out of a sheet, I'd like to cut it out
> of a hollow cylinder with some wall thickness.  Instead of specifying
> basically x and y, I'd like to specify something like theta and y.  Think
> of it as a laser cutting out the logo as it moves up and down along the
> axis of the cylinder and points in the direction of theta.  Is that
> possible?

> I'm not the best at describing what I want but I hope that gets the point
> across.

> Thanks,
> Carl


Possible solution, if the desired cylinder have a ralatively large radius:
difference{
	object{wwwmwww}
	cylinder{<100,0,0><-100,0,0>,20}//must be longer than your prism
//the radius should be reasonably larger that the height of the prism
	cylinder{<101,0,0><-101,0,0>,17}//longer to avoid coincident surfaces
	texture{YourTexture}
	}
Here, the faces are curved, but the sides are still parallel.

Another way, is to use object pattern with a cylindrical warp to project it on a 
cylinder. This have the advantage of the sides been perpendicular to the 
surface. As this is meant for pigments, it must be converted to a function and 
used in an isosurface (extreem max_gradient) or directly as a media density. 
Both are slow.

-- 
Alain
-------------------------------------------------
Lutheran: If shit happens, don't talk about it.

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