Users of 3D CAD systems will feel instantly at home with GEMS. Other
application engineers who have no wish to become CAD experts will find
GEMS considerably easier to master than the large, and sometimes
unwieldy, contemporary CAD systems. GEMS provides "customised CAD":
the functionality you need to perform the specific task, in an
accessible and customised form.
GEMS features interactive and intuitive mouse or spaceball-driven 3D
viewing and picking. Any viewer may be configured to view from a
particular axis-aligned or general direction, with orthographic or
perspective projection. One or several views may be displayed
simultaneously, in which the same or a different set of entities are
displayed. Viewpoints may be slaved, to allow different models to be
compared side-by-side from identical viewing directions. There is both
automatic and manual control available over the positioning of the
rotation centre, the point about which the model appears to rotate in
Entities may be displayed in various styles, such as wireframe
(with or without hidden lines) and as lit and shaded solids/surfaces.
Display parameters such as surface tessellation angle and deflection
limits may be customised. Hardcopy output to Postscript or TIFF is
Comprehensive graphical picking of entities includes single selection,
box selection, line and loop selection. If several entities are being
displayed over the top of one another, pick cycling allows you to
easily select the one you want. It is usually possible to pick an
entity at any one of several different "levels" - for example a single
point, a single section, a complete grid, or the whole model.
The Entity Selector provides its own structural "window" onto the GEMS
database. It may be used to manage and view the grouping of entities
into assemblies, to see which entities are displayed and which are
selected, and to pick entities by name. The tree structure of the
database may be explored and the contents of individual assemblies
expanded or hidden. Entities may be displayed in different sequences,
for example sorting by name or by type. Different types of entities
are instantly recognisable by their individual icons.
To access functions a main menu bar contains most of the available
operations. This is supplemented by a context sensitive popup menu
allowing various operations depending upon the type of entity
selected. Sometimes a more complex operation may accept several user
inputs, in which case these options will be presented in a dialog box.
There is short-cut access to all of the most common commands,
including the last 10 commands you entered.
One of the most powerful capabilities of the user interface is support
for macros/scripting. Despite the highly interactive nature of GEMS,
with careful design it has been possible to make available a macro
command language. A complex series of operations may be "captured" and
written to a macro file, which may be edited, called from other
scripts, and replayed in whole or in part. Scripts may be replayed
interactively, or in non-graphical "quiet" mode. Macros are extremely
useful when performing edits on several topologically similar, but
geometrically different, models.
Multiple level undo/redo is supported - not only for database/entity
changes, but also for display changes. Full Save and Restore is
provided, allowing projects to be shared, subdivided, and continued at
a later date, and affording peace of mind that your work cannot be
lost. Context sensitive help uses your favourite web browser to
display the specific section of the manual pertaining to the current
operation you're performing. On-line tutorials are also accessible.