text: # ----------------------------------------------------------------------------
  # pyglet
  # Copyright (c) 2006-2008 Alex Holkner
  # Copyright (c) 2008-2019 pyglet contributors
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  # ----------------------------------------------------------------------------
  
  """Low-level graphics rendering.
  
  This module provides an efficient low-level abstraction over OpenGL.  It gives
  very good performance for rendering OpenGL primitives. The module is used
  internally by other areas of pyglet.
  
  See the :ref:`programming-guide-graphics` for details on how to use this
  graphics API.
  
  Batches and groups
  ==================
  
  Without even needing to understand the details on how to draw primitives with
  the graphics API, developers can make use of :py:class:`~pyglet.graphics.Batch`
  and :py:class:`~pyglet.graphics.Group` objects to improve performance of sprite
  and text rendering.
  
  The :py:class:`~pyglet.sprite.Sprite`, :py:func:`~pyglet.text.Label` and
  :py:func:`~pyglet.text.layout.TextLayout` classes all accept a ``batch`` and
  ``group`` parameter in their constructors.  A batch manages a set of objects
  that will be drawn all at once, and a group describes the manner in which an
  object is drawn.
  
  The following example creates a batch, adds two sprites to the batch, and then
  draws the entire batch::
      
      batch = pyglet.graphics.Batch()
      car = pyglet.sprite.Sprite(car_image, batch=batch)
      boat = pyglet.sprite.Sprite(boat_image, batch=batch)
      
      def on_draw()
          batch.draw()
  
  Drawing a complete batch is much faster than drawing the items in the batch
  individually, especially when those items belong to a common group.  
  
  Groups describe the OpenGL state required for an item.  This is for the most
  part managed by the sprite and text classes, however you can also use custom
  groups to ensure items are drawn in a particular order. For example, the
  following example adds a background sprite which is guaranteed to be drawn
  before the car and the boat::
  
      batch = pyglet.graphics.Batch()
      background = pyglet.sprite.SpriteGroup(0)
      foreground = pyglet.sprite.SpriteGroup(1)
  
      background = pyglet.sprite.Sprite(background_image, 
                                        batch=batch, group=background)
      car = pyglet.sprite.Sprite(car_image, batch=batch, group=foreground)
      boat = pyglet.sprite.Sprite(boat_image, batch=batch, group=foreground)
      
      def on_draw()
          batch.draw()
  
  It's preferable to manage sprites and text objects within as few batches as
  possible.  If the drawing of sprites or text objects need to be interleaved
  with other drawing that does not use the graphics API, multiple batches will
  be required.
  
  Data item parameters
  ====================
  
  Many of the functions and methods in this module accept any number of ``data``
  parameters as their final parameters.  In the documentation these are notated
  as ``*data`` in the formal parameter list.
  
  A data parameter describes a vertex attribute format and an optional sequence
  to initialise that attribute.  Examples of common attribute formats are:
  
  ``"v3f"``
      Vertex position, specified as three floats.
  ``"c4B"``
      Vertex color, specified as four unsigned bytes.
  ``"t2f"``
      Texture coordinate, specified as two floats.
  
  See `pyglet.graphics.vertexattribute` for the complete syntax of the vertex
  format string.
  
  When no initial data is to be given, the data item is just the format string.
  For example, the following creates a 2 element vertex list with position and
  color attributes::
  
      vertex_list = pyglet.graphics.vertex_list(2, 'v2f', 'c4B')
  
  When initial data is required, wrap the format string and the initial data in
  a tuple, for example::
  
      vertex_list = pyglet.graphics.vertex_list(2, 
                                                ('v2f', (0.0, 1.0, 1.0, 0.0)),
                                                ('c4B', (255, 255, 255, 255) * 2))
  
  Drawing modes
  =============
  
  Methods in this module that accept a ``mode`` parameter will accept any value
  in the OpenGL drawing mode enumeration: ``GL_POINTS``, ``GL_LINE_STRIP``,
  ``GL_LINE_LOOP``, ``GL_LINES``, ``GL_TRIANGLE_STRIP``, ``GL_TRIANGLE_FAN``,
  ``GL_TRIANGLES``, ``GL_QUAD_STRIP``, ``GL_QUADS``, and ``GL_POLYGON``.
  
