appli offset given distanc normal vector comput line specifi point param point line us comput normal vector param point line us comput normal vector param offset distanc displac fig normal vector param anchor start point appli offset modifi comput point describ locat offset appli anchor point appli offset theta offset point anchor point result point anchor set follow backward compat old algorithm right log debug slope theta math pi pi theta math pi add displac angl slope swap theta math pi theta math pi theta theta angl theta theta angl transform pi rang ve gone wai circl theta math pi theta math pi theta theta math pi comput delta dx offset math co theta dy offset math sin theta backward compat right todo polar domain right dx math ab dx dy math ab dy result dx result dy log debug result result theta theta math pi dx dx dy dy result 