Table 6.44 — DRM_Cone_Directional_Light
Property |
Description |
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Class |
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Superclass |
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Subclass |
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Definition |
An instance of this DRM class specifies a <DRM Directional Light Behaviour> instance, the intensity of which varies depending on the position of the observer relative to the light’s location, direction, and shape. This light takes the shape of a cone, which can be elliptical. A <DRM Cone Directional Light> instance can specify a plane that divides the light cone into an upper and a lower section along the body of the cone. This occurs when the has_plane field has value TRUE. If the value of the has_plane field is TRUE, a plane, based at the cone apex and extending along the body of the cone, divides the light cone into an upper and a lower section. The upper section receives the primary colour. If a secondary colour is used, the lower section receives it. If a secondary colour is not used, the lower section also receives the primary colour. If the value of the has_plane field is FALSE, the cone is not divided and always receives the primary colour. The value of the plane_angular_offset field defines the angular offset of the plane measured in radians, if the value of the has_plane field is TRUE. The offset is measured from the <DRM Lobe Data> instance’s LIGHT_DIRECTION vector and along its VERTICAL_AXIS vector. The resulting upper section of the light is taken to be between the plane and the positive end of the VERTICAL_AXIS vector. The value of the plane_angular_offset field is ignored if has_plane is FALSE. If the value of the use_full_intensity field is TRUE, it indicates that the full intensity of the light is shown in the cone shaped area. Otherwise, the intensity of the light decreases (towards the minimum_colour_intensity value) as one moves away from the LIGHT_DIRECTION vector. The value of the minimum_colour_intensity value is used in conjunction with the full intensity value of the primary colour. If the primary colour is represented by a <DRM Colour Index> instance, the full intensity is specified by its intensity_level field. If the primary colour is represented by a <DRM Inline Colour> instance, the full intensity is 1,0. A location in the direct path of the <DRM Lobe Data> instance’s LIGHT_DIRECTION vector receives the full intensity value. If use_full_intensity is FALSE, the intensity decreases with increasing angular distance from the LIGHT_DIRECTION vector, until the boundary specified by the horizontal and vertical <DRM Lobe Data> instance widths is reached. Outside the lobe, the intensity is minimum_colour_intensity. If the minimum_colour_intensity value is 0,0, the secondary colour (if present) will be seen outside the lobe at full intensity. If no secondary colour is present, nothing is visible outside the lobe. If the value of the invisible_behind field is TRUE, the directional light is invisible when viewed from behind the plane located at the apex and perpendicular to the LIGHT_DIRECTION vector. If the value of the invisible_behind field is FALSE, the directional light is visible when viewed from behind. |
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Class diagram |
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Inherited field elements |
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Field elements |
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Default field values |
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Associated to (one-way) (inherited) |
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Associated to (one-way) |
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Associated by (one-way) (inherited) |
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Associated by (one-way) |
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Associated with (two-way) (inherited) |
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Associated with (two-way) |
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Composed of (two-way) (inherited) |
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Composed of (two-way) |
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Composed of (two-way metadata) (inherited) |
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Composed of (two-way metadata) |
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Component of (two-way) (inherited) |
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Component of (two-way) |
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Constraints |
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Clarifications |
1The <DRM Lobe Data> component specifies the lobe shape. |
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Example(s) |
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