the bow.
@var{bow-height} determines the height of the bow.
@var{orientation} determines, whether the bow is concave or convex.
-@var{orientation} should be set to @val{-1} or @val{1}, other values are
-possible but will affect the bow's height as well.
Both variables are supplied to support independent usage.
Done by calculating a horizontal unit-bow first, then moving all control-points
;;;; (1) calculate control-points for the horizontal unit-bow,
;; y-values for 2nd/3rd control-points
(outer-control
- (* 4/3 orientation (/ bow-height length-to-print)))
+ (* 4/3 (sign orientation) (/ bow-height length-to-print)))
(inner-control
- (* orientation
+ (* (sign orientation)
(- (abs outer-control) (/ thickness length-to-print))))
;; x-values for 2nd/3rd control-points depending on `angularity'
(offset-index