@cesium/engine
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CesiumJS is a JavaScript library for creating 3D globes and 2D maps in a web browser without a plugin.
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JavaScript
import BoundingSphere from "../Core/BoundingSphere.js";
import Cartesian3 from "../Core/Cartesian3.js";
import Cartographic from "../Core/Cartographic.js";
import Check from "../Core/Check.js";
import ColorGeometryInstanceAttribute from "../Core/ColorGeometryInstanceAttribute.js";
import defined from "../Core/defined.js";
import Ellipsoid from "../Core/Ellipsoid.js";
import GeometryInstance from "../Core/GeometryInstance.js";
import IntersectionTests from "../Core/IntersectionTests.js";
import Matrix4 from "../Core/Matrix4.js";
import OrientedBoundingBox from "../Core/OrientedBoundingBox.js";
import Plane from "../Core/Plane.js";
import Ray from "../Core/Ray.js";
import Rectangle from "../Core/Rectangle.js";
import RectangleOutlineGeometry from "../Core/RectangleOutlineGeometry.js";
import PerInstanceColorAppearance from "./PerInstanceColorAppearance.js";
import Primitive from "./Primitive.js";
import SceneMode from "./SceneMode.js";
/**
* A tile bounding volume specified as a longitude/latitude/height region.
* @alias TileBoundingRegion
* @constructor
*
* @param {object} options Object with the following properties:
* @param {Rectangle} options.rectangle The rectangle specifying the longitude and latitude range of the region.
* @param {number} [options.minimumHeight=0.0] The minimum height of the region.
* @param {number} [options.maximumHeight=0.0] The maximum height of the region.
* @param {Ellipsoid} [options.ellipsoid=Cesium.Ellipsoid.WGS84] The ellipsoid.
* @param {boolean} [options.computeBoundingVolumes=true] True to compute the {@link TileBoundingRegion#boundingVolume} and
* {@link TileBoundingVolume#boundingSphere}. If false, these properties will be undefined.
*
* @private
*/
function TileBoundingRegion(options) {
//>>includeStart('debug', pragmas.debug);
Check.typeOf.object("options", options);
Check.typeOf.object("options.rectangle", options.rectangle);
//>>includeEnd('debug');
this.rectangle = Rectangle.clone(options.rectangle);
this.minimumHeight = options.minimumHeight ?? 0.0;
this.maximumHeight = options.maximumHeight ?? 0.0;
/**
* The world coordinates of the southwest corner of the tile's rectangle.
*
* @type {Cartesian3}
* @default Cartesian3()
*/
this.southwestCornerCartesian = new Cartesian3();
/**
* The world coordinates of the northeast corner of the tile's rectangle.
*
* @type {Cartesian3}
* @default Cartesian3()
*/
this.northeastCornerCartesian = new Cartesian3();
/**
* A normal that, along with southwestCornerCartesian, defines a plane at the western edge of
* the tile. Any position above (in the direction of the normal) this plane is outside the tile.
*
* @type {Cartesian3}
* @default Cartesian3()
*/
this.westNormal = new Cartesian3();
/**
* A normal that, along with southwestCornerCartesian, defines a plane at the southern edge of
* the tile. Any position above (in the direction of the normal) this plane is outside the tile.
* Because points of constant latitude do not necessary lie in a plane, positions below this
* plane are not necessarily inside the tile, but they are close.
*
* @type {Cartesian3}
* @default Cartesian3()
*/
this.southNormal = new Cartesian3();
/**
* A normal that, along with northeastCornerCartesian, defines a plane at the eastern edge of
* the tile. Any position above (in the direction of the normal) this plane is outside the tile.
*
* @type {Cartesian3}
* @default Cartesian3()
*/
this.eastNormal = new Cartesian3();
/**
* A normal that, along with northeastCornerCartesian, defines a plane at the eastern edge of
* the tile. Any position above (in the direction of the normal) this plane is outside the tile.
* Because points of constant latitude do not necessary lie in a plane, positions below this
* plane are not necessarily inside the tile, but they are close.