  :: 
  
      pyglet.graphics.draw(1, GL_POINTS, ('v2i',(10,20)))
  
  However, because of the way the graphics API renders multiple primitives with 
  shared state, ``GL_POLYGON``, ``GL_LINE_LOOP`` and ``GL_TRIANGLE_FAN`` cannot
  be used --- the results are undefined.
  
  When using ``GL_LINE_STRIP``, ``GL_TRIANGLE_STRIP`` or ``GL_QUAD_STRIP`` care
  must be taken to insert degenerate vertices at the beginning and end of each
  vertex list.  For example, given the vertex list::
  
      A, B, C, D
  
  the correct vertex list to provide the vertex list is::
  
      A, A, B, C, D, D
  
  Alternatively, the ``NV_primitive_restart`` extension can be used if it is
  present.  This also permits use of ``GL_POLYGON``, ``GL_LINE_LOOP`` and
  ``GL_TRIANGLE_FAN``.   Unfortunately the extension is not provided by older
  video drivers, and requires indexed vertex lists.
  
  .. versionadded:: 1.1
  """
  import ctypes
  
  import pyglet
  from pyglet.gl import *
  from pyglet.graphics import vertexbuffer, vertexattribute, vertexdomain
  from pyglet.graphics.shader import Shader, ShaderProgram, UniformBufferObject
  from pyglet.graphics.vertexarray import VertexArray
  
  _debug_graphics_batch = pyglet.options['debug_graphics_batch']
  
  
  def draw(size, mode, *data):
      """Draw a primitive immediately.
  
      :Parameters:
          `size` : int
              Number of vertices given
          `mode` : gl primitive type 
              OpenGL drawing mode, e.g. ``GL_TRIANGLES``, 
              avoiding quotes.
          `data` : data items
              Attribute formats and data.  See the module summary for 
              details.
  
      """
      # Create and bind a throwaway VAO
      vao_id = GLuint()
      glGenVertexArrays(1, vao_id)
      glBindVertexArray(vao_id)
      # Activate shader program:
      group = get_default_group()
      group.set_state()
  
      buffers = []
      for fmt, array in data:
          attribute = vertexattribute.create_attribute(group.program.id, fmt)
          assert size == len(array) // attribute.count, 'Data for %s is incorrect length' % fmt
  
          buffer = vertexbuffer.create_buffer(size * attribute.stride, mappable=False)
  
          attribute.set_region(buffer, 0, size, array)
          attribute.enable()
          attribute.set_pointer(buffer.ptr)
  
          buffers.append(buffer)      # Don't garbage collect it.
  
      glDrawArrays(mode, 0, size)
  
      # Deactivate shader program:
      group.unset_state()
      # Discard everything after drawing:
      del buffers
      glBindVertexArray(0)
      glDeleteVertexArrays(1, vao_id)
  
  
  def draw_indexed(size, mode, indices, *data):
      """Draw a primitive with indexed vertices immediately.
  
      :Parameters:
          `size` : int
              Number of vertices given
          `mode` : int
              OpenGL drawing mode, e.g. ``GL_TRIANGLES``
          `indices` : sequence of int
              Sequence of integers giving indices into the vertex list.
          `data` : data items
              Attribute formats and data.  See the module summary for details.
  
