double OEGetTorsion(const OEHierResidue &res, unsigned torType)
double OEGetTorsion(const OEChem::OEAtomBase *atom, unsigned torType,
                    unsigned assume=OEAssumption::Default)

Returns the angle in radians for one of the standard torsion angles in a residue. The specific torsion is indicated by passing one of the constants from the OEProtTorType namespace into the ‘torType’ parameter. The residue is specified by its OEHierResidue class or by any OEAtomBase from the residue. If the specified torsion type does not exist in the given residue, the function returns -100.0.