code: /**
   * License: GPL
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License 2
   * as published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
   */
  package net.imglib2.render.volume;
  
  import net.imglib2.RandomAccess;
  import net.imglib2.type.numeric.AbstractARGBDoubleType;
  
  /**
   * 
   *
   * @author Stephan Saalfeld <saalfeld@mpi-cbg.de>
   */
  public class ARGBDoubleLayers< T extends AbstractARGBDoubleType< T > > implements RowAccumulator< T >
  {
  	@Override
  	public void accumulateRow(
  			final T accumulator,
  			final RandomAccess< T > access,
  			final long min,
  			final long max,
  			final long step,
  			final int d )
  	{
  		access.setPosition( max, d );
  		double a = accumulator.getA();
  		double r = accumulator.getR();
  		double g = accumulator.getG();
  		double b = accumulator.getB();
  		while ( access.getLongPosition( d ) >= min )
  		{
  			final T argb = access.get();
  			final double alpha = argb.getA();
  			
  			a *= 1.0 - alpha;
  			r *= 1.0 - alpha;
  			g *= 1.0 - alpha;
  			b *= 1.0 - alpha;
  			
  			a += alpha * alpha;
  			r += argb.getR() * alpha;
  			g += argb.getG() * alpha;
  			b += argb.getB() * alpha;
  			
  			access.move( -step, d );
  		}
  		accumulator.set( a, r, g, b );
  	}
  }
  