Package gov.nasa.worldwind.util

Class WWMath

  • public class WWMath
extends java.lang.Object
    Collection of static methods for performing common WorldWind computations.

    • Constructor Summary

      Constructors 
      Constructor Description
      WWMath()  

    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method 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 fract​(double value)
      Returns the fractional part of a specified number
      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 int mod​(int value, int modulus)
      Returns the integer modulus of a specified number.
      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

      • fract

        public static double fract​(double value)
        Returns the fractional part of a specified number
        Parameters:
        value - the number whose fractional part to compute
        Returns:
        The fractional part of the specified number: value - floor(value)

      • 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

      • mod

        public static int mod​(int value,
                      int modulus)
        Returns the integer modulus of a specified number. This differs from the % operator in that the result is always positive when the modulus is positive. For example -1 % 10 = -1, whereas mod(-1, 10) = 1.
        Parameters:
        value - the integer number whose modulus to compute
        modulus - the modulus
        Returns:
        the remainder after dividing the number by the modulus

      • 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