equation

package
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 Go to latest Published: Mar 10, 2023 License: BSD-2-Clause Imports: 1 Imported by: 0

Documentation

Overview

Package equation implements SPOOK equations based on the 2007 PhD thesis of Claude Lacoursière titled "Ghosts and Machines: Regularized Variational Methods for Interactive Simulations of Multibodies with Dry Frictional Contacts"

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

This section is empty.

Types

type Cone 

type Cone struct {
	Equation
	// contains filtered or unexported fields
}

Cone is a cone constraint equation. Works to keep the given body world vectors aligned, or tilted within a given angle from each other.

func NewCone 

func NewCone(bodyA, bodyB IBody, axisA, axisB *math32.Vector3, angle, maxForce float32) *Cone

NewCone creates and returns a pointer to a new Cone equation object.

func (*Cone) Angle 

func (ce *Cone) Angle() float32

MaxAngle returns the cone angle.

func (*Cone) AxisA 

func (ce *Cone) AxisA() math32.Vector3

AxisA returns the axis of body A.

func (*Cone) AxisB 

func (ce *Cone) AxisB() math32.Vector3

AxisB returns the axis of body B.

func (*Cone) ComputeB 

func (ce *Cone) ComputeB(h float32) float32

ComputeB

func (*Cone) SetAngle 

func (ce *Cone) SetAngle(angle float32)

SetAngle sets the cone angle.

func (*Cone) SetAxisA 

func (ce *Cone) SetAxisA(axisA *math32.Vector3)

SetAxisA sets the axis of body A.

func (*Cone) SetAxisB 

func (ce *Cone) SetAxisB(axisB *math32.Vector3)

SetAxisB sets the axis of body B.

type Contact 

type Contact struct {
	Equation
	// contains filtered or unexported fields
}

Contact is a contact/non-penetration constraint equation.

func NewContact 

func NewContact(bodyA, bodyB IBody, minForce, maxForce float32) *Contact

NewContact creates and returns a pointer to a new Contact equation object.

func (*Contact) ComputeB 

func (ce *Contact) ComputeB(h float32) float32

ComputeB

func (*Contact) Normal 

func (ce *Contact) Normal() math32.Vector3

func (*Contact) RA 

func (ce *Contact) RA() math32.Vector3

func (*Contact) RB 

func (ce *Contact) RB() math32.Vector3

func (*Contact) Restitution 

func (ce *Contact) Restitution() float32

func (*Contact) SetNormal 

func (ce *Contact) SetNormal(newNormal *math32.Vector3)

func (*Contact) SetRA 

func (ce *Contact) SetRA(newRa *math32.Vector3)

func (*Contact) SetRB 

func (ce *Contact) SetRB(newRb *math32.Vector3)

func (*Contact) SetRestitution 

func (ce *Contact) SetRestitution(r float32)

type Equation 

type Equation struct {
	// contains filtered or unexported fields
}

Equation is a SPOOK constraint equation.

func NewEquation 

func NewEquation(bi, bj IBody, minForce, maxForce float32) *Equation

NewEquation creates and returns a pointer to a new Equation object.

func (*Equation) BodyA 

func (e *Equation) BodyA() IBody

func (*Equation) BodyB 

func (e *Equation) BodyB() IBody

func (*Equation) ComputeB 

func (e *Equation) ComputeB(h float32) float32

ComputeB computes the RHS of the SPOOK equation.

func (*Equation) ComputeC 

func (e *Equation) ComputeC() float32

ComputeC computes the denominator part of the SPOOK equation: C = G*inv(M)*G' + eps.

func (*Equation) ComputeGW 

func (e *Equation) ComputeGW() float32

ComputeGW computes G*W, where W are the body velocities.

func (*Equation) ComputeGiMGt 

func (e *Equation) ComputeGiMGt() float32

ComputeGiMGt computes G*inv(M)*G'.

func (*Equation) ComputeGiMf 

func (e *Equation) ComputeGiMf() float32

ComputeGiMf computes G*inv(M)*f, where M is the mass matrix with diagonal blocks for each body, and f are the forces on the bodies.

