[Visualpython-users] Parallelism of forward and up ...

[Stef M. <s.m...@ru...>]

hello,

while trying to get the correct the user zoom changed by code (as Bruce 
suggested),
I bounced into another problem, parallelism of up and forward.
Normally this problem won't occur, but switching between application, 
made by different persons,
within the same scene (as I do right now) can cause this problem.
So I've made a convenience procedure to prevent the problem,
maybe some of you might benefit from it ,...
... or even have better (simpler) solutions.
cheers,
Stef


# ***********************************************************************
def Forward_Up ( Forward, Up ) :
  """
  Sets both FORWARD and UP,
  preventing temporary parallelism of FORWARD and UP
  """
  # Be sure we've vectors
  Forward = vector ( Forward )
  Up      = vector ( Up      )

  # Temp_Forward should not allign with
  #   1. scene.up
  #   2. Up
  #   3. Forward
  # And we may assume that Up and Forward don't allign
  # The sum of Forward and Up, will fullfill conditions 2,3
  Temp_Forward = Up + Forward

  # calculate alfa, critical a=0  and alfa=pi
  alfa = Temp_Forward.diff_angle ( scene.up )
  # make alfa in range 0 .. pi/2, critical alfa = pi/2
  alfa = abs ( alfa - pi/2 )
  # make alfa in range pi/2 .. 0, critical alfa = 0
  alfa = pi/2 - alfa
  # if Temp_Forward alligned with current scene.up
  if alfa < 0.1 :
    # Create the product vector,
    # which is perpendicular to Up and Forward (conditions 2,3)
    # and will not allign with scene.up
    Temp_Forward = dot ( Up, Forward )

  scene.forward = Temp_Forward
  scene.up = Up
  scene.forward = Forward