      """
      # Create and bind a throwaway VAO
      vao_id = GLuint()
      glGenVertexArrays(1, vao_id)
      glBindVertexArray(vao_id)
      # Activate shader program:
      group = get_default_group()
      group.set_state()
  
      buffers = []
      for fmt, array in data:
          attribute = vertexattribute.create_attribute(group.program.id, fmt)
          assert size == len(array) // attribute.count, 'Data for %s is incorrect length' % fmt
  
          buffer = vertexbuffer.create_buffer(size * attribute.stride, mappable=False)
  
          attribute.set_region(buffer, 0, size, array)
          attribute.enable()
          attribute.set_pointer(buffer.ptr)
          buffers.append(buffer)
  
      if size <= 0xff:
          index_type = GL_UNSIGNED_BYTE
          index_c_type = ctypes.c_ubyte
      elif size <= 0xffff:
          index_type = GL_UNSIGNED_SHORT
          index_c_type = ctypes.c_ushort
      else:
          index_type = GL_UNSIGNED_INT
          index_c_type = ctypes.c_uint
  
      index_array = (index_c_type * len(indices))(*indices)
      glDrawElements(mode, len(indices), index_type, index_array)
      glFlush()
  
      # Deactivate shader program:
      group.unset_state()
      # Discard everything after drawing:
      del buffers
      glBindVertexArray(0)
      glDeleteVertexArrays(1, vao_id)
  
  
  def _parse_data(data):
      """Given a list of data items, returns (formats, initial_arrays)."""
      assert data, 'No attribute formats given'
  
      # Return tuple (formats, initial_arrays).
      formats = []
      initial_arrays = []
      for i, fmt in enumerate(data):
          if isinstance(fmt, tuple):
              fmt, array = fmt
              initial_arrays.append((i, array))
          formats.append(fmt)
      formats = tuple(formats)
      return formats, initial_arrays
  
  
  def get_default_batch():
      try:
          return pyglet.gl.current_context.object_space.pyglet_graphics_default_batch
      except AttributeError:
          pyglet.gl.current_context.object_space.pyglet_graphics_default_batch = Batch()
          return pyglet.gl.current_context.object_space.pyglet_graphics_default_batch
  
  
  def get_default_group():
      try:
          return pyglet.gl.current_context.object_space.pyglet_graphics_default_group
      except AttributeError:
          pyglet.gl.current_context.object_space.pyglet_graphics_default_group = Group()
          return pyglet.gl.current_context.object_space.pyglet_graphics_default_group
  
  
  def vertex_list(count, *data):
      """Create a :py:class:`~pyglet.graphics.vertexdomain.VertexList` not associated with a batch, group or mode.
  
      :Parameters:
          `count` : int
              The number of vertices in the list.
          `data` : data items
              Attribute formats and initial data for the vertex list.  See the
              module summary for details.
  
      :rtype: :py:class:`~pyglet.graphics.vertexdomain.VertexList`
      """
      # Note that mode=0 because the default batch is never drawn: vertex lists
      # returned from this function are drawn directly by their draw() method.
      return get_default_batch().add(count, 0, None, *data)
  
  
  def vertex_list_indexed(count, indices, *data):
      """Create an `IndexedVertexList` not associated with a batch, group or mode.
  
      :Parameters:
          `count` : int
              The number of vertices in the list.
          `indices` : sequence
              Sequence of integers giving indices into the vertex list.
          `data` : data items
              Attribute formats and initial data for the vertex list.  See the
              module summary for details.
  
      :rtype: `IndexedVertexList`
      """
      # Note that mode=0 because the default batch is never drawn: vertex lists
      # returned from this function are drawn directly by their draw() method.
      return get_default_batch().add_indexed(count, 0, None, indices, *data)
  
  
  class Batch:
      """Manage a collection of vertex lists for batched rendering.
  
      Vertex lists are added to a :py:class:`~pyglet.graphics.Batch` using the `add` and `add_indexed`
      methods.  An optional group can be specified along with the vertex list,
      which gives the OpenGL state required for its rendering.  Vertex lists
      with shared mode and group are allocated into adjacent areas of memory and
      sent to the graphics card in a single operation.
  
