Realtime
Displays a realtime sightline's visibility within the WorldWind scene, resolved every frame against the rendered geometry (terrain and world-space 3D content such as 3D Tiles meshes, filled shapes and COLLADA models) — unlike ViewshedSightline, which ray-marches a static elevation grid. The sightline's placement and coverage are defined by a center position, a range, and a horizontal wedge given by heading and fieldOfView; the default 360-degree field of view covers the full sphere (the former OmnidirectionalSightline), while narrower angles model directional sensors (the former DirectionalSightline, no longer limited to 90).
Terrain and scene features within the coverage appear in the sightline's normal attributes or its highlight attributes when there is a direct line-of-sight to the center position, and in the occlude attributes otherwise. Features outside the range or wedge are untinted.
Limitations and Planned Improvements
Surface decals and screen-space sprites such as placemarks and leader lines are intentionally excluded as they do not represent occluding volumes. The visibility overlay is drawn in ShapeAttributes' interior color only. Requires a depth-texture-capable context (GLES3 / WebGL2 / desktop GL3+); on older contexts the sightline is not rendered.Constructors
Properties
The sightline's altitude mode. See AltitudeMode
Indicates this sightline's "normal" attributes. These attributes are used for the sightline's overlay when the highlighted flag is false, and there is a direct line-of-sight from the sightline's center position to a terrain feature. If null and this sightline is not highlighted, visible terrain features are excluded from the overlay.
The sightline's horizontal field of view about heading. Elevation coverage above the horizon is capped at half the field of view for angles below 180 degrees. A zero field of view is an empty wedge; the sightline renders nothing.
The attributes to use for visible features, when the sightline is highlighted.
Determines whether the normal or highlighted attributes should be used for visible features.
true when this shape's referencePosition coincides with where the user actually sees the shape (Placemark, Label, sightlines — the reference is the rendered location). false for shapes whose reference is computed from extended geometry and may sit far from where the user grabbed (Polygon centroid, Path centroid, Mesh).
The attributes to use for occluded features.
A position associated with the object that indicates its aggregate geographic position. For a RealtimeSightline, this is simply it's position property.