This is gid.info, produced by Makeinfo version 3.12h from gid.texinfo.

   This is the GiD manual

   Copyright 1997-2002 CIMNE


File: gid.info,  Node: Data,  Next: Meshing,  Prev: Geometry,  Up: Top

DATA
****

   All the data that defines the problem and that is managed in the
data menus, depends on the problem type and will change for every
different problem type. The following help will describe the common
interfaces to all the possible data.

   Data for a problem is defined by the following parameters: conditions
(*note Conditions::.), materials properties (*note Materials::.),
problem data (*note Problem data::.) and intervals data (*note Interval
data::.) that define the problem. The conditions and materials have to
be assigned to geometrical entities. It is also possible to define new
reference systems (*note Local axes::.).

* Menu:

* Problem type::
* Transform problem type::
* Conditions::
* Materials::
* Problem data::
* Intervals::
* Interval data::
* Local axes::


File: gid.info,  Node: Problem type,  Next: Transform problem type,  Prev: Data,  Up: Data

Problem type
============

   This option permits to select between all installed problem types.
When selecting a new problem type, all information about materials,
conditions and other data parameters that were already selected or
defined is lost.

   Option `Others...' permits to enter one installed problem type or one
that is in the current directory. This last possibility is useful when
creating a new problem type and it cannot be installed until finished.

   *Note:* When defining a new problem type, as this is not installed,
it must be selected by other means. One possibility is to use the
'Others...' possibility in the 'problem types' menu. Another
possibility is to use  the following commands in the right buttons menu
or written in the command line: `data defaults problemtype'.

   One problem type is considered to be installed when it is copied to
the GiD executable directory or inside the subdirectory `problemtypes'
or inside another subdirectory inside this last.


File: gid.info,  Node: Transform problem type,  Next: Conditions,  Prev: Problem type,  Up: Data

Transform problem type
======================

   This option can be found inside `Problem type' menu and is useful to
actualize one model from an old problem type to a newer one that is
similar to the first.

   When converting, it tries to maintain all the conditions and
materials assigned to the geometry or mesh. Also, it tries to maintain
the rest of the data.

   It will be typically used when a problem type has been updated and is
necessary to use again a model defined with the old version.


File: gid.info,  Node: Conditions,  Next: Materials,  Prev: Transform problem type,  Up: Data

Conditions
==========

   Conditions are all the properties of a problem (except materials),
that can be assigned to an entity.

   One example would be the boundary forces and displacement
constraints in a solid mechanic analysis or initial velocities in a CFD
analysis. Information about contact between master-slave nodes can also
be considered as `conditions'.

   *Caution:* If a mesh has already been generated, any change in the
condition assignments, requires to mesh again to transfer these new
conditions to the mesh. If this new generation has not been made, user
will be warned when the data for the analysis is being written.

* Menu:

* Assign condition::
* Draw condition::
* Unassign condition::


File: gid.info,  Node: Assign condition,  Next: Draw condition,  Prev: Conditions,  Up: Conditions

Assign condition
----------------

   The condition is assigned to the entities with the given field
values.

   If assigning from the command `Assign Cond', the option `Change'
allows the definition of the field values. Do not forget to change
these values before assigning. Option `Delete all' erases all the
assigned entities of this particular condition.

   Conditions can be assigned both on the geometry and on the mesh but
it is advisable to assign them on the geometry and the conditions will
then be automatically transferred to the mesh. If assigned on the mesh,
when remeshing, conditions are lost.

   Conditions that are to be attached to the boundary of the elements,
are assigned to the elements and GiD searches the boundaries of the
elements that are boundaries of the total mesh.

   Option `Unassign' inside `AssignCond', permits to unassign this
condition. It is also possible to unassign from only certain entities.

   *Caution:* If a mesh has already been generated, for any change in
the condition assignments, it is necessary to mesh again.

   Some conditions may have a behavior that depends on the type of the
chosen axes.  The user can choose whether to use global axes or any of
the local axes previously described with the command `Local axes'
(*note Local axes::.), or, alternatively, another option of automatic
local axes calculations. In this latter case, different axes are created
according to the adopted criteria of tangency and orthogonality with
the geometry.

   The user can apply all graphical functions (`zoom', `rotate', ...)
and all the condition symbols are maintained in active mode in the
graphical window until the user selects `escape' or presses `Finish' in
the conditions window.


File: gid.info,  Node: Draw condition,  Next: Unassign condition,  Prev: Assign condition,  Up: Conditions

Draw condition
--------------

   Option `Draw all' draws all the conditions assigned to all the
entities.  This means to draw a graphical symbol or condition number
over every entity that has this condition.

   If one particular condition is selected, it is possible to choose
between `Draw' and one of the fields. `Draw' is like `Draw all' but
only for one particular condition. If one field is chosen, the value of
this field is written over all the entities that have this condition
assigned.

   When the condition has any field referred to the type of axes, the
latter can be visualized by means of `Draw local axes'.

   Option `Draw colors' Draws groups of entities with different colors
depending on the values assigned to them for this condition.


