Method createFrictionFromAverage

experimental/physics/narrowphase.go:80–131

TODO test this

(contactEqs []*equation.Contact)

// TODO test this
func (n *Narrowphase) createFrictionFromAverage(contactEqs []*equation.Contact) (*equation.Friction, *equation.Friction) {

	// The last contactEquation
	lastContactEq := contactEqs[len(contactEqs)-1]

	// Create a friction equation based on the last contact (we will modify it to take into account all contacts)
	fEq1, fEq2 := n.createFrictionEquationsFromContact(lastContactEq)
	if (fEq1 == nil && fEq2 == nil) || len(contactEqs) == 1 {
		return fEq1, fEq2
	}

	averageNormal := math32.NewVec3()
	averageContactPointA := math32.NewVec3()
	averageContactPointB := math32.NewVec3()

	bodyA := lastContactEq.BodyA()
	//bodyB := lastContactEq.BodyB()
	normal := lastContactEq.Normal()
	rA := lastContactEq.RA()
	rB := lastContactEq.RB()

	for _, cEq := range contactEqs {
		if cEq.BodyA() != bodyA {
			averageNormal.Add(&normal)
			averageContactPointA.Add(&rA)
			averageContactPointB.Add(&rB)
		} else {
			averageNormal.Sub(&normal)
			averageContactPointA.Add(&rB)
			averageContactPointB.Add(&rA)
		}
	}

	invNumContacts := float32(1) / float32(len(contactEqs))

	averageContactPointA.MultiplyScalar(invNumContacts)
	averageContactPointB.MultiplyScalar(invNumContacts)

	// Should be the same for both friction equations
	fEq1.SetRA(averageContactPointA)
	fEq1.SetRB(averageContactPointB)
	fEq2.SetRA(averageContactPointA)
	fEq2.SetRB(averageContactPointB)

	// Set tangents
	averageNormal.Normalize()
	t1, t2 := averageNormal.RandomTangents()
	fEq1.SetTangent(t1)
	fEq2.SetTangent(t2)

	return fEq1, fEq2
}

// GenerateEquations is the Narrowphase entry point.
func (n *Narrowphase) GenerateEquations(pairs []CollisionPair) ([]*equation.Contact, []*equation.Friction) {