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# FILES

Browser to read and write files and projects.

GiD includes the usual ways of saving and reading saved information (`Save`, `Read`) and other file capabilities, such as importing external files, saving in other formats and so on.

## New

`New` opens a new project with no title assigned.

If this option is chosen from inside a project where some changes have been introduced, GiD asks to save them before entering the new project. Next, a new problem without a title begins.

## Open

With this command, a project previously saved with `Save` (see section Save) or with `Save ASCII project` (see section ASCII project) can be open.

Generally, there is no difference between using a project name with the `.gid` extension or without it.

## Save

`Save` a project is the way of saving all the information relative to the project: geometry, conditions, materials, mesh, etc. onto the disk.

To save a project, GiD creates a directory with its name and extension `.gid`. Some files are written into this directory containing all the information. Some of these files are binary and others are ASCII. The user can then work with this project directory as if it were a file.

User doesn't need to write the `.gid` extension because it will be automatically added to the directory name.

Caution: Be careful if changing some files manually into the `Project.gid` directory. If done in this way, some information may be corrupted.

Advice: It is advisable to save often to prevent losing information. It is possible to automatically save a model backup by selecting a user frequence (see section Preferences).

## Save as

With this command, GiD allows the user to save the current project with another name.

When it is selected, an auxiliary window appears with all the existing projects and directories to facilitate the introduction of the project's new name and directory.

## Import

### IGES

With this option it is possible to read a file in IGES format, version 5.1.

GiD can read files in IGES version 5.1 format, including most of the entities, which are:

    Entity number and type ( Notes)
    100	Circular arc
    102	Composite curve
    104	Conic arc ( ellipse, hyperbola and parabola)
    106	Copious data ( forms 1, 2, 12 and 63)
    108	Plane (form1 bounded)
    110	Line
    112	Parametric spline curve
    114     Parametric spline surface
    116     Point
    118     Ruled surface
    120     Surface of revolution
    122     Tabulated cylinder
    124     Transformation matrix ( form 0)
    126	Rational B-spline curve
    128	Rational B-spline surface
    140     Offset surface entity
    141     Bounded entity
    142     Curve on a parametric surface
    143     Bounded surface
    144     Trimmed surface
    308     Subfigure definition
    402     Associativity instance
    408     Singular subfigure instance

The variable `ImportTolerance` (see section Preferences) controls the creation of new points when an IGES file is read. Points are therefore defined as unique if they lie further away than this tolerance distance from another already defined point. Curves are also considered identical if they have the same points at their extremes and the "mean proportional distance" between them is smaller than the tolerance. Surfaces can also be collapsed.

Entities that are read in and transformed are not necessarily identical to the original entity. For example, surfaces may be transformed into plane,into Coons or into NURBS surfaces defining their contours and shape.

### DXF

With this option it is possible to read a file in DXF format, version AutoCAD 2002.

Mostly all the geometry in the DXF is read except the solid modeled entities.

A very important parameter to consider is related to how the points must be joined. This means that points that are close to each other must be converted to a single point. This is done by defining variable ImportTolerance (see section Preferences). Points closer together than `ImportTolerance` will be considered to be a single point. Straight lines that share both points are also converted to a single line.

User can perform one `Collapse` (see section Collapse) to join more entities.

### Parasolid

With this option it is possible to read a file in Parasolid format, version 11.

GiD can read files in Parasolid version 11 format (ASCII or binary formats).

The most usual Parasolid file extension is `.x_t` for ASCII and `.x_b` for binary format.

The variable `ImportTolerance` (see section Preferences) controls the creation of new points when a Parasolid file is read. Points are therefore defined as unique if they lie further away than this tolerance distance from another already defined point. Curves are also considered identical if they have the same points at their extremes and the "mean proportional distance" between them is smaller than the tolerance. Surfaces can also be collapsed.

### ACIS

With this option it is possible to read a file in ACIS format, version 5.0. GiD reads the ASCII version, the SAT Save File Format. ACIS files (in ASCII) have the `.sat` extension.

### VDA

With this option it is possible to read a file in VDA 2.0 format.

A very important parameter to consider is related to how the points must be joined. This means that points that are close to each other must be converted to a single point. This is done by defining variable `ImportTolerance` (see section Preferences. Points closer together than `ImportTolerance` will be considered to be a single point. Straight lines that share both points are also converted to a single line.

User can perform one `Collapse` (see section Collapse) to join more entities.

### Shapefile

With this option it is possible to read a GIS file written in ESRI Shapefile format, version 1000. Shapefiles have the `.shp` extension.

### NASTRAN mesh

With this option it is possible to read a file in the NASTRAN format, version 68.