File: gid.info,  Node: Unassign condition,  Prev: Draw condition,  Up: Conditions

Unassign condition
------------------

   In window mode, command `UnAssign' lets the user choose between three
possibilities:

   * Unassign one condition from some selected entities.

   * Unassign one condition from all the entities that may have this
     assigned.

   * Unassign all conditions from all the entities that may have them
     assigned.

   In command mode `UnAssing', do it for all the conditions. To
unassign only one condition, use command `Delete All' (*note Assign
condition::.).


File: gid.info,  Node: Materials,  Next: Problem data,  Prev: Conditions,  Up: Data

Materials
=========

   For any problem that needs definition of materials, there is a
database of existing materials that can be assigned to entities. The
user can also create new materials derived from existing ones and
assign them as well.

   *Caution:* If a mesh has already been generated, for any change in
the assigned materials, it is necessary to mesh again or assign the
materials directly to the mesh.

* Menu:

* Assign material::
* Draw material::
* Unassign material::
* New material::
* Import/Export material::


File: gid.info,  Node: Assign material,  Next: Draw material,  Prev: Materials,  Up: Materials

Assign material
---------------

   The material is assigned to the selected entities.

   If assigning from a window, every time the assigned material
changes, button `Assign' must be pressed again.

   The user must select the entity where to assign the materials over:
`line, surface or volume' when working in geometry mode or directly
over the `elements' when working in mesh mode.

   If assigning from the command line, option `UnAssignMat' erases all
the assignments of this particular material.

   *Caution:* Although a mesh had been already generated, for any change
in the assigned materials, it is necessary to mesh again or assign the
materials directly to the mesh.


File: gid.info,  Node: Draw material,  Next: Unassign material,  Prev: Assign material,  Up: Materials

Draw material
-------------

   This option draws a color indicating the selected material for all
the entities that have the required material assigned. It is possible
to draw just one material type or alternatively, draw all materials. To
select some of them use `a:b' and all material numbers that lie between
`a' and `b' will be drawn.

   *Caution:* When drawing materials in 3 dimensions, it may be
necessary to change the viewing mode to polygons or render (*note
Render::.) to distinguish the front and back of the objects.


File: gid.info,  Node: Unassign material,  Next: New material,  Prev: Draw material,  Up: Materials

Unassign material
-----------------

   Command `Unassign' unassigns all the materials from all the
entities. For only one material, use `UnAssignMat' (*note Assign
material::.).


File: gid.info,  Node: New material,  Next: Import/Export material,  Prev: Unassign material,  Up: Materials

New material
------------

   When using command `NewMaterial', a new material is created taking
an existing one as a base material. Base material means that the new
material will have the same fields as the base one. Then, all the new
values for the fields can be entered in the command line.

   It is possible to redefine an existing material.

   To create a new material or redefine an old one in the materials
window, write a new name or the same one and change some of the
properties. Then, push `Accept'.


File: gid.info,  Node: Import/Export material,  Prev: New material,  Up: Materials

Import/Export material
----------------------

   It is possible to import and export materials from the model
database to one external database. Typically, one centralized database
of materials is mantained and every new model gets its properties from
there.

   *Note:* If it is desired to interchange materials with the `Problem
type' database, it is necessary to check that the current user has
enough permissions to read/write in that directory.


File: gid.info,  Node: Problem data,  Next: Intervals,  Prev: Materials,  Up: Data

Problem data
============

   Problem data refers to all the data that is general to the problem.
This means that it is not related to a geometrical entity and it does
not change in every interval of the analysis.

   It can be entered with the command `ProblemData' or in the problem
data window.

   If entered in a window, the data is not accepted until the  button
`Accept' is pressed.

   This data can be entered before or after meshing.


File: gid.info,  Node: Intervals,  Next: Interval data,  Prev: Problem data,  Up: Data

Intervals
=========

   Intervals are a way to separate some information into several
groups. The information that can be duplicated for every group can also
be duplicated, if desired. When a new interval is defined, it is
possible to copy all the new information about conditions, assigned to
entities or not.

   Therefore, the correct way to work is to define all the conditions
first and afterwards create the new intervals.

   Options are:

   * New: It is allowed to define as many intervals as desired with
     this command.  When creating a new one, user can choose whether
     copy the assigned conditions or not. To copy them, conditions must
     already be assigned (*note Conditions::.).

   * Current: Chooses the current interval to use. Next assigned
     conditions or interval data (*note Interval data::.), will be
     considered inside this interval.

   * Delete: Deletes one existing interval and all its related data.

   These groups called intervals can be used to change some conditions
or information like increment factor in an incremental analysis.  It
may also be useful to define some load states for the same geometry.


File: gid.info,  Node: Interval data,  Next: Local axes,  Prev: Intervals,  Up: Data

Interval data
=============

   This is the amount of information that is maintained different for
every interval (*note Intervals::.).

   It can be entered with the command `IntervalData' or in the
intervals data window.

   If entered in a window, the  data is not accepted until button
`Accept' is pressed.

   This data can be entered before or after meshing.


