#include <IndependentAxisConstraintPart.h>

Public Member Functions
void	CalculateConstraintProperties (const Body &inBody1, const Body &inBody2, Vec3Arg inR1, Vec3Arg inN1, Vec3Arg inR2, Vec3Arg inN2, float inRatio)

void	Deactivate ()
	Deactivate this constraint.

bool	IsActive () const
	Check if constraint is active.

void	WarmStart (Body &ioBody1, Body &ioBody2, Vec3Arg inN1, Vec3Arg inN2, float inRatio, float inWarmStartImpulseRatio)

bool	SolveVelocityConstraint (Body &ioBody1, Body &ioBody2, Vec3Arg inN1, Vec3Arg inN2, float inRatio, float inMinLambda, float inMaxLambda)

float	GetTotalLambda () const
	Return lagrange multiplier.

bool	SolvePositionConstraint (Body &ioBody1, Body &ioBody2, Vec3Arg inN1, Vec3Arg inN2, float inRatio, 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 part to an AxisConstraintPart but both bodies have an independent axis on which the force is applied.

Constraint equation:

\[C = (x_1 + r_1 - f_1) . n_1 + r (x_2 + r_2 - f_2) \cdot n_2\]

Calculating the Jacobian:

\[dC/dt = (v_1 + w_1 \times r_1) \cdot n_1 + (x_1 + r_1 - f_1) \cdot d n_1/dt + r (v_2 + w_2 \times r_2) \cdot n_2 + r (x_2 + r_2 - f_2) \cdot d n_2/dt\]

Assuming that d n1/dt and d n2/dt are small this becomes:

\[(v_1 + w_1 \times r_1) \cdot n_1 + r (v_2 + w_2 \times r_2) \cdot n_2\]

\[= v_1 \cdot n_1 + r_1 \times n_1 \cdot w_1 + r v_2 \cdot n_2 + r r_2 \times n_2 \cdot w_2\]

Jacobian:

\[J = \begin{bmatrix}n_1 & r_1 \times n_1 & r n_2 & r r_2 \times n_2\end{bmatrix}\]

Effective mass:

\[K = m_1^{-1} + r_1 \times n_1 I_1^{-1} r_1 \times n_1 + r^2 m_2^{-1} + r^2 r_2 \times n_2 I_2^{-1} r_2 \times n_2\]

Used terms (here and below, everything in world space):
n1 = (x1 + r1 - f1) / |x1 + r1 - f1|, axis along which the force is applied for body 1
n2 = (x2 + r2 - f2) / |x2 + r2 - f2|, axis along which the force is applied for body 2
r = ratio how forces are applied between bodies.
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 IndependentAxisConstraintPart::CalculateConstraintProperties	(	const Body &	inBody1,
		const Body &	inBody2,
		Vec3Arg	inR1,
		Vec3Arg	inN1,
		Vec3Arg	inR2,
		Vec3Arg	inN2,
		float	inRatio
	)

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
inR1	The position on which the constraint operates on body 1 relative to COM
inN1	The world space normal in which the constraint operates for body 1
inR2	The position on which the constraint operates on body 1 relative to COM
inN2	The world space normal in which the constraint operates for body 2
inRatio	The ratio how forces are applied between bodies

◆ Deactivate()

void IndependentAxisConstraintPart::Deactivate ( )

inline

Deactivate this constraint.

◆ GetTotalLambda()

float IndependentAxisConstraintPart::GetTotalLambda ( ) const

inline

Return lagrange multiplier.

◆ IsActive()

bool IndependentAxisConstraintPart::IsActive ( ) const

inline

Check if constraint is active.

◆ RestoreState()

void IndependentAxisConstraintPart::RestoreState ( StateRecorder & inStream )

inline

Restore state of this constraint part.

◆ SaveState()

void IndependentAxisConstraintPart::SaveState ( StateRecorder & inStream ) const

inline

Save state of this constraint part.

◆ SolvePositionConstraint()

bool IndependentAxisConstraintPart::SolvePositionConstraint	(	Body &	ioBody1,
		Body &	ioBody2,
		Vec3Arg	inN1,
		Vec3Arg	inN2,
		float	inRatio,
		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
inN1	The world space normal in which the constraint operates for body 1
inN2	The world space normal in which the constraint operates for body 2
inRatio	The ratio how forces are applied between bodies
inC	Value of the constraint equation (C)
inBaumgarte	Baumgarte constant (fraction of the error to correct)

◆ SolveVelocityConstraint()

bool IndependentAxisConstraintPart::SolveVelocityConstraint	(	Body &	ioBody1,
		Body &	ioBody2,
		Vec3Arg	inN1,
		Vec3Arg	inN2,
		float	inRatio,
		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
inN1	The world space normal in which the constraint operates for body 1
inN2	The world space normal in which the constraint operates for body 2
inRatio	The ratio how forces are applied between bodies
inMinLambda	Minimum angular impulse to apply (N m s)
inMaxLambda	Maximum angular impulse to apply (N m s)

◆ WarmStart()

void IndependentAxisConstraintPart::WarmStart	(	Body &	ioBody1,
		Body &	ioBody2,
		Vec3Arg	inN1,
		Vec3Arg	inN2,
		float	inRatio,
		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
inN1	The world space normal in which the constraint operates for body 1
inN2	The world space normal in which the constraint operates for body 2
inRatio	The ratio how forces are applied between bodies
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/IndependentAxisConstraintPart.h

Public Member Functions

Detailed Description

Member Function Documentation

◆ CalculateConstraintProperties()

◆ Deactivate()

◆ GetTotalLambda()

◆ IsActive()

◆ RestoreState()

◆ SaveState()

◆ SolvePositionConstraint()

◆ SolveVelocityConstraint()

◆ WarmStart()