geom/matrix3x3f32.go

package geom

// Matrix3x3F32 is an matrix with 3 vectors, i, j and k (floating point, 32 bits).
type Matrix3x3F32 struct {
	I Vector3F32
	J Vector3F32
	K Vector3F32
}

// Mx3x3F32 is a shorthand function to create a matrix.
func Mx3x3F32(i, j, k Vector3F32) Matrix3x3F32 {
	return Matrix3x3F32{i, j, k}
}

// Adj calculates the adjugate matrix of matrix m.
func (m Matrix3x3F32) Adj() Matrix3x3F32 {
	return Mx3x3F32(
		Vec3F32(m.J.Y*m.K.Z-m.K.Y*m.J.Z, m.K.Y*m.I.Z-m.I.Y*m.K.Z, m.I.Y*m.J.Z-m.J.Y*m.I.Z),
		Vec3F32(m.K.X*m.J.Z-m.J.X*m.K.Z, m.I.X*m.K.Z-m.K.X*m.I.Z, m.J.X*m.I.Z-m.I.X*m.J.Z),
		Vec3F32(m.J.X*m.K.Y-m.K.X*m.J.Y, m.K.X*m.I.Y-m.I.X*m.K.Y, m.I.X*m.J.Y-m.J.X*m.I.Y),
	)
}

// Det calculates the determinant of the matrix m.
func (m Matrix3x3F32) Det() float32 {
	return m.I.X*m.J.Y*m.K.Z +
		m.J.X*m.K.Y*m.I.Z +
		m.K.X*m.I.Y*m.J.Z -
		m.K.X*m.J.Y*m.I.Z -
		m.J.X*m.I.Y*m.K.Z -
		m.I.X*m.K.Y*m.J.Z
}

// MulMx multiplies the matrix m with matrix n.
func (m Matrix3x3F32) MulMx(n Matrix3x3F32) Matrix3x3F32 {
	return Matrix3x3F32{
		Vec3F32(
			n.I.X*m.I.X+n.I.Y*m.J.X+n.I.Z*m.K.X,
			n.I.X*m.I.Y+n.I.Y*m.J.Y+n.I.Z*m.K.Y,
			n.I.X*m.I.Z+n.I.Y*m.J.Z+n.I.Z*m.K.Z),
		Vec3F32(
			n.J.X*m.I.X+n.J.Y*m.J.X+n.J.Z*m.K.X,
			n.J.X*m.I.Y+n.J.Y*m.J.Y+n.J.Z*m.K.Y,
			n.J.X*m.I.Z+n.J.Y*m.J.Z+n.J.Z*m.K.Z),
		Vec3F32(
			n.K.X*m.I.X+n.K.Y*m.J.X+n.K.Z*m.K.X,
			n.K.X*m.I.Y+n.K.Y*m.J.Y+n.K.Z*m.K.Y,
			n.K.X*m.I.Z+n.K.Y*m.J.Z+n.K.Z*m.K.Z),
	}
}

// MulVec multiplies the matrix m with vector v.
func (m Matrix3x3F32) MulVec(v Vector3F32) Vector3F32 {
	return Vec3F32(
		v.X*m.I.X+v.Y*m.J.X+v.Z*m.K.X,
		v.X*m.I.Y+v.Y*m.J.Y+v.Z*m.K.Y,
		v.X*m.I.Z+v.Y*m.J.Z+v.Z*m.K.Z)
}

// ScaleVec scales the matrix m by vector v.
func (m Matrix3x3F32) ScaleVec(v Vector3F32) Matrix3x3F32 {
	return Matrix3x3F32{
		Vec3F32(v.X*m.I.X, v.X*m.I.Y, v.X*m.I.Z),
		Vec3F32(v.Y*m.I.X, v.Y*m.I.Y, v.Y*m.I.Z),
		Vec3F32(v.Z*m.I.X, v.Z*m.I.Y, v.Z*m.I.Z),
	}
}