File: gid.info,  Node: Local axes,  Prev: Interval data,  Up: Data

Local axes
==========

   With this option, GiD allows to define new different coordinates
reference systems.  It is possible to write them, not only as cartesian
reference systems, but also referring to as Euler angles. All user
defined systems are automatically calculated and can be visualized one
by one or all together.

   There are several ways to define new local axes:

   * `3 Points XZ' User enter three points that corresponds to the
     origin, the X-direction and the Z-direction. The origin and the
     last introduced point define the Z-axis, whereas the second point
     indicates the side of the `x-z' plane where the point lies.  item
     `X and angle' User enter 2 points and one angle. The first one is
     the center, the second one indicates the X-axe and the angle
     indicates the position of the Y and Z axes. In the graphical
     window, it is possible to set dynamically this angle by moving the
     mouse. It also indicates where the origin of the angle is. The
     angle can be either enter by pressing the mouse or by entering the
     exact value in degrees.

   When defining local axes, the definition mode is done through three
points `3PointsXZ', what

   Local axes can later be used when creating a point (*note Point
creation::.) or in some conditions that have a field related to these
axes (*note Conditions::.).


File: gid.info,  Node: Meshing,  Next: View,  Prev: Data,  Up: Top

MESHING
*******

   Generating a mesh is the process where a finite element mesh is
calculated from the geometry definition. This mesh will be used for the
FEM analysis in a later step.  Conditions (*note Conditions::.) and
materials (*note Materials::.) assigned to geometric entities will be
transferred to the nodes and elements of the new mesh.

   What is meshed and how, is controlled by some default options which
can be changed with the commands described later.

   The generation does not depend on the state of the layers at the
moment of generation (*note Layers::.). All layers are meshed and every
node and element will be assigned to the layer in which the original
geometrical entity was defined.

   Defaults are:

   * An entity is meshed if does not belong to a higher level entity.

   * A line mesh is made of two-noded elements and a surface mesh is
     made of non-structured triangular elements. The default for
     structured meshes are quadrilateral elements.  Volume meshes are
     composed by non-structured tetrahedral elements.  Structured
     volume meshes are composed by hexahedra.

   All these default elements use linear interpolations for the unknown
variables.

* Menu:

* Generate::
* Mesh view::
* View boundaries::
* Assign unstruct sizes::
* Draw Sizes ::
* Structured mesh::
* Structured concentrate::
* Mesh criteria::
* Element type::
* Quadratic::
* Reset mesh data::
* Cancel mesh::
* Mesh quality::
* Edit mesh::


File: gid.info,  Node: Generate,  Next: Mesh view,  Prev: Meshing,  Up: Meshing

Generate
========

   When everything is ready for mesh generation, select this command.
If there is a previously generated mesh, GiD asks if this should be
deleted, i.e., make it disappear from memory, not from disk until the
next save (*note Save::.).

   The mesher or mesher combination, can be chosen in  (*note
Preferences::.).

   Next, GiD asks for a general element size which will be applied to
all lines, surfaces and volumes that do not have a previously defined
one (*note Assign unstruct sizes::.).  GiD offers to the user to
default possibilities:
   * One default size automatically calculated by the program to define
     a coarse mesh.

   * Last size given by the user in previus meshings.

   User can choose one of these or enter a new one.

   Size is given by the average side of the corresponding triangle or
quadrilateral.

   Progress in meshing is shown by one progress bar that indicates
number of generated surfaces or volumes related to total number of
surfaces or volumes.

   Meshing can be stopped at any time by pressing button `Stop'.
Sometimes it is necessary to press this button for some time to get the
action done.


File: gid.info,  Node: Mesh view,  Next: View boundaries,  Prev: Generate,  Up: Meshing

Mesh view
=========

   When a mesh has already been generated, this option changes the
visualization to mesh viewing. The reverse, the return to geometry, is
automatically performed either by the same command or when selecting
option `View geometry' (*note View geometry::.) or any command related
to geometry.


File: gid.info,  Node: View boundaries,  Next: Assign unstruct sizes,  Prev: Mesh view,  Up: Meshing

View boundaries
===============

   This option draws the boundaries of the mesh on the screen when
chosen.

   It is useful to notice adjacent surfaces with inverted normals, as
in this case an edge between them appears. Analogously, it can detect
meshing errors in closed volumes, as in this case there would not exist
any boundary.

   Boundaries for triangular or quadrilateral meshes are line-elements.
Boundaries for tetrahedra or bricks meshes are triangles or
quadrilaterals.  This option can be useful to render a volume mesh
(*note Render::.).


File: gid.info,  Node: Assign unstruct sizes,  Next: Draw Sizes,  Prev: View boundaries,  Up: Meshing

Assign unstruct sizes
=====================

   Size is given by the average side (edge) of the corresponding
triangle or quadrilateral.
Assign sizes to points, lines, surfaces or volumes:
It is possible to assign different sizes to different entities of the
mesh.  This means that in the vicinity of these entities, the generated
elements will be approximately of that size. All the entities that have
not an assigned size when meshing, take the default size. Points do not
take any size if none is given to them.

