cesium/Apps/Sandcastle/gallery/Star Burst.html

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<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta
name="viewport"
content="width=device-width, initial-scale=1, maximum-scale=1, minimum-scale=1, user-scalable=no"
/>
<meta name="description" content="Star burst overlapping billboards." />
<meta name="cesium-sandcastle-labels" content="Showcases" />
<title>Cesium Demo</title>
<script type="text/javascript" src="../Sandcastle-header.js"></script>
<script
type="text/javascript"
src="../../../Build/CesiumUnminified/Cesium.js"
nomodule
></script>
<script type="module" src="../load-cesium-es6.js"></script>
</head>
<body class="sandcastle-loading" data-sandcastle-bucket="bucket-requirejs.html">
<style>
@import url(../templates/bucket.css);
</style>
<div id="cesiumContainer" class="fullSize"></div>
<div id="loadingOverlay"><h1>Loading...</h1></div>
<div id="toolbar">
<div id="zoomButtons"></div>
</div>
<script id="cesium_sandcastle_script">
window.startup = async function (Cesium) {
"use strict";
//Sandcastle_Begin
const viewer = new Cesium.Viewer("cesiumContainer", {
selectionIndicator: false,
});
// Add labels clustered at the same location
const numBillboards = 30;
for (let i = 0; i < numBillboards; ++i) {
const position = Cesium.Cartesian3.fromDegrees(-75.59777, 40.03883);
viewer.entities.add({
position: position,
billboard: {
image: "../images/facility.gif",
scale: 2.5,
},
label: {
text: `Label${i}`,
show: false,
},
});
}
const scene = viewer.scene;
const camera = scene.camera;
const handler = new Cesium.ScreenSpaceEventHandler(scene.canvas);
handler.setInputAction(function (movement) {
// Star burst on left mouse click.
starBurst(movement.position);
}, Cesium.ScreenSpaceEventType.LEFT_CLICK);
handler.setInputAction(function (movement) {
// Remove the star burst when the mouse exits the circle or show the label of the billboard the mouse is hovering over.
updateStarBurst(movement.endPosition);
}, Cesium.ScreenSpaceEventType.MOUSE_MOVE);
camera.moveStart.addEventListener(function () {
// Reset the star burst on camera move because the lines from the center
// because the line end points rely on the screen space positions of the billboards.
undoStarBurst();
});
// State saved across mouse click and move events
const starBurstState = {
enabled: false,
pickedEntities: undefined,
billboardEyeOffsets: undefined,
labelEyeOffsets: undefined,
linePrimitive: undefined,
radius: undefined,
center: undefined,
pixelPadding: 10.0,
angleStart: 0.0,
angleEnd: Cesium.Math.PI,
maxDimension: undefined,
};
function offsetBillboard(
entity,
entityPosition,
angle,
magnitude,
lines,
billboardEyeOffsets,
labelEyeOffsets,
) {
const x = magnitude * Math.cos(angle);
const y = magnitude * Math.sin(angle);
const offset = new Cesium.Cartesian2(x, y);
const drawingBufferWidth = scene.drawingBufferWidth;
const drawingBufferHeight = scene.drawingBufferHeight;
const pixelRatio = scene.pixelRatio;
const diff = Cesium.Cartesian3.subtract(
entityPosition,
camera.positionWC,
new Cesium.Cartesian3(),
);
const distance = Cesium.Cartesian3.dot(camera.directionWC, diff);
const dimensions = camera.frustum.getPixelDimensions(
drawingBufferWidth,
drawingBufferHeight,
distance,
pixelRatio,
new Cesium.Cartesian2(),
);
Cesium.Cartesian2.multiplyByScalar(
offset,
Cesium.Cartesian2.maximumComponent(dimensions),
offset,
);
let labelOffset;
const billboardOffset = entity.billboard.eyeOffset;
const eyeOffset = new Cesium.Cartesian3(offset.x, offset.y, 0.0);
entity.billboard.eyeOffset = eyeOffset;
if (Cesium.defined(entity.label)) {
labelOffset = entity.label.eyeOffset;
entity.label.eyeOffset = new Cesium.Cartesian3(offset.x, offset.y, -10.0);
}
const endPoint = Cesium.Matrix4.multiplyByPoint(
camera.viewMatrix,
entityPosition,
new Cesium.Cartesian3(),
);
Cesium.Cartesian3.add(eyeOffset, endPoint, endPoint);
Cesium.Matrix4.multiplyByPoint(camera.inverseViewMatrix, endPoint, endPoint);
lines.push(endPoint);
billboardEyeOffsets.push(billboardOffset);
labelEyeOffsets.push(labelOffset);
}
function starBurst(mousePosition) {
if (Cesium.defined(starBurstState.pickedEntities)) {
return;
}
const pickedObjects = scene.drillPick(mousePosition);
if (!Cesium.defined(pickedObjects) || pickedObjects.length < 2) {
return;
}
const billboardEntities = [];
let length = pickedObjects.length;
let i;
for (i = 0; i < length; ++i) {
const pickedObject = pickedObjects[i];
if (pickedObject.primitive instanceof Cesium.Billboard) {
billboardEntities.push(pickedObject);
}
}
if (billboardEntities.length === 0) {
return;
}
const pickedEntities = (starBurstState.pickedEntities = []);
const billboardEyeOffsets = (starBurstState.billboardEyeOffsets = []);
const labelEyeOffsets = (starBurstState.labelEyeOffsets = []);
const lines = [];
starBurstState.maxDimension = Number.NEGATIVE_INFINITY;
const angleStart = starBurstState.angleStart;
const angleEnd = starBurstState.angleEnd;
let angle = angleStart;
let angleIncrease;
let magnitude;
let magIncrease;
let maxDimension;
// Drill pick gets all of the entities under the mouse pointer.
