--- /dev/null
+
+.. _reorient_faces_page:
+
+************
+Orient faces
+************
+
+This operation allows fixing the orientation of a set of faces in the following ways:
+
+* The required orientation of a set of neighboring faces can be defined by a vector giving the direction of a normal to a certain face. Since the direction of face normals in the set can be even opposite, it is necessary to specify a *control* face, the normal to which will be compared with the vector. This face can be either:
+ * found by proximity to a given point, or
+ * specified explicitly.
+* The required orientation is given by faces of specified reference groups or/and sub-meshes. The reference groups can be omitted, then orientation of an arbitrary selected face to orient defines common orientation.
+* Alternatively, the faces can be oriented relatively to the adjacent volumes.
+
+The orientation of a face is changed by reverting the order of its nodes.
+
+*To set orientation of faces:*
+
+.. |imgfac| image:: ../images/reorient_faces_face.png
+.. |imgpnt| image:: ../images/reorient_faces_point.png
+.. |imggrp| image:: ../images/reorient_faces_ref_groups.png
+.. |imgvol| image:: ../images/reorient_faces_volume.png
+
+#. In the **Modification** menu select **Reorient faces** item or click *"Reorient faces"* button |imgfac| in the toolbar.
+#. In the "Reorient faces" dialog box
+
+ * Select a way to define orientation:
+
+ * |imgpnt| - by specifying a point and a vector
+ * |imgfac| - by specifying a face and a vector
+ * |imggrp| - by specifying reference face groups
+ * |imgvol| - by specifying reference volume groups
+
+ * Select the **Object(s)** (mesh, groups and/or sub-meshes) containing faces to reorient, in the Object Browser or in the 3D Viewer.
+ * To reorient by direction of the face normal:
+
+ * Specify the coordinates of the **Point** by which the control face will be found. You can specify the **Point** by picking a node in the 3D Viewer or selecting a vertex in the Object Browser.
+ * Set up the **Direction** vector to be compared with the normal of the control face. There are following options:
+
+ * adjust vector components directly;
+ * select a vertex in the Object Browser or a node in the 3D Viewer; their coordinates will define vector components;
+ * pick two nodes (holding Shift button), the **Direction** vector will go from the first to the second node.
+
+ .. image:: ../images/reorient_2d_point.png
+ :align: center
+
+ .. centered::
+ The orientation of adjacent faces is chosen according to a vector. The control face is found by point.
+
+ * In the second mode it is possible to pick the **Face** by mouse in the 3D Viewer or directly enter the **Face** ID in the corresponding field.
+
+ .. image:: ../images/reorient_2d_face.png
+ :align: center
+
+ .. centered::
+ The orientation of adjacent faces is chosen according to a vector. The control face is explicitly given.
+
+
+ * In the third mode, the faces can be reoriented equally to reference faces:
+
+ * If necessary, select 2D **Reference objects** (groups or/and sub-meshes) containing the reference faces, in the Object Browser or in the 3D Viewer. This field can be left empty, then orientation of an arbitrary face will be used as a reference.
+
+
+ .. image:: ../images/reorient_2d_refgroup.png
+ :align: center
+
+ .. centered::
+ The orientation of faces is given by reference face groups and/or sub-meshes.
+
+ * In the fourth mode, the faces can be reoriented according to volumes:
+
+ * Select an object (mesh, sub-mesh or group) containing reference **Volumes**, in the Object Browser or in the 3D Viewer.
+ * Specify whether face normals should point outside or inside the reference volumes using **Face normal outside volume** check-box.
+
+ .. image:: ../images/reorient_2d_volume.png
+ :align: center
+
+ .. centered::
+ The orientation of faces is chosen relatively to adjacent volumes.
+
+#. Click the **Apply** or **Apply and Close** button to confirm the operation.
+
+**See Also** a sample TUI Script of a :ref:`tui_reorient_faces` operation.
+
+