      Call `VertexList.delete` to remove a vertex list from the batch.
      """
      def __init__(self):
          """Create a graphics batch."""
          # Mapping to find domain.  
          # group -> (attributes, mode, indexed) -> domain
          self.group_map = {}
  
          # Mapping of group to list of children.
          self.group_children = {}
  
          # List of top-level groups
          self.top_groups = []
  
          self._draw_list = []
          self._draw_list_dirty = False
  
          # Each Batch encompasses one VAO
          self.vao = VertexArray()
  
          if _debug_graphics_batch:
              print("Batch created. VAO ID: {0}".format(self.vao.id))
  
      def invalidate(self):
          """Force the batch to update the draw list.
  
          This method can be used to force the batch to re-compute the draw list
          when the ordering of groups has changed.
  
          .. versionadded:: 1.2
          """
          self._draw_list_dirty = True
  
      def add(self, count, mode, group, *data):
          """Add a vertex list to the batch.
  
          :Parameters:
              `count` : int
                  The number of vertices in the list.
              `mode` : int
                  OpenGL drawing mode enumeration; for example, one of
                  ``GL_POINTS``, ``GL_LINES``, ``GL_TRIANGLES``, etc.
                  See the module summary for additional information.
              `group` : `~pyglet.graphics.Group`
                  Group of the vertex list, or ``None`` if no group is required.
              `data` : data items
                  Attribute formats and initial data for the vertex list.  See
                  the module summary for details.
  
          :rtype: :py:class:`~pyglet.graphics.vertexdomain.VertexList`
          """
          formats, initial_arrays = _parse_data(data)
          domain = self._get_domain(False, mode, group, formats)
  
          # Create vertex list and initialize
          vlist = domain.create(count)
          for i, array in initial_arrays:
              vlist.set_attribute_data(i, array)
  
          return vlist
  
      def add_indexed(self, count, mode, group, indices, *data):
          """Add an indexed vertex list to the batch.
  
          :Parameters:
              `count` : int
                  The number of vertices in the list.
              `mode` : int
                  OpenGL drawing mode enumeration; for example, one of
                  ``GL_POINTS``, ``GL_LINES``, ``GL_TRIANGLES``, etc.
                  See the module summary for additional information.
              `group` : `~pyglet.graphics.Group`
                  Group of the vertex list, or ``None`` if no group is required.
              `indices` : sequence
                  Sequence of integers giving indices into the vertex list.
              `data` : data items
                  Attribute formats and initial data for the vertex list.  See
                  the module summary for details.
  
          :rtype: `IndexedVertexList`
          """
          formats, initial_arrays = _parse_data(data)
          domain = self._get_domain(True, mode, group, formats)
  
          # Create vertex list and initialize
          vlist = domain.create(count, len(indices))
          start = vlist.start
          vlist.set_index_data([i + start for i in indices])
          for i, array in initial_arrays:
              vlist.set_attribute_data(i, array)
  
          return vlist
  
      def migrate(self, vertex_list, mode, group, batch):
          """Migrate a vertex list to another batch and/or group.
  
          `vertex_list` and `mode` together identify the vertex list to migrate.
          `group` and `batch` are new owners of the vertex list after migration.  
  
          The results are undefined if `mode` is not correct or if `vertex_list`
          does not belong to this batch (they are not checked and will not
          necessarily throw an exception immediately).
  
          `batch` can remain unchanged if only a group change is desired.
          
          :Parameters:
              `vertex_list` : `~pyglet.graphics.vertexdomain.VertexList`
                  A vertex list currently belonging to this batch.
              `mode` : int
                  The current GL drawing mode of the vertex list.
              `group` : `~pyglet.graphics.Group`
                  The new group to migrate to.
              `batch` : `~pyglet.graphics.Batch`
                  The batch to migrate to (or the current batch).
  
