| Modelling Environment |
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| Focus |
| The most important aspect of PolyCAD is its modelling environment.
Many CAD systems promote a wide range of features and functions, but
in doing so make it difficult for the user to realise the design idea.
In PolyCAD, the modelling enviroment has been developed over many
versions to provide an interface that allows users to accuratly control
geometric entities whether they are modelling interactively with the
mouse or specifying exact values for entity attributes using the keyboard. |
| Curves and Surfaces |
| The majority of entities supported in PolyCAD are curve or surface
type entities. Given the growth of the use NURBS based entities certainly
for representing hull surfaces, effective manipulation of these entities
is one of the most important factors in providing an effective and
efficient design tool. PolyCAD optimises the display of these elements,
and hence the operational speed of software, by keeping a display
list for each complex entity and updating them only when there is
a change. With each entity having their own edit mode, locking the
geometry others unless relationally linked, manipulation becomes more
focused and the user no longer needs to worry if other entities will
be accidentally affected by any erroneous selection. To further optimise
the editing process, entities can be hidden, shown as only bound boxes,
displayed in wire frame or rendered. In addition, the viewer employs
adaptive degradation which maintains rapid updates of the model environment
when manipulating the view. |
| Control Points |
| All editable entities support control polygon points used to manipulate
the geometrical definition of the element. PolyCAD primary is to provide
effective ways manipulating control points so that the user can realise
their design. To these ends, when manipulating control points, the
user has the choice of using the SnapToGrid, SnapToObject and Enhanced
3D Editing features. These tools provide the means to accurate
manipulate control points using the mouse with respect to accurate
dimensions within the model enviroment, to other entities and to contraint
reducing the number directions a point can be edited in. |
| View Operations |
| In version 8, the OpenGL graphics system underwent a major upgrade
to improve the editing experience. The biggest change is that the
manipulation of the viewer has change from being based around the
transformation matrix to a camera based system. This allows much more
flexible view manipulations and now makes it possible to allow editing
in perspective views. All of the old functions are still available
but the camera now, but default, rotates about a look at point rather
that the centre of the model. The view can now rotate about the edit
location and is particular effective if used with zoom to selection.
The viewer functions are summaries as follows. |
| Adaptive Degradation |
| When viewer complex or rendered models, the increased time required
to update the screen can make positioning of the viewer difficult.
In these situations, the adaptive degradation can be used to temporarily
simplify the model to bounding boxes for the duration of the view
manipulation. |
| Colors |
| Colors are extensively used for highlighting features while manipulating
entities. While each entity has its own color, in edit mode specific
colors are used to define parts of the editing framework and control
polygon. |
| Geometric Analysis |
| As the major aim of PolyCAD provide the user with the ability to
achieve a higher level of accuracy and quality in the geometric definition,
curve and surface analysis tools are provided to give feedback on
shape. For curves the a porcupine plot displays the magnitude and
direction of curvature, while in surfaces, gaussian and mean curvature
can be displayed using various color models which highlight different
qualities in the curvature values. |
| Interative Creation |
| Create on the File menu lists all the entities that can be interactively
created. PolyCAD standardises the way all curves and surfaces are
created so that the same full range of features, such as SnapToGrid
and SnapToObjects, can be employed regardless of entity. |
| Interactive Editing |
| Like the creation process, editing of curves and surfaces is also
standarised. But the user now has access to a greater range of features
such as Enhanced 3D Editing. The
attributes of Entities can also be specifed directly using the Entity
Attirbute Panel in the Entity Properties Tool Window. |
| Context Sensive Popup (Right-Click) Menus |
PolyCAD features context sensitive popup menus. These display
and allow the user to access all the current available commands
for that entity, rather than have loads of inactive buttons or a
command line system. In addition, the "multiple select"
menu shows commands applicable to the range of entities selected.
This is one of the primary means of creating constructive entities
such as Coons patchs or IntelliHull.
|
| Edit Tool Windows |
| In addition to the main model view, several dockable tool windows
provide ways to select, review and display information about entities
in the model environment. |
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