Table 6.201—DRM_Positional_Light

Property

Description

Superclass

· <DRM Base Positional Light>

Class

· <DRM Positional Light>

Subclass

· none

Definition

An object of this DRM class specifies a <DRM Base Positional Light> that radiates in all directions from a specified point in 3D space.

<DRM Positional Light> specifies a sphere of influence, whose radius is specified by its radius field. Only objects located within this sphere can be affected. In addition, if apply_to_children is true, then (as with all <DRM Light Source>s) only <DRM Primitive Geometry> which are below the <DRM Aggregate Geometry> to which the <DRM Positional Light> is attached will be affected.

Example(s)

· A bare light bulb.

Inherited field elements

field_name	range	Field_Data_Type
apply_to_children^1		Boolean
override_positional_lights^2		Boolean
override_infinite_lights^3		Boolean
active_light_value^4		Boolean
radius^5	≥ 0,0	Float
constant_attenuation_factor^6	≥ 0,0	Long_Float
linear_attenuation_factor^7	≥ 0,0	Long_Float
quadratic_attenuation_factor^8	≥ 0,0	Long_Float

Field elements

field_name	range	Field_Data_Type
none

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)

· none

Composed of (two-way) (inherited)

· one <DRM Ambient Colour>

· one <DRM Diffuse Colour>

· optionally, a DRM_Light_Source_Control_Link

· one DRM_Location_3D⁹

· one <DRM Specular Colour>

Composed of (two-way)

· none

Composed of (two-way metadata) (inherited)

· none

Composed of (two-way metadata)

· none

Component of (two-way) (inherited)

· one or more <DRM Aggregate Geometry>s

Component of (two-way)

· none

Constraints

· none

Notes

¹ Flag to allow lights to limit their scope to only affecting their children. If apply_to_children is FALSE, the light is assumed to apply globally.

² Flag to reset the current cumulative definition of local <DRM Light_Sources> If override_positional_lights is TRUE, all <DRM Positional Light Sources> in the current scope are cleared.

³ Flag to reset the current cumulative definition of <DRM Infinite Light Sources>. If override_infinite_lights is TRUE, all <DRM Positional Light Sources> in the current scope are cleared.

⁴ A value of TRUE indicates the light is on while a value of FALSE indicates the light is off. This is the default/active state of the light

⁵ The radius (in meters) and position define the sphere of influence. This will be affected by hierarchical transformations.

⁶ Constant 'a' in the attenuation quadratic (a + bd + cd**2).

⁷ Constant 'b' in the attenuation quadratic (a + bd + cd**2).

⁸ Constant 'c' in the attenuation quadratic (a + bd + cd**2).

⁹ Position in three-space that will be affected by hierarchical transformations.

Class diagram

<DRM Positional Light>