Your parameters do not make sense geometrically.
w = 1 // width
h = 5 // height
t = 1 // thick
r = 3 // radius corner => double radius of the corners is 6, but the width and height is much smaller
s = 1 // smoothness
I have not included a check, as nonsensical values sometimes result in interesting things.
See RoundedRectangle + Squircle (5th and 6th picture)