MetaFun - Pragma ADE

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direction and magnitude of the shade. The next macro demonstrates the principles in a different
way.
def test_shade (expr a, b, ra, rb) =
pickup pencircle scaled 1mm ;
color ca ; ca := \MPcolor{a} ;
color cb ; cb := \MPcolor{b} ;
color cc ; cc := \MPcolor{c} ;
path pa ; pa := fullcircle scaled 2ra shifted a ;
path pb ; pb := fullcircle scaled 2rb shifted b ;
sh := define_circular_shade(a,b,ra,rb,ca,cb) ;
fill pb withshade sh ;
draw pb withcolor cc ;
draw pa withcolor cc ;
enddef ;
The shade is distributed between two circles, each with a radius and center point. All four can be
set, but as the next calls demonstrate, we can normally do with less, which is why we provided
the macro with less parameters.
test_shade(origin, origin, 0cm, 1cm) ;
test_shade(origin, origin, .25cm, 1cm) ;
test_shade(origin, origin, .50cm, 1cm) ;
test_shade(origin, origin shifted (.25cm,0), 0cm, 1cm) ;
test_shade(origin, origin shifted (.25cm,0), .25cm, 1cm) ;
test_shade(origin, origin shifted (.25cm,0), .50cm, 1cm) ;
Special effects Shading