toVector3
Converts this 4D vector to a 3D vector by discarding the w-component.
This is a straightforward truncation, useful when you want to get the 3D spatial coordinates from a 4D vector representation (like one resulting from a matrix transformation before perspective division) and are not concerned with the w-component. Note that this is a lossy conversion as the w component is ignored.
Return
A Vector3 containing the x, y, and z components of this vector.