Math

Math()
Core/Math.js 13

数学函数。

Members

staticconstantCesium.Math.DEGREES_PER_RADIAN : Number
Core/Math.js 419

The number of degrees in a radian.
Default Value: 180.0 / Math.PI

staticconstantCesium.Math.EPSILON1 : Number
Core/Math.js 20

0.1

staticconstantCesium.Math.EPSILON2 : Number
Core/Math.js 27

0.01

staticconstantCesium.Math.EPSILON3 : Number
Core/Math.js 34

0.001

staticconstantCesium.Math.EPSILON4 : Number
Core/Math.js 41

0.0001

staticconstantCesium.Math.EPSILON5 : Number
Core/Math.js 48

0.00001

staticconstantCesium.Math.EPSILON6 : Number
Core/Math.js 55

0.000001

staticconstantCesium.Math.EPSILON7 : Number
Core/Math.js 62

0.0000001

staticconstantCesium.Math.EPSILON8 : Number
Core/Math.js 69

0.00000001

staticconstantCesium.Math.EPSILON9 : Number
Core/Math.js 76

0.000000001

staticconstantCesium.Math.EPSILON10 : Number
Core/Math.js 83

0.0000000001

staticconstantCesium.Math.EPSILON11 : Number
Core/Math.js 90

0.00000000001

staticconstantCesium.Math.EPSILON12 : Number
Core/Math.js 97

0.000000000001

staticconstantCesium.Math.EPSILON13 : Number
Core/Math.js 104

0.0000000000001

staticconstantCesium.Math.EPSILON14 : Number
Core/Math.js 111

0.00000000000001

staticconstantCesium.Math.EPSILON15 : Number
Core/Math.js 118

0.000000000000001

staticconstantCesium.Math.EPSILON16 : Number
Core/Math.js 125

0.0000000000000001

staticconstantCesium.Math.EPSILON17 : Number
Core/Math.js 132

0.00000000000000001

staticconstantCesium.Math.EPSILON18 : Number
Core/Math.js 139

0.000000000000000001

staticconstantCesium.Math.EPSILON19 : Number
Core/Math.js 146

0.0000000000000000001

staticconstantCesium.Math.EPSILON20 : Number
Core/Math.js 153

0.00000000000000000001

staticconstantCesium.Math.EPSILON21 : Number
Core/Math.js 160

0.000000000000000000001

staticconstantCesium.Math.FOUR_GIGABYTES : Number
Core/Math.js 198

4 * 1024 * 1024 * 1024

staticconstantCesium.Math.GRAVITATIONALPARAMETER : Number
Core/Math.js 168

The gravitational parameter of the Earth in meters cubed per second squared as defined by the WGS84 model: 3.986004418e14

staticconstantCesium.Math.LUNAR_RADIUS : Number
Core/Math.js 184

The mean radius of the moon, according to the "Report of the IAU/IAG Working Group on Cartographic Coordinates and Rotational Elements of the Planets and satellites: 2000", Celestial Mechanics 82: 83-110, 2002.

staticconstantCesium.Math.ONE_OVER_PI : Number
Core/Math.js 345

1/pi

staticconstantCesium.Math.ONE_OVER_TWO_PI : Number
Core/Math.js 401

1/2pi

staticconstantCesium.Math.PI : Number
Core/Math.js 337

pi

staticconstantCesium.Math.PI_OVER_FOUR : Number
Core/Math.js 369

pi/4

staticconstantCesium.Math.PI_OVER_SIX : Number
Core/Math.js 377

pi/6

staticconstantCesium.Math.PI_OVER_THREE : Number
Core/Math.js 361

pi/3

staticconstantCesium.Math.PI_OVER_TWO : Number
Core/Math.js 353

pi/2

staticconstantCesium.Math.RADIANS_PER_ARCSECOND : Number
Core/Math.js 428

The number of radians in an arc second.
Default Value: CesiumMath.RADIANS_PER_DEGREE / 3600.0

staticconstantCesium.Math.RADIANS_PER_DEGREE : Number
Core/Math.js 410

The number of radians in a degree.
Default Value: Math.PI / 180.0

staticconstantCesium.Math.SIXTY_FOUR_KILOBYTES : Number
Core/Math.js 191

64 * 1024

staticconstantCesium.Math.SOLAR_RADIUS : Number
Core/Math.js 175

以米为单位的太阳半径： 6.955e8

staticconstantCesium.Math.THREE_PI_OVER_TWO : Number
Core/Math.js 385

3pi/2

staticconstantCesium.Math.TWO_PI : Number
Core/Math.js 393

2pi

Methods

staticCesium.Math.acosClamped(value) → Number
Core/Math.js 888

Computes Math.acos(value), but first clamps value to the range [-1.0, 1.0] so that the function will never return NaN.
Name Type Description
value Number The value for which to compute acos.
Returns:
The acos of the value if the value is in the range [-1.0, 1.0], or the acos of -1.0 or 1.0, whichever is closer, if the value is outside the range.

