Occluder

Members

cameraPosition :Cartesian3

The position of the camera.

Source: Core/Occluder.js, line 96

position :Cartesian3

The position of the occluder.

Source: Core/Occluder.js, line 74

radius :Number

The radius of the occluder.

Source: Core/Occluder.js, line 85

Methods

staticOccluder.computeOccludeePoint(occluderBoundingSphere, occludeePosition, positions) → Object

Computes a point that can be used as the occludee position to the visibility functions. Use a radius of zero for the occludee radius. Typically, a user computes a bounding sphere around an object that is used for visibility; however it is also possible to compute a point that if seen/not seen would also indicate if an object is visible/not visible. This function is better called for objects that do not move relative to the occluder and is large, such as a chunk of terrain. You are better off not calling this and using the object's bounding sphere for objects such as a satellite or ground vehicle.

Name	Type	Description
occluderBoundingSphere	BoundingSphere	The bounding sphere surrounding the occluder.
occludeePosition	Cartesian3	The point where the occludee (bounding sphere of radius 0) is located.
positions	Array.<Cartesian3>	List of altitude points on the horizon near the surface of the occluder.

Returns:

An object containing two attributes: occludeePoint and valid which is a boolean value.

Throws:

• DeveloperError : positions must contain at least one element.
• DeveloperError : occludeePosition must have a value other than occluderBoundingSphere.center.

Example:

var cameraPosition = new Cesium.Cartesian3(0, 0, 0);
var occluderBoundingSphere = new Cesium.BoundingSphere(new Cesium.Cartesian3(0, 0, -8), 2);
var occluder = new Cesium.Occluder(occluderBoundingSphere, cameraPosition);
var positions = [new Cesium.Cartesian3(-0.25, 0, -5.3), new Cesium.Cartesian3(0.25, 0, -5.3)];
var tileOccluderSphere = Cesium.BoundingSphere.fromPoints(positions);
var occludeePosition = tileOccluderSphere.center;
var occludeePt = Cesium.Occluder.computeOccludeePoint(occluderBoundingSphere, occludeePosition, positions);

Source: Core/Occluder.js, line 344

staticOccluder.computeOccludeePointFromRectangle(rectangle, ellipsoid) → Object

Computes a point that can be used as the occludee position to the visibility functions from an rectangle.

Name	Type	Default	Description
rectangle	Rectangle		The rectangle used to create a bounding sphere.
ellipsoid	Ellipsoid	Ellipsoid.WGS84	optional The ellipsoid used to determine positions of the rectangle.

Returns:

An object containing two attributes: occludeePoint and valid which is a boolean value.

Source: Core/Occluder.js, line 407

staticOccluder.fromBoundingSphere(occluderBoundingSphere, cameraPosition, result) → Occluder

Creates an occluder from a bounding sphere and the camera position.

Name	Type	Description
occluderBoundingSphere	BoundingSphere	The bounding sphere surrounding the occluder.
cameraPosition	Cartesian3	The coordinate of the viewer/camera.
result	Occluder	optional The object onto which to store the result.

Returns:

The occluder derived from an object's position and radius, as well as the camera position.

Source: Core/Occluder.js, line 139

computeVisibility(occludeeBS) → Number

Determine to what extent an occludee is visible (not visible, partially visible, or fully visible).

Name	Type	Description
occludeeBS	BoundingSphere	The bounding sphere of the occludee.

Returns:

Visibility.NONE if the occludee is not visible, Visibility.PARTIAL if the occludee is partially visible, or Visibility.FULL if the occludee is fully visible.

Example:

var sphere1 = new Cesium.BoundingSphere(new Cesium.Cartesian3(0, 0, -1.5), 0.5);
var sphere2 = new Cesium.BoundingSphere(new Cesium.Cartesian3(0, 0, -2.5), 0.5);
var cameraPosition = new Cesium.Cartesian3(0, 0, 0);
var occluder = new Cesium.Occluder(sphere1, cameraPosition);
occluder.computeVisibility(sphere2); //returns Visibility.NONE

See:

• Occluder#isVisible

Source: Core/Occluder.js, line 266

isBoundingSphereVisible(occludee) → Boolean

Determines whether or not a sphere, the occludee, is hidden from view by the occluder.

Name	Type	Description
occludee	BoundingSphere	The bounding sphere surrounding the occludee object.

Returns:

true if the occludee is visible; otherwise false.

Example:

var cameraPosition = new Cesium.Cartesian3(0, 0, 0);
var littleSphere = new Cesium.BoundingSphere(new Cesium.Cartesian3(0, 0, -1), 0.25);
var occluder = new Cesium.Occluder(littleSphere, cameraPosition);
var bigSphere = new Cesium.BoundingSphere(new Cesium.Cartesian3(0, 0, -3), 1);
occluder.isBoundingSphereVisible(bigSphere); //returns true

See:

• Occluder#computeVisibility

Source: Core/Occluder.js, line 208

isPointVisible(occludee) → Boolean

Determines whether or not a point, the occludee, is hidden from view by the occluder.

Name	Type	Description
occludee	Cartesian3	The point surrounding the occludee object.

Returns:

true if the occludee is visible; otherwise false.

Example:

var cameraPosition = new Cesium.Cartesian3(0, 0, 0);
var littleSphere = new Cesium.BoundingSphere(new Cesium.Cartesian3(0, 0, -1), 0.25);
var occluder = new Cesium.Occluder(littleSphere, cameraPosition);
var point = new Cesium.Cartesian3(0, 0, -3);
occluder.isPointVisible(point); //returns true

See:

• Occluder#computeVisibility

Source: Core/Occluder.js, line 177