          """
          formats = vertex_list.domain.__formats
          if isinstance(vertex_list, vertexdomain.IndexedVertexList):
              domain = batch._get_domain(True, mode, group, formats)
          else:
              domain = batch._get_domain(False, mode, group, formats)
          vertex_list.migrate(domain)
  
      def _get_domain(self, indexed, mode, group, formats):
          if group is None:
              group = get_default_group()
  
          # Batch group
          if group not in self.group_map:
              self._add_group(group)
  
          # Find domain given formats, indices and mode
          domain_map = self.group_map[group]
          key = (formats, mode, indexed, group.program.id)
          try:
              domain = domain_map[key]
          except KeyError:
              # Create domain
              if indexed:
                  domain = vertexdomain.create_indexed_domain(group.program.id, *formats)
              else:
                  domain = vertexdomain.create_domain(group.program.id, *formats)
              domain.__formats = formats
              domain_map[key] = domain
              self._draw_list_dirty = True
  
          return domain
  
      def _add_group(self, group):
          self.group_map[group] = {}
          self.top_groups.append(group)
          # else:
          #     if group.parent not in self.group_map:
          #         self._add_group(group.parent)
          #     if group.parent not in self.group_children:
          #         self.group_children[group.parent] = []
          #     self.group_children[group.parent].append(group)
          # self._draw_list_dirty = True
  
      def _update_draw_list(self):
          """Visit group tree in preorder and create a list of bound methods
          to call.
          """
  
          def visit(group):
              draw_list = []
  
              # Draw domains using this group
              domain_map = self.group_map[group]
              for (formats, mode, indexed, program_id), domain in list(domain_map.items()):
                  # Remove unused domains from batch
                  if domain.is_empty:
                      del domain_map[(formats, mode, indexed, program_id)]
                      continue
                  draw_list.append((lambda d, m: lambda: d.draw(m))(domain, mode))
  
              # Sort and visit child groups of this group
              children = self.group_children.get(group)
              if children:
                  children.sort()
                  for child in list(children):
                      draw_list.extend(visit(child))
  
              if children or domain_map:
                  return [group.set_state] + draw_list + [group.unset_state]
              else:
                  # Remove unused group from batch
                  del self.group_map[group]
                  # if group.parent:
                  #     self.group_children[group.parent].remove(group)
                  try:
                      del self.group_children[group]
                  except KeyError:
                      pass
                  try:
                      self.top_groups.remove(group)
                  except ValueError:
                      pass
                  return []
  
          self._draw_list = []
  
          self.top_groups.sort()
          for group in list(self.top_groups):
              self._draw_list.extend(visit(group))
  
          self._draw_list_dirty = False
  
          if _debug_graphics_batch:
              self._dump_draw_list()
  
      def _dump_draw_list(self):
          def dump(group, indent=''):
              print(indent, 'Begin group', group)
              domain_map = self.group_map[group]
              for _, domain in domain_map.items():
                  print(indent, '  ', domain)
                  for start, size in zip(*domain.allocator.get_allocated_regions()):
                      print(indent, '    ', 'Region %d size %d:' % (start, size))
                      for key, attribute in domain.attribute_names.items():
                          print(indent, '      ', end=' ')
                          try:
                              region = attribute.get_region(attribute.buffer,
                                                            start, size)
                              print(key, region.array[:])
                          except:
                              print(key, '(unmappable)')
              for child in self.group_children.get(group, ()):
                  dump(child, indent + '  ')
              print(indent, 'End group', group)
  
          print('Draw list for %r:' % self)
          for group in self.top_groups:
              dump(group)
  
      def draw(self):
          """Draw the batch."""
          self.vao.bind()
  
          if self._draw_list_dirty:
              self._update_draw_list()
  
          for func in self._draw_list:
              func()
  
      def draw_subset(self, vertex_lists):
          """Draw only some vertex lists in the batch.
  
          The use of this method is highly discouraged, as it is quite
          inefficient.  Usually an application can be redesigned so that batches
          can always be drawn in their entirety, using `draw`.
  
          The given vertex lists must belong to this batch; behaviour is
          undefined if this condition is not met.
  
          :Parameters:
              `vertex_lists` : sequence of `VertexList` or `IndexedVertexList`
                  Vertex lists to draw.
  
