APPENDIX A

A BRIEF SUMMARY OF SOME COMMANDS USED IN HOBBIES

A.0 SUMMARY

In this appendix, a brief summary is provided for some commands used in Higher Order Basis Based Integral Equation Solver (HOBBIES), such as Preferences and Layers. More details can be found in [1].

A.1 DESCRIPTION OF THE COMMANDS USED IN HOBBIES

The commands including Preferences and Layers are located in the Utilities menu and will be briefly described.

A.1.1 Preferences

Menu: UtilitiesPreferences…

Toolbar:

In this section, the Preferences window (Figure A.1) is shown and it has several tabs for different settings. Some of the commonly used options are explained as follows:

• General: The first tab of Preferences is the General option, and it is used to set the different ways of working with HOBBIES.
  • Create new point: it alters the way in which the points are entered in HOBBIES when trying to create a new point in the vicinity of an existing one. The options are:
    • Always: the new point is always created.
    • Ask: asks whether to make use of the existing point or create a new one.
    • Never: only allows existing points to be selected.
  • Display coordinates: If set, HOBBIES shows the coordinates in the graphical window.
  • Popup messages: If Beginner is selected then the user will receive more pop up messages.

  

  Figure A.1. A window displaying the various preferences.

• Graphical: The second tab of Preferences is the Graphical option, and it is used to set different ways of visualizing the model. They do not change the geometry or the model information.
  • Fast visualization mode/Safe visualization mode: select to use the graphic card or software driver for OpenGL. The fast visualization mode will apply the graphic card to draw the model, while the safe visualization mode will apply the software driver.
  • Selection lines by software: if there are problems drawing lines, check this box.
  • Two colors background: to set a two colors degradation for the background.
• Meshing: The third tab of Preferences is the Meshing option, and it is used to set different ways of meshing a model.
  • Unstructured mesher: HOBBIES can use three kinds of surface mesher:
    • Rfast meshes are the most efficient in speed and reliability. Geometrical entities are meshed hierarchically: lines are first meshed, and then the surfaces. The line elements size depends on the shape of surfaces. With deformed surfaces, they can give distorted elements. This mesher is used by default.
    • Rsurf meshes are generated directly in the space. Quality is better, but it is slower and can fail for distorted surfaces.
    • Rjump meshes are generated directly in the space, and contact lines between surfaces or points between lines that are tangent enough are skipped when meshing. With this surface mesher, the user can generate meshes with fewer elements, but it is slower and can fail for distorted surface patches. By selecting MeshDrawSkip entities (Rjump), the entities that RJump is going to skip and the ones that it is not going to skip are displayed in different colors.
  • Automatic correct sizes: This preference lets HOBBIES make an automatic mesh size correction when meshing begins. If None is set, no size correction is made; if Normal is set, a size correction is made according to the sizes of the geometrical entities and the compatibility between meshing sizes of neighboring entities; if Hard is set, the Normal correction is made and, furthermore, an automatic chordal error criteria is applied to assign sizes to surfaces that are the contours of some volume.
  • Unstructured size transitions: This controls whether the transitions between different element sizes are slow or fast.
  • No Mesh Frozen layers: If this preference is set, entities belonging to a frozen layer will not be meshed.
• Exchange: The fourth tab of Preferences is the geometry Exchange (import and export) option.
  • Automatic Collapse After Import: If this option is set, then after reading one IGES file, one global collapse is made. If it is not set, all surfaces and lines will be independent of each other.
  • Automatic Import tolerance: When importing a file or collapsing entities, any points closer together than this distance are considered to be the same. Lines and surfaces can also be collapsed.
  • Collapse:
    • Ignoring Layers: Entities are also collapsed if they belong to different layers.
    • Each layer separately: Entities in different layers are not collapsed. (Entities belonging to frozen layers are never considered.)
• Fonts: The fifth tab of Preferences deals with the Fonts used inside HOBBIES.
  • Normal font: This is the font normally used inside HOBBIES.
  • Fixed font: This font must have the same spacing for every letter. It is used in places where this property is necessary.
  • Big font: Used in some dialog boxes.
  • Comments/Legend font: Used for comments and legend.
  • Labels/Dimensions font: Used in labels and dimensions.
  • Asian font: Used to draw Asian characters in the graphical window.
• Format: The sixth tab of Preferences deals with the numerical Formats used inside HOBBIES.
  • Generic format: This option refers to numerical formats used in other HOBBIES utilities (for example, in the coordinates display).
  • Results format: This option refers to numerical formats in results (Post-process).
• Grid: The seventh tab of Preferences contains the Grid options.
  • Show grid lines: If this option is set, grid lines are shown. It is available to show/hide grid with the grid button that is located on the bottom right part of the main window.
  • Show labels: If this option is set, labels of the major lines are showed.
  • Activate snap: If this option is set, snap is activated.
  • X/Y Spacing: These options determine the spacing between grid lines in the x and y directions.
  • Major line every: This option specifies the number of lines between principal lines in the grid.
  • X/Y Extents: These options determine the extension of the grid in the x and y directions.
  • Draw axis: If this option is set, two-dimensional axes are shown in the grid (x and y).
  • X/Y Center: These options determine the position of the center of the grid.

