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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 | 50x 50x 50x 50x 50x 1x 4x 27x 4x 60x 60x 43x 2x 43x 43x 41x 6x 43x 2x 2x 1x 1x 1x 1x 1x 1x 1x 1x 1x 39x 1x 50x 1x 50x 18x 50x 50x 27x 23x 23x 23x 2x 21x 6x 6x 6x 2x 19x 3x 16x 5x 16x 16x 13x 3x 1x 11x | import Cartesian3 from "../Core/Cartesian3.js";
import defined from "../Core/defined.js";
import Event from "../Core/Event.js";
import JulianDate from "../Core/JulianDate.js";
import Property from "./Property.js";
/**
* A {@link Property} which evaluates to a {@link Cartesian3} vector
* based on the velocity of the provided {@link PositionProperty}.
*
* @alias VelocityVectorProperty
* @constructor
*
* @param {PositionProperty} [position] The position property used to compute the velocity.
* @param {boolean} [normalize=true] Whether to normalize the computed velocity vector.
*
* @example
* //Create an entity with a billboard rotated to match its velocity.
* const position = new Cesium.SampledProperty();
* position.addSamples(...);
* const entity = viewer.entities.add({
* position : position,
* billboard : {
* image : 'image.png',
* alignedAxis : new Cesium.VelocityVectorProperty(position, true) // alignedAxis must be a unit vector
* }
* }));
*/
function VelocityVectorProperty(position, normalize) {
this._position = undefined;
this._subscription = undefined;
this._definitionChanged = new Event();
this._normalize = normalize ?? true;
this.position = position;
}
Object.defineProperties(VelocityVectorProperty.prototype, {
/**
* Gets a value indicating if this property is constant.
* @memberof VelocityVectorProperty.prototype
*
* @type {boolean}
* @readonly
*/
isConstant: {
get: function () {
return Property.isConstant(this._position);
},
},
/**
* Gets the event that is raised whenever the definition of this property changes.
* @memberof VelocityVectorProperty.prototype
*
* @type {Event}
* @readonly
*/
definitionChanged: {
get: function () {
return this._definitionChanged;
},
},
/**
* Gets or sets the position property used to compute the velocity vector.
* @memberof VelocityVectorProperty.prototype
*
* @type {Property|undefined}
*/
position: {
get: function () {
return this._position;
},
set: function (value) {
const oldValue = this._position;
if (oldValue !== value) {
if (defined(oldValue)) {
this._subscription();
}
this._position = value;
if (defined(value)) {
this._subscription = value._definitionChanged.addEventListener(
function () {
this._definitionChanged.raiseEvent(this);
},
this,
);
}
this._definitionChanged.raiseEvent(this);
}
},
},
/**
* Gets or sets whether the vector produced by this property
* will be normalized or not.
* @memberof VelocityVectorProperty.prototype
*
* @type {boolean}
*/
normalize: {
get: function () {
return this._normalize;
},
set: function (value) {
if (this._normalize === value) {
return;
}
this._normalize = value;
this._definitionChanged.raiseEvent(this);
},
},
});
const position1Scratch = new Cartesian3();
const position2Scratch = new Cartesian3();
const timeScratch = new JulianDate();
const timeNowScratch = new JulianDate();
const step = 1.0 / 60.0;
/**
* Gets the value of the property at the provided time.
*
* @param {JulianDate} [time=JulianDate.now()] The time for which to retrieve the value. If omitted, the current system time is used.
* @param {Cartesian3} [result] The object to store the value into, if omitted, a new instance is created and returned.
* @returns {Cartesian3} The modified result parameter or a new instance if the result parameter was not supplied.
*/
VelocityVectorProperty.prototype.getValue = function (time, result) {
return this._getValue(time, result);
};
/**
* @private
*/
VelocityVectorProperty.prototype._getValue = function (
time,
velocityResult,
positionResult,
) {
if (!defined(time)) {
time = JulianDate.now(timeNowScratch);
}
if (!defined(velocityResult)) {
velocityResult = new Cartesian3();
}
const property = this._position;
if (Property.isConstant(property)) {
return this._normalize
? undefined
: Cartesian3.clone(Cartesian3.ZERO, velocityResult);
}
let position1 = property.getValue(time, position1Scratch);
let position2 = property.getValue(
JulianDate.addSeconds(time, step, timeScratch),
position2Scratch,
);
//If we don't have a position for now, return undefined.
if (!defined(position1)) {
return undefined;
}
//If we don't have a position for now + step, see if we have a position for now - step.
if (!defined(position2)) {
position2 = position1;
position1 = property.getValue(
JulianDate.addSeconds(time, -step, timeScratch),
position2Scratch,
);
if (!defined(position1)) {
return undefined;
}
}
if (Cartesian3.equals(position1, position2)) {
return this._normalize
? undefined
: Cartesian3.clone(Cartesian3.ZERO, velocityResult);
}
if (defined(positionResult)) {
position1.clone(positionResult);
}
const velocity = Cartesian3.subtract(position2, position1, velocityResult);
if (this._normalize) {
return Cartesian3.normalize(velocity, velocityResult);
}
return Cartesian3.divideByScalar(velocity, step, velocityResult);
};
/**
* Compares this property to the provided property and returns
* <code>true</code> if they are equal, <code>false</code> otherwise.
*
* @param {Property} [other] The other property.
* @returns {boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
*/
VelocityVectorProperty.prototype.equals = function (other) {
return (
this === other || //
(other instanceof VelocityVectorProperty &&
Property.equals(this._position, other._position))
);
};
export default VelocityVectorProperty;
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