Image:Triskele-Symbol-spiral.svg

[edit] Summary

A spiral Triskelion symbol, constructed from mathematical Archimedean spirals. For a less elaborate version, see Image:Triskele-Symbol-spiral-five-thirds-turns.svg . For a more elaborate spiral triskelion symbol (with three turns instead of two), see Image:Triple-Spiral-Symbol-filled.svg, and for the most elaborate version, see Image:Triple-Spiral-Symbol-4turns-filled.svg. For a basic triple-spiral, see Image:Triple-Spiral-Symbol.svg, and for "wheeled" forms of the spiral triskelion/triple spiral symbol, see Image:Wheeled-Triskelion-basic.svg , Image:Roissy triskelion iron ring signet.png , Image:Triple-spiral-wheeled-simple.svg , or Image:Triskelion-spiral-threespoked-inspiral.svg . For a spiral triskelion with a hollow triangle in the center, see Image:Triskele-hollow-triangle.svg . For versions of a triple-spiral labyrinth, see Image:Triple-Spiral-labyrinth.svg and Image:Triple-Spiral-labyrinth-variant.svg .

SVG version of Image:Triskele-Symbol-spiral.png .

Converted from the following PostScript code:

%!
/archimdouble{
%%%%%%%%%%%%%%%%
% PostScript program to display an Archimedean spiral by approximating
% it with Bezier curves.  Can display a double spiral (two spirals
% rotated by 180 degrees with respect to each other).
%%%  Parameters:
                 % centerx = horizontal coordinate of center of spiral
                 % centery = vertical coordinate of center of spiral
                 % rotf = degrees to rotate
/sepwid 110 def  % width separating successive turnings of spiral
                 % (half this if double spiral is selected)
/incrm 15 def    % insert a curve point after this number of degrees
/sweeps 2 def    % number of 360 degree turnings to show
/double 1 def    % change to 0 to display single spiral
%%%  Procedures:
/pi 3.1415926535898 def/radians 57.295779513082 def
/sepwid sepwid pi div 2 div def
gsave centerx centery translate rotf rotate
/aspiral{/prevbezy 0 def 0 0 moveto
    0 incrm sweeps 360 mul{7{dup}repeat
        phase add cos/costh exch def
        phase add sin/sinth exch def
        costh mul radians div/thcosth exch def
        sinth mul radians div/thsinth exch def
        thcosth sepwid mul/x exch def
        thsinth sepwid mul/y exch def
        /slope sinth thcosth add costh thsinth sub div def
        sinth 0 gt sinth 0 eq costh -1 eq and or{/flag -1 def}{/flag 1
            def}ifelse
        /A exch def A 49.29348 lt A 180 gt A 196.273450852 lt and A 360
            gt A 368.8301 lt and A 540 gt A 545.9907 lt and A 720 gt A
            724.5217 lt and A 900 gt A 903.6281968 lt and or or or or
            or{/flag flag neg def}if
        incrm sub 3{dup}repeat phase add cos sepwid mul mul radians div
            /prevx exch def phase add sin sepwid mul mul radians div
            /prevy exch def
        incrm add 3{dup}repeat phase add cos sepwid mul mul radians div
            /nextx exch def phase add sin sepwid mul mul radians div
            /nexty exch def
        /prevdist x prevx sub dup mul y prevy sub dup mul add sqrt pi
            div def
        /nextdist x nextx sub dup mul y nexty sub dup mul add sqrt pi
            div def
        /normaliz slope slope mul 1 add sqrt def
        0 eq{/prevbezx phase cos nextdist mul def}{prevbezx prevbezy
        x 1 flag mul normaliz div prevdist mul sub y slope flag mul
            normaliz div prevdist mul sub
        x y curveto
        /prevbezx x 1 flag mul normaliz div nextdist mul add def
        /prevbezy y slope flag mul normaliz div nextdist mul add def}
        ifelse}
    for stroke}def
/phase 0 def aspiral
%%% If different sweeps parameter for second spiral, define here:
/sweeps 1.67 def
%%%
double 0 ne{/phase 180 def aspiral}if grestore
%%%%%%%%%%%%%%%%
}def
gsave
712 -134 translate -.75 .75 scale -3 rotate
/centerx 304 def/centery 550 def/rotf 0 def archimdouble
/centerx 707.333 def/centery 550 def/rotf 120 def archimdouble
/centerx 505.667 def/centery 899.2967 def/rotf 240 def archimdouble
grestore
showpage
%%EOF

[edit] Licensing

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