Code:
Public Sub TestTwo()
    Dim Vec1 As Vector, Vec2 As Vector, Vec3 As Vector
    Dim sngScaleFactor As Single, sngRet As Single
    
    With Vec1
        .x = 10
        .y = 14
        .z = 15
    End With
    
    With Vec2
        .x = 15
        .y = 14
        .z = 16
    End With
    
    With Vec3
        .x = 14
        .y = 17
        .z = 15
    End With
    
    
    Vec3.x = Vec1.x - Vec2.x
    Vec3.y = Vec1.y - Vec2.y
    Vec3.z = Vec1.z - Vec2.z
    
    sngRet = (Vec1.x * Vec3.x) + (Vec1.y * Vec3.y) + (Vec1.z * Vec3.z)


    sngScaleFactor = 1 / Sqr((Vec2.x * Vec2.x) + (Vec2.y * Vec2.y) + 
(Vec2.z * Vec2.z))
                                                                        '
    Vec2.x = Vec2.x * sngScaleFactor
    Vec2.y = Vec2.y * sngScaleFactor
    Vec2.z = Vec2.z * sngScaleFactor
End Sub

Public Sub TestOne()
    Dim Vec1 As Vector, Vec2 As Vector, Vec3 As Vector
    Dim sngRet As Single
    
    With Vec1
        .x = 10
        .y = 14
        .z = 15
    End With
    
    With Vec2
        .x = 15
        .y = 14
        .z = 16
    End With
    
    With Vec3
        .x = 14
        .y = 17
        .z = 15
    End With
    
    VectorSub Vec1, Vec2, Vec3
    sngRet = VectorDot(Vec1, Vec3)
    VectorNormalize Vec2
End Sub

Public Sub VectorSub(a As Vector, b As Vector, result As Vector)
    '//Result = a - b
    result.x = a.x - b.x
    result.y = a.y - b.y
    result.z = a.z - b.z
End Sub
Public Function VectorDot(a As Vector, b As Vector) As Single
    VectorDot = (a.x * b.x) + (a.y * b.y) + (a.z * b.z)
End Function

Public Sub VectorNormalize(v As Vector)
    Dim sngScaleFactor As Single
    sngScaleFactor = 1 / Sqr((v.x * v.x) + (v.y * v.y) + (v.z * v.z))
                                                                       
    v.x = v.x * sngScaleFactor
    v.y = v.y * sngScaleFactor
    v.z = v.z * sngScaleFactor
End Sub