// Find the billboards and set their pixel offsets in a circle pattern.
length = billboardEntities.length;
i = 0;
while (i < length) {
let object = billboardEntities[i];
if (pickedEntities.length === 0) {
starBurstState.center = Cesium.Cartesian3.clone(object.primitive.position);
}
if (!Cesium.defined(angleIncrease)) {
const width = object.primitive.width;
const height = object.primitive.height;
maxDimension =
Math.max(width, height) * object.primitive.scale +
starBurstState.pixelPadding;
magnitude = maxDimension + maxDimension * 0.5;
magIncrease = magnitude;
angleIncrease = maxDimension / magnitude;
}
offsetBillboard(
object.id,
object.primitive.position,
angle,
magnitude,
lines,
billboardEyeOffsets,
labelEyeOffsets,
);
pickedEntities.push(object);
const reflectedAngle = angleEnd - angle;
if (
i + 1 < length &&
reflectedAngle - angleIncrease * 0.5 > angle + angleIncrease * 0.5
) {
object = billboardEntities[++i];
offsetBillboard(
object.id,
object.primitive.position,
reflectedAngle,
magnitude,
lines,
billboardEyeOffsets,
labelEyeOffsets,
);
pickedEntities.push(object);
}
angle += angleIncrease;
if (reflectedAngle - angleIncrease * 0.5 < angle + angleIncrease * 0.5) {
magnitude += magIncrease;
angle = angleStart;
angleIncrease = maxDimension / magnitude;
}
++i;
}
// Add lines from the pick center out to the translated billboard.
const instances = [];
length = lines.length;
for (i = 0; i < length; ++i) {
const pickedEntity = pickedEntities[i];
starBurstState.maxDimension = Math.max(
pickedEntity.primitive.width,
pickedEntity.primitive.height,
starBurstState.maxDimension,
);
instances.push(
new Cesium.GeometryInstance({
geometry: new Cesium.SimplePolylineGeometry({
positions: [starBurstState.center, lines[i]],
arcType: Cesium.ArcType.NONE,
granularity: Cesium.Math.PI_OVER_FOUR,
}),
attributes: {
color: Cesium.ColorGeometryInstanceAttribute.fromColor(
Cesium.Color.WHITE,
),
},
}),
);
}
starBurstState.linePrimitive = scene.primitives.add(
new Cesium.Primitive({
geometryInstances: instances,
appearance: new Cesium.PerInstanceColorAppearance({
flat: true,
translucent: false,
}),
asynchronous: false,
}),
);
viewer.selectedEntity = undefined;
starBurstState.radius = magnitude + magIncrease;
}
function updateStarBurst(mousePosition) {
if (!Cesium.defined(starBurstState.pickedEntities)) {
return;
}
if (!starBurstState.enabled) {
// For some reason we get a mousemove event on click, so
// do not show a label on the first event.
starBurstState.enabled = true;
return;
}
// Remove the star burst if the mouse exits the screen space circle.
// If the mouse is inside the circle, show the label of the billboard the mouse is hovering over.
const screenPosition = Cesium.SceneTransforms.worldToWindowCoordinates(
scene,
starBurstState.center,
);
const fromCenter = Cesium.Cartesian2.subtract(
mousePosition,
screenPosition,
new Cesium.Cartesian2(),
);
const radius = starBurstState.radius;
if (
Cesium.Cartesian2.magnitudeSquared(fromCenter) > radius * radius ||
fromCenter.y >
3.0 * (starBurstState.maxDimension + starBurstState.pixelPadding)
) {
undoStarBurst();
} else {
showLabels(mousePosition);
}
}
function undoStarBurst() {
const pickedEntities = starBurstState.pickedEntities;
if (!Cesium.defined(pickedEntities)) {
return;
}
const billboardEyeOffsets = starBurstState.billboardEyeOffsets;
const labelEyeOffsets = starBurstState.labelEyeOffsets;
// Reset billboard and label pixel offsets.
// Hide overlapping labels.
for (let i = 0; i < pickedEntities.length; ++i) {
const entity = pickedEntities[i].id;
entity.billboard.eyeOffset = billboardEyeOffsets[i];
if (Cesium.defined(entity.label)) {
entity.label.eyeOffset = labelEyeOffsets[i];
entity.label.show = false;
}
}
// Remove lines from the scene.
// Free resources and reset state.
scene.primitives.remove(starBurstState.linePrimitive);
starBurstState.linePrimitive = undefined;
starBurstState.pickedEntities = undefined;
starBurstState.billboardEyeOffsets = undefined;
starBurstState.labelEyeOffsets = undefined;
starBurstState.radius = undefined;
starBurstState.enabled = false;
}
let currentObject;
function showLabels(mousePosition) {
const pickedObjects = scene.drillPick(mousePosition);
let pickedObject;
if (Cesium.defined(pickedObjects)) {
const length = pickedObjects.length;
for (let i = 0; i < length; ++i) {
if (pickedObjects[i].primitive instanceof Cesium.Billboard) {
pickedObject = pickedObjects[i];
break;
}
}
}
if (pickedObject !== currentObject) {
if (Cesium.defined(pickedObject) && Cesium.defined(pickedObject.id.label)) {
if (Cesium.defined(currentObject)) {
currentObject.id.label.show = false;
}
currentObject = pickedObject;
pickedObject.id.label.show = true;
} else if (Cesium.defined(currentObject)) {
currentObject.id.label.show = false;
currentObject = undefined;
}
}
}
//Sandcastle_End
};
if (typeof Cesium !== "undefined") {
window.startupCalled = true;
window.startup(Cesium).catch((error) => {
"use strict";
console.error(error);
});
Sandcastle.finishedLoading();
}
</script>
</body>
</html>