text: #!/usr/bin/env python
  # encoding: utf-8
  
  import random
  import pygame
  import flappy_bird_utils
  from itertools import cycle
  
  FPS = 30
  SCREENWIDTH = 288
  SCREENHEIGHT = 512
  
  pygame.init()
  FPSCLOCK = pygame.time.Clock()
  SCREEN = pygame.display.set_mode((SCREENWIDTH, SCREENHEIGHT))
  pygame.display.set_caption('Flappy Bird')
  
  IMAGES, SOUNDS, HITMASKS = flappy_bird_utils.load()
  PIPEGAPSIZE = 100  # 在管道上边界和下边界的可通过区域的宽度
  BASEY = SCREENHEIGHT * 0.79
  
  PLAYER_WIDTH = IMAGES['player'][0].get_width()
  PLAYER_HEIGHT = IMAGES['player'][0].get_height()
  PIPE_WIDTH = IMAGES['pipe'][0].get_width()
  PIPE_HEIGHT = IMAGES['pipe'][0].get_height()
  BACKGROUND_WIDTH = IMAGES['background'].get_width()
  
  PLAYER_INDEX_GEN = cycle([0, 1, 2, 1])
  
  
  class GameState:
      def __init__(self):
          self.score = self.playerIndex = self.loopIter = 0
          self.playerx = int(SCREENWIDTH * 0.2)
          self.playery = int((SCREENHEIGHT - PLAYER_HEIGHT) / 2)
          self.basex = 0
          self.baseShift = IMAGES['base'].get_width() - BACKGROUND_WIDTH
  
          newPipe1 = getRandomPipe()
          newPipe2 = getRandomPipe()
          self.upperPipes = [
              {'x': SCREENWIDTH, 'y': newPipe1[0]['y']},
              {'x': SCREENWIDTH + (SCREENWIDTH / 2), 'y': newPipe2[0]['y']},
          ]
          self.lowerPipes = [
              {'x': SCREENWIDTH, 'y': newPipe1[1]['y']},
              {'x': SCREENWIDTH + (SCREENWIDTH / 2), 'y': newPipe2[1]['y']},
          ]
  
          self.pipeVelX = -4
          self.playerVelY = 0  # player's velocity along Y, default same as playerFlapped
          self.playerMaxVelY = 10  # max vel along Y, max descend speed
          self.playerMinVelY = -8  # min vel along Y, max ascend speed
          self.playerAccY = 1  # players downward accleration
          self.playerFlapAcc = -7  # players speed on flapping
          self.playerFlapped = False  # True when player flaps
  
      def frame_step(self, input_actions):
          pygame.event.pump()
  
          reward = 0.1
          terminal = False
  
          if sum(input_actions) != 1:
              raise ValueError('Multiple input actions!')
  
          # input_actions[0] == 1: do nothing
          # input_actions[1] == 1: flap the bird
          if input_actions[1] == 1:
              if self.playery > -2 * PLAYER_HEIGHT:
                  self.playerVelY = self.playerFlapAcc
                  self.playerFlapped = True
                  # SOUNDS['wing'].play()
  
          # check for score
          playerMidPos = self.playerx + PLAYER_WIDTH / 2
          for pipe in self.upperPipes:
              pipeMidPos = pipe['x'] + PIPE_WIDTH / 2
              if pipeMidPos <= playerMidPos < pipeMidPos + 4:
                  self.score += 1
                  # SOUNDS['point'].play()
                  reward = 1
  
          # playerIndex basex change
          if (self.loopIter + 1) % 3 == 0:
              self.playerIndex = next(PLAYER_INDEX_GEN)
          self.loopIter = (self.loopIter + 1) % 30
          self.basex = -((-self.basex + 100) % self.baseShift)
  
          # player's movement
          if self.playerVelY < self.playerMaxVelY and not self.playerFlapped:
              self.playerVelY += self.playerAccY
          if self.playerFlapped:
              self.playerFlapped = False
          self.playery += min(self.playerVelY, BASEY - self.playery - PLAYER_HEIGHT)
          if self.playery < 0:
              self.playery = 0
  
          # move pipes to left
          for uPipe, lPipe in zip(self.upperPipes, self.lowerPipes):
              uPipe['x'] += self.pipeVelX
              lPipe['x'] += self.pipeVelX
  
          # add new pipe when first pipe is about to touch left of screen
          if 0 < self.upperPipes[0]['x'] < 5:
              newPipe = getRandomPipe()
              self.upperPipes.append(newPipe[0])
              self.lowerPipes.append(newPipe[1])
  