staticCesium.Math.asinClamped(value) → Number
Core/Math.js 905

Computes Math.asin(value), but first clamps value to the range [-1.0, 1.0] so that the function will never return NaN.
Name Type Description
value Number The value for which to compute asin.
Returns:
The asin of the value if the value is in the range [-1.0, 1.0], or the asin of -1.0 or 1.0, whichever is closer, if the value is outside the range.

staticCesium.Math.cbrt(number) → Number
Core/Math.js 960

Finds the cube root of a number. Returns NaN if number is not provided.
Name Type Description
number Number optional The number.
Returns:
The result.

staticCesium.Math.chordLength(angle, radius) → Number
Core/Math.js 921

Finds the chord length between two points given the circle's radius and the angle between the points.
Name Type Description
angle Number The angle between the two points.
radius Number The radius of the circle.
Returns:
The chord length.

staticCesium.Math.clamp(value, min, max) → Number
Core/Math.js 825

将一个值限制在两个值之间。
Name Type Description
value Number 要限制的值。
min Number 最小值。
max Number 最大值。
Returns:
value被夹住，使得min <= value <= max。

staticCesium.Math.clampToLatitudeRange(angle) → Number
Core/Math.js 499

Convenience function that clamps a latitude value, in radians, to the range [-Math.PI/2, Math.PI/2). Useful for sanitizing data before use in objects requiring correct range.
Name Type Description
angle Number The latitude value, in radians, to clamp to the range [-Math.PI/2, Math.PI/2).
Returns:
The latitude value clamped to the range [-Math.PI/2, Math.PI/2).
Example:
// Clamp 108 degrees latitude to 90 degrees latitude
var latitude = Cesium.Math.clampToLatitudeRange(Cesium.Math.toRadians(108.0));

staticCesium.Math.convertLongitudeRange(angle) → Number
Core/Math.js 468

Converts a longitude value, in radians, to the range [-Math.PI, Math.PI).
Name Type Description
angle Number The longitude value, in radians, to convert to the range [-Math.PI, Math.PI).
Returns:
The equivalent longitude value in the range [-Math.PI, Math.PI).
Example:
// Convert 270 degrees to -90 degrees longitude
var longitude = Cesium.Math.convertLongitudeRange(Cesium.Math.toRadians(270.0));

staticCesium.Math.cosh(value) → Number
Core/Math.js 312

Returns the hyperbolic cosine of a number. The hyperbolic cosine of value is defined to be (ex + e-x)/2.0 where e is Euler's number, approximately 2.71828183.

Special cases:

  • If the argument is NaN, then the result is NaN.
  • If the argument is infinite, then the result is positive infinity.
  • If the argument is zero, then the result is 1.0.

Name Type Description
value Number The number whose hyperbolic cosine is to be returned.
Returns:
The hyperbolic cosine of value.

staticCesium.Math.equalsEpsilon(left, right, relativeEpsilon, absoluteEpsilon) → Boolean
Core/Math.js 585

使用绝对或相对容差测试确定两个值是否相等。在直接比较浮点值时，这有助于避免由于舍入错误造成的问题。这些值首先使用绝对容差测试进行比较。 如果失败，则执行相对容错测试。如果你不确定左右的大小，可以使用这个测试。
Name Type Default Description
left Number 要比较的第一个值。
right Number 要比较的另一个值。
relativeEpsilon Number 相对容差测试用的left 和 right
absoluteEpsilon Number relativeEpsilon optional 绝对容差测试用的left 和 right
Returns:
true，如果值在epsilon内相等;否则,false。
Example:
var a = Cesium.Math.equalsEpsilon(0.0, 0.01, Cesium.Math.EPSILON2); // true
var b = Cesium.Math.equalsEpsilon(0.0, 0.1, Cesium.Math.EPSILON2);  // false
var c = Cesium.Math.equalsEpsilon(3699175.1634344, 3699175.2, Cesium.Math.EPSILON7); // true
var d = Cesium.Math.equalsEpsilon(3699175.1634344, 3699175.2, Cesium.Math.EPSILON9); // false

staticCesium.Math.factorial(n) → Number
Core/Math.js 712

计算所提供数字的阶乘。
Name Type Description
n Number 要计算其阶乘的数。
Returns:
给定数的阶乘，如果该数小于0，则未定义。
Throws:
Example:
//Compute 7!, which is equal to 5040
var computedFactorial = Cesium.Math.factorial(7);
See:

