text: from threading import Lock
  import glfw
  import time
  import copy
  from multiprocessing import Process, Queue
  import numpy as np
  import imageio
  
  from .generated import const
  from .utils import rec_copy, rec_assign
  import ..cythonized as cymj
  
  
  class MjViewerBasic(cymj.MjRenderContextWindow):
      """
      A simple display GUI showing the scene of an :class:`.MjSim` with a mouse-movable camera.
  
      :class:`.MjViewer` extends this class to provide more sophisticated playback and interaction controls.
  
      Parameters
      ----------
      sim : :class:`.MjSim`
          The simulator to display.
      """
  
      def __init__(self, sim):
          super().__init__(sim)
  
          self._gui_lock = Lock()
          self._button_left_pressed = False
          self._button_right_pressed = False
          self._last_mouse_x = 0
          self._last_mouse_y = 0
  
          framebuffer_width, _ = glfw.get_framebuffer_size(self.window)
          window_width, _ = glfw.get_window_size(self.window)
          self._scale = framebuffer_width * 1.0 / window_width
  
          glfw.set_cursor_pos_callback(self.window, self._cursor_pos_callback)
          glfw.set_mouse_button_callback(
              self.window, self._mouse_button_callback)
          glfw.set_scroll_callback(self.window, self._scroll_callback)
          glfw.set_key_callback(self.window, self.key_callback)
  
      def render(self):
          """
          Render the current simulation state to the screen or off-screen buffer.
          Call this in your main loop.
          """
          if self.window is None:
              return
          elif glfw.window_should_close(self.window):
              exit(0)
  
          with self._gui_lock:
              super().render()
  
          glfw.poll_events()
  
      def key_callback(self, window, key, scancode, action, mods):
          if action == glfw.RELEASE and key == glfw.KEY_ESCAPE:
              print("Pressed ESC")
              print("Quitting.")
              exit(0)
  
      def _cursor_pos_callback(self, window, xpos, ypos):
          if not (self._button_left_pressed or self._button_right_pressed):
              return
  
          # Determine whether to move, zoom or rotate view
          mod_shift = (
              glfw.get_key(window, glfw.KEY_LEFT_SHIFT) == glfw.PRESS or
              glfw.get_key(window, glfw.KEY_RIGHT_SHIFT) == glfw.PRESS)
          if self._button_right_pressed:
              action = const.MOUSE_MOVE_H if mod_shift else const.MOUSE_MOVE_V
          elif self._button_left_pressed:
              action = const.MOUSE_ROTATE_H if mod_shift else const.MOUSE_ROTATE_V
          else:
              action = const.MOUSE_ZOOM
  
          # Determine
          dx = int(self._scale * xpos) - self._last_mouse_x
          dy = int(self._scale * ypos) - self._last_mouse_y
          width, height = glfw.get_framebuffer_size(window)
  
          with self._gui_lock:
              self.move_camera(action, dx / height, dy / height)
  
          self._last_mouse_x = int(self._scale * xpos)
          self._last_mouse_y = int(self._scale * ypos)
  
      def _mouse_button_callback(self, window, button, act, mods):
          self._button_left_pressed = (
              glfw.get_mouse_button(window, glfw.MOUSE_BUTTON_LEFT) == glfw.PRESS)
          self._button_right_pressed = (
              glfw.get_mouse_button(window, glfw.MOUSE_BUTTON_RIGHT) == glfw.PRESS)
  
          x, y = glfw.get_cursor_pos(window)
          self._last_mouse_x = int(self._scale * x)
          self._last_mouse_y = int(self._scale * y)
  
      def _scroll_callback(self, window, x_offset, y_offset):
          with self._gui_lock:
              self.move_camera(const.MOUSE_ZOOM, 0, -0.05 * y_offset)
  
  
  class MjViewer(MjViewerBasic):
      """
      Extends :class:`.MjViewerBasic` to add video recording, interactive time and interaction controls.
  
