#!/usr/local/bin/perl -w
#
#  tartan disc drawer, this one makes filled intersections
#
# to make all at once,
# tartan2.p c=1 all=3 ; xv figs/tartan1.pbm &
#
# see also images/tartan.README
#
# to make them one by one,
$fiduc = 0 ; # whether to put a ruddy big x in the middle
$filled = 0 ; # whether to fill in the intersections. 
$circle = 1 ; # whether to exclude points outside circle
$circle2 = 1 ; # whether to exclude points inside circle2
$repeat = 3 ; # number of times to periodic
$pbmplot = 1 ; 
$pbmfile = "tartan" ; 
$pbmx = 286 ; # for width=6,  4 more than mult of 6
$pbmx = 202 ; # for width=8,   mult of 8 plus 2
$pbmx = 276 ; # for width=12,
$c = 1 ; # colour (1,2,3) or 1 for all
$all = 3 ; # set to zero to force only one colour
$ascii = 1 ; # whether also to write an ascii summary to stdout.
$low = 0 ; $high = 1 - $low;
$xoff = 0.35 ; # offset of centre of circle
$yoff = 0.42 ;
$ex = 0.41 ;
$ey = 0.56 ; # fraction of the whole repeated picture
$efx = 0.1 ; # ellipticity (stretch by sqrt 1/this) along x dirn
$re = 0.05 ;  # radius in the y direction 
$elip = 0.0 ; # ellipticity in 45 degree sense
$radius = 0.31 ; # was .3
$shelf = 0.1 ; # how far before the dots die out
$eshelf = 0.3 ;
$xmax = 580 ; # clip size
$ymax = 670 ; # clip size
$maxpbm = 3 ;
$verbose = 0 ; 
#
eval "\$$1=\$2" while @ARGV && $ARGV[0]=~ /^(\w+)=(.*)/ && shift;
#
$period = $pbmx ; 
$pbmx = $repeat * $pbmx ;
$pbmy = $pbmx ; 
$pbmfile .= $c.".pbm" ;
$P = $pbmx * $pbmy ;
$centrex = $pbmx * $xoff ;
$centrey = $pbmy * $yoff ;
print  "centre is at $centrex, $centrey\n" ; 
$radius *= $pbmx ;
$trueradius = $radius ; 
$radius *= $radius ;  # radius squared
$re *= $pbmx ;
$re *= $re ; 
$ex = $pbmx * $ex ;
$ey = $pbmy * $ey ;

print "ellipse at $ex $ey\n" ;

$pbmx = $xmax ; 
$pbmy = $ymax ; 
if ( $ascii ) {
    print "$pbmx $pbmy\n" ;
}
if ( $pbmplot ) { # note I actually write a pgm file .
    open (PBM,"> $pbmfile");
    if ( $all > 1 ) {
	print PBM "P2\n# CREATOR: tartan.p DJCM 99 05\n" ;
	print PBM "$pbmx $pbmy\n" ; 
	print PBM "$maxpbm\n" ;
	$low = 3 ;
	$high = 0 ; 
    } else {
	print PBM "P1\n# CREATOR: tartan.p DJCM 99 05\n" ;
	print PBM "$pbmx $pbmy\n" ; 
    }	
}
for ( $i = 1 ; $i <= $P ; $i ++ ) {  $c[$i] =  $low ; }

do {
    $stripe3start = 0 ; 
    $stripe4start = 0 ; 
    $stripe5start = 0 ;
    $stripe3end = 0 ; 
    $stripe4end = 0 ; 
    $stripe5end = 0 ;
    if ( $c == 2 ) {
	
	$stripe1start = 89 ;
	$stripe1width = 39 ;	# 
	$stripe2start =  139 ;
	$stripe2width =  $stripe1width  ; 
	$lwidth = 12 ;
	$onwidth = 4 ; 
	$o0 = 0 ;
	$oh = 7 ;
	
