File Coverage

blib/lib/Math/PlanePath/HexSpiralSkewed.pm

Criterion	Covered	Total	%
statement	100	126	79.3
branch	16	24	66.6
condition	1	2	50.0
subroutine	22	24	91.6
pod	4	4	100.0
total	143	180	79.4

# Copyright 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020 Kevin Ryde

# This file is part of Math-PlanePath.
#
# Math-PlanePath 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 3, or (at your option) any later
# version.
#
# Math-PlanePath 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 Math-PlanePath.  If not, see .


package Math::PlanePath::HexSpiralSkewed;
use 5.004;
use strict;
#use List::Util 'max';
*max = \&Math::PlanePath::_max;

use vars '$VERSION', '@ISA';
$VERSION = 129;
use Math::PlanePath;
*_sqrtint = \&Math::PlanePath::_sqrtint;
@ISA = ('Math::PlanePath');

use Math::PlanePath::HexSpiral;
use Math::PlanePath::Base::Generic
  'round_nearest';

# uncomment this to run the ### lines
#use Devel::Comments;


use Math::PlanePath::SquareSpiral;
*parameter_info_array = \&Math::PlanePath::SquareSpiral::parameter_info_array;
use constant xy_is_visited => 1;

use constant dx_minimum => -1;
use constant dx_maximum => 1;
use constant dy_minimum => -1;
use constant dy_maximum => 1;

use constant 1.02 _UNDOCUMENTED__dxdy_list => (1,0,   # E    four plus
                                               0,1,   # N    NW and SE
                                               -1,1,  # NW
                                               -1,0,  # W
                                               0,-1,  # S
                                               1,-1,  # SE
                                              );
*x_negative_at_n = \&Math::PlanePath::HexSpiral::x_negative_at_n;
*y_negative_at_n
  = \&Math::PlanePath::HexSpiral::y_negative_at_n;
*_UNDOCUMENTED__dxdy_list_at_n
  = \&Math::PlanePath::HexSpiral::_UNDOCUMENTED__dxdy_list_at_n;

use constant dsumxy_minimum => -1; # W,S straight
use constant dsumxy_maximum => 1;  # N,E straight
use constant ddiffxy_minimum => -2; # NW diagonal
use constant ddiffxy_maximum => 2;  # SE diagonal
use constant dir_maximum_dxdy => (1,-1); # South-East

use constant turn_any_right => 0; # only left or straight
sub _UNDOCUMENTED__turn_any_left_at_n {
  my ($self) = @_;
  return $self->n_start + $self->{'wider'} + 1;
}


#------------------------------------------------------------------------------

sub new {
  my $self = shift->SUPER::new (@_);

  # parameters
  $self->{'wider'} ||= 0;  # default
  if (! defined $self->{'n_start'}) {
    $self->{'n_start'} = $self->default_n_start;
  }

  return $self;
}

# Same as HexSpiral, but diagonal down and to the left is the downwards
# vertical at x=-$w_left.

sub n_to_xy {
  my ($self, $n) = @_;
  ### HexSpiralSkewed n_to_xy(): $n

  $n = $n - $self->{'n_start'};  # N=0 basis
  if ($n < 0) { return; }

  my $w = $self->{'wider'};
  my $w_right = int($w/2);
  my $w_left = $w - $w_right;
  #### $w
  #### $w_left
  #### $w_right

  my $d = int((_sqrtint(3*$n + ($w+2)*$w + 1) - 1 - $w) / 3);
  #### d frac: (_sqrtint(3*$n + ($w+2)*$w + 1) - 1 - $w) / 3
  #### $d
  $n -= (3*$d + 2 + 2*$w)*$d + 1;
  #### remainder: $n