GiD can read files written in NASTRAN version 68 format, accepting most of its entities, whic are:

    Entity name ( Notes)
    GRID
    CBAR
    CBEAM ( translated as 2 node bars)
    CELAS2 ( translated as 2 node bars)
    CHEXA ( 8 or 20 nodes)
    CONM2
    CORD1C
    CORD1R
    CORD1S
    CORD2C
    CORD2R
    CORD2S
    CQUAD4
    CROD ( translated as 2 node bars)
    CTRIA3
    CTETRA

There are two options that can be used when reading a mesh if GiD already contains a mesh:

- a) Erasing the old mesh (`Erase`)
- b) Adding the new mesh to the old without sharing the nodes; the nodes will be duplicated although they will occupy the same position in the space (`AddNotShare`).

The properties and materials of elements are currently ignored, because of the difficulties in associating the NASTRAN file properties with the requirements of the analysis programs. The user must therefore assign the materials "a posteriori" accordingly. However, in order to make this easier, the elements will be partitioned into different layers each with the name PIdn, where n is the property identity number associated with the elements as defined in the NASTRAN file. Note that CELAS2 elements do not have associated property identities so these will be created by default during the reading of the file.

### STL mesh

With this option it is possible to read a mesh in the STL format. The STL binary format is also supported.

The variable `ImportTolerance` (see section Preferences) controls the creation of new points when the file is read.

### GiD mesh

With this option it is possible to read a GiD ASCII mesh (saved with `Export GiD Mesh`) in order to visualize it within GiD.

It is also possible to read a new mesh and add it to the existing one. In this case, the user is prompted to keep the former one or join it to the new mesh.

The format of the file (whose name is introduced by means of the command line or directly by getting it from the auxiliary window) describing the mesh must have the following structure:

    mesh dimension = 3 elemtype tetrahedra nnode = 4
    coordinates
    1 0 0 0
    2 3 0 0
    3 6 0 0
    4 3 3 0
    5 3 1.5 4
    6 3 1.5 -4
    7 1.5 0 2
    end coordinates
    elements
    1 1 2 4 5 1
    2 2 3 4 5 1
    3 1 4 2 6 1
    4 2 4 3 6 1
    5 1 2 5 7 1
    end elements

Code `nnode` means the number of nodes per element and `dimension` can be either:

- `2`: 2 dimensions. Nodes have just two coordinates.
- `3`: 3 dimensions. Nodes have three coordinates.

Where `elemtype` must be:

- Linear
- Triangle
- Quadrilateral
- Tetrahedra
- Hexahedra

Every element may have an optional number after the connectivities definition. This number usually defines the material type and it is useful to divide the mesh into layers to visualize it better. GiD offers the possibility of dividing the problem into different layers according to the different materials through the option `Material` (see section Layers).

Note: The sign `=` is optional, but if it is present it is necessary to leave a space.

If it is necessary to enter different types of elements, every type must belong to a different mesh. More than one mesh can be entered by writing one after the other, all of them in the same file. The only difference is that all meshes except the first one have nothing between `coordinates` and `end coordinates`. They share the first mesh's points. Example: to enter tetrahedra elements and triangle elements,

    mesh dimension = 3 elemtype tetrahedra nnode = 4
    coordinates
    1 0 0 0
    2 3 0 0
    3 6 0 0
    4 3 3 0
    5 3 1.5 4
    6 3 1.5 -4
    7 1.5 0 2
    end coordinates
    elements
    1 1 2 4 5 1
    2 2 3 4 5 1
    3 1 4 2 6 1
    4 2 4 3 6 1
    5 1 2 5 7 1
    end elements
    mesh dimension = 3 elemtype triangle nnode = 3
    coordinates
    end coordinates
    elements
    1 1 2 4 1
    2 2 3 4 1
    3 1 4 2 1
    4 2 4 3 1
    5 1 2 5 1
    end elements

### Surface mesh

With this option, a mesh can be read from a file in GiD or STL format (see section GiD mesh). Elements of this mesh must be triangles or quadrilaterals. This mesh is converted by GiD in a set of surfaces, points and lines. The geometric definition of surfaces is the mesh itself, but GiD treat them as truly geometric entities. For example: this surfaces can be used as the boundary of a volume, and a new mesh can be generated over them.

User is asked for the value of an angle. An angle between elements bigger than this value, is considered to be an edge and lines are inserted over them. As a consequence, a set of boundary and interior lines are created and attached to the surfaces to mark their edges.

### Batch file

Sometimes, it may be useful not to use GiD interactively. To do so, commands can be written into a file and GiD will read this file and execute the commands. These commands are the same that are used in GiD when written in the command line or using the commands in the right side commands menu.

Example: Many points have been digitalized and their coordinates saved in a file. These points are to be joined with straight lines to create the outline of the geometry. To do so, the file would look similar to this:

    geometry create line
    3.7 4.5 8
    2 5 9
    4,5,6
     ...
    1 7 0.0
    escape

A batch file can also be loaded into GiD by giving its name with option -b when opening GiD. (see section INVOKING GiD) Another way to read batch files to create dynamic presentations is with the `Read batch window` (see section Read batch window). One GiD session can be registered in a batch file. This can be useful to check the batch commands or to repeat one session (see section Preferences).

