.. include:: /icons.rst

.. _regions:

========
Regions
========

The Regions pane defines spatial regions (points, lines, planes, boxes, or STLs)
of the geometry that are used for:

-  Initial Conditions
-  Boundary Conditions
-  Point Sources
-  Internal Surfaces
-  Monitors
-  Outputs

The following buttons are at the top of the Regions pane:

+-------------------+-----------------------------------------------------+
| Icon              | Description                                         |
+===================+=====================================================+
| |add|             | create a new region                                 |
+-------------------+-----------------------------------------------------+
| |remove|          | delete the selected region                          |
+-------------------+-----------------------------------------------------+
| |copy|            | duplicate the selected region                       |
+-------------------+-----------------------------------------------------+
| |all region|      | create a region that encompasses the entire domain  |
+-------------------+-----------------------------------------------------+
| |left region|     | create a region on the left side of the domain      |
+-------------------+-----------------------------------------------------+
| |right region|    | create a region on the right side of the domain     |
+-------------------+-----------------------------------------------------+
| |top region|      | create a region on the top side of the domain       |
+-------------------+-----------------------------------------------------+
| |bottom region|   | create a region on the bottom side of the domain    |
+-------------------+-----------------------------------------------------+
| |front region|    | create a region on the front side of the domain     |
+-------------------+-----------------------------------------------------+
| |back region|     | create a region on the back side of the domain      |
+-------------------+-----------------------------------------------------+

The |add| (Add) button creates a new region. The region will be created with a
generic name such as ``R_1``; it is strongly recommended to rename the region to
something more descriptive, so that it is easier to refer to it later.
The Color button will change the color of the region in the model setup view.

The table created with the "From" and "To" fields for the X, Y, and Z axes define the extents of the
region. These widgets take special parameters, ``min`` and ``max``, that
reference the minimum and maximum values of the domain, as specified in the
geometry section. These values will get automatically updated when the
extents in the geometry section are updated. The region type will be
inferred from the specified extents.

If the region needs to be a collection of triangles from the STL file,
select the Select Facets (STL) check-box. The selection shape can be
changed between a box and an ellipsoid. Triangles that fall on the edge of
the shape can be sliced by selecting the Slice Facets check-box. The
triangles can be further filtered by the normal direction by specifying
a vector and a deviation angle around that vector.

.. hint::
    If a region is referenced by an item in the ``Used By`` column, the region
    can not be deleted and its type (STL vs non-STL) cannot be changed.