def drawCoordinate():
  '''
  繪制三維的坐標系，并繪制由坐標軸構成的平面的網格，各個坐標軸的顏色以及由坐標軸所引出的網格線的顏色為：
  x: (1.0, 0.0, 0.0)
  y: (0.0, 1.0, 0.0)
  z: (0.0, 0.0, 1.0)
  :return:
  '''
  #設置網格線間的步長
  step = 0.2
  #設置網格線的數量、長度
  line_num = 15
  line_len = 4
  grid_color = [(1.0, 0.0, 0.0), (0.0, 1.0, 0.0), (0.0, 0.0, 1.0)]

  glLineWidth(3)
  origin = [0.0, 0.0, 0.0]
  #畫出xyz軸
  for i in range(3):
    tmp = [0.0, 0.0, 0.0]
    tmp[i] = line_len*1.02
    glColor3f(*grid_color[i])
    glBegin(GL_LINES)
    glVertex3f(*origin)
    glVertex3f(*tmp)
    glEnd()


  # 畫出由坐標軸構成的平面的網格
  glLineWidth(1)
  for i in range(3):
  	#每次把一個坐標軸上引出的網格線都畫出來，所以起點都是一致的
    start = [0.0, 0.0, 0.0]
    glColor3f(*grid_color[i])
    for j in range(line_num):
      end = [0.0, 0.0, 0.0]
      glBegin(GL_LINES)
      start[i] = start[i] + step
      end[i] = start[i]
      for k in {0,1,2} - {i,}:
        end[k] = line_len
        glVertex3f(*start)
        glVertex3f(*end)
        end[k] = 0.0
      glEnd()