program main

c*********************************************************************72
c
cc MAIN is the main program for POLYGON_TRIANGULATE_PRB.
c
c  Discussion:
c
c    POLYGON_TRIANGULATE_PRB tests the POLYGON_TRIANGULATE library.
c
c  Licensing:
c
c    This code is distributed under the GNU LGPL license.
c
c  Modified:
c
c    05 May 2014
c
c  Author:
c
c    John Burkardt
c
      implicit none

      call timestamp ( )
      write ( *, '(a)' ) ''
      write ( *, '(a)' ) 'POLYGON_TRIANGULATE_PRB'
      write ( *, '(a)' ) '  FORTRAN77 version.'
      write ( *, '(a)' ) '  Test the POLYGON_TRIANGULATE library.'

      call test01 ( )

      call test02 ( 'comb' )
      call test02 ( 'hand' )
      call test02 ( 'i18' )

      call test03 ( 'comb' )
      call test03 ( 'hand' )
      call test03 ( 'i18' )
c
c  Terminate.
c
      write ( *, '(a)' ) ''
      write ( *, '(a)' ) 'POLYGON_TRIANGULATE_PRB'
      write ( *, '(a)' ) '  Normal end of execution.'
      write ( *, '(a)' ) ''
      call timestamp ( )

      return
      end
      subroutine test01 ( )

c*********************************************************************72
c
cc TEST01 tests the "comb_10" polygon.
c
c  Discussion:
c
c    There are N-3 triangles in the triangulation.
c
c    For the first N-2 triangles, the first edge listed is always an
c    internal diagonal.
c
c  Licensing:
c
c    This code is distributed under the GNU LGPL license.
c
c  Modified:
c
c    04 May 2014
c
      implicit none

      integer n
      parameter ( n = 10 )

      integer triangles(3,n-2)
      double precision x(n)
      double precision y(n)

      save x
      save y

      data x /
     &  8.0D+00, 7.0D+00, 6.0D+00, 5.0D+00, 4.0D+00,
     &  3.0D+00, 2.0D+00, 1.0D+00, 0.0D+00, 4.0D+00 /
      data y /
     &   0.0D+00, 10.0D+00,  0.0D+00, 10.0D+00,  0.0D+00,
     &  10.0D+00,  0.0D+00, 10.0D+00,  0.0D+00, -2.0D+00 /

      write ( *, '(a)' ) ''
      write ( *, '(a)' ) 'TEST01'
      write ( *, '(a)' ) '  Triangulate the comb_10 polygon.'

      call polygon_triangulate ( n, x, y, triangles )

      call i4mat_print ( 3, n - 2, triangles, '  Triangles' )

      return
      end
      subroutine test02 ( prefix )

c*********************************************************************72
c
cc TEST02 triangulates a polygon described in a file.
c
c  Licensing:
c
c    This code is distributed under the GNU LGPL license.
c
c  Modified:
c
c    04 May 2014
c
c  Author:
c
c    John Burkardt.
c
      implicit none

      integer n_max
      parameter ( n_max = 100 )

      integer dim_num
      character * ( 255 ) element_filename
      integer n
      character * ( 255 ) node_filename
      character * ( * ) prefix
      integer triangle_num
      integer triangles(3,n_max-2)
      double precision xy(2,n_max)
c
c  Create filenames.
c
      node_filename = trim ( prefix ) // '_nodes.txt'
      element_filename = trim ( prefix ) // '_elements.txt'

      write ( *, '(a)' ) ''
      write ( *, '(a)' ) 'TEST02'
      write ( *, '(a)' ) '  Read polygon coordinates in "'
     &  // trim ( node_filename ) // '"'
c
c  Read the node coordinates.
c
      call r8mat_header_read ( node_filename, dim_num, n )

      call r8mat_data_read ( node_filename, 2, n, xy )
c
c  Get the triangulation.
c
      call polygon_triangulate ( n, xy(1,:), xy(2,:), triangles )
c
c  Write the triangulation to a file.
c
      triangle_num = n - 2
      call i4mat_write ( element_filename, 3, triangle_num, triangles )

      write ( *, '(a)' ) '  Write triangulation to "'
     &  // trim ( element_filename ) // '"'

      return
      end
      subroutine test03 ( prefix )

c*********************************************************************72
c
cc TEST03 plots a triangulation.
c
c  Licensing:
c
c    This code is distributed under the GNU LGPL license.
c
c  Modified:
c
c    04 May 2014
c
c  Author:
c
c    John Burkardt.
c
      implicit none

