I'm doing scales sim for animated snake.I'm using constraint to make scales follow the body and solve collisions. My scales are packed RBD, i have a position constraint to lock the scales to snake body, which work fine. And i need to set up another rotation constraint, which controls the scales to only rotate in one direction. I tried Spring Constraint Relationship, it seems no where to set up the angle? By default it lock the rotation to initial state.

usually by setting various attributes on your constraint geo
here is the full list https://www.sidefx.com/docs/houdini/nodes/dop/constraintnetwork.html#attributes [www.sidefx.com]

the ones you may want (on top of the usual ones) are p@orient, v@condof, v@condir