text: # a number of constants
  
  from .custom_types import ForceFactor
  
  # scaling between pixels and metres
  SCALE = 100.0
  
  
  # scaling factors the social force model
  SF_FACTORS = ForceFactor(
      social = 2.1, 
      desired = 1.0, 
      obstacle = 3.0, 
      lookahead = 1.0
      )
  
  
  SIGN = lambda x: (1, -1)[x < 0.0]