Noise Experiment

When the difference between two noise seeds is x2 the resulting noise bits are shifted by one bit to the left and only the lowest bit in each byte has a new value

by Quasimondo 04 Oct 2010

Tags

bitmapData noise
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/**
 * Copyright Quasimondo ( http://wonderfl.net/user/Quasimondo )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/drMx
 */

package {
    import flash.display.Bitmap;
    import flash.display.BitmapData;
    import flash.display.Sprite;
    
    
    public class NoiseExperiment extends Sprite 
    {
        
        public function NoiseExperiment() 
        {
            test();
        }
        
        private function test():void
        {
            var bm:Bitmap;
            
            var a1:BitmapData = new BitmapData(100,100,false,0);
            var a2:BitmapData = a1.clone();
            addChild ( new Bitmap( a1 ) );
            addChild( new Bitmap(a2) ).x = 110;
           
            a1.noise( 0xcaffee, 0, 255, 7, false );
            a2.noise( 0xbada55, 0, 255, 7, false );
            
            var a3:BitmapData = a1.clone();
            a3.draw( a2, null, null, "difference");
            addChild( new Bitmap(a3) ).x = 220;
            
            
            
            var b1:BitmapData = new BitmapData(100,100,false,0);
            var b2:BitmapData = b1.clone();
            addChild ( bm = new Bitmap( b1 ) ).y = 110;
            addChild( bm = new Bitmap(b2) ).y = 110;
            bm.x = 110;
           
           
            b1.noise( 10, 0, 255, 7, false );
            
            // The seed of noise b2 is twice the seed value of b1:
            b2.noise( 20, 0, 255, 7, false );
            
            
            var b3:BitmapData = b1.clone();
            b3.draw( b2, null, null, "difference");
            addChild( bm = new Bitmap(b3) ).y = 110;
            bm.x = 220;
            
            var v1:Vector.<uint> = b1.getVector( b1.rect );
            var v2:Vector.<uint> = b2.getVector( b2.rect );
            
            for ( var i:int = 0; i < v1.length; i++ )
            {
                v1[i] &= 0xff7f7f7f // clear the highest rgb bits of b1
                v2[i] &= 0xfefefefe; // clear the lowser rgb bits of b2
                v2[i] >>= 1;  // and shift it one bit to the right
                v2[i] |= 0xff000000; // fix the alpha channel
            }
            
            var b1a:BitmapData = b1.clone()
            b1a.setVector( b1.rect, v1 );
            addChild( new Bitmap(b1a) ).y = 220;
            
            
            var b2a:BitmapData = b1.clone()
            b2a.setVector( b2.rect, v2 );
            
            addChild( bm = new Bitmap(b2a) ).y = 220;
            bm.x = 110;
            
            var b3a:BitmapData = b1a.clone();
            
            // Check the difference between both noises....
            // after the shift it shows that they are identical:
            b3a.draw( b2a, null, null, "difference" );
            
            addChild( bm = new Bitmap(b3a) ).y = 220;
            bm.x = 220;
            
            
        }
    }
}