MetaFun - Pragma ADE

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This rather nice circle is defined as:
colorcircle(4cm,(.4,.6,.8),(.8,.4,.6),(.6,.8,.4));
The final implementation, which is part of METAFUN, is slightly more efficient.
vardef colorcircle (expr size, red, green, blue) =
save r, g, b, c, m, y, w ; save radius ;
path r, g, b, c, m, y, w ; numeric radius ;
radius := 5cm ; pickup pencircle scaled (radius/25) ;
transform t ; t := identity rotatedaround(origin,120) ;
r := fullcircle rotated 90 scaled radius
shifted (0,radius/4) rotatedaround(origin,135) ;
b := r transformed t ; g := b transformed t ;
c := buildcycle(subpath(1,7) of g, subpath(1,7) of b) ;
y := c transformed t ; m := y transformed t ;
w := buildcycle(subpath(3,5) of r,
subpath(3,5) of g, subpath(3,5) of b) ;
pushcurrentpicture ;
fill r withcolor red ;
fill g withcolor green ;
fill b withcolor blue ;
fill c withcolor white-red ;
fill m withcolor white-green ;
fill y withcolor white-blue ;
fill w withcolor white ;
for i = r,g,b,c,m,y : draw i withcolor .5white ; endfor ;
currentpicture := currentpicture xsized size ;
A few applications Color circles