      The key bindings are as follows:
  
      - TAB: Switch between MuJoCo cameras.
      - H: Toggle hiding all GUI components.
      - SPACE: Pause/unpause the simulation.
      - RIGHT: Advance simulation by one step.
      - V: Start/stop video recording.
      - T: Capture screenshot.
      - I: Drop into ``ipdb`` debugger.
      - S/F: Decrease/Increase simulation playback speed.
      - C: Toggle visualization of contact forces (off by default).
      - D: Enable/disable frame skipping when rendering lags behind real time.
      - R: Toggle transparency of geoms.
      - M: Toggle display of mocap bodies.
      - 0-4: Toggle display of geomgroups
  
      Parameters
      ----------
      sim : :class:`.MjSim`
          The simulator to display.
      """
  
      def __init__(self, sim):
          super().__init__(sim)
  
          self._ncam = sim.model.ncam
          self._paused = False  # is viewer paused.
          # should we advance viewer just by one step.
          self._advance_by_one_step = False
  
          # Vars for recording video
          self._record_video = False
          self._video_queue = Queue()
          self._video_idx = 0
          self._video_path = "/tmp/video_%07d.mp4"
  
          # vars for capturing screen
          self._image_idx = 0
          self._image_path = "/tmp/frame_%07d.png"
  
          # run_speed = x1, means running real time, x2 means fast-forward times
          # two.
          self._run_speed = 1.0
          self._loop_count = 0
          self._render_every_frame = False
  
          self._show_mocap = True  # Show / hide mocap bodies.
          self._transparent = False  # Make everything transparent.
  
          # this variable is estamated as a running average.
          self._time_per_render = 1 / 60.0
          self._hide_overlay = False  # hide the entire overlay.
          self._user_overlay = {}
  
      def render(self):
          """
          Render the current simulation state to the screen or off-screen buffer.
          Call this in your main loop.
          """
  
          def render_inner_loop(self):
              render_start = time.time()
  
              self._overlay.clear()
              if not self._hide_overlay:
                  for k, v in self._user_overlay.items():
                      self._overlay[k] = copy.deepcopy(v)
                  self._create_full_overlay()
              super().render()
              if self._record_video:
                  frame = self._read_pixels_as_in_window()
                  self._video_queue.put(frame)
              else:
                  self._time_per_render = 0.9 * self._time_per_render + \
                      0.1 * (time.time() - render_start)
  
          self._user_overlay = copy.deepcopy(self._overlay)
          # Render the same frame if paused.
          if self._paused:
              while self._paused:
                  render_inner_loop(self)
                  if self._advance_by_one_step:
                      self._advance_by_one_step = False
                      break
          else:
              # inner_loop runs "_loop_count" times in expectation (where "_loop_count" is a float).
              # Therefore, frames are displayed in the real-time.
              self._loop_count += self.sim.model.opt.timestep * self.sim.nsubsteps / \
                  (self._time_per_render * self._run_speed)
              if self._render_every_frame:
                  self._loop_count = 1
              while self._loop_count > 0:
                  render_inner_loop(self)
                  self._loop_count -= 1
          # Markers and overlay are regenerated in every pass.
          self._markers[:] = []
          self._overlay.clear()
  
      def _read_pixels_as_in_window(self):
          # Reads pixels with markers and overlay from the same camera as screen.
          resolution = glfw.get_framebuffer_size(
              self.sim._render_context_window.window)
  
          resolution = np.array(resolution)
          resolution = resolution * min(1000 / np.min(resolution), 1)
          resolution = resolution.astype(np.int32)
          resolution -= resolution % 16
          if self.sim._render_context_offscreen is None:
              self.sim.render(resolution[0], resolution[1])
          offscreen_ctx = self.sim._render_context_offscreen
          window_ctx = self.sim._render_context_window
          # Save markers and overlay from offscreen.
          saved = [copy.deepcopy(offscreen_ctx._markers),
                   copy.deepcopy(offscreen_ctx._overlay),
                   rec_copy(offscreen_ctx.cam)]
          # Copy markers and overlay from window.
          offscreen_ctx._markers[:] = window_ctx._markers[:]
          offscreen_ctx._overlay.clear()
          offscreen_ctx._overlay.update(window_ctx._overlay)
          rec_assign(offscreen_ctx.cam, rec_copy(window_ctx.cam))
  
