package Manticore::Geometry::Polygon;

use strict;
use warnings;

use POSIX;
use Math::Trig;

use Manticore::Geometry::Vector;

# Data representation:
#  List of {p=>polygon, v=>value}
#  Each of these polygons shall be normalized, hence intersection free with itself
#  Value is summarized if several polygons are around the same point
#  Polygons are a list of points
sub new {
  my ($pkg, $pts) = @_;
  return bless $pts;
}

# Angle between 3 points A B C, that is between the line segments AB and BC
sub _threePointAngular {
  my ($A, $B, $C) = @_;
  my $AB = $B->diff($A);
  my $BC = $C->diff($B);
  #$_ = $_->asFloatVector($_) for $AB, $BC;
  #my $cos = $AB->scalar($BC)/$AB->size()/$BC->size();
  #my $phi = acos($cos);
  #$phi -= 2*pi if $phi>pi;
  #return $phi;
  my $phi = $BC->angle() - $AB->angle();
  $phi -= 2*pi if $phi>pi;
  $phi += 2*pi if $phi<-pi;
  return $phi
}

# Count of full circles done by the polygon, that is the
# Angular sum over all corners divided by 2pi;
# shall be 1 for normalized polygons
# computed as floats as we only need the precision of what multiple
# of 2pi it is
# the result is then rounded to the next integer number
sub fullCircles {
  my $self = shift;
  my $sum = 0;
  for(0..$#$self) {
    $sum += _threePointAngular(@{$self}[$_-2,$_-1,$_]);
  }
  my $ret = $sum/(2*pi);
  floor($ret+0.5)
}


1;