DualAxisConstraintPart Class Reference

#include <DualAxisConstraintPart.h>

Public Types
using	Vec2 = Vector< 2 >
using	Mat22 = Matrix< 2, 2 >

Public Member Functions
void	CalculateConstraintProperties (const Body &inBody1, Mat44Arg inRotation1, Vec3Arg inR1PlusU, const Body &inBody2, Mat44Arg inRotation2, Vec3Arg inR2, Vec3Arg inN1, Vec3Arg inN2)
void	Deactivate ()
	Deactivate this constraint.
bool	IsActive () const
	Check if constraint is active.
void	WarmStart (Body &ioBody1, Body &ioBody2, Vec3Arg inN1, Vec3Arg inN2, float inWarmStartImpulseRatio)
bool	SolveVelocityConstraint (Body &ioBody1, Body &ioBody2, Vec3Arg inN1, Vec3Arg inN2)
bool	SolvePositionConstraint (Body &ioBody1, Body &ioBody2, Vec3Arg inU, Vec3Arg inN1, Vec3Arg inN2, float inBaumgarte) const
void	SetTotalLambda (const Vec2 &inLambda)
	Override total lagrange multiplier, can be used to set the initial value for warm starting.
const Vec2 &	GetTotalLambda () const
	Return lagrange multiplier.
void	SaveState (StateRecorder &inStream) const
	Save state of this constraint part.
void	RestoreState (StateRecorder &inStream)
	Restore state of this constraint part.

Detailed Description

Constrains movement on 2 axis

See also

"Constraints Derivation for Rigid Body Simulation in 3D" - Daniel Chappuis, section 2.3.1

Constraint equation (eq 51):

\[C = \begin{bmatrix} (p_2 - p_1) \cdot n_1 \\ (p_2 - p_1) \cdot n_2\end{bmatrix}\]

Jacobian (transposed) (eq 55):

\[J^T = \begin{bmatrix} -n_1 & -n_2 \\ -(r_1 + u) \times n_1 & -(r_1 + u) \times n_2 \\ n_1 & n_2 \\ r_2 \times n_1 & r_2 \times n_2 \end{bmatrix}\]

Used terms (here and below, everything in world space):
n1, n2 = constraint axis (normalized).
p1, p2 = constraint points.
r1 = p1 - x1.
r2 = p2 - x2.
u = x2 + r2 - x1 - r1 = p2 - p1.
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 Typedef Documentation

Mat22

using DualAxisConstraintPart::Mat22 = Matrix<2, 2>

Vec2

using DualAxisConstraintPart::Vec2 = Vector<2>

Member Function Documentation

CalculateConstraintProperties()

void DualAxisConstraintPart::CalculateConstraintProperties ( const Body &  inBody1, Mat44Arg  inRotation1, Vec3Arg  inR1PlusU, const Body &  inBody2, Mat44Arg  inRotation2, Vec3Arg  inR2, Vec3Arg  inN1, Vec3Arg  inN2  )

inline

Calculate properties used during the functions below All input vectors are in world space

Deactivate()

void DualAxisConstraintPart::Deactivate ( )

inline

Deactivate this constraint.

GetTotalLambda()

const Vec2 & DualAxisConstraintPart::GetTotalLambda ( ) const

inline

Return lagrange multiplier.

IsActive()

bool DualAxisConstraintPart::IsActive ( ) const

inline

Check if constraint is active.

RestoreState()

void DualAxisConstraintPart::RestoreState ( StateRecorder &  inStream )

inline

Restore state of this constraint part.

SaveState()

void DualAxisConstraintPart::SaveState ( StateRecorder &  inStream ) const

inline

Save state of this constraint part.

SetTotalLambda()

void DualAxisConstraintPart::SetTotalLambda ( const Vec2 &  inLambda )

inline

Override total lagrange multiplier, can be used to set the initial value for warm starting.

SolvePositionConstraint()

bool DualAxisConstraintPart::SolvePositionConstraint ( Body &  ioBody1, Body &  ioBody2, Vec3Arg  inU, Vec3Arg  inN1, Vec3Arg  inN2, float  inBaumgarte  ) const

inline

Iteratively update the position constraint. Makes sure C(...) = 0. All input vectors are in world space

SolveVelocityConstraint()

bool DualAxisConstraintPart::SolveVelocityConstraint ( Body &  ioBody1, Body &  ioBody2, Vec3Arg  inN1, Vec3Arg  inN2  )

inline

Iteratively update the velocity constraint. Makes sure d/dt C(...) = 0, where C is the constraint equation. All input vectors are in world space

WarmStart()

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

inline

Must be called from the WarmStartVelocityConstraint call to apply the previous frame's impulses All input vectors are in world space

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

• Jolt/Physics/Constraints/ConstraintPart/DualAxisConstraintPart.h