Skeudenn:Triple-Spiral-Symbol-filled.png

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[edit] Summary

Version of the Triple Spiral symbol (see Image:Triple-Spiral-Symbol.png) with the area enclosed between the spirals filled in (and mirror-reflected with respect to Image:Triple-Spiral-Symbol.png). For a less elaborate triskelion symbol, see Image:Triskele-Symbol-spiral.png or Image:Triskele-Symbol-spiral-five-thirds-turns.png -- for a more elaborate version, see Image:Triple-Spiral-Symbol-4turns-filled.png. For "wheeled" forms of the spiral triskelion/triple spiral symbol, see Image:Wheeled-Triskelion-basic.png , Image:Roissy triskelion iron ring signet.png , Image:Triple-spiral-wheeled-simple.png , or Image:Triskelion-spiral-threespoked-inspiral.png . For a spiral triskelion with a hollow triangle in the center, see Image:Triskele-hollow-triangle.png . For versions of a triple-spiral labyrinth, see Image:Triple-Spiral-labyrinth.png and Image:Triple-Spiral-labyrinth-variant.png .

Generated by means of 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 = insert a curve point every these degrees
/sweeps swp2 def % number of 360 degree turnings to show
                 % double - 0 to display single spiral, else double
%%%  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/first 1 def
    lower 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{0 0 moveto/prevbezx phase cos nextdist mul def/first 0 def
            }{first 1 eq{x y moveto/first 0 def}{prevbezx prevbezy x 1
            flag mul normaliz div prevdist mul sub y slope flag mul
            normaliz div prevdist mul sub x y curveto}ifelse
        /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 2.67 def
%%%
double 0 ne{/phase 180 def aspiral}if grestore
%%%%%%%%%%%%%%%%
}def
gsave
618.5 0 translate
-.4875 dup neg scale %%% decrease to .47 to fit on A4-size page
-2 rotate
/lower 0 def/double 1 def/swp2 3 def/incrm 15 def
/centerx 304 def/centery 550 def/rotf 0 def archimdouble
/centerx 927.334 def/centery 550 def/rotf 120 def archimdouble
/centerx 615.667 def/centery 1089.823 def/rotf 240 def archimdouble
/lower 1103.4 def/double 0 def/swp2 1117 360 div def/incrm 13.5 def
/centerx 304 def/centery 550 def/rotf 0 def archimdouble
/centerx 927.334 def/centery 550 def/rotf 120 def archimdouble
/centerx 615.667 def/centery 1089.823 def/rotf 240 def archimdouble
grestore
showpage
%%EOF

[edit] Licensing

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