CesiumMath

Math functions.

Members

staticconstantCesiumMath.DEGREES_PER_RADIAN :Number

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

staticconstantCesiumMath.EPSILON1 :Number

0.1

staticconstantCesiumMath.EPSILON2 :Number

0.01

staticconstantCesiumMath.EPSILON3 :Number

0.001

staticconstantCesiumMath.EPSILON4 :Number

0.0001

staticconstantCesiumMath.EPSILON5 :Number

0.00001

staticconstantCesiumMath.EPSILON6 :Number

0.000001

staticconstantCesiumMath.EPSILON7 :Number

0.0000001

staticconstantCesiumMath.EPSILON8 :Number

0.00000001

staticconstantCesiumMath.EPSILON9 :Number

0.000000001

staticconstantCesiumMath.EPSILON10 :Number

0.0000000001

staticconstantCesiumMath.EPSILON11 :Number

0.00000000001

staticconstantCesiumMath.EPSILON12 :Number

0.000000000001

staticconstantCesiumMath.EPSILON13 :Number

0.0000000000001

staticconstantCesiumMath.EPSILON14 :Number

0.00000000000001

staticconstantCesiumMath.EPSILON15 :Number

0.000000000000001

staticconstantCesiumMath.EPSILON16 :Number

0.0000000000000001

staticconstantCesiumMath.EPSILON17 :Number

0.00000000000000001

staticconstantCesiumMath.EPSILON18 :Number

0.000000000000000001

staticconstantCesiumMath.EPSILON19 :Number

0.0000000000000000001

staticconstantCesiumMath.EPSILON20 :Number

0.00000000000000000001

staticconstantCesiumMath.GRAVITATIONALPARAMETER :Number

3.986004418e14

staticconstantCesiumMath.LUNAR_RADIUS :Number

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.

staticconstantCesiumMath.ONE_OVER_PI :Number

1/pi

staticconstantCesiumMath.ONE_OVER_TWO_PI :Number

1/2pi

staticconstantCesiumMath.PI :Number

pi

staticconstantCesiumMath.PI_OVER_FOUR :Number

pi/4

staticconstantCesiumMath.PI_OVER_SIX :Number

pi/6

staticconstantCesiumMath.PI_OVER_THREE :Number

pi/3

staticconstantCesiumMath.PI_OVER_TWO :Number

pi/2

staticconstantCesiumMath.RADIANS_PER_ARCSECOND :Number

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

staticconstantCesiumMath.RADIANS_PER_DEGREE :Number

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

staticconstantCesiumMath.SIXTY_FOUR_KILOBYTES :Number

64 * 1024

staticconstantCesiumMath.SOLAR_RADIUS :Number

Radius of the sun in meters: 6.955e8

staticconstantCesiumMath.THREE_PI_OVER_TWO :Number

3pi/2

staticconstantCesiumMath.TWO_PI :Number

2pi

Methods

staticCesiumMath.acosClamped(value)Number

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.

staticCesiumMath.asinClamped(value)Number

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.

staticCesiumMath.chordLength(angle, radius)Number

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.

staticCesiumMath.clamp(value, min, max)Number

Constraint a value to lie between two values.
Name Type Description
value Number The value to constrain.
min Number The minimum value.
max Number The maximum value.
Returns:
The value clamped so that min <= value <= max.

staticCesiumMath.convertLongitudeRange(angle)Number

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));

staticCesiumMath.cosh(value)

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.

staticCesiumMath.equalsEpsilon(left, right, relativeEpsilon, absoluteEpsilon)Boolean

Determines if two values are equal using an absolute or relative tolerance test. This is useful to avoid problems due to roundoff error when comparing floating-point values directly. The values are first compared using an absolute tolerance test. If that fails, a relative tolerance test is performed. Use this test if you are unsure of the magnitudes of left and right.
Name Type Default Description
left Number The first value to compare.
right Number The other value to compare.
relativeEpsilon Number The maximum inclusive delta between left and right for the relative tolerance test.
absoluteEpsilon Number relativeEpsilon optional The maximum inclusive delta between left and right for the absolute tolerance test.
Returns:
true if the values are equal within the epsilon; otherwise, 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

staticCesiumMath.factorial(n)Number

Computes the factorial of the provided number.
Name Type Description
n Number The number whose factorial is to be computed.
Returns:
The factorial of the provided number or undefined if the number is less than 0.
Throws:
Example:
//Compute 7!, which is equal to 5040
var computedFactorial = Cesium.Math.factorial(7);
See:

staticCesiumMath.fromSNorm(value)Number

Converts a SNORM value in the range [0, 255] to a scalar in the range [-1.0, 1.0].
Name Type Description
value Number SNORM value in the range [0, 255]
Returns:
Scalar in the range [-1.0, 1.0].
See:

staticCesiumMath.incrementWrap(n, maximumValue, minimumValue)Number

Increments a number with a wrapping to a minimum value if the number exceeds the maximum value.
Name Type Default Description
n Number optional The number to be incremented.
maximumValue Number optional The maximum incremented value before rolling over to the minimum value.
minimumValue Number 0.0 optional The number reset to after the maximum value has been exceeded.
Returns:
The incremented number.
Throws:
Example:
var n = Cesium.Math.incrementWrap(5, 10, 0); // returns 6
var n = Cesium.Math.incrementWrap(10, 10, 0); // returns 0

staticCesiumMath.isPowerOfTwo(n)Boolean

Determines if a positive integer is a power of two.
Name Type Description
n Number The positive integer to test.
Returns:
true if the number if a power of two; otherwise, false.
Throws:
Example:
var t = Cesium.Math.isPowerOfTwo(16); // true
var f = Cesium.Math.isPowerOfTwo(20); // false

staticCesiumMath.lerp(p, q, time)Number

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

staticCesiumMath.mod(m, n)Number

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

staticCesiumMath.negativePiToPi(angle)Number

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].

staticCesiumMath.nextPowerOfTwo(n)Number

Computes the next power-of-two integer greater than or equal to the provided positive integer.
Name Type Description
n Number The positive integer to test.
Returns:
The next power-of-two integer.
Throws:
Example:
var n = Cesium.Math.nextPowerOfTwo(29); // 32
var m = Cesium.Math.nextPowerOfTwo(32); // 32

staticCesiumMath.nextRandomNumber()Number

Generates a random number in the range of [0.0, 1.0) using a Mersenne twister.
Returns:
A random number in the range of [0.0, 1.0).
See:

staticCesiumMath.setRandomNumberSeed(seed)

Sets the seed used by the random number generator in CesiumMath#nextRandomNumber.
Name Type Description
seed Number An integer used as the seed.

staticCesiumMath.sign(value)Number

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.

staticCesiumMath.signNotZero(value)Number

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.

staticCesiumMath.sinh(value)

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.

staticCesiumMath.toDegrees(radians)Number

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

staticCesiumMath.toRadians(degrees)Number

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

staticCesiumMath.toSNorm(value)Number

Converts a scalar value in the range [-1.0, 1.0] to a 8-bit 2's complement number.
Name Type Description
value Number The scalar value in the range [-1.0, 1.0]
Returns:
The 8-bit 2's complement number, where 0 maps to -1.0 and 255 maps to 1.0.
See:

staticCesiumMath.zeroToTwoPi(angle)Number

Produces an angle in the range 0 <= angle <= 2Pi which is equivalent to the provided angle.
Name Type Description
angle Number in radians
Returns:
The angle in the range [0, CesiumMath.TWO_PI].