The SEDRIS Data Representation Model
APPENDIX A - Classes
Light Rendering Properties Control Link

Class Name: Light Rendering Properties Control Link

Superclass - <Control Link>

Subclasses

This DRM class is concrete and has no subclasses.

Definition

An instance of this DRM class is a specialized <Control Link> instance providing the connection between one or more <Light Rendering Properties> instances and the <Expression> instances that are used to determine whether the target <Light Rendering Properties> instances are active and/or their candela_value field values are varying.

Primary Page in DRM Diagram:

Secondary Pages in DRM Diagram:

Example

  1. Consider a flight simulator database containing an area of terrain representing a city as seen from the air. Some of the <Polygon> instances of this terrain representation have <Light Rendering Properties> instances with <Twinkling Light Behaviour> components, representing city lights. These <Light Rendering Properties> instances share a <Light Rendering Properties Control Link> component that turns them on and off depending on the time of day (on at dusk, off at dawn).

  2. Consider a runway, bordered on each side by a <Line> instance representing the runway lights. Each <Line> instance has a <Light Rendering Properties> component with a <Strobing Light Behaviour> component, and a <Light Rendering Properties Control Link> component that turns the lights on and off depending on the time of day (on at dusk, off at dawn).

FAQs

What does a <Light Rendering Properties Control Link> instance control?

A <Light Rendering Properties Control Link> instance controls whether the associated <Light Rendering Properties> instances are on or off, and the candela_value of the <Light Rendering Properties> instances.

Can a <Light Rendering Properties Control Link> instance be used to change the <Light Rendering Behaviour> components of the <Light Rendering Properties> instances?

No. The links to the <Light Rendering Behaviour> instances are associations within the transmittal, and associations cannot be changed dynamically.

Constraints

Composed of (two-way) (inherited)

Component of (two-way)

Inherited Field Elements

SE_String description; 1

Field Elements

SE_Integer_Unsigned active_expression_index; 2
SE_Integer_Unsigned candela_value_expression_index; 3
SE_Integer_Unsigned lower_candela_value_index; 4
SE_Integer_Unsigned upper_candela_value_index; 5

Notes

Fields Notes

description

The description field specifies a text description of the purpose of the <Control Link> instance.

active_expression_index

The active_expression_index field specifies which <Expression> component, if any, specifies the active_light_value of the target <Light Rendering Properties> instances. If active_expression_index is zero (0), the active_light_value field values of the target instances are not controlled. Otherwise, the value is a one-based index into the ordered aggregation of <Expression> instances.

candela_value_expression_index

The candela_value_expression_index field specifies which <Expression> component, if any, specifies the candela_value of the target <Light Rendering Properties> instances. If candela_value_expression_index is zero (0), the candela_value field values of the target instances are not controlled. Otherwise, the value is a one-based index into the ordered aggregation of <Expression> instances.

lower_candela_value_index

The lower_candela_value_index field specifies which <Expression> component, if any, specifies the lower limit of the candela_value of the target <Light Rendering Properties> instances. If lower_candela_value_index is zero (0), no lower limit is specified. Otherwise, the value is a one-based index into the ordered aggregation of <Expression> instances.

NOTE 1  If candela_value_expression_index is zero, the candela_value field values of the target instances are not controlled, so the lower_candela_value_index value is also zero.

upper_candela_value_index

The upper_candela_value_index field specifies which <Expression> component, if any, specifies the upper limit of the candela_value of the target <Light Rendering Properties> instances. If upper_candela_value_index is zero (0), no upper limit is specified. Otherwise, the value is a one-based index into the ordered aggregation of <Expression> instances.

NOTE 2  If candela_value_expression_index is zero, the candela_value field values of the target instances are not controlled, so the upper_candela_value_index value is also zero.


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Last updated: July 26, 2006 Copyright © 2006 SEDRIS