3D Graphics Programming with QuickDraw 3D 1.5.4

Highlight Styles

A model's highlight style determines the material attributes of a geometric object (or a group of geometric objects) that override the normal attributes of the object (or group of objects). For example, it is often useful during interaction with the objects in a model to highlight a selected shape by changing its color. You can define the specific highlight style to be applied to a selected object, thus avoiding the need to edit the geometric description of the object simply to change its color or other attributes.

If a highlight style is defined for a model, any renderers that support highlighting will use the attributes in that style to override the material attributes defined for any geometric objects in the model. However, the highlight style is used for a particular geometric object only if the object's highlight state (that is, an attribute of type kQ3AttributeTypeHighlightState that has data of type TQ3Boolean ) is set to kQ3True . For example, suppose that the attribute set of a box contains an attribute of type kQ3AttributeTypeHighlightState , which is set to kQ3True . Further, suppose that the face attribute sets of the box do not contain any attributes of that type. In this case, the attribute set of the current highlight style is used during rendering.