#include <AngleConstraintPart.h>

Public Member Functions
void	CalculateConstraintProperties (const Body &inBody1, const Body &inBody2, Vec3Arg inWorldSpaceAxis, float inBias=0.0f)

void	CalculateConstraintPropertiesWithFrequencyAndDamping (float inDeltaTime, const Body &inBody1, const Body &inBody2, Vec3Arg inWorldSpaceAxis, float inBias, float inC, float inFrequency, float inDamping)

void	CalculateConstraintPropertiesWithStiffnessAndDamping (float inDeltaTime, const Body &inBody1, const Body &inBody2, Vec3Arg inWorldSpaceAxis, float inBias, float inC, float inStiffness, float inDamping)

void	CalculateConstraintPropertiesWithSettings (float inDeltaTime, const Body &inBody1, const Body &inBody2, Vec3Arg inWorldSpaceAxis, float inBias, float inC, const SpringSettings &inSpringSettings)
	Selects one of the above functions based on the spring settings.

void	Deactivate ()
	Deactivate this constraint.

bool	IsActive () const
	Check if constraint is active.

void	WarmStart (Body &ioBody1, Body &ioBody2, float inWarmStartImpulseRatio)

bool	SolveVelocityConstraint (Body &ioBody1, Body &ioBody2, Vec3Arg inWorldSpaceAxis, float inMinLambda, float inMaxLambda)

float	GetTotalLambda () const
	Return lagrange multiplier.

bool	SolvePositionConstraint (Body &ioBody1, Body &ioBody2, float inC, float inBaumgarte) const

void	SaveState (StateRecorder &inStream) const
	Save state of this constraint part.

void	RestoreState (StateRecorder &inStream)
	Restore state of this constraint part.

Detailed Description

Constraint that constrains rotation along 1 axis

Based on: "Constraints Derivation for Rigid Body Simulation in 3D" - Daniel Chappuis, see section 2.4.5

Constraint equation (eq 108):

\[C = \theta(t) - \theta_{min}\]

Jacobian (eq 109):

\[J = \begin{bmatrix}0 & -a^T & 0 & a^T\end{bmatrix}\]

Used terms (here and below, everything in world space):
a = axis around which rotation is constrained (normalized).
x1, x2 = center of mass for the bodies.
v = [v1, w1, v2, w2].
v1, v2 = linear velocity of body 1 and 2.
w1, w2 = angular velocity of body 1 and 2.
M = mass matrix, a diagonal matrix of the mass and inertia with diagonal [m1, I1, m2, I2].
\(K^{-1} = \left( J M^{-1} J^T \right)^{-1}\) = effective mass.
b = velocity bias.
\(\beta\) = baumgarte constant.

Member Function Documentation

◆ CalculateConstraintProperties()

void AngleConstraintPart::CalculateConstraintProperties	(	const Body &	inBody1,
		const Body &	inBody2,
		Vec3Arg	inWorldSpaceAxis,
		float	inBias = `0.0f`
	)

inline

Calculate properties used during the functions below

Parameters

inBody1	The first body that this constraint is attached to
inBody2	The second body that this constraint is attached to
inWorldSpaceAxis	The axis of rotation along which the constraint acts (normalized) Set the following terms to zero if you don't want to drive the constraint to zero with a spring:
inBias	Bias term (b) for the constraint impulse: lambda = J v + b

◆ CalculateConstraintPropertiesWithFrequencyAndDamping()

void AngleConstraintPart::CalculateConstraintPropertiesWithFrequencyAndDamping	(	float	inDeltaTime,
		const Body &	inBody1,
		const Body &	inBody2,
		Vec3Arg	inWorldSpaceAxis,
		float	inBias,
		float	inC,
		float	inFrequency,
		float	inDamping
	)

inline

Calculate properties used during the functions below

Parameters

inDeltaTime	Time step
inBody1	The first body that this constraint is attached to
inBody2	The second body that this constraint is attached to
inWorldSpaceAxis	The axis of rotation along which the constraint acts (normalized) Set the following terms to zero if you don't want to drive the constraint to zero with a spring:
inBias	Bias term (b) for the constraint impulse: lambda = J v + b
inC	Value of the constraint equation (C)
inFrequency	Oscillation frequency (Hz)
inDamping	Damping factor (0 = no damping, 1 = critical damping)

◆ CalculateConstraintPropertiesWithSettings()

void AngleConstraintPart::CalculateConstraintPropertiesWithSettings	(	float	inDeltaTime,
		const Body &	inBody1,
		const Body &	inBody2,
		Vec3Arg	inWorldSpaceAxis,
		float	inBias,
		float	inC,
		const SpringSettings &	inSpringSettings
	)

inline

Selects one of the above functions based on the spring settings.

