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>> Depends on exactly which way it isn't perfectly cylindrical in.
>
> How about simply a stretched cylinder, ie an extruded ellipse. You
> can't simply scale the torus or cone otherwise the radius/bevel will not
> be constant around the perimeter.
Yeah. In that case you'd have to use a sphere-sweep [which is
inexplicably slow for no defined reason].
> As well as having elliptical buttons, the top surface of the buttons on
> my phone are also curved (concave inwards). I suppose you could model
> this in POV by subtracting a big sphere from the extruded oval.
Indeed, that's exactly how you'd do it. Much like if you wanted a convex
top instead.
> But how
> to do the rounded edge then? Matching up a round with the vertical
> sides (actually they're slightly off-vertical) of the button with the
> curved top surface doesn't sound very easy to me.
It does to me, but hey...
>> Really, you can go a seriously long way using only quadratics and CSG.
>
> Do you have any examples?
Not to hand, no.
>> Think about it - if you wanted to model the Natural History Museum,
>> would you built it out of a few quadrillion triangles? Or just cut a
>> few solids out of each other? I know what I'd choose...
>
> And I know which one would look like a photo-realistic model and which
> one would look like a few solids cut out of each other :-)
Yes, because crude approximations to cylindrical columns look so much
more photo-realistic than actually cylindrical columns. Oh, wait...
>> Mmm, interesting. In all the years I've been using POV-Ray, I've never
>> actually noticed that before...
>
> I didn't realise it either until I got into designing stuff that people
> will actually see (as opposed to internal components). Most companies
> will reject any curvature discontinuities.
Ah, well, presumably if you're doing CAD rather than just pretty
pictures, you have *real* modelling tools. ;-)
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