Avogadro::Core::Constraint

class Constraint

Constraints for optimization / dynamics.

This class represents a distance, angle, or torsional constraint / restraint during optimization or dynamics. More technically, these are implemented as stiff harmonic oscillators restraining a particular atom set towards the value.

Author

Geoffrey R. Hutchison

Public Types

enum Type

Values:

enumerator None

enumerator DistanceConstraint

enumerator AngleConstraint

enumerator TorsionConstraint

enumerator OutOfPlaneConstraint

enumerator UnknownConstraint

Public Functions

inline Constraint(Index a, Index b, Index c = MaxIndex, Index d = MaxIndex, Real value = 0.0)

Constructor, results in a zero distance constraint

Parameters:

• a – Atom index of the first atom of the constraint

• b – Atom index of the second atom of the constraint

• c – Atom index of the third atom (for angles or torsions) or MaxIndex

• d – Atom index of the fourth atom (for torsion constraints) or MaxIndex

• value – The value of the constraint, either Angstrom for distance or radians)

inline void set(Index a, Index b, Index c = MaxIndex, Index d = MaxIndex, Real value = 0.0)

Set the constraint

Parameters:

• a – Atom index of the first atom of the constraint

• b – Atom index of the second atom of the constraint

• c – Atom index of the third atom (for angles or torsions) or MaxIndex

• d – Atom index of the fourth atom (for torsion constraints) or MaxIndex

• value – The value of the constraint, either Angstrom for distance or radians)

inline void setValue(Real value)

Set the constraint value (distance, angle, dihedral)

Parameters:

value – The value of the constraint, either Angstrom for distance or radians)

inline Real value() const

Returns:

the constraint value

inline std::tuple<Index, Index, Index, Index> atoms() const

Returns:

the atoms in the constraint as a tuple

inline Index aIndex() const

Returns:

the atom index from the constraint or MaxIndex

inline Index bIndex() const

inline Index cIndex() const

inline Index dIndex() const

inline Real k() const

inline void setK(Real k)

inline Constraint::Type type() const

Returns:

the type of constraint

inline void setType(Constraint::Type type) const

Set the type of constraint

Parameters:

type – The type of constraint

Protected Attributes

Index m_aIndex = MaxIndex

Index m_bIndex = MaxIndex

Index m_cIndex = MaxIndex

Index m_dIndex = MaxIndex

Real m_value = 0.0

Real m_k = 1000.0

mutable Constraint::Type m_type = None