◆ CalculateConstraintPropertiesWithStiffnessAndDamping()

void AngleConstraintPart::CalculateConstraintPropertiesWithStiffnessAndDamping	(	float	inDeltaTime,
		const Body &	inBody1,
		const Body &	inBody2,
		Vec3Arg	inWorldSpaceAxis,
		float	inBias,
		float	inC,
		float	inStiffness,
		float	inDamping
	)

inline

Calculate properties used during the functions below

Parameters

inDeltaTime	Time step
inBody1	The first body that this constraint is attached to
inBody2	The second body that this constraint is attached to
inWorldSpaceAxis	The axis of rotation along which the constraint acts (normalized) Set the following terms to zero if you don't want to drive the constraint to zero with a spring:
inBias	Bias term (b) for the constraint impulse: lambda = J v + b
inC	Value of the constraint equation (C)
inStiffness	Spring stiffness k.
inDamping	Spring damping coefficient c.

◆ Deactivate()

void AngleConstraintPart::Deactivate ( )

inline

Deactivate this constraint.

◆ GetTotalLambda()

float AngleConstraintPart::GetTotalLambda ( ) const

inline

Return lagrange multiplier.

◆ IsActive()

bool AngleConstraintPart::IsActive ( ) const

inline

Check if constraint is active.

◆ RestoreState()

void AngleConstraintPart::RestoreState ( StateRecorder & inStream )

inline

Restore state of this constraint part.

◆ SaveState()

void AngleConstraintPart::SaveState ( StateRecorder & inStream ) const

inline

Save state of this constraint part.

◆ SolvePositionConstraint()

bool AngleConstraintPart::SolvePositionConstraint	(	Body &	ioBody1,
		Body &	ioBody2,
		float	inC,
		float	inBaumgarte
	)		const

inline

Iteratively update the position constraint. Makes sure C(...) == 0.

Parameters

ioBody1	The first body that this constraint is attached to
ioBody2	The second body that this constraint is attached to
inC	Value of the constraint equation (C)
inBaumgarte	Baumgarte constant (fraction of the error to correct)

◆ SolveVelocityConstraint()

bool AngleConstraintPart::SolveVelocityConstraint	(	Body &	ioBody1,
		Body &	ioBody2,
		Vec3Arg	inWorldSpaceAxis,
		float	inMinLambda,
		float	inMaxLambda
	)

inline

Iteratively update the velocity constraint. Makes sure d/dt C(...) = 0, where C is the constraint equation.

Parameters

ioBody1	The first body that this constraint is attached to
ioBody2	The second body that this constraint is attached to
inWorldSpaceAxis	The axis of rotation along which the constraint acts (normalized)
inMinLambda	Minimum angular impulse to apply (N m s)
inMaxLambda	Maximum angular impulse to apply (N m s)

◆ WarmStart()

void AngleConstraintPart::WarmStart	(	Body &	ioBody1,
		Body &	ioBody2,
		float	inWarmStartImpulseRatio
	)

inline

Must be called from the WarmStartVelocityConstraint call to apply the previous frame's impulses

Parameters

ioBody1	The first body that this constraint is attached to
ioBody2	The second body that this constraint is attached to
inWarmStartImpulseRatio	Ratio of new step to old time step (dt_new / dt_old) for scaling the lagrange multiplier of the previous frame

The documentation for this class was generated from the following file:

Jolt/Physics/Constraints/ConstraintPart/AngleConstraintPart.h

Public Member Functions

Detailed Description

Member Function Documentation

◆ CalculateConstraintProperties()

◆ CalculateConstraintPropertiesWithFrequencyAndDamping()

◆ CalculateConstraintPropertiesWithSettings()

◆ CalculateConstraintPropertiesWithStiffnessAndDamping()

◆ Deactivate()

◆ GetTotalLambda()

◆ IsActive()

◆ RestoreState()

◆ SaveState()

◆ SolvePositionConstraint()

◆ SolveVelocityConstraint()

◆ WarmStart()