Why Symmetry is not global?

Support Modeling
1

Another not logic feature on Blender, the symmetry option is not global as we could expect.

For example select face, extrude on same mesh, symmetry does not work when we choose symmetry on X, while in other modeling apps this works.

824Ă—587 65.1 KB

2

The mesh symmetry option in blender tries to manipulate the other side of the model in the same way… but symetrical. This also works on the symetrical parts of an asymetrical model. For mirroring every model manipulation in every aspect there is the mirror modifier.
This you also can read in the docu docs.blender Manual Tool Settings Symmetrical

Mirror:
Mirror allows you to transform vertices symmetrically according to the chosen axis. When you transform an element (vertex, edge or face), if there is its exact axis-mirrored counterpart (in local space), it will be transformed accordingly, through a symmetry along the chosen axis.
Note:
The conditions for Mirror to work are quite strict, which can make it difficult to use. To have an exact mirrored version of a (half) mesh, it’s easier and simpler to use the Mirror Modifier.

(Anyway: i always wonder why people just compare with other software and think other behaviour is unlogical… even different other apps does things different and blender even calld this two functions different.)

3

You want an object symetry for their own axis. Global makes no sense for me.
You can rotate the local axis or the object to align to the global to work on this if you really need it.

4

Thanks.

From the doc

The conditions for Mirror to work are quite strict, which can make it difficult to use. To have an exact mirrored version of a (half) mesh, it’s easier and simpler to use the [Mirror Modifier]

So use mirror option for sculpting and some othe features, while it is not global.
And use a mirror modifier for other things where mirror option does not work like polygon modeling.

Just an observation, the mirror option once checked could have designed to work on any mode, working as regular in sculpting and using same mirroring features as mirror modifier when polygon modeling for example.

5

Which is what exactly? The “mirrored” side of the modifier does not even exist before applying (and so it can’t really cause any issues while modeling).

6

Im not sure which software you mean. Afaik symmetry doesnt exist as a toggle button in 3ds max, as examply, and for symmetry you need a symmetry modifier in stack, which are literally mirror modifier in blender.