Class

• <DRM Colour Index Control Link>

Superclass

• <DRM Control Link>

Subclass

• None.

Definition

An instance of this DRM class specifies an <DRM Expression> instance that determines the index field value and / or an <DRM Expression> instance that determines the intensity_level field value of all target <DRM Colour Index> instances, thus controlling which <DRM Primitive Colour> instance is referenced by each such <DRM Colour Index> instance and / or its intensity.

Note that since each controlled <DRM Colour Index> instance may be bound to a different <DRM Colour Table Group> instance, and thus to a different primary <DRM Colour Table> instance; the fact that their index values are the same does not mean that the set of <DRM Colour Index> instances controlled by a given <DRM Colour Index Control Link> instance reference the same <DRM Primitive Colour> instance.

The colour_index field specifies which <DRM Expression> component, if any, specifies the index field value of the affected <DRM Colour Index> instances. If this value is zero, the index field values of the <DRM Colour Index> instances are not controlled.

The intensity_level_index field specifies which <DRM Expression> component, if any, specifies the intensity_level field value of the affected <DRM Colour Index> instances. If this value is zero, the intensity_level field values of the <DRM Colour Index> instances are not controlled.

Class diagram

Figure 6.43 — DRM_Colour_Index_Control_Link

Constraints

• Publishable Object

Example(s)

• Consider a <DRM Geometry Model> within a <DRM Model> representing a tree, where the geometry consists of a single Polygon defined with <DRM Stamp Behaviour>.

  

  Figure 6.44 — <DRM Colour Index Control Link> example

  The Polygon’s appearance is determined by a <DRM Colour Index> and an <DRM Image Mapping Function>. However, for every <DRM Geometry Model Instance> of this tree, the data provider wants to be able to vary the intensity_level of the <DRM Colour Index>, so that its contribution to the overall colour of the tree changes from instance to instance. Consequently, the <DRM Colour Index> has a <DRM Colour Index Control Link>, which specifies a <DRM Variable> that controls the intensity_level of the <DRM Colour Index>, so that each <DRM Geometry Model Instance> can supply its own <DRM Literal> to determine the percent contribution of the <DRM Colour Index> to the appearance of the Polygon.