staticCesium.Math.fastApproximateAtan(x) → Number
Core/Math.js 995

Computes a fast approximation of Atan for input in the range [-1, 1]. Based on Michal Drobot's approximation from ShaderFastLibs, which in turn is based on "Efficient approximations for the arctangent function," Rajan, S. Sichun Wang Inkol, R. Joyal, A., May 2006. Adapted from ShaderFastLibs under MIT License.
Name Type Description
x Number An input number in the range [-1, 1]
Returns:
An approximation of atan(x)

staticCesium.Math.fastApproximateAtan2(x, y) → Number
Core/Math.js 1012

Computes a fast approximation of Atan2(x, y) for arbitrary input scalars. Range reduction math based on nvidia's cg reference implementation: http://developer.download.nvidia.com/cg/atan2.html
Name Type Description
x Number An input number that isn't zero if y is zero.
y Number An input number that isn't zero if x is zero.
Returns:
An approximation of atan2(x, y)

staticCesium.Math.fromSNorm(value, rangeMaximum) → Number
Core/Math.js 249

Converts a SNORM value in the range [0, rangeMaximum] to a scalar in the range [-1.0, 1.0].
Name Type Default Description
value Number SNORM value in the range [0, rangeMaximum]
rangeMaximum Number 255 optional The maximum value in the SNORM range, 255 by default.
Returns:
Scalar in the range [-1.0, 1.0].
See:
  • CesiumMath.toSNorm

staticCesium.Math.greaterThan(left, right, absoluteEpsilon) → Boolean
Core/Math.js 657

确定左值是否大于右值。如果这两个值在absoluteEpsilon内，则认为它们相等，此函数返回false。
Name Type Description
left Number 第一个要比较的数字。
right Number 第二个要比较的数字。
absoluteEpsilon Number 用于比较的绝对值。
Returns:
true如果left大于right超过absoluteEpsilon。 false如果left小于或如果两个值接近相等。

staticCesium.Math.greaterThanOrEquals(left, right, absoluteEpsilon) → Boolean
Core/Math.js 680

确定左值是否大于或等于右值。如果这两个值在absoluteEpsilon内，则认为它们相等，此函数返回true。
Name Type Description
left Number 第一个要比较的数字。
right Number 第二个要比较的数字。
absoluteEpsilon Number 用于比较的绝对值。
Returns:
true如果left大于right或者如果值接近相等。

staticCesium.Math.incrementWrap(n, maximumValue, minimumValue) → Number
Core/Math.js 745

Increments a number with a wrapping to a minimum value if the number exceeds the maximum value. 如果一个数字超过了最大值，则使用包装将其递增到最小值。
Name Type Default Description
n Number optional 要增加的数。
maximumValue Number optional 在转到最小值之前增加的最大值。
minimumValue Number 0.0 optional 超过最大值后重置的数字。
Returns:
增加的数。
Throws:
Example:
var n = Cesium.Math.incrementWrap(5, 10, 0); // returns 6
var n = Cesium.Math.incrementWrap(10, 10, 0); // returns 0

staticCesium.Math.isPowerOfTwo(n) → Boolean
Core/Math.js 776

确定一个正整数是否是2的幂。
Name Type Description
n Number 要测试的正整数。
Returns:
true如果数是2的幂;否则,false。
Throws:
Example:
var t = Cesium.Math.isPowerOfTwo(16); // true
var f = Cesium.Math.isPowerOfTwo(20); // false

staticCesium.Math.lerp(p, q, time) → Number
Core/Math.js 327

Computes the linear interpolation of two values.
Name Type Description
p Number The start value to interpolate.
q Number The end value to interpolate.
time Number The time of interpolation generally in the range [0.0, 1.0].
Returns:
The linearly interpolated value.
Example:
var n = Cesium.Math.lerp(0.0, 2.0, 0.5); // returns 1.0

staticCesium.Math.lessThan(left, right, absoluteEpsilon) → Boolean
Core/Math.js 610

确定左值是否小于右值。如果这两个值在absoluteEpsilon内，则认为它们相等，此函数返回false。
Name Type Description
left Number 第一个要比较的数字。
right Number 第二个要比较的数字。
absoluteEpsilon Number 用于比较的绝对值。
Returns:
true如果left小于right超过absoluteEpsilon。 false如果left大于或如果两个值接近相等。

staticCesium.Math.lessThanOrEquals(left, right, absoluteEpsilon) → Boolean
Core/Math.js 633

确定左值是否小于或等于右值。如果这两个值在absoluteEpsilon内，则认为它们相等，此函数返回true。
Name Type Description
left Number 第一个要比较的数字。
right Number 第二个要比较的数字。
absoluteEpsilon Number 用于比较的绝对值。
Returns:
true如果left小于right或者如果值接近相等。

staticCesium.Math.log2(number) → Number
Core/Math.js 972

Finds the base 2 logarithm of a number.
Name Type Description
number Number The number.
Returns:
The result.

