profile p1 x 3 y 1 x -2 y 2 x -1 y -3
prism pr p1 0 0 1
profile p2 x 2 y 2 x -2 y -2
ttranslate p2 1 1 0

featprism pr p2 p2 0 0 1 1 1
featperformval prism result 0.5

set square 30