class Basis(
    var xx: Double = 1.0, var xy: Double = 0.0, var xz: Double = 0.0,
    var yx: Double = 0.0, var yy: Double = 1.0, var yz: Double = 0.0,
    var zx: Double = 0.0, var zy: Double = 0.0, var zz: Double = 1.0
) {
    constructor(x: Vector3 = Vector3.x(), y: Vector3 = Vector3.y(), z: Vector3 = Vector3.z()) : this(
        x.x, x.y, x.z,
        y.x, y.y, y.z,
        z.x, z.y, z.z
    )

    companion object {
        fun ident() = Basis()
        fun scale(x: Double = 1.0, y: Double = 1.0, z: Double = 1.0) = Basis(xx = x, yy = y, zz = z)
    }
}

ident

Vector3

If the class has a primary constructor, each secondary constructor needs to delegate to the primary constructor, either directly or indirectly through another secondary constructor(s). Delegation to another constructor of the same class is done using the this keyword

INVOKESPECIAL transformation/transform/Basis.<init> (Ltransformation/transform/Vector3;Ltransformation/transform/Vector3;Ltransformation/transform/Vector3;ILkotlin/jvm/internal/DefaultConstructorMarker;)V

@NotNull
public final Basis ident() {
    return new Basis((Vector3)null, (Vector3)null, (Vector3)null, 7, (DefaultConstructorMarker)null);
}

class Foo (bar: Boolean = true) {
    constructor(thing: Int = 0) : this(thing == 1)

    companion object {
        fun ident() = Foo()
    }
}

Foo()