          img = self.sim.render(*resolution)
          img = img[::-1, :, :]  # Rendered images are upside-down.
          # Restore markers and overlay to offscreen.
          offscreen_ctx._markers[:] = saved[0][:]
          offscreen_ctx._overlay.clear()
          offscreen_ctx._overlay.update(saved[1])
          rec_assign(offscreen_ctx.cam, saved[2])
          return img
  
      def _create_full_overlay(self):
          if self._render_every_frame:
              self.add_overlay(const.GRID_TOPLEFT, "", "")
          else:
              self.add_overlay(const.GRID_TOPLEFT, "Run speed = %.3f x real time" %
                               self._run_speed, "[S]lower, [F]aster")
          self.add_overlay(
              const.GRID_TOPLEFT, "Ren[d]er every frame", "Off" if self._render_every_frame else "On")
          self.add_overlay(const.GRID_TOPLEFT, "Switch camera (#cams = %d)" % (self._ncam + 1),
                                               "[Tab] (camera ID = %d)" % self.cam.fixedcamid)
          self.add_overlay(const.GRID_TOPLEFT, "[C]ontact forces", "Off" if self.vopt.flags[
                           10] == 1 else "On")
          self.add_overlay(
              const.GRID_TOPLEFT, "Referenc[e] frames", "Off" if self.vopt.frame == 1 else "On")
          self.add_overlay(const.GRID_TOPLEFT,
                           "T[r]ansparent", "On" if self._transparent else "Off")
          self.add_overlay(
              const.GRID_TOPLEFT, "Display [M]ocap bodies", "On" if self._show_mocap else "Off")
          if self._paused is not None:
              if not self._paused:
                  self.add_overlay(const.GRID_TOPLEFT, "Stop", "[Space]")
              else:
                  self.add_overlay(const.GRID_TOPLEFT, "Start", "[Space]")
              self.add_overlay(const.GRID_TOPLEFT,
                               "Advance simulation by one step", "[right arrow]")
          self.add_overlay(const.GRID_TOPLEFT, "[H]ide Menu", "")
          if self._record_video:
              ndots = int(7 * (time.time() % 1))
              dots = ("." * ndots) + (" " * (6 - ndots))
              self.add_overlay(const.GRID_TOPLEFT,
                               "Record [V]ideo (On) " + dots, "")
          else:
              self.add_overlay(const.GRID_TOPLEFT, "Record [V]ideo (Off) ", "")
          if self._video_idx > 0:
              fname = self._video_path % (self._video_idx - 1)
              self.add_overlay(const.GRID_TOPLEFT, "   saved as %s" % fname, "")
  
          self.add_overlay(const.GRID_TOPLEFT, "Cap[t]ure frame", "")
          if self._image_idx > 0:
              fname = self._image_path % (self._image_idx - 1)
              self.add_overlay(const.GRID_TOPLEFT, "   saved as %s" % fname, "")
          self.add_overlay(const.GRID_TOPLEFT, "Start [i]pdb", "")
          if self._record_video:
              extra = " (while video is not recorded)"
          else:
              extra = ""
          self.add_overlay(const.GRID_BOTTOMLEFT, "FPS", "%d%s" %
                           (1 / self._time_per_render, extra))
          self.add_overlay(const.GRID_BOTTOMLEFT, "Solver iterations", str(
              self.sim.data.solver_iter + 1))
          step = round(self.sim.data.time / self.sim.model.opt.timestep)
          self.add_overlay(const.GRID_BOTTOMRIGHT, "Step", str(step))
          self.add_overlay(const.GRID_BOTTOMRIGHT, "timestep",
                           "%.5f" % self.sim.model.opt.timestep)
          self.add_overlay(const.GRID_BOTTOMRIGHT, "n_substeps",
                           str(self.sim.nsubsteps))
          self.add_overlay(const.GRID_TOPLEFT,
                           "Toggle geomgroup visibility", "0-4")
  