    }
    elsif ( $c == 1 ) {
	$stripe3width = 7 ; 
	$stripe3start = 268 ; 
	$stripe1start = 42 ; 
	$stripe1width = 39 ; 
	$stripe2start = 186 ;
	$stripe2width =  $stripe1width  ; # 14
	$lwidth = 12 ; # period (was 6 and 2) (or 8 and 3)
	$onwidth = 4 ; # amount of ink
	$o0 = 0 ;
	$oh = 7 ; 
	$stripe3end = $stripe3start + $stripe3width ; 
    }
    elsif ( $c == 3 ) {
	$stripe3start = 130 ; 
	$stripe3width = 7 ; 
	$stripe4start = 180 ; 
	$stripe4width = 4 ; 
	$stripe5start = 227 ; 
	$stripe5width = 39 ;
	$stripe1start = 1 ; 
	$stripe1width = 39 ;
	$stripe2start = 83 ;
	$stripe2width =  4 ;
	$lwidth = 12 ; # period (was 6 and 2) (or 8 and 3)
	$onwidth = 4 ; # amount of ink
	$o0 = 0 ;
	$oh = 7 ; 
	$stripe3end = $stripe3start + $stripe3width ; 
	$stripe4end = $stripe4start + $stripe4width ; 
	$stripe5end = $stripe5start + $stripe5width ; 
    }
    $stripe1end = $stripe1start + $stripe1width ; 
    $stripe2end = $stripe2start + $stripe2width ;
    @stripes = () ; 
    @stripes = ($stripe1start..$stripe1end,
		$stripe5start..$stripe5end,
		$stripe2start..$stripe2end,
		$stripe3start..$stripe3end,
		$stripe4start..$stripe4end) ; 
    print @stripes if ($verbose) ; 
    $off = 0 ;
    foreach $t ( @stripes ) {
	if ( $t ) { # ignore zeroes
	    &doit() ;
	}
    }
    if ( $filled ) {
	# fill in intersections
	foreach $t ( @stripes ) {
	    if ( $t ) { # ignore zeroes
		foreach $tt ( @stripes ) {
		    if ( $tt ) { # ignore zeroes
			$x =  $period+1-$t ; $y = $tt ; 
			&checkdraw ;
			if ( $repeat ) {
			    &dorepeat ; 
			}
		    }
		}		# 
	    }			# 
	}			#
    }
    print "pbmx = $pbmx\n" ; 
    &markers ;
    $c ++ ; $high ++ ; # assumes high was 1...
} while ( $c <= $all ) ;

