1: Lack of separation option, to mirror an object and automatically separate it
2: (most frustrating/important) Lost/out of phase local orientation
Rezzing an object with a peculiar shape we’ll call this object “A”. Upon editing you need local rotation and movement, so you set your orientation to local. Let’s imagine the peculiar object as a cube for a quick second, your local gimbal is 0 degrees phase to that cube, meaning the local axis are all 90 degrees to the outer faces if that makes sense. The Gimbal is squared to the cube if the object was a cube…
Now, if I rotate that object 45 degrees, the local axis will also rotate 45 degrees to keep in phase with the imaginary cube, keeping all the axis point away from each face of the cube, the gimbal is still 0 degrees phase to the cube, but 45 degrees phase to global orientation. All is fine and dandy, the gimbal is true local and I can move the box in each direction each face is facing.
After that object is rotated, I will rez another object B… Object B is an object that requires perfect symmetry, so we will position object A where we want (location/scale/rotation) and then add a mirror modifier to object A, and tell it to mirror to use object B’s axis to mirror object A on the X-axis, afterwards we can apply the mirror…
Here’s where the first problem occurs. The mirror modifier lacks the feature to mirror objects as their own objects. Instead of joining them together as one… The mirror image of object “B” becomes a part of itself, instead of becoming another object of it’s own, “C”… This destroys some of the information that needs to be kept for both “A” and “B” such as local rotation/orientation, because how does two joined meshes keep two origins and gimbals?
The more frustrating second issue… Now that we applied the mirror we are forced to separate that newly added mesh on object A into another object C using edit mode and [P] key to separate selection, to make two symmetrical objects… After you separate that mesh you’ll notice the problem with the local orientation gimbal. Although the rotation of object C changed after applying the mirror, the local gimbal did not change rotation with the newly mirrored and separated object C and is now out of phase and using the local gimbal of the original mirror object, and can be out of phase on multiple axis and angles, making local editing on that object useless…
Let’s say that Object B, which we are using as a mirror and surface is wavy, and is on a <33, 10, 23> degree angles. We now need to use global orientation since the local axis are off-whack. But with editing in global axis, you must use 3 axis to position and rotate it much more painstakingly than using local axis, and not being able to transform on those axis either because they don’t face correctly…
This allows huge accuracy issues, discrepancies, and essentially kills the local gimbal and workflow, and wastes a lot of my time and energy and makes me question Blender ALOT…
These are features that have no excuse being excluded from the mirror modifier, and there’s no existing add-ons to repair the mirror tool and improve it in these ways… It’s a very rare and tricky problem to understand, but when the problem bites you, it bites you hard and makes you realize how badly designed some tools are…