BATCH FILE COMMANDS

There are some especial commands to be added to a batch than are treated differently than regular GiD commands. Their format is one or several words after the control string ***** (five stars) and everything in one line.

- Write a log file

      *****OUTPUTFILENAME filename

  `filename` is substituted with a real file name where all the session warnings (that which appear in the GiD messages warn line) are written. This can be useful when running GiD in batch with option -n (see section INVOKING GiD) and GiD output is desired.
- Execute a TCL command in a batch file

      *****TCL tcl_command

  Note: If this command is used in batch file and GiD is invoked with option `-n` it will not work. To make TCL commands execute when GiD is executed without any window, you should use the `-n2` option. (see section INVOKING GiD)
- Insert comments in the code of a batch file

      geometry create line
      1,2
      *****COMMENTS -this is a comment-
      2,3
      escape

- Print messages in the inferior GiD messages line

      geometry create line
      1,2
      *****PRINT  -This is a message which will appear in the messages line-
      2,3
      escape

- Print messages in a window

      geometry create line
      1,2
      *****PRINT1  -This is a message which will appear in a new window-
      2,3
      escape

### Insert GiD geometry

This command permits to insert one previously created GiD model inside another one. Entities from the old and the new model are not collapsed.

User can perform one `Collapse` (see section Collapse) to join the old and new model.

## Export

### IGES

GiD can export the geometry in IGES format (version 5.1). Points, curves and surfaces are exported and volumes are ignored.

The IGES entities generated are:

    116	Point
    110	Line
    102	Composite curve
    126	Rational B-spline curve
    128	Rational B-spline surface
    142	Curve on a parametric surface
    144	Trimmed surface

### DXF

GiD can export the geometry in DXF format (version AutoCAD 2002). Points and curves are exported. Surfaces are ignored because DXF does not support Trimmed NURBS Surfaces.

### GiD mesh

With this option a file is written with all the project's mesh or meshes inside. This file can be read with `Import GiD Mesh` See section GiD mesh.

### Text data report

With this option a file is written containing all the information within the project. It is created in a way that is easily understood when read with an editor. This is useful for checking the information.

Note: This ASCII format is only used to check information. It cannot be read again by GiD. To write ASCII files that can be read again use the option `SaveAsciiProj` (see section ASCII project).

### ASCII project

This option saves a project in the same way as the regular `save` (see section Save) but files are written in ASCII. It may be useful to copy projects between non-binary-compatible machines. GiD also allows this information to be written in a file (see section Text data report).

Projects saved in this way may be read with the same `open` command (see section Open).

### ON layers

With this option, only the geometrical entities with its layer set to `ON` will be saved in a new project (see section Layers).

Note: Lower entities necessary to define the saved entities will be also saved into the new project (example: The two points extremes of a line are also saved if the line is saved).

### Calculation file

If GiD runs the solver module automatically, this command is not necessary. It is however useful if the solver program is required to be run outside GiD, or to check the data input prior to any calculations.

This command writes the data file needed by the solver module.

The format of this file must be defined in a Template File (see section Template File). GiD uses the template file of the current Problem Type to write the data file; so, to run this command, a problem type must be selected.

When testing a new problem type definition, GiD produces messages about errors within the configuration. When the error is corrected, the command can be used again without quitting the example and without having to reassign any condition or meshing again.

### Using template

This command does the same as `Export calculation file` (see section Calculation file), but it uses a `.bas` file provided by the user, instead of using the template file of the current Problem Type. So, it's not necessary to select a Problem Type to run this command.

When choosing option `Others...` from the submenu, GiD asks for a `.bas` file (see section Template File) and, using that file, writes the data file needed by the solver module. There are some `.bas` codes available in the submenu which write output files in some formats (DXF, NASTRAN, STL, VRML). These example `.bas` files are located in the `Templates` directory of the main GiD directory. It's possible to add other `.bas` files to that directory so that they appear in the submenu.

## Print to file

This option asks the user for a file name and save an image in the required format.

Accepted formats are:

- `TIFF:` Tagged Image File Format.
- `EPS:` Encapsulated postscript. Useful to insert in documents.
- `Postscript screen:` Postscript. Useful to send to a postscript printer. It is a snapshot of the screen.
- `Postscript vectorial:` Postscript. Useful to send to a postscript printer. It gives higher quality but it is only usable for small modells. Otherwise, very large files are created and it takes very long time to print them.
- `VRML:` Writes a VRML model file with the current visualization.
- Other supported formats are: `BMP`, `GIF`, `JPG`, `PNG`, `TGA`

## About

This command gives some information about the program, such as the version number which is being run, the system or libraries.

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