text: from __future__ import print_function, division
  
  from threading import RLock
  
  # it is sufficient to import "pyglet" here once
  try:
      import pyglet.gl as pgl
  except ImportError:
      raise ImportError("pyglet is required for plotting.\n "
                        "visit http://www.pyglet.org/")
  
  from sympy.core.compatibility import is_sequence, SYMPY_INTS
  from sympy.core.numbers import Integer
  from sympy.geometry.entity import GeometryEntity
  from sympy.plotting.pygletplot.plot_axes import PlotAxes
  from sympy.plotting.pygletplot.plot_mode import PlotMode
  from sympy.plotting.pygletplot.plot_object import PlotObject
  from sympy.plotting.pygletplot.plot_window import PlotWindow
  from sympy.plotting.pygletplot.util import parse_option_string
  from sympy.utilities.decorator import doctest_depends_on
  
  from time import sleep
  from os import getcwd, listdir
  
  import ctypes
  
  @doctest_depends_on(modules=('pyglet',))
  class PygletPlot(object):
      """
      Plot Examples
      =============
  
      See examples/advanced/pyglet_plotting.py for many more examples.
  
      >>> from sympy.plotting.pygletplot import PygletPlot as Plot
      >>> from sympy.abc import x, y, z
  
      >>> Plot(x*y**3-y*x**3)
      [0]: -x**3*y + x*y**3, 'mode=cartesian'
  
      >>> p = Plot()
      >>> p[1] = x*y
      >>> p[1].color = z, (0.4,0.4,0.9), (0.9,0.4,0.4)
  
      >>> p = Plot()
      >>> p[1] =  x**2+y**2
      >>> p[2] = -x**2-y**2
  
  
      Variable Intervals
      ==================
  
      The basic format is [var, min, max, steps], but the
      syntax is flexible and arguments left out are taken
      from the defaults for the current coordinate mode:
  
      >>> Plot(x**2) # implies [x,-5,5,100]
      [0]: x**2, 'mode=cartesian'
      >>> Plot(x**2, [], []) # [x,-1,1,40], [y,-1,1,40]
      [0]: x**2, 'mode=cartesian'
      >>> Plot(x**2-y**2, [100], [100]) # [x,-1,1,100], [y,-1,1,100]
      [0]: x**2 - y**2, 'mode=cartesian'
      >>> Plot(x**2, [x,-13,13,100])
      [0]: x**2, 'mode=cartesian'
      >>> Plot(x**2, [-13,13]) # [x,-13,13,100]
      [0]: x**2, 'mode=cartesian'
      >>> Plot(x**2, [x,-13,13]) # [x,-13,13,10]
      [0]: x**2, 'mode=cartesian'
      >>> Plot(1*x, [], [x], mode='cylindrical')
      ... # [unbound_theta,0,2*Pi,40], [x,-1,1,20]
      [0]: x, 'mode=cartesian'
  
  
      Coordinate Modes
      ================
  
      Plot supports several curvilinear coordinate modes, and
      they independent for each plotted function. You can specify
      a coordinate mode explicitly with the 'mode' named argument,
      but it can be automatically determined for Cartesian or
      parametric plots, and therefore must only be specified for
      polar, cylindrical, and spherical modes.
  
      Specifically, Plot(function arguments) and Plot[n] =
      (function arguments) will interpret your arguments as a
      Cartesian plot if you provide one function and a parametric
      plot if you provide two or three functions. Similarly, the
      arguments will be interpreted as a curve if one variable is
      used, and a surface if two are used.
  
      Supported mode names by number of variables:
  
      1: parametric, cartesian, polar
      2: parametric, cartesian, cylindrical = polar, spherical
  
      >>> Plot(1, mode='spherical')
  
  
      Calculator-like Interface
      =========================
  
      >>> p = Plot(visible=False)
      >>> f = x**2
      >>> p[1] = f
      >>> p[2] = f.diff(x)
      >>> p[3] = f.diff(x).diff(x)
      >>> p
      [1]: x**2, 'mode=cartesian'
      [2]: 2*x, 'mode=cartesian'
      [3]: 2, 'mode=cartesian'
      >>> p.show()
      >>> p.clear()
      >>> p
      <blank plot>
      >>> p[1] =  x**2+y**2
      >>> p[1].style = 'solid'
      >>> p[2] = -x**2-y**2
      >>> p[2].style = 'wireframe'
      >>> p[1].color = z, (0.4,0.4,0.9), (0.9,0.4,0.4)
      >>> p[1].style = 'both'
      >>> p[2].style = 'both'
      >>> p.close()
  
