Abstract Class Name: Linear Geometry

Superclass - <Primitive Geometry>

Subclasses

• <Arc>
• <Line>

Definition

An instance of this DRM class is a geometric linear representation.

Primary Page in DRM Diagram:

• 5

Secondary Pages in DRM Diagram:

• 13
• 23

Example

1. A <Line> instance can be rendered as a single light point, as depicted in Figure 6.28.

   

   Figure 28 — <DRM Linear Geometry> light point example

2. A <Line> instance can be rendered as three line segments, as depicted in Figure 6.29.

   

   Figure 29 — <DRM Linear Geometry> line segment example

Constraints

• <<Publishable Object>>
• <<Constraints On Components>>
• <<Non Cyclic Aggregations>>
• <<Precedence of Property Set Index>>
• <<Property Constraints>>
• <<Colour Mapping Constraints>>
• <<Continuous LOD Constraints>>
• <<Image Mapping Functions and Texture Coordinates>>
• <<Nested Primitive Geometry>>
• <<Presentation Domain Constraints>>
• <<Linear Geometry Structure>>

Associated with (two-way)

• zero or more {ordered} <Geometry Edge> instances, each through the use of a <Edge Directions> link object

Composed of (two-way) (inherited)

• zero or one <Classification Data> instance
• zero or more {ordered} <Property Set Index> instances
• zero or more <Property Table> instances
• zero or more <Property Table Reference> instances
• zero or more <Property Value> instances
• zero or more <Colour> instances
• zero or more {ordered} <Image Mapping Function> instances
• zero or one <Light Rendering Properties> instance
• zero or one <Presentation Domain> instance
• zero or one <Rendering Priority Level> instance
• zero or one <Rendering Properties> instance
• zero or more <Tack Point> instances
• zero or one <Union Of Primitive Geometry> instance¹

Composed of (two-way metadata) (inherited)

• zero or one <Time Constraints Data> instance

Component of (two-way) (inherited)

• zero or more <Union Of Primitive Geometry> instances

Inherited Field Elements

Field Elements

Notes

Composed of Notes

Union_Of_Primitive_Geometry

EXAMPLE  A <Polygon> instance can be decomposed into multiple <Polygon> instances representing subfaces.

Fields Notes

count

The count field of a <Linear Geometry> instance indicates how the <Linear Geometry> instance is to be rendered. A count field value of zero for a given <Linear Geometry> instance L indicates that L is to be rendered as one solid line segment, and the suppress_last field does not apply.

If count is greater than zero and L has a <Light Rendering Properties> component, the following applies:

1. count is the number of evenly spaced light points to be rendered along L.
2. The distance between light points is calculated by dividing the total length of L by count - 1.
3. If count is one, a single light point is placed at the halfway point of L and the suppress_last field does not apply.
4. The fields of the <Light Rendering Properties> component are applicable to each light point as described in 4.15.3.6 Simulating lighting effects of ISO/IEC 18023-1.
5. If a <Rendering Properties> component is present, it is applicable to each light point as described in 4.15.3.4 Lighting effects of ISO/IEC 18023-1.
6. No additional factors apply.

If count is greater than zero and L does not have a <Light Rendering Properties> component, the following applies:

1. count is the number of evenly spaced line segments to be rendered along L.
2. The length of a segment is calculated by dividing the total length of L by count.
3. If count is one, a single solid line segment is used and the suppress_last field does not apply.
4. If a <Rendering Properties> component is present, it is applicable to each light point as described in 4.15.3.4 Lighting effects of ISO/IEC 18023-1.
5. No additional factors apply.

suppress_last

If count is greater than one, the suppress_last field specifies whether the last segment or point in the sequence is suppressed or rendered.