*
* @type {Cartesian3}
* @default Cartesian3()
*/
this.northNormal = new Cartesian3();
const ellipsoid = options.ellipsoid ?? Ellipsoid.WGS84;
computeBox(this, options.rectangle, ellipsoid);
this._orientedBoundingBox = undefined;
this._boundingSphere = undefined;
if (options.computeBoundingVolumes ?? true) {
this.computeBoundingVolumes(ellipsoid);
}
}
Object.defineProperties(TileBoundingRegion.prototype, {
/**
* The underlying bounding volume
*
* @memberof TileBoundingRegion.prototype
*
* @type {object}
* @readonly
*/
boundingVolume: {
get: function () {
return this._orientedBoundingBox;
},
},
/**
* The underlying bounding sphere
*
* @memberof TileBoundingRegion.prototype
*
* @type {BoundingSphere}
* @readonly
*/
boundingSphere: {
get: function () {
return this._boundingSphere;
},
},
});
TileBoundingRegion.prototype.computeBoundingVolumes = function (ellipsoid) {
// An oriented bounding box that encloses this tile's region. This is used to calculate tile visibility.
this._orientedBoundingBox = OrientedBoundingBox.fromRectangle(
this.rectangle,
this.minimumHeight,
this.maximumHeight,
ellipsoid,
);
this._boundingSphere = BoundingSphere.fromOrientedBoundingBox(
this._orientedBoundingBox,
);
};
const cartesian3Scratch = new Cartesian3();
const cartesian3Scratch2 = new Cartesian3();
const cartesian3Scratch3 = new Cartesian3();
const westNormalScratch = new Cartesian3();
const eastWestNormalScratch = new Cartesian3();
const westernMidpointScratch = new Cartesian3();
const easternMidpointScratch = new Cartesian3();
const cartographicScratch = new Cartographic();
const planeScratch = new Plane(Cartesian3.UNIT_X, 0.0);
const rayScratch = new Ray();
function computeBox(tileBB, rectangle, ellipsoid) {
ellipsoid.cartographicToCartesian(
Rectangle.southwest(rectangle),
tileBB.southwestCornerCartesian,
);
ellipsoid.cartographicToCartesian(
Rectangle.northeast(rectangle),
tileBB.northeastCornerCartesian,
);
// The middle latitude on the western edge.
cartographicScratch.longitude = rectangle.west;
cartographicScratch.latitude = (rectangle.south + rectangle.north) * 0.5;
cartographicScratch.height = 0.0;
const westernMidpointCartesian = ellipsoid.cartographicToCartesian(
cartographicScratch,
westernMidpointScratch,
);
// Compute the normal of the plane on the western edge of the tile.
const westNormal = Cartesian3.cross(
westernMidpointCartesian,
Cartesian3.UNIT_Z,
westNormalScratch,
);
Cartesian3.normalize(westNormal, tileBB.westNormal);
// The middle latitude on the eastern edge.
cartographicScratch.longitude = rectangle.east;
const easternMidpointCartesian = ellipsoid.cartographicToCartesian(
cartographicScratch,
easternMidpointScratch,
);
// Compute the normal of the plane on the eastern edge of the tile.
const eastNormal = Cartesian3.cross(
Cartesian3.UNIT_Z,
easternMidpointCartesian,
cartesian3Scratch,
);
Cartesian3.normalize(eastNormal, tileBB.eastNormal);
let westVector = Cartesian3.subtract(
westernMidpointCartesian,
easternMidpointCartesian,
cartesian3Scratch,
);
if (Cartesian3.magnitude(westVector) === 0.0) {
westVector = Cartesian3.clone(westNormal, westVector);
}
const eastWestNormal = Cartesian3.normalize(
westVector,
eastWestNormalScratch,
);
// Compute the normal of the plane bounding the southern edge of the tile.
const south = rectangle.south;
let southSurfaceNormal;
if (south > 0.0) {
// Compute a plane that doesn't cut through the tile.
