MetaFun - Pragma ADE

z0 .. z1 .. z2
z0 {curl 1} .. z1 .. {curl 1} z2
So, a curl of 1 is the default. When set to 1, the begin and/or end points are approached. Given
the following definitions:
u := 1cm ; z1 = (0,0) ; z2 = (2u,4u) ; z3 = (4u,0) ;
def sample (expr p, c) =
draw p withpen pencircle scaled 2.5mm withcolor white ;
draw p withpen pencircle scaled 2.0mm withcolor c ;
enddef ;
We can draw three curved paths.
sample (z1 {curl 0} .. z2 .. {curl 0} z3, .625red) ;
sample (z1 {curl 2} .. z2 .. {curl 2} z3, .625yellow) ;
sample (z1 {curl 1} .. z2 .. {curl 1} z3, .625white) ;
The third (gray) curve is the default situation, so we could have left the curl specifier out of the
expression.
The curly specs have a lower bound of zero and no upper bound. When we use METAPOST maximum
value of infinity instead of 2, we get:
These curves were defined as:
Inflection, tension and curl A few more details
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