Language > Objects > Creating an Object Graphics Display > Overview of Object Graphics Classes

# Overview of Object Graphics Classes

The following sections provide an overview of the different types of objects included in the class library. In order to describe the attributes of the classes, we have grouped the objects into functional categories: Display Objects, Visualization Objects, and Destination Objects.

Note: These category names are purely descriptive; for example, display objects contain the IDLgrModel, IDLgrScene, and IDLgrView classes, but no class named display.

See Object Graphics Display Hierarchy for a discussion of the object tree, which shows the relationships between object classes.

There is some commonality among visualization object properties Following sections provide information about common properties including color, depth-buffering (how objects are layered in a view), and alpha-channel setting (transparency).

## Naming Conventions

In general, object classes shipped with IDL have names of the form:

IDLxxYyyy

where xx represents the broad functional grouping (gr for graphics objects, db for database objects, and an for analysis, for example). Yyyy is the class name itself (such as Axis or Surface). Object classes that are useful in more than one functional context (container objects, for example) omit the functional grouping code entirely (IDL_Container). All object classes shipped with IDL are prepended with the letters IDL—we strongly suggest that you do not use this prefix when writing your own object classes, as we will continue to add new object classes using this convention.

The typographical convention used to describe IDL objects is slightly different from that used for non-object functions and procedures. Whereas non-object procedures are presented in upper case letters, object classes and methods use mixed case. For example, we refer to the PLOT routine, but to the IDLgrPlot object. Method names are also presented in mixed case (IDLgrAxis::GetProperty).