cartographicScratch.longitude = (rectangle.west + rectangle.east) * 0.5;
cartographicScratch.latitude = south;
const southCenterCartesian = ellipsoid.cartographicToCartesian(
cartographicScratch,
rayScratch.origin,
);
Cartesian3.clone(eastWestNormal, rayScratch.direction);
const westPlane = Plane.fromPointNormal(
tileBB.southwestCornerCartesian,
tileBB.westNormal,
planeScratch,
);
// Find a point that is on the west and the south planes
IntersectionTests.rayPlane(
rayScratch,
westPlane,
tileBB.southwestCornerCartesian,
);
southSurfaceNormal = ellipsoid.geodeticSurfaceNormal(
southCenterCartesian,
cartesian3Scratch2,
);
} else {
southSurfaceNormal = ellipsoid.geodeticSurfaceNormalCartographic(
Rectangle.southeast(rectangle),
cartesian3Scratch2,
);
}
const southNormal = Cartesian3.cross(
southSurfaceNormal,
westVector,
cartesian3Scratch3,
);
Cartesian3.normalize(southNormal, tileBB.southNormal);
// Compute the normal of the plane bounding the northern edge of the tile.
const north = rectangle.north;
let northSurfaceNormal;
if (north < 0.0) {
// Compute a plane that doesn't cut through the tile.
cartographicScratch.longitude = (rectangle.west + rectangle.east) * 0.5;
cartographicScratch.latitude = north;
const northCenterCartesian = ellipsoid.cartographicToCartesian(
cartographicScratch,
rayScratch.origin,
);
Cartesian3.negate(eastWestNormal, rayScratch.direction);
const eastPlane = Plane.fromPointNormal(
tileBB.northeastCornerCartesian,
tileBB.eastNormal,
planeScratch,
);
// Find a point that is on the east and the north planes
IntersectionTests.rayPlane(
rayScratch,
eastPlane,
tileBB.northeastCornerCartesian,
);
northSurfaceNormal = ellipsoid.geodeticSurfaceNormal(
northCenterCartesian,
cartesian3Scratch2,
);
} else {
northSurfaceNormal = ellipsoid.geodeticSurfaceNormalCartographic(
Rectangle.northwest(rectangle),
cartesian3Scratch2,
);
}
const northNormal = Cartesian3.cross(
westVector,
northSurfaceNormal,
cartesian3Scratch3,
);
Cartesian3.normalize(northNormal, tileBB.northNormal);
}
const southwestCornerScratch = new Cartesian3();
const northeastCornerScratch = new Cartesian3();
const negativeUnitY = new Cartesian3(0.0, -1.0, 0.0);
const negativeUnitZ = new Cartesian3(0.0, 0.0, -1.0);
const vectorScratch = new Cartesian3();
function distanceToCameraRegion(tileBB, frameState) {
const camera = frameState.camera;
const cameraCartesianPosition = camera.positionWC;
const cameraCartographicPosition = camera.positionCartographic;
let result = 0.0;
if (!Rectangle.contains(tileBB.rectangle, cameraCartographicPosition)) {
let southwestCornerCartesian = tileBB.southwestCornerCartesian;
let northeastCornerCartesian = tileBB.northeastCornerCartesian;
let westNormal = tileBB.westNormal;
let southNormal = tileBB.southNormal;
let eastNormal = tileBB.eastNormal;
let northNormal = tileBB.northNormal;
if (frameState.mode !== SceneMode.SCENE3D) {
southwestCornerCartesian = frameState.mapProjection.project(
Rectangle.southwest(tileBB.rectangle),
southwestCornerScratch,
);
southwestCornerCartesian.z = southwestCornerCartesian.y;
southwestCornerCartesian.y = southwestCornerCartesian.x;
southwestCornerCartesian.x = 0.0;
northeastCornerCartesian = frameState.mapProjection.project(
Rectangle.northeast(tileBB.rectangle),
northeastCornerScratch,
);
northeastCornerCartesian.z = northeastCornerCartesian.y;
northeastCornerCartesian.y = northeastCornerCartesian.x;
northeastCornerCartesian.x = 0.0;
westNormal = negativeUnitY;
eastNormal = Cartesian3.UNIT_Y;
southNormal = negativeUnitZ;
northNormal = Cartesian3.UNIT_Z;
}
const vectorFromSouthwestCorner = Cartesian3.subtract(
cameraCartesianPosition,
southwestCornerCartesian,
vectorScratch,
);
const distanceToWestPlane = Cartesian3.dot(
vectorFromSouthwestCorner,