      integer n_max
      parameter ( n_max = 100 )

      character * ( 255 ) command_filename
      integer command_unit
      character * ( 255 ) diagonal_filename
      integer diagonal_unit
      integer dim_num
      character * ( 255 ) edge_filename
      integer edge_unit
      integer i
      integer i2
      integer j
      integer j2
      integer n
      integer node
      character * ( 255 ) node_filename
      character * ( 255 ) plot_filename
      character * ( * ) prefix
      integer triangle_num
      integer triangles(3,n_max-3)
      double precision xy(2,n_max)
c
c  Create filenames.
c
      node_filename = trim ( prefix ) // '_nodes.txt'
      edge_filename = trim ( prefix ) // '_edges.txt'
      diagonal_filename = trim ( prefix ) // '_diagonals.txt'
      command_filename = trim ( prefix ) // '_commands.txt'
      plot_filename = trim ( prefix ) // '.png'

      write ( *, '(a)' ) ''
      write ( *, '(a)' ) 'TEST03'
      write ( *, '(a)' ) 
     &  '  Read node coordinates in "' // trim ( node_filename ) // '"'
c
c  Read the node coordinates.
c
      call r8mat_header_read ( node_filename, dim_num, n )

      call r8mat_data_read ( node_filename, 2, n, xy )
c
c  Get the triangulation.
c
      call polygon_triangulate ( n, xy(1,:), xy(2,:), triangles )
c
c  Plot the edges.
c
      call get_unit ( edge_unit )
      open ( unit = edge_unit, file = edge_filename, 
     &  status = 'replace' )

      do j = 1, n + 1
        j2 = mod ( j - 1, n ) + 1
        write ( edge_unit, '(g14.6,2x,g14.6)' ) xy(1,j2), xy(2,j2)
      end do

      close ( unit = edge_unit )
c
c  Plot the diagonals.
c
      call get_unit ( diagonal_unit )
      open ( unit = diagonal_unit, file = diagonal_filename, 
     &  status = 'replace' )

      do j = 1, n - 3
        do i = 1, 2
          node = triangles(i,j)
          write ( diagonal_unit, '(g14.6,2x,g14.6)' ) 
     &      xy(1,node), xy(2,node)
        end do
        write ( diagonal_unit, '(1x)' )
      end do

      close ( unit = diagonal_unit )
c
c  Write the GNUPLOT command file.
c
      call get_unit ( command_unit )
      open ( unit = command_unit, file = command_filename, 
     &  status = 'replace' )

      write ( command_unit, '(a)' ) '# ' // trim ( command_filename )
      write ( command_unit, '(a)' ) '#'
      write ( command_unit, '(a)' ) '# Usage:'
      write ( command_unit, '(a)' ) 
     &  '#  gnuplot < ' // trim ( command_filename )
      write ( command_unit, '(a)' ) '#'
      write ( command_unit, '(a)' ) 'set term png'
      write ( command_unit, '(a)' ) 
     &  'set output "' // trim ( plot_filename ) // '"'
      write ( command_unit, '(a)' ) 'set nokey'
      write ( command_unit, '(a)' ) 'set size ratio 1'
      write ( command_unit, '(a)' ) 'set timestamp'
      write ( command_unit, '(a)' ) 'set xlabel "<---X--->"'
      write ( command_unit, '(a)' ) 'set ylabel "<---Y--->"'
      write ( command_unit, '(a)' ) 
     &  'set title "Edges (green) and Diagonals (red)"'
      write ( command_unit, '(a)' ) 'set grid'
      write ( command_unit, '(a)' ) 'set style data lines'
      write ( command_unit, '(a)' ) 
     &  'plot "' // trim ( edge_filename ) // 
     &  '" using 1:2 lw 3 linecolor rgb "green",\'
      write ( command_unit, '(a)' ) 
     &  '     "' // trim ( diagonal_filename ) //
     &  '" using 1:2 lw 3 linecolor rgb "red",\'
      write ( command_unit, '(a)' ) 
     &  '     "' // trim ( node_filename ) //
     &  '" using 1:2 with points pt 7 ps 2 lc rgb "black"'

      close ( unit = command_unit )

      write ( *, '(a)' ) ''
      write ( *, '(a)' ) 
     &  '  Write edges to "' // trim ( edge_filename ) // '"'
      write ( *, '(a)' ) 
     &  '  Write diagonals to "' // trim ( diagonal_filename ) // '"'
      write ( *, '(a)' ) 
     &  '  Write gnuplot commands to "' 
     &  // trim ( command_filename ) // '"'

      return
      end