The Mirror Modifier mirrors a mesh along its local X-, Y- and/or Z-Axes, across the object's center (the mirror plane is then defined by the two other axes).
The X-, Y-, Z-axis along which to mirror (i.e. the axis perpendicular to the mirror plane of symmetry).
You can select more than one of these axes. And will then get more mirrored copies. With one axis you get a single mirror, with two axes four mirrors, and with all three axes eight mirrors.
- 作为镜像并在同一个位置的顶点（在 合并限度 距离之内），它将与镜像顶点合并。
如果已启用 裁剪 选项，但顶点超出了镜面且在 合并限制 之外，顶点是不会合并的。但只要顶点是在 合并限制 之内，它们会吸附在一起，且不能穿越镜子到另一边。
只要启用了 裁剪 选项，镜面上的顶点将无法移离镜面。你必须禁用 裁剪 选项才能沿镜轴移动顶点。
When enabled, the Mirror Modifier will try to mirror existing vertex groups.
- The vertex groups you want to mirror must be named following the usual left/right pattern (i.e. suffixed by something like ".R", ".right", ".L", etc.).
The U and V options allows you to mirror the UV texture coordinates across the middle of the image.
E.g. if you have a vertex with UV coordinates of (0.3, 0.9), its mirror copy will have UV coordinates of (0.7, 0.1).
- UV Offsets
- Amount to shift mirrored UVs from the 0.5 point on the U/V axis.
- An Object Selector to select an object (usually an empty), to be used as the reference for the mirror process: its center and axes will drive the plane(s) of symmetry. You can of course animate its position/rotation to animate the mirror effect.
Many modeling tasks involve creating objects that are symmetrical. However, there used to be no quick way to model both halves of an object without using one of the workarounds that have been discovered by clever Blender artists over the years. A common technique was to model one half of an object and use Alt-D to create a linked duplicate which can then be scaled on one axis by -1 to produce a perfect mirror-image copy which updates in real time as you edit.
The Mirror Modifier offers a simpler way to do this. Once your modeling is completed you can either click Apply to make a real version of your mesh or leave it as is for future editing.
When using the Mirror Modifier along with a Subdivision Surface modifier, the order in which the modifiers are placed is important.
The above image shows the Subdivision Surface Modifier placed before the Mirror one; as you can see the effect of this is that the mesh is split down the center line of the mirror effect. This is because the Subdivision calculation moves vertices away from the mirror plane, too far away from the Merge Limit.
The above image shows the Mirror Modifier placed before the Subdivision Surface Modifier. In this order, the mirror calculation is done and the vertices are merged together. Only after that does the Subdivision Surface Modifier move any vertices.
To apply a Mirror Modifier, it is common to have to move the object's center onto the edge or face that is to be the axis for mirroring. This can be tricky when attempted visually.
A good technique to achieve an exact position is to select the edge, then use Shift-S and choosing Cursor to Selection. This will position the 3D Cursor in the center of the edge. Finally, press Shift-Ctrl-Alt-C for the Set Origin menu, then select Origin to 3D Cursor. This will move the object's center (and thus, the mirror plane) to where the 3D cursor is located, and the mirroring will be exact.