   To assign a size of 0.0 to an entity is the same as setting the
default size.  The transition between different sizes is controlled by
a parameter in preferences (*note Preferences::.).
Assign sizes by cordal error:
Option `By cordal error' asks the user for a minimum and a maximum size
and a cordal error (the maximum distance between the generated element
and the real geometry). GiD assigns the corresponding sizes to all the
entities to accomplish this condition. It will only change the current
sizes if the new one is smaller than the previously defined. In
structured surfaces, stretching is permitted. It means that if
necessary, elements can have very different size along both principal
directions.

   In this window the effect of different cordal error values over the
number of elements that will be created over a line can be viewed. Any
line of the geometry can be picked up and be used in this window.
Correct sizes:
When option `Correct sizes' is selected, a window appears. In this
window it is possible to enter a minimum and a maximum mesh size.

   If option `By geometry' is activated, sizes are assigned to all the
entities depending on the shape of the geometry. This means that
smaller surfaces will have smaller elements. It will only change the
existing sizes if the new size is smaller than that previously defined.

   If option `Correct incompatible sizes' is activated, some sizes are
reduced in order to control that the transitions between sizes in close
entities are not too fast. It will only change the current sizes if the
new one is smaller than that previously defined.
NOTE: Applying last two options with default values is exactly the same
than setting the preference `Automatic correct sizes' to on in the
preferences window (*note Preferences::.).

   NOTE: To mesh a difficult volume trying to adjust element sizes to
geometry detail, it may be useful to use `By geometry' and `Correct
incompatible sizes' options setting the larger size equal to the
default size for meshing, and the smaller size reflecting the details (
10 times smaller, for example).
Background Mesh:
With this option it's possible to assign sizes using a background mesh
of triangles or tetrahedrons. When the option is selected GiD asks for
a file; that file must contain the background mesh. The background mesh
must cover all the new mesh, so usually the background mesh will be a
previous mesh of the same model.
The format of the file containing the background mesh is the following:
   * First line: `BackgroundMesh V 1.0'

   * Description of the mesh. The format of that mesh is described in
     the Mesh read section (*note Mesh read::.).

   * Desired sizes in the following format:
          DesiredSize (Nodes or Elements)
            number of        size
            node/element
          ...

     Background mesh file example:
          BackgroundMesh V 1.0
          MESH dimension       2 ElemType Triangle  Nnode 3
          Coordinates
                1          5.61705         4.81504         0.00000
           ...
               51         -5.64191        -1.53335         0.00000
          end coordinates
          
          Elements
                1         24         16         26
                2         16         10         14
          ...
               76         34         31         28
          end elements
          
          DesiredSize Elements
                1         0.20000
                2         0.20000
          ...
               75         1.50000
               76         1.50000
          End DesiredSize

CAUTION: Be careful when assigning big sizes to entities close to
others where a small size has been given. It may be impossible to
obtain a mesh.

   CAUTION: When using contact elements (*note Contact creation::.),
the same size must be used for contact and for duplicate entities.


File: gid.info,  Node: Draw Sizes,  Next: Structured mesh,  Prev: Assign unstruct sizes,  Up: Meshing

Draw Sizes
==========

   When sizes are assigned to points, lines, surfaces or volumes using
the Assign Unstruct sizes option, it is possible to draw in different
colors the different assigned sizes.

EXAMPLE

   In the following example some different sizes are assigned to
surfaces. Sizes of 3, 5 and 6 are assigned depending on the surface.
After choosing the Draw Sizes option, (over surfaces) we get the
following result:

File: gid.info,  Node: Structured mesh,  Next: Structured concentrate,  Prev: Draw Sizes,  Up: Meshing

Structured mesh
===============

A structured mesh is defined as a mesh where all the nodes have the
same number of elements around it.

   The size of the elements is defined in a different way than for a
non-structured mesh. In this case, the mesh is not defined by the size
but by the number of elements that are required on every line. This
number must be the same for all lines that are opposite to each other
on each surface. When meshing volumes, this definition must be the same
for opposite surfaces.

   To create a structured mesh, choose `structured' and volumes,
surfaces or lines. Surfaces can be 4-sided or NURBS ones. Planar
surfaces meshes cannot be structured. After choosing `escape', the
number of elements per line is given.  Later, lines can be selected and
related lines (in option surface or volume), are added or deleted from
the group. This process can be repeated as many times as necessary
until all lines have a new value. By default, the generated elements
will be quadrilateral or hexahedra and the lines with no numbering
given will have two elements over them. All no selected lines will also
have two elements by default.

   Structured volumes must have 6 contour surfaces. Structured surfaces
must be 4-sided surfaces or NURBS surfaces.

   It is possible to mix some entities with structured meshes and
others with unstructured ones.

   To convert a structured entity to a non-structured one, select reset
(*note Reset mesh data::.) or assign a size to it (*note Assign
unstruct sizes::.).

   To change the default element type *Note Element type::.

   *Note 1:* One NURBS surface can be structured with any number of
contour lines but must have a good shape form. This means that it must
have 4 big angles and the other angles must be small. With this
criteria, the shape will be topologically similar to one quadrilateral.