func (*Equation) ComputeGq 

func (e *Equation) ComputeGq() float32

ComputeGq computes G*q, where q are the generalized body coordinates.

func (*Equation) Enabled 

func (e *Equation) Enabled() bool

Enabled returns the enabled flag of the equation.

func (*Equation) Eps 

func (e *Equation) Eps() float32

Returns epsilon - the regularization constant which is multiplied by the identity matrix.

func (*Equation) JeA 

func (e *Equation) JeA() JacobianElement

func (*Equation) JeB 

func (e *Equation) JeB() JacobianElement

func (*Equation) MaxForce 

func (e *Equation) MaxForce() float32

MaxForce returns the maximum force to be applied by the constraint.

func (*Equation) MinForce 

func (e *Equation) MinForce() float32

MinForce returns the minimum force to be applied by the constraint.

func (*Equation) Multiplier 

func (e *Equation) Multiplier() float32

MaxForce returns the multiplier.

func (*Equation) SetBodyA 

func (e *Equation) SetBodyA(ibody IBody)

func (*Equation) SetBodyB 

func (e *Equation) SetBodyB(ibody IBody)

func (*Equation) SetEnabled 

func (e *Equation) SetEnabled(state bool)

SetEnable sets the enabled flag of the equation.

func (*Equation) SetMaxForce 

func (e *Equation) SetMaxForce(maxForce float32)

SetMaxForce sets the maximum force to be applied by the constraint.

func (*Equation) SetMinForce 

func (e *Equation) SetMinForce(minForce float32)

SetMinForce sets the minimum force to be applied by the constraint.

func (*Equation) SetMultiplier 

func (e *Equation) SetMultiplier(multiplier float32)

SetMultiplier sets the multiplier.

func (*Equation) SetSpookParams 

func (e *Equation) SetSpookParams(stiffness, relaxation float32, timeStep float32)

SetSpookParams recalculates a, b, eps.

type Friction 

type Friction struct {
	Equation
	// contains filtered or unexported fields
}

Friction is a friction constraint equation.

func NewFriction 

func NewFriction(bodyA, bodyB IBody, slipForce float32) *Friction

NewFriction creates and returns a pointer to a new Friction equation object. slipForce should be +-F_friction = +-mu * F_normal = +-mu * m * g

func (*Friction) ComputeB 

func (fe *Friction) ComputeB(h float32) float32

ComputeB

func (*Friction) RA 

func (fe *Friction) RA() math32.Vector3

func (*Friction) RB 

func (fe *Friction) RB() math32.Vector3

func (*Friction) SetRA 

func (fe *Friction) SetRA(newRa *math32.Vector3)

func (*Friction) SetRB 

func (fe *Friction) SetRB(newRb *math32.Vector3)

func (*Friction) SetTangent 

func (fe *Friction) SetTangent(newTangent *math32.Vector3)

func (*Friction) Tangent 

func (fe *Friction) Tangent() math32.Vector3

type IBody 

type IBody interface {
	Index() int
	Position() math32.Vector3
	Velocity() math32.Vector3
	AngularVelocity() math32.Vector3
	Force() math32.Vector3
	Torque() math32.Vector3
	InvMassEff() float32
	InvRotInertiaWorldEff() *math32.Matrix3
}

IBody is the interface of all body types.

type IEquation 

type IEquation interface {
	SetBodyA(IBody)
	BodyA() IBody
	SetBodyB(IBody)
	BodyB() IBody
	JeA() JacobianElement
	JeB() JacobianElement
	SetEnabled(state bool)
	Enabled() bool
	MinForce() float32
	MaxForce() float32
	Eps() float32
	SetMultiplier(multiplier float32)
	ComputeB(h float32) float32
	ComputeC() float32
}

IEquation is the interface type for all equations types.

type JacobianElement 

type JacobianElement struct {
	// contains filtered or unexported fields
}

JacobianElement contains 6 entries, 3 spatial and 3 rotational degrees of freedom.