  $n += 1; # N=1 basis

  if ($n <= $d+1+$w) {
    #### bottom horizontal
    return ($n - $w_left,
            -$d);
  }
  $n -= $d+1+$w;
  if ($n <= $d) {
    #### right lower vertical, being 1 shorter: $n
    return ($d + 1 + $w_right,
            $n - $d);
  }
  $n -= $d;
  if ($n <= $d+1) {
    #### right upper diagonal: $n
    return (-$n + $d + 1 + $w_right,
            $n);
  }
  $d = $d + 1; # no warnings if $d==infinity
  $n -= $d;
  if ($n <= $d+$w) {
    #### top horizontal
    return (-$n + $w_right,
            $d);
  }
  $n -= $d+$w;
  if ($n <= $d) {
    #### left upper vertical
    return (-$d - $w_left,
            -$n + $d);
  }
  #### left lower diagonal
  $n -= $d;
  return ($n - $d - $w_left,
          -$n);
}

sub xy_to_n {
  my ($self, $x, $y) = @_;
  ### xy_to_n(): "$x, $y"

  $x = round_nearest ($x);
  $y = round_nearest ($y);

  my $w = $self->{'wider'};
  my $w_right = int($w/2);
  my $w_left = $w - $w_right;

  if ($y > 0) {
    $x -= $w_right;
    if ($x < -$y-$w) {
      ### left upper vertical
      my $d = -$x - $w;
      ### $d
      ### base: (3*$d + 1 + 2*$w)*$d
      return ((3*$d + 1 + 2*$w)*$d
              - $y
              + $self->{'n_start'});
    } else {
      my $d = $y + max($x,0);
      ### right upper diagonal and top horizontal
      ### $d
      ### base: (3*$d - 1 + 2*$w)*$d - $w
      return ((3*$d - 1 + 2*$w)*$d - $w
              - $x
              + $self->{'n_start'});
    }

  } else {
    # $y < 0
    $x += $w_left;
    if ($x-$w <= -$y) {
      my $d = -$y + max(-$x,0);
      ### left lower diagonal and bottom horizontal
      ### $d
      ### base: (3*$d + 2 + 2*$w)*$d + 1
      return ((3*$d + 2 + 2*$w)*$d
              + $x
              + $self->{'n_start'});
    } else {
      ### right lower vertical
      my $d = $x - $w;
      ### $d
      ### base: (3*$d - 2 + 2*$w)*$d + 1 - $w
      return ((3*$d - 2 + 2*$w)*$d - $w
              + $y
              + $self->{'n_start'});
    }
  }
}

# not exact
sub rect_to_n_range {
  my ($self, $x1,$y1, $x2,$y2) = @_;
  ### HexSpiralSkewed rect_to_n_range(): $x1,$y1, $x2,$y2

  $x1 = round_nearest ($x1);
  $y1 = round_nearest ($y1);
  $x2 = round_nearest ($x2);
  $y2 = round_nearest ($y2);

  my $w = $self->{'wider'};
  my $w_right = int($w/2);
  my $w_left = $w - $w_right;

  my $d = 0;
  foreach my $x ($x1, $x2) {
    $x += $w_left;
    if ($x >= $w) {
      $x -= $w;
    }
    foreach my $y ($y1, $y2) {
      $d = max ($d,
                (($y > 0) == ($x > 0)
                 ? abs($x) + abs($y)      # top right or bottom left diagonals
                 : max(abs($x),abs($y)))); # top left or bottom right squares
    }
  }
  $d += 1;

  # diagonal downwards bottom right being the end of a revolution
  # s=0
  # s=1  n=7
  # s=2  n=19
  # s=3  n=37
  # s=4  n=61
  # n = 3*$d*$d + 3*$d + 1
  #
  ### gives: "sum $d is " . (3*$d*$d + 3*$d + 1)

  # ENHANCE-ME: find actual minimum if rect doesn't cover 0,0
  return ($self->{'n_start'},
          (3*$d + 3 + 2*$self->{'wider'})*$d + $self->{'n_start'});
}

1;
__END__