      def key_callback(self, window, key, scancode, action, mods):
          if action != glfw.RELEASE:
              return
          elif key == glfw.KEY_TAB:  # Switches cameras.
              self.cam.fixedcamid += 1
              self.cam.type = const.CAMERA_FIXED
              if self.cam.fixedcamid >= self._ncam:
                  self.cam.fixedcamid = -1
                  self.cam.type = const.CAMERA_FREE
          elif key == glfw.KEY_H:  # hides all overlay.
              self._hide_overlay = not self._hide_overlay
          elif key == glfw.KEY_SPACE and self._paused is not None:  # stops simulation.
              self._paused = not self._paused
          # Advances simulation by one step.
          elif key == glfw.KEY_RIGHT and self._paused is not None:
              self._advance_by_one_step = True
              self._paused = True
          elif key == glfw.KEY_V or \
                  (key == glfw.KEY_ESCAPE and self._record_video):  # Records video. Trigers with V or if in progress by ESC.
              self._record_video = not self._record_video
              if self._record_video:
                  fps = (1 / self._time_per_render)
                  self._video_process = Process(target=save_video,
                                                args=(self._video_queue, self._video_path % self._video_idx, fps))
                  self._video_process.start()
              if not self._record_video:
                  self._video_queue.put(None)
                  self._video_process.join()
                  self._video_idx += 1
          elif key == glfw.KEY_T:  # capture screenshot
              img = self._read_pixels_as_in_window()
              imageio.imwrite(self._image_path % self._image_idx, img)
              self._image_idx += 1
          elif key == glfw.KEY_I:  # drops in debugger.
              print('You can access the simulator by self.sim')
              import ipdb
              ipdb.set_trace()
          elif key == glfw.KEY_S:  # Slows down simulation.
              self._run_speed /= 2.0
          elif key == glfw.KEY_F:  # Speeds up simulation.
              self._run_speed *= 2.0
          elif key == glfw.KEY_C:  # Displays contact forces.
              vopt = self.vopt
              vopt.flags[10] = vopt.flags[11] = not vopt.flags[10]
          elif key == glfw.KEY_D:  # turn off / turn on rendering every frame.
              self._render_every_frame = not self._render_every_frame
          elif key == glfw.KEY_E:
              vopt = self.vopt
              vopt.frame = 1 - vopt.frame
          elif key == glfw.KEY_R:  # makes everything little bit transparent.
              self._transparent = not self._transparent
              if self._transparent:
                  self.sim.model.geom_rgba[:, 3] /= 5.0
              else:
                  self.sim.model.geom_rgba[:, 3] *= 5.0
          elif key == glfw.KEY_M:  # Shows / hides mocap bodies
              self._show_mocap = not self._show_mocap
              for body_idx1, val in enumerate(self.sim.model.body_mocapid):
                  if val != -1:
                      for geom_idx, body_idx2 in enumerate(self.sim.model.geom_bodyid):
                          if body_idx1 == body_idx2:
                              if not self._show_mocap:
                                  # Store transparency for later to show it.
                                  self.sim.extras[
                                      geom_idx] = self.sim.model.geom_rgba[geom_idx, 3]
                                  self.sim.model.geom_rgba[geom_idx, 3] = 0
                              else:
                                  self.sim.model.geom_rgba[
                                      geom_idx, 3] = self.sim.extras[geom_idx]
          elif key in (glfw.KEY_0, glfw.KEY_1, glfw.KEY_2, glfw.KEY_3, glfw.KEY_4):
              self.vopt.geomgroup[key - glfw.KEY_0] ^= 1
          super().key_callback(window, key, scancode, action, mods)
  
  # Separate Process to save video. This way visualization is
  # less slowed down.
  
  
  def save_video(queue, filename, fps):
      writer = imageio.get_writer(filename, fps=fps)
      while True:
          frame = queue.get()
          if frame is None:
              break
          writer.append_data(frame)
      writer.close()
  