/*
    This file is part of "life", a Filter plugin for Adobe Photoshop
    Copyright (C) 2003-6 Toby Thain, toby@telegraphics.com.au

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by  
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    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
*/

/* Photoshop filter implementing Conway's Life cellular automaton. */

#include "world.h"

#include "PIFilter.h"

OSErr process(FilterRecordPtr pb);

OSErr process(FilterRecordPtr pb){
	unsigned char *inrow,*outrow,*inp,*outp;
	int i,j,n,ncols = pb->inRect.right - pb->inRect.left,
		nrows = pb->inRect.bottom - pb->inRect.top,
		pl=pb->planes;
	long rb=pb->inRowBytes,t,ticks = TICKCOUNT();

	for(inrow=pb->inData,outrow=pb->outData,j=0 ; j<nrows ; inrow+=rb,outrow+=pb->outRowBytes,++j){
		/* handle coordinate wraparound at top and bottom of image */
		long yprev = j ? -rb : (nrows-1)*rb,
			 ynext = j==nrows-1 ? -(nrows-1)*rb : rb;

		for(inp=inrow,outp=outrow,i=0 ; i<ncols ; inp+=pl,outp+=pl,++i){
			/* handle coordinate wraparound at left and right of image */
			long xprev = i ? -pl : (ncols-1)*pl,
				 xnext = i==ncols-1 ? -(ncols-1)*pl : pl;

			/* count living neighbours */
			n = (inp[xprev+yprev]>>7) + (inp[yprev]>>7) + (inp[xnext+yprev]>>7)
			  + (inp[xprev]>>7)                         + (inp[xnext]>>7)
			  + (inp[xprev+ynext]>>7) + (inp[ynext]>>7) + (inp[xnext+ynext]>>7);

			if(pl==3){
				outp[2] = outp[1]; // copy Green to Blue (T-2)
				outp[1] = outp[0]; // copy Red to Green (T-1)
			}

			/* next cell state: 
			   if 2 neighbours, cell is unchanged
			   if 3 neighbours, it's a birth
			   otherwise, it dies. */

			outp[0] = n==2 ? -(inp[0]>>7) : -(n==3); // compute generation T
		}

		if((t = TICKCOUNT()) > ticks){
			ticks = t + TICKS_SEC/4; /* check every 1/4 sec */
			/* allow user to cancel */
			if (pb->abortProc())
				return userCanceledErr;
			else /* report progress */
				pb->progressProc(j + pb->inRect.top - pb->filterRect.top, pb->filterRect.bottom - pb->filterRect.top);
		}
	}
	return noErr;
}