plane.go

package math

type Plane struct {
	normal *Vector3
	constant float32
}

func NewPlane(normal *Vector3, constant float32) *Plane {
	np := &Plane{}
	np.Set(normal, constant)
	return np
}

func (plane *Plane) Clone() *Plane {
	return NewPlane(plane.normal, plane.constant)
}

func (plane *Plane) Copy(source *Plane) {
	plane.normal.Copy(source.normal)
	plane.constant = source.constant
}

func (plane *Plane) GetNormal() *Vector3 {
	return plane.normal
}

func (plane *Plane) GetConstant() float32 {
	return plane.constant
}

func (plane *Plane) Set(normal *Vector3, constant float32) {
	plane.normal = normal.Clone()
	plane.constant = constant
}

func (plane *Plane) SetComponents(x, y, z float32, w float32) {
	plane.normal.Set(x, y, z)
	plane.constant = w
}

func (plane *Plane) SetFromNormalAndCoplanarPoint(normal *Vector3, point *Vector3) {
	plane.normal = normal.Clone()
	plane.constant = -point.Dot(point)
}

func (plane *Plane) SetFromCoplanarPoints(a *Vector3, b *Vector3, c *Vector3) {
	v1 := NewVector3(0, 0, 0)
	v2 := NewVector3(0, 0, 0)

	v1.SetSubVectors(c, b)
	v2.SetSubVectors(a, b)
	v1.Cross(v2)
	v1.Normalize()

	plane.SetFromNormalAndCoplanarPoint(v1, a)
}

func (plane *Plane) GetCoplanarPoint() *Vector3 {
	target := NewDefaultVector3()
	plane.CopyCoplanarPoint(target)
	return target
}

func (plane *Plane) CopyCoplanarPoint(target *Vector3) {
	target.Copy(plane.normal)
	target.MultiplyScalar(-plane.constant)
}

func (plane *Plane) ApplyMatrix4(matrix *Matrix4) {
	m3 := NewDefaultMatrix3()
	m3.SetNormalMatrix(matrix)

	plane.ApplyMatrix4AndNormal(matrix, m3)
}

func (plane *Plane) ApplyMatrix4AndNormal(matrix *Matrix4, normalMatrix *Matrix3) {
	v1 := NewDefaultVector3()

	plane.CopyCoplanarPoint(v1)
	referencePoint := v1.Clone()
	referencePoint.ApplyMatrix4(matrix)

	normal := plane.GetNormal()
	normal.ApplyMatrix3(normalMatrix)
	normal.Normalize()

	plane.constant = - referencePoint.Dot(normal)
}