   *Note 2:* When assigning structured divisions to one line or with
difficult topology, GiD may need to reassign some sizes to make the
structured mesh conformal. It will be done automatically. If it is
impossible to create compatibility between surfaces, a message is given.


File: gid.info,  Node: Structured concentrate,  Next: Mesh criteria,  Prev: Structured mesh,  Up: Meshing

Structured concentrate
======================

   By default, all partitions in one structured line have the same
length.  This command lets the user select one line. Then, in the
graphical window the sense of the line is shown with one arrow. The
user will enter a positive or negative weight.  If the weight is
positive the size of the elements will be smaller at the beginning of
the line. If negative, the elements will be concentrated at the end of
the line.
As the magnitude of the weight increases, the diference between element
sizes will be bigger.


File: gid.info,  Node: Mesh criteria,  Next: Element type,  Prev: Structured concentrate,  Up: Meshing

Mesh criteria
=============

   GiD provides three different criteria to generate the mesh. The
`Default' option skips meshing the boundaries, that is, lines for
surface meshes and surfaces for volume meshes. The `Mesh' option allows
the user to choose the entities to be meshed, whilst the `No Mesh'
option does the opposite.


File: gid.info,  Node: Element type,  Next: Quadratic,  Prev: Mesh criteria,  Up: Meshing

Element type
============

   With this command, the type of element desired is selected. It is
only necessary to do this when the element type is different from the
default (*note Meshing::.).

   Types are:

   * Linear: for lines.

   * Triangle and Quadrilateral: for surfaces.

   * Tetrahedra and Hexahedra: for volumes.

   * Only points: Just for volumes. Point elements are generated.

   * Linear and  Quadrilateral: for contact surfaces.

   * Linear, Prism and Hexaedra: for contact volumes.

   By default, the elements are of minimum order: 3-noded triangle,
4-noded quadrilateral and so on. To increase the degree, use command
`Quadratic' (*note Quadratic::.). Option `Quadratic' applies to all the
elements of the problem.

   · `Point': 1 node,

   · `Linear': 2 or 3 nodes,

   · `Triangle': 3 or 6 nodes,

   · `Quadrilateral': 4, 8 or 9 nodes,

   · `Tetrahedra': 4 or 10 nodes,

   · `Hexahedra': 8, 20 or 27 nodes.


   The `Linear' option assures, not only the meshing of lines, but also
the creation of 2-node contact lines between surfaces or volumes, if
desired.

   At contact surfaces, GiD elements are:
   * Linear: 2 nodes.

   * Triangle: 3 nodes.

   * Quadrilateral: 4 nodes.

   At contact volumes (and separated contacts), elements are:
   * Linear: 2 nodes.

   * Prisma: 6 nodes.

   * Hexahedra: 8 nodes.

   To decide what parts of the geometry should be meshed use command:
*Note Mesh criteria::.


File: gid.info,  Node: Quadratic,  Next: Reset mesh data,  Prev: Element type,  Up: Meshing

Quadratic
=========

   Option `Quadratic' applies to all the elements of the problem. If
chosen, elements will be:

   * Linear: 3 nodes.

   * Triangle: 6 nodes.

   * Quadrilateral: 8 nodes.

   * Tetrahedra: 10 nodes.

   * Hexahedra: 20 nodes.

   Option `Quadratic9' is similar to option `Quadratic', but will
generate 9-noded Quadrilaterals and 27-noded Hexahedra.


File: gid.info,  Node: Reset mesh data,  Next: Cancel mesh,  Prev: Quadratic,  Up: Meshing

Reset mesh data
===============

   This command resets, all the sizes assigned to entities. This means
that all of them will be unassigned.

   To unassign only some entities, assign size 0.0 (*note Assign
unstruct sizes::.) to the entities where the default size is required.

   The information about element types, mesh criteria and quadratic
parameters is also reset.


File: gid.info,  Node: Cancel mesh,  Next: Mesh quality,  Prev: Reset mesh data,  Up: Meshing

Cancel mesh
===========

   If a mesh has been previously generated, this option erases the mesh
and makes it disappear.


File: gid.info,  Node: Mesh quality,  Next: Edit mesh,  Prev: Cancel mesh,  Up: Meshing

Mesh quality
============

   This option opens a window that shows graphics about the quality of
the mesh elements.

   There are four criteria in order to measure the quality of the
elements:
  1. Minimum angle: The quality criteria is the minimum angle in
     surface elements and the minimum dihedral angle for volume
     elements. This means that elements with a small angle are
     considered of a worse quality than the ones with bigger angles.

  2. Maximum angle: It gives the maximum angle for every element.
     Elements with bigger angles are considered worse.
     Typically, the Minimum angle criteria is good to qualify triangles
     or tetrahedra and the Maximum angle criteria is good for
     quadrilaterals and hexahedra
  3. Element vol: The quality criteria is the size of elements
     (distance for lines, area for surfaces and volume for volumes).
     Elements with little "volume" are considered worse.