  
      Plot Window Keyboard Controls
      =============================
  
      Screen Rotation:
          X,Y axis      Arrow Keys, A,S,D,W, Numpad 4,6,8,2
          Z axis        Q,E, Numpad 7,9
  
      Model Rotation:
          Z axis        Z,C, Numpad 1,3
  
      Zoom:             R,F, PgUp,PgDn, Numpad +,-
  
      Reset Camera:     X, Numpad 5
  
      Camera Presets:
          XY            F1
          XZ            F2
          YZ            F3
          Perspective   F4
  
      Sensitivity Modifier: SHIFT
  
      Axes Toggle:
          Visible       F5
          Colors        F6
  
      Close Window:     ESCAPE
  
      =============================
  
      """
  
      @doctest_depends_on(modules=('pyglet',))
      def __init__(self, *fargs, **win_args):
          """
          Positional Arguments
          ====================
  
          Any given positional arguments are used to
          initialize a plot function at index 1. In
          other words...
  
          >>> from sympy.plotting.pygletplot import PygletPlot as Plot
          >>> from sympy.abc import x
          >>> p = Plot(x**2, visible=False)
  
          ...is equivalent to...
  
          >>> p = Plot(visible=False)
          >>> p[1] = x**2
  
          Note that in earlier versions of the plotting
          module, you were able to specify multiple
          functions in the initializer. This functionality
          has been dropped in favor of better automatic
          plot plot_mode detection.
  
  
          Named Arguments
          ===============
  
          axes
              An option string of the form
              "key1=value1; key2 = value2" which
              can use the following options:
  
              style = ordinate
                  none OR frame OR box OR ordinate
  
              stride = 0.25
                  val OR (val_x, val_y, val_z)
  
              overlay = True (draw on top of plot)
                  True OR False
  
              colored = False (False uses Black,
                               True uses colors
                               R,G,B = X,Y,Z)
                  True OR False
  
              label_axes = False (display axis names
                                  at endpoints)
                  True OR False
  
          visible = True (show immediately
              True OR False
  
  
          The following named arguments are passed as
          arguments to window initialization:
  
          antialiasing = True
              True OR False
  
          ortho = False
              True OR False
  
          invert_mouse_zoom = False
              True OR False
  
          """
          # Register the plot modes
          from . import plot_modes # noqa
  
          self._win_args = win_args
          self._window = None
  
          self._render_lock = RLock()
  
          self._functions = {}
          self._pobjects = []
          self._screenshot = ScreenShot(self)
  
          axe_options = parse_option_string(win_args.pop('axes', ''))
          self.axes = PlotAxes(**axe_options)
          self._pobjects.append(self.axes)
  
          self[0] = fargs
          if win_args.get('visible', True):
              self.show()
  
      ## Window Interfaces
  
      def show(self):
          """
          Creates and displays a plot window, or activates it
          (gives it focus) if it has already been created.
          """
          if self._window and not self._window.has_exit:
              self._window.activate()
          else:
              self._win_args['visible'] = True
              self.axes.reset_resources()
  
              #if hasattr(self, '_doctest_depends_on'):
              #    self._win_args['runfromdoctester'] = True
  
              self._window = PlotWindow(self, **self._win_args)
  
      def close(self):
          """
          Closes the plot window.
          """
          if self._window:
              self._window.close()
  
      def saveimage(self, outfile=None, format='', size=(600, 500)):
          """
          Saves a screen capture of the plot window to an
          image file.
  
          If outfile is given, it can either be a path
          or a file object. Otherwise a png image will
          be saved to the current working directory.
          If the format is omitted, it is determined from
          the filename extension.
          """
          self._screenshot.save(outfile, format, size)
  
      ## Function List Interfaces
  
      def clear(self):
          """
          Clears the function list of this plot.
          """
          self._render_lock.acquire()
          self._functions = {}
          self.adjust_all_bounds()
          self._render_lock.release()
  
      def __getitem__(self, i):
          """
          Returns the function at position i in the
          function list.
          """
          return self._functions[i]
  
      def __setitem__(self, i, args):
          """
          Parses and adds a PlotMode to the function
          list.
          """
          if not (isinstance(i, (SYMPY_INTS, Integer)) and i >= 0):
              raise ValueError("Function index must "
                               "be an integer >= 0.")
  
