"ingo" <ing### [at] homenl> wrote in message
news:Xns### [at] povrayorg...
> From the scene below the expected result is a square, yet I get a
> thing like:
>  ____
> |    |
> |  \ |
> |   \|
>
>  When the first point of the spline is omitted, the result is a square.
> I.M.O the first point should be of no influence when using a
> linear_spline.
>  When using a quadratic or cubic spline something simmiliar happens,
> with the first point the shape is not closed. Without the first point
> the shape is closed, but not smooth at the point where it closes.

I don't know splines too well but seems strange to me that leaving off both
the first and last points close the loop although adding them opens it.  I
thought cubic and quadratic required the control or anchor points, which in
this case are the T=-0.25 and T=1.25 here.
For linear, you can see that the points beyond T=0 through T=1 are ignored.
Well, except if I=-25 then the first is seen, but N=125 or 150 doesn't show
the last T value.  If you get what I'm saying.

Bob H.

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