Le 19/04/2016 15:58, clipka a écrit :
> Am 18.04.2016 um 18:52 schrieb Le_Forgeron:
> 
>> Prism can have more than one loop/fold.
>>
>> I can reproduce the issue with :
>>
>> #declare P0=<0,0>;
>> #declare P1=<1,0>;
>> #declare P2=<2,1>;
>> #declare P3=P1;
>> #declare P4=<4,1>;
>> #declare P5=<5,0>;
>>
>> prism{cubic_spline 0, 1, 7, P0, P1, P2, P3, P4, P1, P5}
>>
>> Notice that the problem is between the keyboard and the chair:
> 
> Hm... I don't think it's that easy. A reasonable case can be made for
> single loops with coincident control points; think e.g. of an hourglass
> shape in an animation, where the narrow portion is supposed to reach
> zero in one frame. The case is even easier to make for Bezier splines.
> 
> So I think we should consider this a flaw in the prism syntax, and think
> of how this could be remedied.

It's only the first point of the curve which is special.

If you expect the prism to have a concentration of points, do not choose that region
for the first point.

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