HingeRotationConstraintPart Class Reference

#include <HingeRotationConstraintPart.h>

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

Public Member Functions
void	CalculateConstraintProperties (const Body &inBody1, Mat44Arg inRotation1, Vec3Arg inWorldSpaceHingeAxis1, const Body &inBody2, Mat44Arg inRotation2, Vec3Arg inWorldSpaceHingeAxis2)
	Calculate properties used during the functions below. More...
void	Deactivate ()
	Deactivate this constraint. More...
void	WarmStart (Body &ioBody1, Body &ioBody2, float inWarmStartImpulseRatio)
	Must be called from the WarmStartVelocityConstraint call to apply the previous frame's impulses. More...
bool	SolveVelocityConstraint (Body &ioBody1, Body &ioBody2)
	Iteratively update the velocity constraint. Makes sure d/dt C(...) = 0, where C is the constraint equation. More...
bool	SolvePositionConstraint (Body &ioBody1, Body &ioBody2, float inBaumgarte) const
	Iteratively update the position constraint. Makes sure C(...) = 0. More...
const Vec2 &	GetTotalLambda () const
	Return lagrange multiplier. More...
void	SaveState (StateRecorder &inStream) const
	Save state of this constraint part. More...
void	RestoreState (StateRecorder &inStream)
	Restore state of this constraint part. More...

Detailed Description

Constrains rotation around 2 axis so that it only allows rotation around 1 axis

Based on: "Constraints Derivation for Rigid Body Simulation in 3D" - Daniel Chappuis, section 2.4.1

Constraint equation (eq 87):

\[C = \begin{bmatrix}a_1 \cdot b_2 \\ a_1 \cdot c_2\end{bmatrix}\]

Jacobian (eq 90):

\[J = \begin{bmatrix} 0 & -b_2 \times a_1 & 0 & b_2 \times a_1 \\ 0 & -c_2 \times a_1 & 0 & c2 \times a_1 \end{bmatrix}\]

Used terms (here and below, everything in world space):
a1 = hinge axis on body 1.
b2, c2 = axis perpendicular to hinge axis on body 2.
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.
E = identity matrix.

Member Typedef Documentation

Mat22

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

Vec2

using HingeRotationConstraintPart::Vec2 = Vector<2>

Member Function Documentation

CalculateConstraintProperties()

void HingeRotationConstraintPart::CalculateConstraintProperties ( const Body &  inBody1, Mat44Arg  inRotation1, Vec3Arg  inWorldSpaceHingeAxis1, const Body &  inBody2, Mat44Arg  inRotation2, Vec3Arg  inWorldSpaceHingeAxis2  )

inline

Calculate properties used during the functions below.

Deactivate()

void HingeRotationConstraintPart::Deactivate ( )

inline

Deactivate this constraint.

GetTotalLambda()

const Vec2 & HingeRotationConstraintPart::GetTotalLambda ( ) const

inline

Return lagrange multiplier.

RestoreState()

void HingeRotationConstraintPart::RestoreState ( StateRecorder &  inStream )

inline

Restore state of this constraint part.

SaveState()

void HingeRotationConstraintPart::SaveState ( StateRecorder &  inStream ) const

inline

Save state of this constraint part.

SolvePositionConstraint()

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

inline

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

SolveVelocityConstraint()

bool HingeRotationConstraintPart::SolveVelocityConstraint ( Body &  ioBody1, Body &  ioBody2  )

inline

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

WarmStart()

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

inline

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

---

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

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