  4. Minimum edge: The quality criteria is the size of the edges of
     elements. Elements with smaller edges are considered worse.

There are two visualization modes:
  1. Normal: the graph shows the number of elements that have an angle
     with a certain degree.

  2. Accumulated: the graph shows the number of elements which have an
     angle with a given degree or smaller.

   In the `MeshQuality' window, if you double click on a value, the
elements below this value are selected in red. These selected elements
can be sent to a layer using the `Send To Layer' button of the `Mesh
Quality' window.

EXAMPLE

   In this example we are studying the mesh using the minimum angle
criteria. We can see that 140 elements of our mesh have an angle of
smaller than 45,7 degrees. If we double click with the mouse on the
graphic, the 140 elements which have an angle smaller than 140 degrees,
will be selected.


File: gid.info,  Node: Edit mesh,  Prev: Mesh quality,  Up: Meshing

Edit mesh
=========

   These option let the user modify one mesh. All modification will be
lost when the mesh is generated again.

* Menu:

* Move node::
* Delete elements::
* Delete lonely nodes::


File: gid.info,  Node: Move node,  Next: Delete elements,  Prev: Edit mesh,  Up: Edit mesh

Move node
---------

   By using this command, an existing node is selected and moved. The
new position is entered in the usual way (*note Point definition::.).


File: gid.info,  Node: Delete elements,  Next: Delete lonely nodes,  Prev: Move node,  Up: Edit mesh

Delete elements
---------------

   To delete elements a selection is made (*note Entities
selection::.). After pressing `escape' (*note Escape::.), the elements
are erased.

   The deletion of entities can be done in two ways: at one level
(`point', `line', `surface' or `volume') or erasing all entities at
once. A selection is made (*note Entities selection::.) in both cases.
After pressing `escape' (*note Escape::.), the elements are erased.

   Nodes that do not belong to any element after the operation are also
erased.

   To avoid erasing the selected elements, press `break'.


File: gid.info,  Node: Delete lonely nodes,  Prev: Delete elements,  Up: Edit mesh

Delete lonely nodes
-------------------

   After confirmation, all the nodes of the mesh that do not belong to
any element are erased.

   *Note:* This command is only necessary for meshes imported from
outside because internally generated or edited meshes, have this
problem implicitly corrected.


File: gid.info,  Node: View,  Next: Utilities,  Prev: Meshing,  Up: Top

VIEW
****

   Visualization commands change the way to display the information in
the graphical window.  They do not change any definition of the
geometry or any other data.

   Generally, they can be used within any other command without leaving
it. When the visualization process finishes, the first command
continues.

   They can be accessed either from the top menu `View' or form the
right mouse button.

* Menu:

* Zoom::
* Rotate::
* Pan::
* Redraw::
* Render::
* Label::
* Entities::
* Layers::
* Multiple windows::
* Save/Read View::


File: gid.info,  Node: Zoom,  Next: Rotate,  Prev: View,  Up: View

Zoom
====

   Zoom is used to change the visualized size of the objects without
deforming them.  This only enlarges or reduces the objects and changes
the orthogonal perspective of the window.

   * `Zoom in:' Pick inside the graphical window. A dynamic rectangle
     is opened. Pick again and the visualization changes to display
     only the part within the defined rectangle.

   * `Zoom out:' Pick inside the graphical window. A dynamic rectangle
     is opened. Pick again and the visualization changes so that
     everything in the graphical window is reduced to the size of the
     rectangle.

   * `Zoom frame:' Choose a visualization size so as to display
     everything inside the window.

   * `Zoom points:' User enters two points (*note Point definition::.),
     and a visualization size is chosen so as to display these two
     points inside the window.

   * `Zoom dynamic:' Moving mouse horizontally, view is enlarged or
     shortened.

   * `Zoom previous:' GiD goes to the previous saved zoom.

   * `Zoom next:' If one previous zoom has been made, this option goes
     to the one after the current view in the stack list.

   `Note:' Instead of picking twice to begin and end the rectangle, it
is possible to maintain the leftmouse pressed and move the cursor.


File: gid.info,  Node: Rotate,  Next: Pan,  Prev: Zoom,  Up: View

Rotate
======

   There are various ways to make a rotation in order to change the
graphical view of the geometry, without changing it.

* Menu:

* Rotate screen axes::
* Rotate object axes::
* Rotate trackball::
* Rotate angle::
* Rotate points::
* Rotate center::
* Rotate original view::

   `Note:' Instead of picking twice to begin and end the rotation, it
is possible to maintain the leftmouse pressed and move the cursor.


File: gid.info,  Node: Rotate screen axes,  Next: Rotate object axes,  Prev: Rotate,  Up: Rotate

Rotate screen axes
------------------

   With this option, a dynamic rotation about the screen axes is made.
Screen axes are defined as:

   * `X-axis': A horizontal axis.

   * `Y-axis': A vertical axis.

   * `Z-axis': An axis orthogonal to the screen.

   When entering this command, `Z-axis' is set by default and moving
the mouse to the left or to the right will rotate the geometry around
this axis. Picking the left mouse changes the axis. To leave this
function, use `escape' (*note Escape::.).

