Power of Two Example

gforcer18 · June 24, 2014, 1:07pm

=D
Hi folks, i know that there are a lot of examples :google: , but maybe it will be useful for someone
Simple example #1
[java]
public static final boolean isPowerOfTwo( final int pNumber ) throws IllegalArgumentException
{
if ( pNumber <= 0 )
throw new IllegalArgumentException( "MathHelper.isPowerOfTwo: given integer is " + pNumber );

    return( ( pNumber &amp; -pNumber ) == pNumber );
    //Method #2
    //return( ( pNumber &amp; ( pNumber - 1 ) ) == 0 );
}

[/java]

Simple example #2
[java]
public static final boolean isPowerOfTwo( final Image pImage ) throws Exception
{
final int width = pImage.getWidth( );
final int height = pImage.getHeight( );

    return( ( ( width &amp; -width ) == width &amp;&amp; ( height &amp; -height ) == height ) );
}

[/java]

jmaasing · June 24, 2014, 1:16pm

There is also the FastMath class in JME

github.com

jMonkeyEngine/jmonkeyengine/blob/3.0/engine/src/core/com/jme3/math/FastMath.java#L86


 * A good implementation found on the Java boards. note: a number is a power
 * of two if and only if it is the smallest number with that number of
 * significant bits. Therefore, if you subtract 1, you know that the new
 * number will have fewer bits, so ANDing the original number with anything
 * less than it will give 0.
 * 
 * @param number
 *            The number to test.
 * @return True if it is a power of two.
 */
public static boolean isPowerOfTwo(int number) {
    return (number > 0) && (number & (number - 1)) == 0;
}

public static int nearestPowerOfTwo(int number) {
    return (int) Math.pow(2, Math.ceil(Math.log(number) / Math.log(2)));
}

/**
 * Linear interpolation from startValue to endValue by the given percent.
 * Basically: ((1 - percent) * startValue) + (percent * endValue)

gforcer18 · June 24, 2014, 1:27pm

@jmaasing said: There is also the FastMath class in JME
jmonkeyengine/FastMath.java at 3.0 · jMonkeyEngine/jmonkeyengine · GitHub

tanks, now i know