sub markers {
    print "pbmx = $pbmx\n" ; 
    docross ( $pbmx - 30 , $pbmy - 80 , $c * 5 -4 , ($c+1)* 5 - 5  ) ;
    docross (  30 ,  130 , $c * 5 -4 , ($c+1)* 5 - 5  ) ;
    print  "centre is at $centrex, $centrey\n" ; 
    if ( $fiduc ) {
	docross ( $centrex , $centrey ,  5 , 165  ) ;
	print (  $centrex + $trueradius , ":" , $centrey + $trueradius , "\n" ) ; 
	dofloor ( ($centrex + $trueradius) , ($centrey + $trueradius) , 1 , 10 ) ;
	print  ( $pbmx , " : " , $pbmy, "\n" ) ;
	doceil  ( $centrex - $trueradius , $centrey - $trueradius , 1 , 10 ) ;
    }
    dofloor ( $pbmx , $pbmy, 1 , 10 ) ;
}
sub docross {
    local ( $xx , $yy , $start , $end ) = @_ ;
    dofloor ( $xx , $yy , $start , $end ) ;
    doceil ( $xx , $yy , $start , $end ) ;
}
sub dofloor {
    local ( $xx , $yy , $start , $end ) = @_ ;
    print "pbmx = $pbmx\n" ; 
    print  ( "floor " , $xx , " : " , $yy, "\n" ) ;
    $y = $yy ; 
    for ( $x = $xx - $end ; $x <= $xx - $start ; $x ++ ) {
	$i0 = $x + ($y-1) * $pbmx ; $c[$i0] = $high;
    }
    $x = $xx ; 
    for ( $y = $yy - $end ; $y <= $yy - $start ; $y ++ ) {
	$i0 = $x + ($y-1) * $pbmx ; $c[$i0] = $high;
    }
}
sub doceil {
    local ( $xx , $yy , $start , $end ) = @_ ;
    $y = $yy ; 
    for ( $x = $xx + $start ; $x <= $xx + $end ; $x ++ ) {
	$i0 = $x + ($y-1) * $pbmx ; $c[$i0] = $high;
    }
    $x = $xx ; 
    for ( $y = $yy + $start ; $y <= $yy + $end ; $y ++ ) {
	$i0 = $x + ($y-1) * $pbmx ; $c[$i0] = $high;
    }
}
sub checkdraw {
#    local ($x,$y) = @_ ;
#    $x -= $dx ;
#    $y -= $dy ;
    return     if ( $x > $pbmx || $y > $pbmy ); 
    if ( $circle ) {
	$rc = ($x-$centrex)**2 + ($y-$centrey)**2  ;
	if ( $rc > $radius )  {
	    $p = 1.0 - ( $rc/$radius - 1.0 ) / $shelf ;
	    if ( $p <= 0.0 || rand() > $p ) {
		return ;
	    }
	}
    }
    if ( $circle2 ) {
	$rc = ($x-$ex)**2*$efx + ($y-$ey)**2 + $elip * ($y-$ey) * ($x-$ex) ;
	if ( $rc < $re )  {
	    $p = 1.0 - ( 1.0 - $rc/$re ) / $eshelf ;
	    if ( $p <= 0.0 || rand() > $p ) {
		return ; 
	    }
	}
    }
    $i0 = $x + ($y-1) * $pbmx ; $c[$i0] = $high;
    
}				# 
				# 
				# 
    if ( $pbmplot ) {
	$tot = 0 ; 
	$i0 = 0 ; 
	for ( $i = 1 ; $i <= $pbmy ; $i ++ ) {
	    for ( $j = 1 ; $j <= $pbmx ; $j ++ ) {
		$i0 ++ ;
	    print PBM  "$c[$i0] " ;
	    $tot += $c[$i0] ;
	}

	print PBM  "\n" ;
    }

# bottom line 
    close ( PBM ) ; 
    print STDERR "$tot pixels high out of $P\n" ; 
}
    print STDERR "\n# xv $pbmfile\n" ;

 

sub dorepeat {
    $x += $period ; 
    &checkdraw ;
    $y += $period ; 
    &checkdraw ;
    $x -= $period ; 
    &checkdraw ;
    if ( $repeat > 2 ) {
	$y += $period ; 
	&checkdraw ;
	$x += $period ; 
	&checkdraw ;
	$x += $period ; 
	&checkdraw ;
	$y -= $period ; 
	&checkdraw ;
	$y -= $period ; 
	&checkdraw ;
    }	
}
sub doit {
    # off is the offset for the very first stripe
    $off = ($t+$o0) % $lwidth + 1 ;
    # off2 is the offset in the current stripe, which rotates.
    $off2 = $off ;
    $off3 = $off + $oh ;
    for ( $s = 1 ; $s <= $period ; $s ++ ) {
	if ( $off2 >= $lwidth ) { $off2 -= $lwidth ; }
	if ( $off3 >= $lwidth ) { $off3 -= $lwidth ; }
	if ( $off3 < $onwidth ) {
	    $x = $period+1-$t ; $y = $period+1-$s ;
	    &checkdraw ;
	    if ( $repeat ) {
		&dorepeat ; 
	    }
	}
	if ( $off2 < $onwidth ) {
	    $x = $s ; $y = $t ; 
	    &checkdraw ;
	    if ( $repeat ) {
		&dorepeat ; 
	    }
	}			# 
	$off2 ++ ;
	$off3 ++ ;
    }
}