   To change the axes is also possible by entering the letters `x', `y'
or `z' in the command line.

   To move the geometry by a fixed angle, enter the number of degrees,
positive or negative, in the command line.


File: gid.info,  Node: Rotate object axes,  Next: Rotate trackball,  Prev: Rotate screen axes,  Up: Rotate

Rotate object axes
------------------

   With this option, a dynamic rotation about the object axes is made.
Object axes are the global axes in the position they are in that
particular moment. i.e.  the axes currently drawn in the graphical
window.

   When entering this command, `Z-axis' is set by default and moving
the mouse to the left or to the right will rotate the geometry around
this axis. Picking the left mouse changes the axes. To leave this
function, use `escape' (*note Escape::.).

   To change the axes is also possible by entering the letters `x', `y'
or `z' in the command line.

   To move the geometry by a fixed angle, enter the number of degrees,
positive or negative, in the command line.


File: gid.info,  Node: Rotate trackball,  Next: Rotate angle,  Prev: Rotate object axes,  Up: Rotate

Rotate trackball
----------------

   With this option, a dynamic rotation is made, resembling a trackball
device. It means that when picking over a geometry point with the left
mouse and moving the mouse, the geometric point tries to follow the
mouse pointer. This can be imagined as a ball over the graphical window
which is moved with the mouse.

   The left mouse button can be pressed several times to connect and
disconnect the movement. To leave this function, use `escape' (*note
Escape::.).


File: gid.info,  Node: Rotate angle,  Next: Rotate points,  Prev: Rotate trackball,  Up: Rotate

Rotate angle
------------

   The new position of the geometry after the rotation can be defined
as the direction orthogonal to the screen via a pair of angles:

  1. The angle in the plane `XY' starting from the `X-axis'.

  2. The elevation angle from the `XY' plane.

   As an example, the initial view (orthogonal to the Z-axis and with
the X-axis horizontal) can be obtained with:

     rotate angle 270 90


File: gid.info,  Node: Rotate points,  Next: Rotate center,  Prev: Rotate angle,  Up: Rotate

Rotate points
-------------

   This option appears only in the right side commands menu.

   The new position of the geometry after the rotation can be defined
as the direction orthogonal to the screen via a pair of points:

  1. The target point, the point to look at.

  2. The view point, the point to look from.


File: gid.info,  Node: Rotate center,  Next: Rotate original view,  Prev: Rotate points,  Up: Rotate

Rotate center
-------------

   The default center of rotation is defined approximately in the
center of the geometry.

   If it is desired to change this center, use this command and enter a
point (*note Point definition::.). This new rotation center will be
maintained until the next `zoom frame' (*note Zoom::.).


File: gid.info,  Node: Rotate original view,  Prev: Rotate center,  Up: Rotate

Rotate original view
--------------------

   This option, that appears only in the graphical pop-up menu, changes
the view to the original one: screen orthogonal to the Z-axis with the
X-axis lying horizontally and pointing to the right.


File: gid.info,  Node: Pan,  Next: Redraw,  Prev: Rotate,  Up: View

Pan
===

   * `Two points:' With this command, the location of the geometry is
     displaced in the graphical window. To do this, pick two points in
     the graphical window.

   * `dynamic:' In this case the displacement is made dynamically,
     moving the mouse horizontally.


File: gid.info,  Node: Redraw,  Next: Render,  Prev: Pan,  Up: View

Redraw
======

   This command redraws the geometrical model in the graphical window.
For those machines that include overlays, all the layers that stay
underneath are not affected, so the redraw goes faster and the
underneath drawings remain untouched.


File: gid.info,  Node: Render,  Next: Label,  Prev: Redraw,  Up: View

Render
======

   By using this option, the way of viewing the model changes. There
are four options:

   * `Normal:' This is the usual way of visualizing. The geometry and
     mesh are viewed including all definition lines.

   * `Filled:' Solid model with no illumination and lines.

   * `Flat lighting:' Solid model with flat illumination and lines.

   * `Smooth lighting:' Solid model with smooth illumination (better
     quality).

   *Note:* The rendering of a volume mesh requires the option `View
boundaries' (*note View boundaries::.).

   *Note:* Quality of visualization is controlled via preferences
(*note Preferences::.).

   *Note:* The light vector direction can be changed interactively with
the menu option `Change Light Vector' inside the menu `Utilities'
(*note Change Light Vector::.).


File: gid.info,  Node: Label,  Next: Entities,  Prev: Render,  Up: View

Label
=====

   With this option, the labels of the entities are drawn or not. It is
possible to select some entities or to apply this option to all
entities viewed in the graphical window.  To select some entities,
choose `select' before applying on the `Points', `Lines', `Surfaces' or
`Volumes'. Then, select entities in the usual way (*note Entities
selection::.). Options are:

   * `All:' All entities in the graphical window will have their labels
     drawn.

   * `points,lines,surfaces' or `volumes:' If `select' is not set, all
     the entities in the graphical window will have their labels drawn.

