Open CASCADE, the 3D modelling kernel
3D modeling & numerical simulation


3D Visualization

This library provides services for:

- Selection of 3D data structures
- Presentation of 3D data structures

3D presentation and selection are accessed through AIS (Application Interactive Services). This packageis a high-level interface that offers access to the lower-level presentation and selection services. AIS extends this underlying functionality with standard 3D selection attributes, presentation management, and standard 3D presentation attributes, and manages it in the definition of GUI viewers. To implement these services, the AIS package includes the following :

- Interactive context
- Interactive objects
- A graphic attributes manager
- Selection filters

The Interactive Context

The interactive context pilots 3D visualizations and selections. The interactive context allows you to manage, in a transparent way, the graphic and "selectable" behavior of interactive objects which is not already defined in the predefined types of these objects.
AIS has two operating context types. The default neutral point type allows you to easily visualize and select entire interactive objects which have been loaded into the context. Opening the local context type allows you to prepare and use a temporary selection environment to select part of an interactive object.

Interactive Objects

Entities which are visualized and selected in the AIS viewer are objects. They connect the underlying reference geometry of a model to its graphic representation in AIS. You can use the Open CASCADE predefined classes of standard interactive objects for which all necessary functions have already been programmed, or if you are an advanced user, you can implement your own classes of interactive objects.

The Graphic Attributes Manager

The graphic attributes manager, or AIS Drawer, stores the graphic attributes for specific interactive objects and for interactive objects controlled by interactive context. The interactive context drawer is valid by default for the objects it controls. When an interactive object is visualized, the required graphic attributes are first taken from its own drawer if one exists, or from the context drawer if there is no specific drawer for that type of object.

Selection Filters

An important need in selection is the filtering of entities which you to select. Selection filters allow you to refine the dynamic detection context which you want to put into effect. Some of these filters can be used at the Neutral Point, others only in an open local context. You can also program your own filters and load them into the context.


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