gov.nasa.worldwind.util

Class WWMath

java.lang.Object

gov.nasa.worldwind.util.WWMath

public class WWMath
extends java.lang.Object

Collection of static methods for performing common World Wind computations.

Constructor Summary

Constructors

Constructor and Description
WWMath()

Method Summary

Modifier and Type	Method and Description
static Viewport	boundingRectForUnitSquare(Matrix4 unitSquareTransform, Viewport result) Computes the bounding rectangle for a unit square after applying a transformation matrix to the square's four corners.
static double	clamp(double value, double min, double max) Restricts a value to the range [min, max] degrees, clamping values outside the range.
static double	clampAngle180(double degrees) Restricts an angle to the range [-180, +180] degrees, clamping angles outside the range.
static double	clampAngle360(double degrees) Restricts an angle to the range [0, 360] degrees, clamping angles outside the range.
static double	interpolate(double amount, double value1, double value2) Computes the linear interpolation of two values according to a specified fractional amount.
static double	interpolateAngle180(double amount, double degrees1, double degrees2) Computes the linear interpolation of two angles in the range [-180, +180] degrees according to a specified fractional amount.
static double	interpolateAngle360(double amount, double degrees1, double degrees2) Computes the linear interpolation of two angles in the range [0, 360] degrees according to a specified fractional amount.
static boolean	isPowerOfTwo(int value) Indicates whether a specified value is a power of two.
static double	normalizeAngle180(double degrees) Restricts an angle to the range [-180, +180] degrees, wrapping angles outside the range.
static double	normalizeAngle360(double degrees) Restricts an angle to the range [0, 360] degrees, wrapping angles outside the range.
static int	powerOfTwoCeiling(int value) Returns the value that is the nearest power of 2 greater than or equal to the given value.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

WWMath

public WWMath()

Method Detail

clamp

public static double clamp(double value,
                           double min,
                           double max)

Restricts a value to the range [min, max] degrees, clamping values outside the range. Values less than min are returned as min, and values greater than max are returned as max. Values within the range are returned unmodified.

The result of this method is undefined if min is greater than max.

Parameters:

value - the values to clamp

min - the minimum value

max - the maximum value

Returns:

the specified values clamped to the range [min, max] degrees

clampAngle180

public static double clampAngle180(double degrees)

Restricts an angle to the range [-180, +180] degrees, clamping angles outside the range. Angles less than -180 are returned as -180, and angles greater than +180 are returned as +180. Angles within the range are returned unmodified.

Parameters:

degrees - the angle to clamp in degrees

Returns:

the specified angle clamped to the range [-180, +180] degrees

clampAngle360

public static double clampAngle360(double degrees)

Restricts an angle to the range [0, 360] degrees, clamping angles outside the range. Angles less than 0 are returned as 0, and angles greater than 360 are returned as 360. Angles within the range are returned unmodified.

Parameters:

degrees - the angle to clamp in degrees

Returns:

the specified angle clamped to the range [0, 360] degrees

interpolate

public static double interpolate(double amount,
                                 double value1,
                                 double value2)

Computes the linear interpolation of two values according to a specified fractional amount. The fractional amount is interpreted as a relative proportion of the two values, where 0.0 indicates the first value, 0.5 indicates a 50/50 mix of the two values, and 1.0 indicates the second value.

The result of this method is undefined if the amount is outside the range [0, 1].

Parameters:

amount - the fractional proportion of the two values in the range [0, 1]

value1 - the first value

value2 - the second value

Returns:

the interpolated value

interpolateAngle180

public static double interpolateAngle180(double amount,
                                         double degrees1,
                                         double degrees2)

Computes the linear interpolation of two angles in the range [-180, +180] degrees according to a specified fractional amount. The fractional amount is interpreted as a relative proportion of the two angles, where 0.0 indicates the first angle, 0.5 indicates an angle half way between the two angles, and 1.0 indicates the second angle.

The result of this method is undefined if the amount is outside the range [0, 1].

Parameters:

amount - the fractional proportion of the two angles in the range [0, 1]

degrees1 - the first angle in degrees

degrees2 - the second angle in degrees

Returns:

the interpolated angle in the range [-180, +180] degrees

interpolateAngle360

public static double interpolateAngle360(double amount,
                                         double degrees1,
                                         double degrees2)

Computes the linear interpolation of two angles in the range [0, 360] degrees according to a specified fractional amount. The fractional amount is interpreted as a relative proportion of the two angles, where 0.0 indicates the first angle, 0.5 indicates an angle half way between the two angles, and 1.0 indicates the second angle.

The result of this method is undefined if the amount is outside the range [0, 1].

Parameters:

amount - the fractional proportion of the two angles in the range [0, 1]

degrees1 - the first angle in degrees

degrees2 - the second angle in degrees

Returns:

the interpolated angle in the range [0, 360] degrees

normalizeAngle180

public static double normalizeAngle180(double degrees)

Restricts an angle to the range [-180, +180] degrees, wrapping angles outside the range. Wrapping takes place as though traversing the edge of a unit circle; angles less than -180 wrap back to +180, while angles greater than +180 wrap back to -180.

Parameters:

degrees - the angle to wrap in degrees

Returns:

the specified angle wrapped to [-180, +180] degrees

normalizeAngle360

public static double normalizeAngle360(double degrees)

Restricts an angle to the range [0, 360] degrees, wrapping angles outside the range. Wrapping takes place as though traversing the edge of a unit circle; angles less than 0 wrap back to 360, while angles greater than 360 wrap back to 0.

Parameters:

degrees - the angle to wrap in degrees

Returns:

the specified angle wrapped to [0, 360] degrees

boundingRectForUnitSquare

public static Viewport boundingRectForUnitSquare(Matrix4 unitSquareTransform,
                                                 Viewport result)

Computes the bounding rectangle for a unit square after applying a transformation matrix to the square's four corners.

Parameters:

unitSquareTransform - the matrix to apply to the unit square

result - a pre-allocated Viewport in which to return the computed bounding rectangle

Returns:

the result argument set to the computed bounding rectangle

isPowerOfTwo

public static boolean isPowerOfTwo(int value)

Indicates whether a specified value is a power of two.

Parameters:

value - the value to test

Returns:

true if the specified value is a power of two, false othwerwise

powerOfTwoCeiling

public static int powerOfTwoCeiling(int value)

Returns the value that is the nearest power of 2 greater than or equal to the given value.

Parameters:

value - the reference value. The power of 2 returned is greater than or equal to this value.

Returns:

the value that is the nearest power of 2 greater than or equal to the reference value