.. _solverdef_define_gridcond:

Defining Grid attributes
-------------------------

Define grid attributes. Grid attributes are defined with
\"GridRelatedCondition\" element. Add definition of grid related condition
to the solver definition file you created, as shown in
:numref:`solverdef_example_with_gridcond`.
The added part is shown with highlight.

.. code-block:: xml
   :caption: Example of solver definition file that now has grid related condition (abbr.)
   :name: solverdef_example_with_gridcond
   :linenos:
   :emphasize-lines: 4-17

   (abbr.)
     </CalculationCondition>
     <GridRelatedCondition>
       <Item name="Elevation" caption="Elevation">
         <Definition position="node" valueType="real" default="max" />
       </Item>
       <Item name="Obstacle" caption="Obstacle">
         <Definition position="cell" valueType="integer" default="0">
           <Enumeration value="0" caption="Normal cell" />
           <Enumeration value="1" caption="Obstacle" />
         </Definition>
       </Item>
       <Item name="Rain" caption="Rain">
         <Definition position="cell" valueType="real" default="0">
           <Dimension name="Time" caption="Time" valueType="real" />
         </Definition>
       </Item>
     </GridRelatedCondition>
   </SolverDefinition>

Now make sure that solver definition file is arranged correctly.

Launch iRIC, and starts a new project with solver \"Sample Solver\".
Now you will see the [Pre-processing Window] like in
:numref:`preprocessor_with_geographicdata`. 
When you create or import a grid, the [Pre-processing Window] will become like in
:numref:`preprocessor_with_gridattributes`.

When you do not know how to create or import a grid,
refer to the User Manual.

.. _preprocessor_with_geographicdata:

.. figure:: images/preprocessor_with_geographicdata.png
   :width: 380pt

   The [Pre-processing Window]

.. _preprocessor_with_gridattributes:

.. figure:: images/preprocessor_with_gridattributes.png
   :width: 380pt

   The [Pre-processing Window] after creating a grid

When you edit the grid attribute \"Elevation\" with the following
procedure, the [Edit Elevation] dialog
(:numref:`dialog_to_edit_elevation`)
will open, and you can check that you can input real number as
\"Elevation\" value.

-  Select [Grid] --> [Node attributes] --> [Elevation] in the [Object
   Browser].
-  Select grid nodes with mouse clicking in the canvas area
-  Show context menu with right-clicking, and click on [Edit].

.. _dialog_to_edit_elevation:

.. figure:: images/dialog_to_edit_elevation.png
   :width: 230pt

   The [Edit Elevation] dialog

When you do the same operation against attribute \"Obstacle\" to edit
\"Obstacle\" value, the [Obstacle edit dialog]
(:numref:`dialog_to_edit_obstacle`) will open,
and you can check that you can select obstacle values from that you
defined in solver definition file, in :numref:`solverdef_example_with_gridcond`.

.. _dialog_to_edit_obstacle:

.. figure:: images/dialog_to_edit_obstacle.png
   :width: 230pt

   The [Obstacle edit dialog]

What it comes down to is:

-  Grid attribute is defined with \"Item\" element under
   \"GridRelatedCondition\" element.

-  The structure under \"Item\" element is basically the same to that for
   calculation condition, but there are different points:

  -  You have to specify \"position\" attribute to determine whether that
     attribute is defined at nodes or cells.
  -  You can not use types \"String\", \"Functional\", \"File name\"
     and \"Folder name\".
  -  You can not define dependency.
  -  You can define dimension of the attribute, using \"Dimension\" element.

For grid attributes, iRIC defines some special names. For attributes for
certain purposes, you should use those names. Refer to
:ref:`special_names` for the special grid attribute names.