About Mirroring Objects Along a Plane (VBA/ActiveX)

With the Mirror3D method, you can mirror objects along a specified mirroring plane specified by three points.

Mirror in 3D

This example creates a box in model space. It then mirrors the box about a plane and colors the mirrored box red.

Sub Ch8_MirrorABox3D()
    ' Create the box object
    Dim boxObj As Acad3DSolid
    Dim length As Double
    Dim width As Double
    Dim height As Double
    Dim center(0 To 2) As Double
    center(0) = 5#: center(1) = 5#: center(2) = 0
    length = 5#: width = 7: height = 10#

    ' Create the box (3DSolid) object in model space
    Set boxObj = ThisDrawing.ModelSpace. _
 AddBox(center, length, width, height)

    ' Define the mirroring plane with three points
    Dim mirrorPt1(0 To 2) As Double
    Dim mirrorPt2(0 To 2) As Double
    Dim mirrorPt3(0 To 2) As Double

    mirrorPt1(0) = 1.25: mirrorPt1(1) = 0: mirrorPt1(2) = 0
    mirrorPt2(0) = 1.25: mirrorPt2(1) = 2: mirrorPt2(2) = 0
    mirrorPt3(0) = 1.25: mirrorPt3(1) = 2: mirrorPt3(2) = 2

    ' Mirror the box
    Dim mirrorBoxObj As Acad3DSolid
    Set mirrorBoxObj = boxObj.Mirror3D _
 (mirrorPt1, mirrorPt2, mirrorPt3)
    mirrorBoxObj.Color = acRed
    ZoomAll
End Sub