ISO/IEC 18023-1:200x(E) — Table 6.291 DRM

Table 6.291 — DRM_Variable

Property

Description

Class

<DRM Variable>

Superclass

<DRM Expression>

Subclass

None.

Definition

An instance of this DRM class is used to connect an <DRM Interface Template> instance to a location within an <DRM Expression> tree where outside control may be exerted.

For a <DRM Variable> instance contained within a <DRM Model>, evaluation is valid only for a specific instance of that <DRM Model>. The value is determined by an <DRM Expression> that is aggregated by the specific <DRM Geometry Model Instance> or <DRM Feature Model Instance>. This <DRM Expression> shall be associated to the same <DRM Interface Template> instance that is associated with the <DRM Variable>.

For a <DRM Variable> instance contained within an <DRM Environment Root>, the evaluation can only be performed within the context of values that shall be supplied by the consuming system.

Class diagram

Figure 6.349 — DRM_Variable

Inherited field elements

Field name	Range	Field data type
None

Field elements

Field name	Range	Field data type
meaning ¹		Element_Type
value_unit ²		EDCS_Unit_Code
value_scale ³		EDCS_Scale_Code
value_type ⁴		Property_Data_Value_Type
description ⁵		String
runtime_label ⁶		String

Associated to (one-way) (inherited)

None.

Associated to (one-way)

None.

Associated by (one-way) (inherited)

None.

Associated by (one-way)

None.

Associated with (two-way) (inherited)

None.

Associated with (two-way)

one <DRM Interface Template> instance

Composed of (two-way) (inherited)

None.

Composed of (two-way metadata) (inherited)

None.

Composed of (two-way metadata)

None.

Component of (two-way) (inherited)

zero or more <DRM Control Link> instances
zero or more <DRM Feature Model Instance> instances, each with a <DRM Model Instance Template Index> link object
zero or more <DRM Function> instances
zero or more <DRM Geometry Model Instance> instances, each with a <DRM Model Instance Template Index> link object

Component of (two-way)

None.

Constraints

Clarifications

¹ This specifies the quantity represented by the given <DRM Variable> instance.

² This specifies the unit of measurement of the quantity represented by the given <DRM Variable> instance.

³ This specifies the scale applicable to value_unit.

⁴ This specifies the value_type. of the given <DRM Variable> instance.

⁵ This provides a meaningful explanation of the purpose of the given <DRM Variable> instance.

⁶ This is used for <DRM Variable> instances that consumers need to identify. These are run-time flags, provided so that appropriate values can be “plugged in”, which then affect any <DRM Control Link> instances driven by such a <DRM Variable> instance. If a <DRM Variable> instance does not need a runtime_label, the field is set to the empty string.

Example(s)

Consider a source database containing a <DRM Model> with some polygons that reference “table driven texture”. Such a polygon is defined as a <DRM Polygon> that has one reference to an <DRM Image> with multiple references to s and t values, which are stored in a <DRM Data Table>. The index into this table is decided at run-time. Each <DRM Polygon> containing a “table-driven texture” has an identifier that is used, along with the index, at run-time.
In SEDRIS, the <DRM Polygon> uses a <DRM Property Table Reference> to index into the <DRM Data Table> containing the different s and t values. Attached to the <DRM Property Table Reference> is a <DRM Property Table Reference Control Link>. The <DRM Variable> attached to this <DRM Property Table Reference Control Link> is ultimately be associated to the <DRM Interface Template> on the <DRM Model>. The original identifier on the <DRM Polygon> shall reside on the <DRM Variable> rather than the <DRM Polygon>, since the <DRM Variable> controls the s,t values.
The following is another example of how a runtime_label on a <DRM Variable> would be used.
On moving models there might be polygons that have IR values attached to them. Consider a tank <DRM Model> in such a database.
In SEDRIS, the IR values are stored in <DRM Property Table> instances. The <DRM Polygon>s of the tank reference these elements through a <DRM Property Table Reference>. A <DRM Property Table Reference Control Link> is used for those <DRM Polygon> instances that have “heat producing” capability (for instance, the gun barrel), so that the index into the IR table can be changed to other values as the gun is used and heats up. More than one <DRM Polygon> will contain the same ID. The consumer shall be able to identify the <DRM Polygon> instances (through the <DRM Control Link> and <DRM Interface Template> instances) by this ID so that he can switch these <DRM Polygon> instances to be “heat producing”.