_wedge t p p' = overlay (_fastGap (1/t) p) (t `rotR` _fastGap (1/(1-t)) p')
_wedge t p p' = overlay (_fastGap (1/t) p) (t `rotR` _fastGap (1/(1-t)) p')
_wedge t p p' = overlay (_fastGap (1/t) p) (t `rotR` _fastGap (1/(1-t)) p')