Class Equation

Base class for constraint equations.

Hierarchy

Constructors

constructor

Properties

B G a b bodyA bodyB enabled epsilon index invC lambda maxBias maxForce maxForceDt minForce minForceDt multiplier needsUpdate offset relativeVelocity relaxation stiffness timeStep DEFAULT_RELAXATION DEFAULT_STIFFNESS

Methods

addToWlambda computeB computeGW computeGWlambda computeGiMGt computeGiMf computeGq computeInvC gmult update

Constructors

constructor

  • Constructor for an Equation

    Parameters

    • bodyA: Body

      First body participating in the equation

    • bodyB: Body

      Second body participating in the equation

    • Optional minForce: number

      Minimum force to apply. Default: -Number.MAX_VALUE

    • Optional maxForce: number

      Maximum force to apply. Default: Number.MAX_VALUE

    Returns Equation

Properties

B

B: number

G

G: Vec2

The Jacobian entry of this equation. 6 numbers, 3 per body (x,y,angle).

a

a: number

b

b: number

bodyA

bodyA: Body

First body participating in the constraint

bodyB

bodyB: Body

Second body participating in the constraint

enabled

enabled: boolean

Whether this equation is enabled or not. If true, it will be added to the solver.

epsilon

epsilon: number

index

index: number

invC

invC: number

lambda

lambda: number

maxBias

maxBias: number

Cap the constraint violation (G*q) to this value.

maxForce

maxForce: number

Max force to apply when solving.

maxForceDt

maxForceDt: number

minForce

minForce: number

Minimum force to apply when solving.

minForceDt

minForceDt: number

multiplier

multiplier: number

The resulting constraint multiplier from the last solve. This is mostly equivalent to the force produced by the constraint.

needsUpdate

needsUpdate: boolean

Indicates if stiffness or relaxation was changed.

offset

offset: number

relativeVelocity

relativeVelocity: number

Relative velocity.

relaxation

relaxation: number

The number of time steps needed to stabilize the constraint equation. Typically between 3 and 5 time steps.

stiffness

stiffness: number

The stiffness of this equation. Typically chosen to a large number (~1e7), but can be chosen somewhat freely to get a stable simulation.

timeStep

timeStep: number

Static DEFAULT_RELAXATION

DEFAULT_RELAXATION: number = 4

The default relaxation when creating a new Equation.

Static DEFAULT_STIFFNESS

DEFAULT_STIFFNESS: number = 1e6

The default stiffness when creating a new Equation.

Methods

addToWlambda

  • Add constraint velocity to the bodies.

    Parameters

    • deltalambda: number

    Returns void

computeB

  • Computes the RHS of the SPOOK equation

    Parameters

    • a: number
    • b: number
    • h: number

    Returns number

computeGW

  • Computes G*W, where W are the body velocities

    Returns number

computeGWlambda

  • Computes G*Wlambda, where W are the body velocities

    Returns number

computeGiMGt

  • Computes G*inv(M)*G'

    Returns number

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.

    Returns number

computeGq

  • Computes G*q, where q are the generalized body coordinates

    Returns number

computeInvC

  • Compute the denominator part of the SPOOK equation: C = G*inv(M)*G' + eps

    Parameters

    • eps: number

    Returns number

gmult

  • Multiply a jacobian entry with corresponding positions or velocities

    Parameters

    Returns number

update

  • Returns void

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