staticCesium.Math.logBase(number, base) → Number
Core/Math.js 940

Finds the logarithm of a number to a base.
Name Type Description
number Number The number.
base Number The base.
Returns:
The result.

staticCesium.Math.mod(m, n) → Number
Core/Math.js 557

The modulo operation that also works for negative dividends.
Name Type Description
m Number The dividend.
n Number The divisor.
Returns:
The remainder.

staticCesium.Math.negativePiToPi(angle) → Number
Core/Math.js 515

Produces an angle in the range -Pi <= angle <= Pi which is equivalent to the provided angle.
Name Type Description
angle Number in radians
Returns:
The angle in the range [-CesiumMath.PI, CesiumMath.PI].

staticCesium.Math.nextPowerOfTwo(n) → Number
Core/Math.js 798

计算下一个大于或等于给定正整数的2次幂。
Name Type Description
n Number 要测试的正整数。
Returns:
下一个2的幂数。
Throws:
Example:
var n = Cesium.Math.nextPowerOfTwo(29); // 32
var m = Cesium.Math.nextPowerOfTwo(32); // 32

staticCesium.Math.nextRandomNumber() → Number
Core/Math.js 865

使用梅森扭距（Mersenne twister）生成一个范围为[0.0,1.0)的随机浮点数。
Returns:
一个在[0.0,1.0)范围内的随机数。
See:

staticCesium.Math.normalize(value, rangeMinimum, rangeMaximum) → Number
Core/Math.js 261

Converts a scalar value in the range [rangeMinimum, rangeMaximum] to a scalar in the range [0.0, 1.0]
Name Type Description
value Number The scalar value in the range [rangeMinimum, rangeMaximum]
rangeMinimum Number The minimum value in the mapped range.
rangeMaximum Number The maximum value in the mapped range.
Returns:
A scalar value, where rangeMinimum maps to 0.0 and rangeMaximum maps to 1.0.

staticCesium.Math.randomBetween(min, max) → Number
Core/Math.js 876

在两个数字之间生成一个随机数。
Name Type Description
min Number 最小值。
max Number 最大值。
Returns:
最小值和最大值之间的一个随机数。

staticCesium.Math.setRandomNumberSeed(seed)
Core/Math.js 847

在CesiumMath#nextRandomNumber中设置随机数生成器使用的种子。
Name Type Description
seed Number 用作种子的整数。

staticCesium.Math.sign(value) → Number
Core/Math.js 208

Returns the sign of the value; 1 if the value is positive, -1 if the value is negative, or 0 if the value is 0.
Name Type Description
value Number The value to return the sign of.
Returns:
The sign of value.

staticCesium.Math.signNotZero(value) → Number
Core/Math.js 224

Returns 1.0 if the given value is positive or zero, and -1.0 if it is negative. This is similar to CesiumMath#sign except that returns 1.0 instead of 0.0 when the input value is 0.0.
Name Type Description
value Number The value to return the sign of.
Returns:
The sign of value.

staticCesium.Math.sinh(value) → Number
Core/Math.js 288

Returns the hyperbolic sine of a number. The hyperbolic sine of value is defined to be (ex - e-x)/2.0 where e is Euler's number, approximately 2.71828183.

Special cases:

  • If the argument is NaN, then the result is NaN.
  • If the argument is infinite, then the result is an infinity with the same sign as the argument.
  • If the argument is zero, then the result is a zero with the same sign as the argument.

Name Type Description
value Number The number whose hyperbolic sine is to be returned.
Returns:
The hyperbolic sine of value.

staticCesium.Math.toDegrees(radians) → Number
Core/Math.js 449

Converts radians to degrees.
Name Type Description
radians Number The angle to convert in radians.
Returns:
The corresponding angle in degrees.

staticCesium.Math.toRadians(degrees) → Number
Core/Math.js 435

Converts degrees to radians.
Name Type Description
degrees Number The angle to convert in degrees.
Returns:
The corresponding angle in radians.

staticCesium.Math.toSNorm(value, rangeMaximum) → Number
Core/Math.js 236

Converts a scalar value in the range [-1.0, 1.0] to a SNORM in the range [0, rangeMaximum]
Name Type Default Description
value Number The scalar value in the range [-1.0, 1.0]
rangeMaximum Number 255 optional The maximum value in the mapped range, 255 by default.
Returns:
A SNORM value, where 0 maps to -1.0 and rangeMaximum maps to 1.0.
See:
  • CesiumMath.fromSNorm

staticCesium.Math.zeroToTwoPi(angle) → Number
Core/Math.js 537

在0 <=角度<= 2PI范围内产生一个角度，该角度与提供的角度相等。
Name Type Description
angle Number 以弧度表示
Returns:
角度在[0， CesiumMath.TWO_PI ]范围内。