A.1.2 Layers

Menu: UtilitiesLayers…

Mouse menu: Layer

Toolbar:

Layers enable the user to split a complex model into separate parts. The idea is that any entity belonging to one layer (an entity cannot belong to more than one layer). In this way, the user can choose to view the preferred layers and operate on the parts of a model that belong to the layers. It is also useful for making it easier to select entities in the graphical window.

To open the Layers window, as shown in Figure A.2, click UtilitiesLayers, right-click the mouse and choose Layerwindow, or click the icon on the Toolbar.

Figure A.2. A window defining the various layers.

The following can be done in the Layers window:

: Create a new layer.

: Create a new folder with one layer.

: Delete a layer.

: Send the selected entities to a layer.

: Send entities to back/front of a layer.

: This option permits to select one entity and set its layer as the layer to use.

: Select layers with filters.

Note that there is a tick mark beside the layer name to indicate which layer is being used. All the new entities will be created within this layer. The user can select the layer to be used. Right-click the mouse on a layer (e.g., Layer0) to display the various options as shown in Figure A.3.

Figure A.3. Right-click menu on a layer.

Each option on the menu is now described:

New layer: To create a new layer, and the new layer will be used as the default layer until another layer is created or another layer is selected as the default.

New folder: To create a new folder with one layer.

Rename: To change the name of a layer.

Delete: To delete a layer. A layer can only be deleted if it has no entities in it.

Color To change entities’ color of a layer. The color can also be chosen by clicking on the colored box next to the layer name in the list (the ‘C’ column). This color is used when performing a rendering.

On/Off : Entities belonging to this layer will be shown/hidden and can/cannot be selected in the graphical window. This can also be chosen by clicking the ‘I/O’ column.

Freeze/Unfreeze : Entities belonging to the frozen layer will be shown but cannot be selected, copied or shared in any way. The opposite command is Unfreeze, where the entities belonging to this layer can be selected, copied and shared. The user can also choose it by clicking the ‘F/U’ column in the list. By default, HOBBIES unfreezes all layers.

Opaque/Transparent : Entities belonging to the layer will be Opaque/Transparent and the opacity gradient can be set by the color window. The user can also do this by clicking the ‘Tr’ column in the list. By default, all layers are opaque.

Send to: To move entities to a new layer. No new entities are created. They are only moved from one layer to another. If ‘Also lower entities’ is checked, lower level entities of the selected ones are also send to the layer. Example: If this flag is set and one surface is selected, its lines and points are also sent to the layer.

To back: To send entities to the back of its layer. When an entity is “at the back” it is not visible and cannot be selected, moved, copied or deleted. To bring the entities of a layer back “to the front” again, 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 all entities of all layers to the front. If the Opposite option is flagged, entities which are not selected will go to the back.

Filter: To select layers with filters (for example: ’b*’select all the layers with name begins with ‘b’.

An example of creating a model by using layers is illustrated next. The model shows a radome formed by two layers of spherical dielectric which encloses a dipole antenna. After drawing the antenna in layer0, create a new layer Layer1 and draw a sphere with a radius of 0.3 m in this layer {Figure A.4(a)}. Then create a new layer Layer2 and draw a sphere with a radius of 0.4 m in this layer {Figure A.4(b)}. Finally create a new layer Layer3 and draw a sphere with a radius of 0.5 m in this layer {Figure A.4(c)}.

Figure A.4. Creating three spheres by using Layers: (a) the first sphere in Layer1, (b) the second sphere in Layer2, (c) the third sphere in Layer3.

Define two new domains to assign the three spheres, namely Domain 2 and Domain 3. Open the domain assign window (see Section 6.4.1), uncheck the other layers, and leave Layer1 checked. HOBBIES will only show the sphere in Layer1, and then assign the sphere with Domain 1 and Domain 2. Assign the other spheres in the same way, and the model is shown as in Figure A.5. Also, the user can view the desired parts of the model by turning on different layers and setting each of the layers transparent or opaque.

Figure A.5. Layer1, Layer2, and Layer3 are all turned on and set to be transparent.

A.2 CONCLUSION

The commands such as Preferences and Layers in the Utilities menu are briefly described in this appendix.

REFERENCES

[1] GiD Reference manual, http://gid.cimne.upc.es/support/manuals.