> I fixed the problem - my spline was out-of-whack, which is why it wasn't lining
> up with the sphere sweep, and producing all sorts of weird results.
>
> I thought that using triangles would be faster than cylinders - but it's slower?
>
> The other thing that I noticed is that using triangles with a small loop step
> made the SKY render slower.  I'm not sure why that would be.
>
> Anyway, after much plotting and puzzling, and backtracing, I fixed it up and I
> think it looks pretty good.
>
> Shown with the propeller are the coordinates of the spline and the scaled trig
> functions I use to curve around the hub.
>

Looking at the cylinders fill, you see that the corresponding triangles 
are long and narrow. Those are known to be slower. If your triangles 
where oriented perpendiculat to the lenght of the blade, they would 
render faster, but would make the face of the blade to flat. To 
compensate, you'd need to have some other splines running the length of 
the blade according to the desired curvature and use smooth triangles. 
Have two sets of such splines, one for the front and one for the back of 
the propeller so the blades have the desired thickness.



Alain

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