          if isinstance(args, PlotObject):
              f = args
          else:
              if (not is_sequence(args)) or isinstance(args, GeometryEntity):
                  args = [args]
              if len(args) == 0:
                  return  # no arguments given
              kwargs = dict(bounds_callback=self.adjust_all_bounds)
              f = PlotMode(*args, **kwargs)
  
          if f:
              self._render_lock.acquire()
              self._functions[i] = f
              self._render_lock.release()
          else:
              raise ValueError("Failed to parse '%s'."
                      % ', '.join(str(a) for a in args))
  
      def __delitem__(self, i):
          """
          Removes the function in the function list at
          position i.
          """
          self._render_lock.acquire()
          del self._functions[i]
          self.adjust_all_bounds()
          self._render_lock.release()
  
      def firstavailableindex(self):
          """
          Returns the first unused index in the function list.
          """
          i = 0
          self._render_lock.acquire()
          while i in self._functions:
              i += 1
          self._render_lock.release()
          return i
  
      def append(self, *args):
          """
          Parses and adds a PlotMode to the function
          list at the first available index.
          """
          self.__setitem__(self.firstavailableindex(), args)
  
      def __len__(self):
          """
          Returns the number of functions in the function list.
          """
          return len(self._functions)
  
      def __iter__(self):
          """
          Allows iteration of the function list.
          """
          return self._functions.itervalues()
  
      def __repr__(self):
          return str(self)
  
      def __str__(self):
          """
          Returns a string containing a new-line separated
          list of the functions in the function list.
          """
          s = ""
          if len(self._functions) == 0:
              s += "<blank plot>"
          else:
              self._render_lock.acquire()
              s += "\n".join(["%s[%i]: %s" % ("", i, str(self._functions[i]))
                              for i in self._functions])
              self._render_lock.release()
          return s
  
      def adjust_all_bounds(self):
          self._render_lock.acquire()
          self.axes.reset_bounding_box()
          for f in self._functions:
              self.axes.adjust_bounds(self._functions[f].bounds)
          self._render_lock.release()
  
      def wait_for_calculations(self):
          sleep(0)
          self._render_lock.acquire()
          for f in self._functions:
              a = self._functions[f]._get_calculating_verts
              b = self._functions[f]._get_calculating_cverts
              while a() or b():
                  sleep(0)
          self._render_lock.release()
  
  class ScreenShot:
      def __init__(self, plot):
          self._plot = plot
          self.screenshot_requested = False
          self.outfile = None
          self.format = ''
          self.invisibleMode = False
          self.flag = 0
  
      def __bool__(self):
          return self.screenshot_requested
  
      def _execute_saving(self):
          if self.flag < 3:
              self.flag += 1
              return
  
          size_x, size_y = self._plot._window.get_size()
          size = size_x*size_y*4*ctypes.sizeof(ctypes.c_ubyte)
          image = ctypes.create_string_buffer(size)
          pgl.glReadPixels(0, 0, size_x, size_y, pgl.GL_RGBA, pgl.GL_UNSIGNED_BYTE, image)
          from PIL import Image
          im = Image.frombuffer('RGBA', (size_x, size_y),
                                image.raw, 'raw', 'RGBA', 0, 1)
          im.transpose(Image.FLIP_TOP_BOTTOM).save(self.outfile, self.format)
  
          self.flag = 0
          self.screenshot_requested = False
          if self.invisibleMode:
              self._plot._window.close()
  
      def save(self, outfile=None, format='', size=(600, 500)):
          self.outfile = outfile
          self.format = format
          self.size = size
          self.screenshot_requested = True
  
          if not self._plot._window or self._plot._window.has_exit:
              self._plot._win_args['visible'] = False
  
              self._plot._win_args['width'] = size[0]
              self._plot._win_args['height'] = size[1]
  
              self._plot.axes.reset_resources()
              self._plot._window = PlotWindow(self._plot, **self._plot._win_args)
              self.invisibleMode = True
  
          if self.outfile is None:
              self.outfile = self._create_unique_path()
              print(self.outfile)
  
      def _create_unique_path(self):
          cwd = getcwd()
          l = listdir(cwd)
          path = ''
          i = 0
          while True:
              if not 'plot_%s.png' % i in l:
                  path = cwd + '/plot_%s.png' % i
                  break
              i += 1
          return path
  