shape=polygon
type: double, default: 0.0, minimum: -100.0
0.0
-100.0
Positive values cause top part to be larger than bottom; negative values do the opposite.
See also skew.
skew
graph { LargeBottom [shape=polygon sides=4 distortion=-.5] LargeTop [shape=polygon sides=4 distortion=.5] }
Search the Graphviz codebase for "distortion"
"distortion"