MetaFun - Pragma ADE

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This rectangle is a scaled instance of the predefined METAFUN path fullsquare which is centered
around the origin.
pickup pencircle scaled 2mm ;
path p ; p := fullsquare scaled 2cm ;
draw p withcolor .625white ;
On this path, halfway between two of its corners, we define a point q:
pair q ; q := .5[llcorner p, lrcorner p] ;
We draw this point in red, using:
draw q withcolor .625red ;
As you can see, this point is drawn on top of the path.
There are four of those midpoints, and when we connect them, we get:
Because path p is centered around the origin, we can simply rotate point q a few times.
draw q -- q rotated 90 -- q rotated 180 -q
rotated 270 -- cycle withcolor .625red ;
There are situations, where you don't want the red path to be drawn inside another path, or more
general: where you want points to touch instead of being overlayed.
A few more details Only this far