Class ContactEquation

Contact/non-penetration constraint equation

Hierarchy (view full)

Constructors

constructor

Properties

a b bi bj enabled eps id jacobianElementA jacobianElementB maxForce minForce multiplier ni restitution ri rj si sj idCounter

Methods

addToWlambda computeB computeC computeGW computeGWlambda computeGiMGt computeGiMf computeGq getImpactVelocityAlongNormal setSpookParams

Constructors

constructor

Properties

a

a: number

SPOOK parameter

b

b: number

SPOOK parameter

bi

bi: Body

bj

bj: Body

enabled

enabled: boolean

eps

eps: number

SPOOK parameter

id

id: number

jacobianElementA

jacobianElementA: JacobianElement

jacobianElementB

jacobianElementB: JacobianElement

maxForce

maxForce: number

Maximum (read: positive max) force to be applied by the constraint.

minForce

minForce: number

Minimum (read: negative max) force to be applied by the constraint.

multiplier

multiplier: number

A number, proportional to the force added to the bodies.

ni

ni: Vec3

Contact normal, pointing out of body i.

restitution

restitution: number

"bounciness": u1 = -e*u0

ri

ri: Vec3

World-oriented vector that goes from the center of bi to the contact point.

rj

rj: Vec3

World-oriented vector that starts in body j position and goes to the contact point.

si

si: Shape

sj

sj: Shape

Static idCounter

idCounter: number

Methods

addToWlambda

  • addToWlambda(deltalambda): void

  • Add constraint velocity to the bodies.

    Parameters

    • deltalambda: number

    Returns void

computeB

  • computeB(h): number

  • Computes the right hand side of the SPOOK equation

    Parameters

    • h: number

    Returns number

computeC

  • computeC(): number

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

    Returns number

computeGW

  • computeGW(): number

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

    Returns number

computeGWlambda

  • computeGWlambda(): number

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

    Returns number

computeGiMGt

computeGiMf

  • computeGiMf(): number

  • 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

  • computeGq(): number

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

    Returns number

getImpactVelocityAlongNormal

  • getImpactVelocityAlongNormal(): number

  • Get the current relative velocity in the contact point.

    Returns number

setSpookParams

  • setSpookParams(stiffness, relaxation, timeStep): void

  • Recalculates a, b, and eps.

    The Equation constructor sets typical SPOOK parameters as such:

    • stiffness = 1e7
    • relaxation = 4
    • timeStep= 1 / 60, note the hardcoded refresh rate.

    Parameters

    • stiffness: number
    • relaxation: number
    • timeStep: number

    Returns void

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