#!/usr/bin/perl
use OpenGL ':all';
use Math::Trig;
use Data::Dumper;
use strict;

my $Window = undef;
my $Width = 500.0;
my $Height = 500.0;
my %config;

my $pos = 0;

sub Resize() {
   glViewport(0, 0, $Width, $Height);
   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
   gluPerspective(45.0,1.0,0.1,500.0);
   glMatrixMode(GL_MODELVIEW);
}

my ($x_rot, $y_rot, $zoom) = (0, 0, -80);

sub render()
{
   my ($section_name, $section, $vertices, $triangles, $positions,
      $strips, $item, $colors);
      
   glLoadIdentity();
   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
   
   glTranslatef( 0.0, -5.0, $zoom );
   
   glRotatef( $x_rot, 1.0, 0.0, 0.0 );
   glRotatef( $y_rot, 0.0, 1.0, 0.0 );
   
   for $section_name (keys %config) {
      $section = $config{$section_name};
      next unless $$section{SectionType} eq 'FRAGMENT';
      
      $vertices = $$section{VERTICES};
      $triangles = $$section{TRIANGLES};
      $strips = $$section{STRIP};
      $positions = $$section{POSITIONS};
      $colors = $$section{COLOURS};
      
      glPushMatrix();
      glTranslatef($$section{POS}[0], $$section{POS}[1], $$section{POS}[2]);
      my $col=0;
      
      for $item ( @$strips )
      {
         glBegin( GL_TRIANGLE_STRIP );
            for( my $i = 0; $i <= $#$item; ++$i ) {
               
               
               $col += 0.1;
               glColor3f(
                  sin($col),
                  cos($col),
                  0.5 );
               glVertex3f(
                  $$positions[$$vertices[$$item[$i]][0]][0],
                  $$positions[$$vertices[$$item[$i]][0]][1],
                  $$positions[$$vertices[$$item[$i]][0]][2],
                );
            }
         glEnd();
      }
      
      $col = 0;
      
      for $item (@$triangles)
      {
         
         glPushMatrix();
         
         glBegin(GL_TRIANGLES);
         
            $col += 0.1;
            glColor3f(
               cos($col),
               0.5,
               0 );
               
            glVertex3f(
               $$positions[$$vertices[$$item[0]][0]][0],
               $$positions[$$vertices[$$item[0]][0]][1],
               $$positions[$$vertices[$$item[0]][0]][2] );
               
            $col += 0.1;
            glColor3f(
               0,
               cos($col),
               0.5 );
               
            glVertex3f(
               $$positions[$$vertices[$$item[1]][0]][0],
               $$positions[$$vertices[$$item[1]][0]][1],
               $$positions[$$vertices[$$item[1]][0]][2] );
               
            $col += 0.1;
            glColor3f(
               0.5,
               0,
               cos($col) );
               
            glVertex3f(
               $$positions[$$vertices[$$item[2]][0]][0],
               $$positions[$$vertices[$$item[2]][0]][1],
               $$positions[$$vertices[$$item[2]][0]][2] );
         glEnd();
         
         glPopMatrix();
      }
      glPopMatrix();
   

   }
   glutSwapBuffers();
}

sub KeyPressed()
{
   my ($key) = uc( chr( shift( ) ) );
   
   if( $key eq 'A' )
      { $y_rot += 10.0 }
   elsif ($key eq 'D')
      { $y_rot -= 10.0 }
   elsif( $key eq 'W' )
      { $x_rot += 10.0 }
   elsif( $key eq 'S' )
      { $x_rot -= 10.0 }
   elsif( $key eq 'Q' )
      { $zoom -= 10.0 }
   elsif( $key eq 'Z' )
      { $zoom += 10.0 }
}

%config = %{&parse_file($ARGV[0])};

glutInit();
glutInitDisplayMode( GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH );
glutInitWindowSize( $Width, $Height );
glutInitWindowPosition( $Width/2, $Height/2 );
$Window = glutCreateWindow("Darwinia Shapefile Viewer");

glutDisplayFunc( \&render );
glutIdleFunc( \&render );
glutReshapeFunc( \&Resize );
glutKeyboardFunc(\&KeyPressed);

# GL
glClearColor( 0.0, 0.0, 0.0, 0.0 );
glClearDepth( 1000.0 );
glDepthFunc( GL_LESS );
glShadeModel( GL_SMOOTH );
glEnable( GL_DEPTH_TEST );
glDisable( GL_CULL_FACE );

Resize();

glutMainLoop();


sub read_line(  )
{
   local $_;
   $_ = '';
   my $file_h = shift;
   
   while( $_ eq '' ) {
      $_ = <$file_h> or return undef;
      chomp();
      tr/,/ /;
      s/\s+/ /g;
      s/#.*$//g;
      s/(^\s)|(\s$)//g;
      s/(\s:)|(:\s)/:/g;
   }
   return uc($_);
   
}


sub parse_file( )
{
   my $file = shift();
   
   my ( %config, $setting, $value, $subsetting, $subvalue, $sub2setting,
      $sub2value, $cur_section );
   
   local $_;
   open( my $file_h, "<$file" ) || die $! ;
   
   for( ;; )
   {
      ($setting, $value) = split( /:/, &read_line( $file_h ) )
         or last;
      
      for( $setting )
      {
         #These set current data context
         ( /^Fragment$/i || /^Marker$/i ) && do {
            $cur_section = $value;
            $config{$cur_section}{SectionType} = $setting;
            last;
         };
         
         #These terminiate current data context
         ( /^EndMarker$/i ) && do {
            $cur_section = '';
            last;
         };
         
          #Space-separated single-line arrays
         ( /^Up$/i || /^Front$/i || /^Pos$/i ) && do {
            $config{$cur_section}{$setting} = [ split(/ /, $value) ];
            last;
         };
         
         # Strips gives count of #r strips
         # each strip gives count of vertices
         # vertices are space-separated and
         # may span multiple lines.
         
         ( /^Strips/i ) && do {
            for( 1 .. $value ) {
               ($subsetting, $subvalue) = split( /:/, &read_line( $file_h ) );
         
               $sub2setting = '';
               while( $sub2setting ne 'VERTS' )
                  {
                     ($sub2setting, $sub2value) = split( /:/, &read_line( $file_h ) );
                     
                  }
                  
               
               $config{$cur_section}{$subsetting}[$subvalue] = [];   

               while( $#{$config{$cur_section}{$subsetting}[$subvalue]} < $sub2value-1 ) {
                  my $line = &read_line( $file_h );
                  $line =~ s/v//gi;
                  push @{$config{$cur_section}{$subsetting}[$subvalue]},
                     split( / /, $line );
               }
            }
            last;
         };
         
         ( /^Colours$/i || /^Vertices$/i || /^Positions$/i ) && do {
            for( 1..$value ) {
               ($subsetting, $subvalue) = split( /:/, &read_line( $file_h ) );
               $config{$cur_section}{$setting}[$subsetting]
                  = [ split(/ /, $subvalue) ];
            }
            last;
         };
         
         ( /^Triangles$/i ) && do {
            $config{$cur_section}{$setting} = [];
            for( 1 .. $value ) {
               push @{$config{$cur_section}{$setting}},
                  [ split( / /, &read_line( $file_h ) ) ];
            }
            last;   
         };
         
         # If nothing else matches it, then just throw it in the hash
         if( $cur_section eq '')
            { $config{$setting} = $value; }
         else
            { $config{$cur_section}{$setting} = $value; }
      }
   }
   
   close( $file_h );
   
   #print Dumper( \%config );
   #die();
   
   return \%config;
}