/*global define*/
define([
'./defaultValue',
'./defined',
'./DeveloperError'
], function(
defaultValue,
defined,
DeveloperError) {
'use strict';
/**
* Creates a curve parameterized and evaluated by time. This type describes an interface
* and is not intended to be instantiated directly.
*
* @alias Spline
* @constructor
*
* @see CatmullRomSpline
* @see HermiteSpline
* @see LinearSpline
* @see QuaternionSpline
*/
function Spline() {
/**
* An array of times for the control points.
* @type {Number[]}
* @default undefined
*/
this.times = undefined;
/**
* An array of control points.
* @type {Cartesian3[]|Quaternion[]}
* @default undefined
*/
this.points = undefined;
DeveloperError.throwInstantiationError();
}
/**
* Evaluates the curve at a given time.
* @function
*
* @param {Number} time The time at which to evaluate the curve.
* @param {Cartesian3|Quaternion} [result] The object onto which to store the result.
* @returns {Cartesian3|Quaternion} The modified result parameter or a new instance of the point on the curve at the given time.
*
* @exception {DeveloperError} time must be in the range <code>[t<sub>0</sub>, t<sub>n</sub>]</code>, where <code>t<sub>0</sub></code>
* is the first element in the array <code>times</code> and <code>t<sub>n</sub></code> is the last element
* in the array <code>times</code>.
*/
Spline.prototype.evaluate = DeveloperError.throwInstantiationError;
/**
* Finds an index <code>i</code> in <code>times</code> such that the parameter
* <code>time</code> is in the interval <code>[times[i], times[i + 1]]</code>.
*
* @param {Number} time The time.
* @param {Number} startIndex The index from which to start the search.
* @returns {Number} The index for the element at the start of the interval.
*
* @exception {DeveloperError} time must be in the range <code>[t<sub>0</sub>, t<sub>n</sub>]</code>, where <code>t<sub>0</sub></code>
* is the first element in the array <code>times</code> and <code>t<sub>n</sub></code> is the last element
* in the array <code>times</code>.
*/
Spline.prototype.findTimeInterval = function(time, startIndex) {
var times = this.times;
var length = times.length;
//>>includeStart('debug', pragmas.debug);
if (!defined(time)) {
throw new DeveloperError('time is required.');
}
if (time < times[0] || time > times[length - 1]) {
throw new DeveloperError('time is out of range.');
}
//>>includeEnd('debug');
// Take advantage of temporal coherence by checking current, next and previous intervals
// for containment of time.
startIndex = defaultValue(startIndex, 0);
if (time >= times[startIndex]) {
if (startIndex + 1 < length && time < times[startIndex + 1]) {
return startIndex;
} else if (startIndex + 2 < length && time < times[startIndex + 2]) {
return startIndex + 1;
}
} else if (startIndex - 1 >= 0 && time >= times[startIndex - 1]) {
return startIndex - 1;
}
// The above failed so do a linear search. For the use cases so far, the
// length of the list is less than 10. In the future, if there is a bottle neck,
// it might be here.
var i;
if (time > times[startIndex]) {
for (i = startIndex; i < length - 1; ++i) {
if (time >= times[i] && time < times[i + 1]) {
break;
}
}
} else {
for (i = startIndex - 1; i >= 0; --i) {
if (time >= times[i] && time < times[i + 1]) {
break;
}
}
}
if (i === length - 1) {
i = length - 2;
}
return i;
};
return Spline;
});