[pstricks] Quartic Bezier curves (of fourth order)

[Jonny Smith]

Awesome! Beautiful! Love it!

I'm using something like

...

\begin{document}
    \psset{xunit=0.1cm,yunit=0.1cm}
    \begin{pspicture}(125,20)

\psbezierIV[linewidth=4pt,showpoints=true]{<->}(0,2)(45,2)(60,40)(75,2)(120,2)
    \end{pspicture}
\end{document}

for my design purposes.

Thanks a lot!

J


On Wed, Mar 19, 2008 at 8:59 PM, Herbert Voss <Herbert.Voss at fu-berlin.de>
wrote:

> a solution created with hot needles ...
>
> Herbert
>
>
> \documentclass{article}
> \usepackage{pst-plot}
>
> \makeatletter
> \pst at def{BezierQuartic}<
>   ] /Points ED %                y4 x4 y3 x3 y2 x2 y1 x1 y0 x0
>   /GetBezierCoor {
>   /t ED                                % t on stack
>   /t1 1 t sub def
> %  the x coordinate
>   Points 8 get t 4 exp mul                              % x0*B0(t)
>   Points 6 get t 3 exp 4 mul mul t1 mul add             % x1*B1(t)
>   Points 4 get t 2 exp 6 mul mul t1 2 exp mul add       % x2*B2(t)
>   Points 2 get t 4 mul mul t1 3 exp mul add             % x3*B3(t)
>   Points 0 get t1 4 exp mul add                         % x4*B4(t)
> %  the y coordinate
>   Points 9 get t 4 exp mul                              % y0*B0(t)
>   Points 7 get t 3 exp 4 mul mul t1 mul add             % y1*B1(t)
>   Points 5 get t 2 exp 6 mul mul t1 2 exp mul add       % y2*B2(t)
>   Points 3 get t 4 mul mul t1 3 exp mul add             % y3*B3(t)
>   Points 1 get t1 4 exp mul add                         % y4*B4(t)
> } def
>   /epsilon 0.01 def
>   /n 5 def
>   epsilon GetBezierCoor         % next Bezier point
>   Points 0 get Points 1 get     % starting point
>   ArrowA moveto
>   epsilon epsilon 1 {
>     /t ED
>     t GetBezierCoor
>     t 0.9999 lt { lineto }{ 1 epsilon sub GetBezierCoor 4 2 roll ArrowB
> pop pop pop pop } ifelse
>   } for >
> %\def\tx at BezierQuartic{BezierQuartic }
> \def\psbezierIV{\pst at object{psbezierIV}}
> \def\psbezierIV at i{%
>   \pst at getarrows{%
>     \begin at OpenObj
>     \pst at getcoors[\psbezierIV at ii%
>   }}
> \def\psbezierIV at ii{%
>   \addto at pscode{%
>     \tx at BezierQuartic
>     \ifshowpoints \tx at BezierShowPoints \fi
>   }%
>   \end at OpenObj}
> %
> \makeatother
>
> \begin{document}
> \psset{xunit=0.2cm}
> \begin{pspicture}(40,15)
>
> \psbezierIV[linewidth=2pt,showpoints=true]{<->}(0,0)(10,5)(20,13)(30,5)(40,0)
> \end{pspicture}
>
> \end{document}
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