March 20, 2011, 1:49 p.m.
posted by nuclear
When Alice transits through the looking glass, she becomes her reflection — her entire body switches its axial symmetry, making her left foot her right foot and so on. Sometimes you may want a selected 3D object to switch its axial symmetry in the same way (for example, if you want to create an identical model of a car with the steering wheel on the opposite side). If this happens, you’ll need to employ a mirroring operation.
Mirroring an object either flips the object in reverse on a selected axis, or performs the same operation on a duplicate (clone) of the object. The mirroring operation is activated from choices you make in the Mirror: Screen Coordinates panel. You can get to this panel from either of two places: the Tools>Mirror selection in the menu bar or the Mirror tool in the Main Toolbar.
Either alternative brings up the Mirror: Screen Coordinates panel shown in Figure.
The area under Mirror Axis in the panel shown in Figure contains options for you to determine the axis variance — the selected axis on which the mirroring takes place. Offset variance is determined by the value in the box next to Offset. This value is in viewport units, so you always have to experiment a little to set the correct amount. The neat thing is that your settings are immediately reflected in the viewports, so you can make adjustments before clicking OK.
You can use any object/model you prefer, primitive or imported, to explore mirroring operations. In this case, I have selected the Standard Primitives Pyramid. I left the pyramid’s Pivot Point at its default. In this case, the only way to illustrate the mirroring without doing any cloning is to set mirroring to the Z (vertical) axis. For working on objects without cloning, you can leave the Offset value set to 0, as shown in Figure.
Using Offset Values other than the default of 0 when no cloning is involved is a waste of time in most cases; all it does is move the object by that amount in relation to the position of the source object. It’s better to move the object after mirroring by using the Move tool.