func (*JacobianElement) MultiplyElement 

func (je *JacobianElement) MultiplyElement(je2 *JacobianElement) float32

MultiplyElement multiplies the JacobianElement with another JacobianElement. None of the elements are changed.

func (*JacobianElement) MultiplyVectors 

func (je *JacobianElement) MultiplyVectors(spatial *math32.Vector3, rotational *math32.Vector3) float32

MultiplyElement multiplies the JacobianElement with two vectors. None of the elements are changed.

func (*JacobianElement) Rotational 

func (je *JacobianElement) Rotational() math32.Vector3

Rotational returns the rotational component of the JacobianElement.

func (*JacobianElement) SetRotational 

func (je *JacobianElement) SetRotational(rotational *math32.Vector3)

Rotational sets the rotational component of the JacobianElement.

func (*JacobianElement) SetSpatial 

func (je *JacobianElement) SetSpatial(spatial *math32.Vector3)

SetSpatial sets the spatial component of the JacobianElement.

func (*JacobianElement) Spatial 

func (je *JacobianElement) Spatial() math32.Vector3

Spatial returns the spatial component of the JacobianElement.

type Rotational 

type Rotational struct {
	Equation
	// contains filtered or unexported fields
}

Rotational is a rotational constraint equation. Works to keep the local vectors orthogonal to each other in world space.

func NewRotational 

func NewRotational(bodyA, bodyB IBody, maxForce float32) *Rotational

NewRotational creates and returns a pointer to a new Rotational equation object.

func (*Rotational) AxisA 

func (re *Rotational) AxisA() math32.Vector3

AxisA returns the axis of body A.

func (*Rotational) AxisB 

func (re *Rotational) AxisB() math32.Vector3

AxisB returns the axis of body B.

func (*Rotational) ComputeB 

func (re *Rotational) ComputeB(h float32) float32

ComputeB

func (*Rotational) MaxAngle 

func (re *Rotational) MaxAngle() float32

MaxAngle returns the maximum angle.

func (*Rotational) SetAxisA 

func (re *Rotational) SetAxisA(axisA *math32.Vector3)

SetAxisA sets the axis of body A.

func (*Rotational) SetAxisB 

func (re *Rotational) SetAxisB(axisB *math32.Vector3)

SetAxisB sets the axis of body B.

func (*Rotational) SetMaxAngle 

func (re *Rotational) SetMaxAngle(angle float32)

SetAngle sets the maximum angle.

type RotationalMotor 

type RotationalMotor struct {
	Equation // TODO maybe this should embed Rotational instead ?
	// contains filtered or unexported fields
}

RotationalMotor is a rotational motor constraint equation. Tries to keep the relative angular velocity of the bodies to a given value.

func NewRotationalMotor 

func NewRotationalMotor(bodyA, bodyB IBody, maxForce float32) *RotationalMotor

NewRotationalMotor creates and returns a pointer to a new RotationalMotor equation object.

func (*RotationalMotor) AxisA 

func (ce *RotationalMotor) AxisA() math32.Vector3

AxisA returns the axis of body A.

func (*RotationalMotor) AxisB 

func (ce *RotationalMotor) AxisB() math32.Vector3

AxisB returns the axis of body B.

func (*RotationalMotor) ComputeB 

func (re *RotationalMotor) ComputeB(h float32) float32

ComputeB

func (*RotationalMotor) SetAxisA 

func (ce *RotationalMotor) SetAxisA(axisA *math32.Vector3)

SetAxisA sets the axis of body A.

func (*RotationalMotor) SetAxisB 

func (ce *RotationalMotor) SetAxisB(axisB *math32.Vector3)

SetAxisB sets the axis of body B.

func (*RotationalMotor) SetTargetSpeed 

func (ce *RotationalMotor) SetTargetSpeed(speed float32)

SetTargetSpeed sets the target speed.

func (*RotationalMotor) TargetSpeed 

func (ce *RotationalMotor) TargetSpeed() float32

TargetSpeed returns the target speed.

Source Files

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