   * `Off:' Finish drawing labels for all entities.


File: gid.info,  Node: Entities,  Next: Layers,  Prev: Label,  Up: View

Entities
========

   With this option, it is possible to choose some of the `points,
lines, surfaces or volumes' to be drawn. It is useful to make drawing
faster or clearer in some instances.
NOTE: this option is only available in the right buttons menu. (*note
User interface::.)


File: gid.info,  Node: Layers,  Next: Multiple windows,  Prev: Entities,  Up: View

Layers
======

   Layers are a way to split a complex drawing into separate pieces.
The idea is that any entity can belong to one layer or to none (an
entity cannot belong to more than one layer). Then, it is possible to
view only some layers and not others. It is also useful to easily select
entities in the graphical window.

   Commands related to layers are:

   * `New:' Creates a new layer. If name is given the layer is called
     "`Layer#'". The new layer will be used as the default layer until
     the end of the session or until it is changed.

   * `Layer To use:' Selects a layer to be used as default. All the new
     entities will be created within this layer. All the layers are
     capable of being selected.
     Next to the `Layer To use' button, there's an arrow facing down.
     This is a menu which lets you select a point, a line, a surface or
     a volume; the layer to which it belongs that entity, will be set
     as the default layer.

   * `On:' Entities belonging to this layer will be drawn and can be
     selected in the graphical window.

   * `Off:' Entities belonging to this layer will not be drawn and
     cannot be selected in the graphical window.

   * `Lock/Unlock (Freeze/Unfreeze):' Entities belonging to this layer
     will be drawn but cannot be selected in any way. When copying
     entities (*note Copy::.) and sharing old entities, entities
     belonging to frozen layers are not taken into account and not even
     a range of numbers (*note Entities selection::.)  can be selected.
     The opposite command is `Unlock', where the entities belonging to
     this layer can be selected, copied and shared.

   * `Delete:' Deletes a layer. A layer can only be deleted if it has
     no entities in it.

   * `View:' Gives information about the layer.

   * `Entities:' Moves entities to a new layer. No new entities are
     created. They are only moved from one layer to another. When
     choosing, in geometry mode, `point', `line', `surface', `volume'
     or `all', option `all' can be used only to select entities in the
     graphical window and change all the entities in the dynamic box to
     the new layer. In mesh mode, it is possible to choose `nodes',
     `elements' or `all'.
     Especial option `Also lower entities' permits to send to the layer
     also the entities that are lower entities of the selected ones.
     Example: If this flag is set and one surface is selected, its
     lines and its points are also sent to the layer.

   * `To back:' Sends entities to the back of its layer. When an entity
     is "at the back" it's not visible and cannot be selected, moved,
     copied or deleted. To bring again the entities of a layer "to the
     front", select a layer and choose the `Bring to front' option,
     from the `To back' menu. There is another option, `Bring ALL to
     front', which brings to front all entities of all layers.
     If the flag `Opposite' is set, entities which are not selected
     will go to the back.

   * `Color:' Change color to layer. This color is used when making a
     render (*note Render::.).

   * `Sel...:' In the layer window, there is the option `select' that
     allows the selection of several layers. This can be useful when
     using a large number of layers. After pressing `Sel...' a new
     window appears to allow the input of a pattern that will match the
     layer's name. In this pattern, characters * and ? are wildcards
     that match any characters or character, respectively, in the
     layer's name. So, the pattern `select' will match `select', `
     selection', ` select-surface' and so on.

   * `Rename:' Changes the name of a layer.

   * `Close:' Closes the Layers window.

   *Important:* The mesh generation does not depend on the state of the
layers when the generation is performed (*note Layers::.). All layers
are meshed and every node and element will be assigned to the layer
where the original geometrical entity was. The only exception to this
rule is for the case of frozen layer if the option `No mesh frozen
layers' is selected.


File: gid.info,  Node: Multiple windows,  Next: Save/Read View,  Prev: Layers,  Up: View

Multiple windows
================

   Command `Multiple windows' permits to have several views of the same
project. Different views can be displayed inside the program main
window or in supplementary windows.


File: gid.info,  Node: Save/Read View,  Prev: Multiple windows,  Up: View

Save/Read View
==============

   These two options permits to save the actual view configuration into
a file. Then, that configuration can be loaded using the `Read View'
command.


File: gid.info,  Node: Utilities,  Next: Calculate,  Prev: View,  Up: Top

UTILITIES
*********

   Within `Utilities' there are included some commands that provide
information or allow actions over both the geometry and the mesh.
Others can act over the whole project.

* Menu:

* Preferences::
* Renumber::
* Calculator::
* Id::
* Signal::
* List::
* Status::
* Distance::
* Draw line normals::
* Draw surface normals::
* Copy::
* Move::
* Repair::
* Collapse::
* Uncollapse::
* Undo::
* Comments::
* Graphical::
* Coordinates window::
* Read batch window::
* Clip planes::
* Save configuration file::
* Perspective::
* Change Light Vector::
* Default background::
* Macros window::
* Selection window::
* Animate controls::
* Dimensions::