          # remove first pipe if its out of the screen
          if self.upperPipes[0]['x'] < -PIPE_WIDTH:
              self.upperPipes.pop(0)
              self.lowerPipes.pop(0)
  
          # check if crash here
          isCrash = checkCrash({'x': self.playerx, 'y': self.playery,
                                'index': self.playerIndex},
                               self.upperPipes, self.lowerPipes)
          if isCrash:
              # SOUNDS['hit'].play()
              # SOUNDS['die'].play()
              terminal = True
              self.__init__()
              reward = -1
  
          # draw sprites
          SCREEN.blit(IMAGES['background'], (0, 0))
  
          for uPipe, lPipe in zip(self.upperPipes, self.lowerPipes):
              SCREEN.blit(IMAGES['pipe'][0], (uPipe['x'], uPipe['y']))
              SCREEN.blit(IMAGES['pipe'][1], (lPipe['x'], lPipe['y']))
  
          SCREEN.blit(IMAGES['base'], (self.basex, BASEY))
          # print score so player overlaps the score
          # showScore(self.score)
          SCREEN.blit(IMAGES['player'][self.playerIndex],
                      (self.playerx, self.playery))
  
          image_data = pygame.surfarray.array3d(pygame.display.get_surface())
          pygame.display.update()
          FPSCLOCK.tick(FPS)
          # print self.upperPipes[0]['y'] + PIPE_HEIGHT - int(BASEY * 0.2)
          return image_data, reward, terminal
  
  
  def getRandomPipe():
      """returns a randomly generated pipe"""
      # y of gap between upper and lower pipe
      gapYs = [20, 30, 40, 50, 60, 70, 80, 90]
      index = random.randint(0, len(gapYs) - 1)
      gapY = gapYs[index]
  
      gapY += int(BASEY * 0.2)
      pipeX = SCREENWIDTH + 10
  
      return [
          {'x': pipeX, 'y': gapY - PIPE_HEIGHT},  # upper pipe
          {'x': pipeX, 'y': gapY + PIPEGAPSIZE},  # lower pipe
      ]
  
  
  def showScore(score):
      """displays score in center of screen"""
      scoreDigits = [int(x) for x in list(str(score))]
      totalWidth = 0  # total width of all numbers to be printed
  
      for digit in scoreDigits:
          totalWidth += IMAGES['numbers'][digit].get_width()
  
      Xoffset = (SCREENWIDTH - totalWidth) / 2
  
      for digit in scoreDigits:
          SCREEN.blit(IMAGES['numbers'][digit], (Xoffset, SCREENHEIGHT * 0.1))
          Xoffset += IMAGES['numbers'][digit].get_width()
  
  
  def checkCrash(player, upperPipes, lowerPipes):
      pi = player['index']
      player['w'] = IMAGES['player'][0].get_width()
      player['h'] = IMAGES['player'][0].get_height()
  
      # if player crashes into ground
      if player['y'] + player['h'] >= BASEY - 1:
          return True
      else:
          playerRect = pygame.Rect(player['x'], player['y'], player['w'], player['h'])
  
          for uPipe, lPipe in zip(upperPipes, lowerPipes):
              # upper and lower pipe rects
              uPipeRect = pygame.Rect(uPipe['x'], uPipe['y'], PIPE_WIDTH, PIPE_HEIGHT)
              lPipeRect = pygame.Rect(lPipe['x'], lPipe['y'], PIPE_WIDTH, PIPE_HEIGHT)
  
              # player and upper/lower pipe hitmasks
              pHitMask = HITMASKS['player'][pi]
              uHitmask = HITMASKS['pipe'][0]
              lHitmask = HITMASKS['pipe'][1]
  
              # if bird collided with upipe or lpipe
              uCollide = pixelCollision(playerRect, uPipeRect, pHitMask, uHitmask)
              lCollide = pixelCollision(playerRect, lPipeRect, pHitMask, lHitmask)
  
              if uCollide or lCollide:
                  return True
  
      return False
  
  
  def pixelCollision(rect1, rect2, hitmask1, hitmask2):
      """Checks if two objects collide and not just their rects"""
      rect = rect1.clip(rect2)
  
      if rect.width == 0 or rect.height == 0:
          return False
  
      x1, y1 = rect.x - rect1.x, rect.y - rect1.y
      x2, y2 = rect.x - rect2.x, rect.y - rect2.y
  
      for x in range(rect.width):
          for y in range(rect.height):
              if hitmask1[x1 + x][y1 + y] and hitmask2[x2 + x][y2 + y]:
                  return True
      return False
  