import * as Cesium from "cesium";
/**
* MeasureDistance class for measuring distances in a Cesium viewer.
* This class provides methods to enable and disable the measurement tool,
* as well as to calculate the distance between points.
* @class MeasureDistance
* @param {Cesium.Viewer} viewer - The Cesium viewer instance.
* @param {Object} [options] - Options for the measurement tool.
* @param {Cesium.Color} [options.color] - The color of the measurement line and points.
* @param {boolean} [options.clampToGround] - Whether to clamp the measurement to the ground.
* @example
* const measureDistance = new MeasureDistance(viewer, { color: Cesium.Color.RED });
* measureDistance.on();
* // To disable the measurement tool and clear entities:
* measureDistance.off();
*/
export class MeasureDistance {
constructor(viewer, options = {}) {
this.viewer = viewer;
this.scene = viewer.scene;
this.handler = new Cesium.ScreenSpaceEventHandler();
this.color = options.color || Cesium.Color.LIGHTGRAY;
this.clampToGround = options.clampToGround || false;
this.status = false;
this.startCartesian = undefined;
this.endCartesian = undefined;
this.startEntity = undefined;
this.endEntity = undefined;
this.lineEntity = undefined;
}
/**
* Enables the distance measurement tool.
* Click to start measuring, and click again to stop.
* @function
* @type {boolean} Continue - Whether to continue measuring after the first click.
* @returns {void}
*/
on = (isContinue = false) => {
this.scene.canvas.style.cursor = "crosshair";
const viewer = this.viewer;
const scene = viewer.scene;
const handler = this.handler;
const mouseLeftClickHandler = (event) => {
if (!this.status) {
this.status = true;
this.clearEntities(viewer);
} else {
this.status = false;
return;
}
// const pickedObject = scene.pick(event.position);
let pickedEllipsoidPosition;
if (scene.pickPositionSupported) {
pickedEllipsoidPosition = viewer.scene.pickPosition(
event.position);
}
if (!pickedEllipsoidPosition) {
pickedEllipsoidPosition = viewer.camera.pickEllipsoid(
event.position,
scene.globe.ellipsoid,
);
const cartographic = Cesium.Cartographic.fromCartesian(
pickedEllipsoidPosition);
const height = viewer.scene.globe.getHeight(
Cesium.Cartographic.fromRadians(cartographic.longitude,
cartographic.latitude, 0));
pickedEllipsoidPosition = Cesium.Cartesian3.fromRadians(
cartographic.longitude, cartographic.latitude, height);
}
// fix height to 1.0m
const manHeight = 0.5;
const convertCartographic = Cesium.Cartographic.fromCartesian(
pickedEllipsoidPosition);
pickedEllipsoidPosition = Cesium.Cartesian3.fromRadians(
convertCartographic.longitude, convertCartographic.latitude,
convertCartographic.height + manHeight);
this.startCartesian = pickedEllipsoidPosition;
this.endCartesian = pickedEllipsoidPosition;
this.startEntity = viewer.entities.add({
position: pickedEllipsoidPosition,
point: {
color: this.color,
pixelSize: 4,
disableDepthTestDistance: Number.POSITIVE_INFINITY,
},
});
this.lineEntity = viewer.entities.add({
polyline: {
positions: new Cesium.CallbackProperty(() => {
return [this.startCartesian, this.endCartesian];
}, false),
width: 3,
material: this.color.withAlpha(0.8),
clampToGround: this.clampToGround,
},
});
this.endEntity = viewer.entities.add({
/* @ts-expect-error */
position: new Cesium.CallbackProperty(() => {
const center = Cesium.Cartesian3.add(this.startCartesian,
this.endCartesian, new Cesium.Cartesian3());
Cesium.Cartesian3.multiplyByScalar(center, 0.5, center);
return center;
}, false),
label: {
showBackground: false,
font: "14px monospace",
fillColor: this.color,
horizontalOrigin: Cesium.HorizontalOrigin.CENTER,
verticalOrigin: Cesium.VerticalOrigin.TOP,
pixelOffset: new Cesium.Cartesian2(0, -20),
disableDepthTestDistance: Number.POSITIVE_INFINITY,
text: new Cesium.CallbackProperty(() => {
let distance = Cesium.Cartesian3.distance(
this.startCartesian,
this.endCartesian);
if (distance > 1000) {
distance = `${(distance / 1000).toFixed(3)}km`;
} else {
distance = `${distance.toFixed(3)}m`;
}
// const distance = Cesium.Cartesian3.distance(this.startCartesian, this.endCartesian).toFixed(3);
return `${distance}`;
}, false),
},
});
};
const mouseMoveHandler = (moveEvent) => {
if (!this.status) {
return;
}
let pickedEllipsoidPosition;
if (scene.pickPositionSupported) {
pickedEllipsoidPosition = viewer.scene.pickPosition(
moveEvent.endPosition);
}
if (!pickedEllipsoidPosition) {
pickedEllipsoidPosition = viewer.camera.pickEllipsoid(
moveEvent.endPosition,
scene.globe.ellipsoid,
);
const cartographic = Cesium.Cartographic.fromCartesian(
pickedEllipsoidPosition);
const height = viewer.scene.globe.getHeight(
Cesium.Cartographic.fromRadians(cartographic.longitude,
cartographic.latitude, 0));
pickedEllipsoidPosition = Cesium.Cartesian3.fromRadians(
cartographic.longitude, cartographic.latitude, height);
}
// fix height to 1.0m
const manHeight = 0.5;
const convertCartographic = Cesium.Cartographic.fromCartesian(
pickedEllipsoidPosition);
pickedEllipsoidPosition = Cesium.Cartesian3.fromRadians(
convertCartographic.longitude, convertCartographic.latitude,
convertCartographic.height + manHeight);
this.endCartesian = pickedEllipsoidPosition;
};
handler.setInputAction(mouseLeftClickHandler,
Cesium.ScreenSpaceEventType.LEFT_CLICK);
handler.setInputAction(mouseLeftClickHandler,
Cesium.ScreenSpaceEventType.RIGHT_CLICK);
handler.setInputAction(mouseMoveHandler,
Cesium.ScreenSpaceEventType.MOUSE_MOVE);
};
/**
* Disables the measurement tool and clears the entities.
* @function
* @returns {void}
*/
off = () => {
this.scene.canvas.style.cursor = "default";
this.status = false;
this.clearEntities();
const handler = this.handler;
if (handler) {
handler.removeInputAction(Cesium.ScreenSpaceEventType.LEFT_CLICK);
handler.removeInputAction(Cesium.ScreenSpaceEventType.RIGHT_CLICK);
handler.removeInputAction(Cesium.ScreenSpaceEventType.MOUSE_MOVE);
}
};
clearEntities = () => {
this.viewer.entities.remove(this.lineEntity);
this.viewer.entities.remove(this.startEntity);
this.viewer.entities.remove(this.endEntity);
this.lineEntity = undefined;
this.startEntity = undefined;
this.endEntity = undefined;
};
}