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"Tor Olav Kristensen" <tor### [at] TOBEREMOVEDgmail com> wrote:
> "Kima" <nomail@nomail> wrote:
> > I try to create a tube by connecting cylinders over a spline. To avoid
> > unnecessary elements, I want to check if three points in line to avoid creation
> > of two cylinders when one is sufficient.
> >
> > To do this, I need to calculate the normalized vector of P2-P1 and compare it
> > with that of P3-P3 using the functions given at
> > https://www.povray.org/documentation/view/3.6.1/459/
> >
> > What is the most efficient way, as it is a continuous calculation, which may
> > enable me to increase the resolution (number of points).
>
> You can do it like this:
>
>
> #declare Nil = 1e-5; // Some small number
>
> #declare p1 = <2, -3, 1>;
> #declare p2 = <-3, 4, -2>;
> #declare p3 = <5, 0, -3>;
> // #declare p3 = (p1 + p2)/2;
>
> #declare vC = vcross(p2 - p1, p3 - p1);
>
>
> Now if vlength(vC) <= Nil, then the points are in line or almost in line.
>
> --
> Tor Olav
> http://subcube.com
> https://github.com/t-o-k/
I first went for calculating vlength because it is straightforward. I then tried
the angle between two vectors since I could set a degree of deviation.
By the way, your artworks are amazing. I am playing with your python notebooks.
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