SwingTwistConstraintPart Class Reference

#include <SwingTwistConstraintPart.h>

Public Member Functions
void	SetLimits (float inTwistMinAngle, float inTwistMaxAngle, float inSwingYHalfAngle, float inSwingZHalfAngle)
	Set limits for this constraint (see description above for parameters) More...
void	ClampSwingTwist (Quat &ioSwing, bool &outSwingYClamped, bool &outSwingZClamped, Quat &ioTwist, bool &outTwistClamped) const
	Clamp twist and swing against the constraint limits, returns which parts were clamped (everything assumed in constraint space) More...
void	CalculateConstraintProperties (float inDeltaTime, const Body &inBody1, const Body &inBody2, QuatArg inConstraintRotation, QuatArg inConstraintToWorld)
void	Deactivate ()
	Deactivate this constraint. More...
bool	IsActive () const
	Check if constraint is active. 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, QuatArg inConstraintRotation, QuatArg inConstraintToBody1, QuatArg inConstraintToBody2, float inBaumgarte) const
float	GetTotalSwingYLambda () const
	Return lagrange multiplier for swing. More...
float	GetTotalSwingZLambda () const
float	GetTotalTwistLambda () const
	Return lagrange multiplier for twist. 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

Quaternion based constraint that decomposes the rotation in constraint space in swing and twist: q = q_swing * q_twist where q_swing.x = 0 and where q_twist.y = q_twist.z = 0

• Rotation around the twist (x-axis) is within [inTwistMinAngle, inTwistMaxAngle].
• Rotation around the swing axis (y and z axis) are limited to an ellipsoid in quaternion space formed by the equation:

(q_swing.y / sin(inSwingYHalfAngle / 2))^2 + (q_swing.z / sin(inSwingZHalfAngle / 2))^2 <= 1

Which roughly corresponds to an elliptic cone shape with major axis (inSwingYHalfAngle, inSwingZHalfAngle).

In case inSwingYHalfAngle = 0, the rotation around Y will be constrained to 0 and the rotation around Z will be constrained between [-inSwingZHalfAngle, inSwingZHalfAngle]. Vice versa if inSwingZHalfAngle = 0.

Member Function Documentation

CalculateConstraintProperties()

void SwingTwistConstraintPart::CalculateConstraintProperties ( float  inDeltaTime, const Body &  inBody1, const Body &  inBody2, QuatArg  inConstraintRotation, QuatArg  inConstraintToWorld  )

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
inConstraintRotation	The current rotation of the constraint in constraint space
inConstraintToWorld	Rotates from constraint space into world space

ClampSwingTwist()

void SwingTwistConstraintPart::ClampSwingTwist ( Quat &  ioSwing, bool &  outSwingYClamped, bool &  outSwingZClamped, Quat &  ioTwist, bool &  outTwistClamped  ) const

inline

Clamp twist and swing against the constraint limits, returns which parts were clamped (everything assumed in constraint space)

Deactivate()

void SwingTwistConstraintPart::Deactivate ( )

inline

Deactivate this constraint.

GetTotalSwingYLambda()

float SwingTwistConstraintPart::GetTotalSwingYLambda ( ) const

inline

Return lagrange multiplier for swing.

GetTotalSwingZLambda()

float SwingTwistConstraintPart::GetTotalSwingZLambda ( ) const

inline

GetTotalTwistLambda()

float SwingTwistConstraintPart::GetTotalTwistLambda ( ) const

inline

Return lagrange multiplier for twist.

IsActive()

bool SwingTwistConstraintPart::IsActive ( ) const

inline

Check if constraint is active.

RestoreState()

void SwingTwistConstraintPart::RestoreState ( StateRecorder &  inStream )

inline

Restore state of this constraint part.

SaveState()

void SwingTwistConstraintPart::SaveState ( StateRecorder &  inStream ) const

inline

Save state of this constraint part.

SetLimits()

void SwingTwistConstraintPart::SetLimits ( float  inTwistMinAngle, float  inTwistMaxAngle, float  inSwingYHalfAngle, float  inSwingZHalfAngle  )

inline

Set limits for this constraint (see description above for parameters)

SolvePositionConstraint()

bool SwingTwistConstraintPart::SolvePositionConstraint ( Body &  ioBody1, Body &  ioBody2, QuatArg  inConstraintRotation, QuatArg  inConstraintToBody1, QuatArg  inConstraintToBody2, 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
inConstraintRotation	The current rotation of the constraint in constraint space
inConstraintToBody1,inConstraintToBody2	Rotates from constraint space to body 1/2 space
inBaumgarte	Baumgarte constant (fraction of the error to correct)

SolveVelocityConstraint()

bool SwingTwistConstraintPart::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 SwingTwistConstraintPart::WarmStart ( Body &  ioBody1, Body &  ioBody2, float  inWarmStartImpulseRatio  )

inline

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

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

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