westNormal,
);
const distanceToSouthPlane = Cartesian3.dot(
vectorFromSouthwestCorner,
southNormal,
);
const vectorFromNortheastCorner = Cartesian3.subtract(
cameraCartesianPosition,
northeastCornerCartesian,
vectorScratch,
);
const distanceToEastPlane = Cartesian3.dot(
vectorFromNortheastCorner,
eastNormal,
);
const distanceToNorthPlane = Cartesian3.dot(
vectorFromNortheastCorner,
northNormal,
);
if (distanceToWestPlane > 0.0) {
result += distanceToWestPlane * distanceToWestPlane;
} else if (distanceToEastPlane > 0.0) {
result += distanceToEastPlane * distanceToEastPlane;
}
if (distanceToSouthPlane > 0.0) {
result += distanceToSouthPlane * distanceToSouthPlane;
} else if (distanceToNorthPlane > 0.0) {
result += distanceToNorthPlane * distanceToNorthPlane;
}
}
let cameraHeight;
let minimumHeight;
let maximumHeight;
if (frameState.mode === SceneMode.SCENE3D) {
cameraHeight = cameraCartographicPosition.height;
minimumHeight = tileBB.minimumHeight;
maximumHeight = tileBB.maximumHeight;
} else {
cameraHeight = cameraCartesianPosition.x;
minimumHeight = 0.0;
maximumHeight = 0.0;
}
if (cameraHeight > maximumHeight) {
const distanceAboveTop = cameraHeight - maximumHeight;
result += distanceAboveTop * distanceAboveTop;
} else if (cameraHeight < minimumHeight) {
const distanceBelowBottom = minimumHeight - cameraHeight;
result += distanceBelowBottom * distanceBelowBottom;
}
return Math.sqrt(result);
}
/**
* Gets the distance from the camera to the closest point on the tile. This is used for level of detail selection.
*
* @param {FrameState} frameState The state information of the current rendering frame.
* @returns {number} The distance from the camera to the closest point on the tile, in meters.
*/
TileBoundingRegion.prototype.distanceToCamera = function (frameState) {
//>>includeStart('debug', pragmas.debug);
Check.defined("frameState", frameState);
//>>includeEnd('debug');
const regionResult = distanceToCameraRegion(this, frameState);
if (
frameState.mode === SceneMode.SCENE3D &&
defined(this._orientedBoundingBox)
) {
const obbResult = Math.sqrt(
this._orientedBoundingBox.distanceSquaredTo(frameState.camera.positionWC),
);
return Math.max(regionResult, obbResult);
}
return regionResult;
};
/**
* Determines which side of a plane this box is located.
*
* @param {Plane} plane The plane to test against.
* @returns {Intersect} {@link Intersect.INSIDE} if the entire box is on the side of the plane
* the normal is pointing, {@link Intersect.OUTSIDE} if the entire box is
* on the opposite side, and {@link Intersect.INTERSECTING} if the box
* intersects the plane.
*/
TileBoundingRegion.prototype.intersectPlane = function (plane) {
//>>includeStart('debug', pragmas.debug);
Check.defined("plane", plane);
//>>includeEnd('debug');
return this._orientedBoundingBox.intersectPlane(plane);
};
/**
* Creates a debug primitive that shows the outline of the tile bounding region.
*
* @param {Color} color The desired color of the primitive's mesh
* @return {Primitive}
*
* @private
*/
TileBoundingRegion.prototype.createDebugVolume = function (color) {
//>>includeStart('debug', pragmas.debug);
Check.defined("color", color);
//>>includeEnd('debug');
const modelMatrix = new Matrix4.clone(Matrix4.IDENTITY);
const geometry = new RectangleOutlineGeometry({
rectangle: this.rectangle,
height: this.minimumHeight,
extrudedHeight: this.maximumHeight,
});
const instance = new GeometryInstance({
geometry: geometry,
id: "outline",
modelMatrix: modelMatrix,
attributes: {
color: ColorGeometryInstanceAttribute.fromColor(color),
},
});
return new Primitive({
geometryInstances: instance,
appearance: new PerInstanceColorAppearance({
translucent: false,
flat: true,
}),
asynchronous: false,
});
};
export default TileBoundingRegion;