          """
  
          self.vao.bind()
  
          # Horrendously inefficient.
          def visit(group):
              group.set_state()
  
              # Draw domains using this group
              domain_map = self.group_map[group]
              for (_, mode, _, _), domain in domain_map.items():
                  for alist in vertex_lists:
                      if alist.domain is domain:
                          alist.draw(mode)
  
              # Sort and visit child groups of this group
              children = self.group_children.get(group)
              if children:
                  children.sort()
                  for child in children:
                      visit(child)
  
              group.unset_state()
  
          self.top_groups.sort()
          for group in self.top_groups:
              visit(group)
  
  
  class Group:
      """Group of common OpenGL state.
  
      Before a vertex list is rendered, its group's OpenGL state is set.
      This should includes at least the Shader Program, in addition to any
      optional state required.
      """
  
      order = 0
  
      def __init__(self, program=None, order=0):
          """Create a group.
  
          :Parameters:
              `program` : `~pyglet.graphics.shader.ShaderProgram`
                  Optional custom Shader Program.
              `order` : int
                  Change the order to render above or below other Groups.
          """
          self.program = program or default_shader_program
          self.order = order
  
      def set_state(self):
          """Bind the Shader, and apply additional OpenGL state."""
          self.program.use_program()
  
      def unset_state(self):
          """Unbind the Shader, and repeal OpenGL state change."""
          self.program.stop_program()
  
      def __lt__(self, other):
          return self.order < other.order
  
      def __eq__(self, other):
          return self.__class__ is other.__class__ and self.program is other.program and self.order == other.order
  
      def __hash__(self):
          return hash((self.order, self.program))
  
      def __repr__(self):
          return "{}(order={})".format(self.__class__.__name__, self.order)
  
  
  class TextureGroup(Group):
      """A group that enables and binds a texture.
  
      Texture groups are equal if their textures' targets and names are equal.
      """
  
      # Don't use this, create your own group classes that are more specific.
      # This is just an example.
      def __init__(self, texture, program=None, order=0):
          """Create a texture group.
  
          :Parameters:
              `texture` : `~pyglet.image.Texture`
                  Texture to bind.
              `program` : `~pyglet.graphics.shader.ShaderProgram`
                  Optional custom Shader Program.
              `order` : int
                  Change the order to render above or below other Groups.
          """
          super(TextureGroup, self).__init__(program, order)
          self.texture = texture
  
      def set_state(self):
          glActiveTexture(GL_TEXTURE0)
          glBindTexture(self.texture.target, self.texture.id)
  
      def unset_state(self):
          glDisable(self.texture.target)
  
      def __hash__(self):
          return hash((self.order, self.program, self.texture.target, self.texture.id))
  
      def __eq__(self, other):
          return (self.__class__ is other.__class__ and
                  self.program is other.program and
                  self.order == other.order and
                  self.texture.target == other.texture.target and
                  self.texture.id == other.texture.id)
  
      def __repr__(self):
          return '%s(id=%d)' % (self.__class__.__name__, self.texture.id)
  
  
  #: The default Group and Shaders
  
  vertex_source = """#version 330 core
      in vec4 vertices;
      in vec4 colors;
      in vec2 tex_coords;
      out vec4 vertex_colors;
      out vec2 texture_coords;
  
      uniform WindowBlock
      {
          mat4 projection;
          mat4 view;
      } window;  
  
  
      void main()
      {
          gl_Position = window.projection * window.view * vertices;
  
          vertex_colors = colors;
          texture_coords = tex_coords;
      }
  """
  
  fragment_source = """#version 330 core
      in vec4 vertex_colors;
      in vec2 texture_coords;
      out vec4 final_colors;
  
      uniform sampler2D our_texture;
  
      void main()
      {
          final_colors = texture(our_texture, texture_coords) + vertex_colors;
      }
  """
  
  _default_vert_shader = Shader(vertex_source, 'vertex')
  _default_frag_shader = Shader(fragment_source, 'fragment')
  default_shader_program = ShaderProgram(_default_vert_shader, _default_frag_shader)
  