# lines: make lots of lines on the screen

import pippy, pygame, sys
from pygame.locals import *
from random import *

# always need to init first thing
pygame.init()

# turn off the cursor
pygame.mouse.set_visible(False)

# create the window and keep track of the surface
# for drawing into
screen = pygame.display.set_mode()

# ask for screen's width and height
size = width, height = screen.get_size()

# start the screen all black
screen.fill((0,0,0))

# we need starting endpoints for the line and seed motion vectors
start=[randint(0,size[0]), randint(0,size[1])]
end  =[randint(0,size[0]), randint(0,size[1])]

# randomize the motion, 1..3 in each direction, positive or negative, but
# never 0
mvect_start = [choice((-1,1)) * randint(1,3), choice((-1,1)) * randint(1,3)]
mvect_end   = [choice((-1,1)) * randint(1,3), choice((-1,1)) * randint(1,3)]

# start with a random color and color direction
color = [randint(0,255), randint(0,255), randint(0,255)]
direction = [choice((-1,1)), choice((-1,1)), choice((-1,1))]

while pippy.pygame.next_frame():

  for event in pygame.event.get():
    if event.type == QUIT:
      sys.exit()

    elif event.type == KEYDOWN:
      sys.exit()

  # draw the line using the current values and width=3
  pygame.draw.line(screen, color, start, end, 3)

  # update the display
  pygame.display.flip()

  # update the end points and the color
  for i in range(2):
    start[i] = start[i] + mvect_start[i]
    end[i]   = end[i]   + mvect_end[i]

  for i in range(3):
    color[i] = color[i] + direction[i]

  # check if anything has gone out of range and
  # if so, bring back to edge and reverse the
  # corresponding motion vector
  if start[0] < 0 :
    start[0] = 0
    mvect_start[0] = -1 * mvect_start[0]
  elif start[0] >= size[0] :
    start[0] = size[0] - 1
    mvect_start[0] = -1 * mvect_start[0]

  if start[1] < 0 :
    start[1] = 0
    mvect_start[1] = -1 * mvect_start[1]
  elif start[1] >= size[1] :
    start[1] = size[1] - 1
    mvect_start[1] = -1 * mvect_start[1]

  if end[0] < 0 :
    end[0] = 0
    mvect_end[0] = -1 * mvect_end[0]
  elif end[0] >= size[0] :
    end[0] = size[0] - 1
    mvect_end[0] = -1 * mvect_end[0]

  if end[1] < 0 :
    end[1] = 0
    mvect_end[1] = -1 * mvect_end[1]
  elif end[1] >= size[1] :
    end[1] = size[1] - 1
    mvect_end[1] = -1 * mvect_end[1]

  for i in range(3) :
    if color[i] < 0:
      color[i] = 0
      direction[i] = direction[i] * -1
    elif color[i] >= 255 :
      color[i] = 255
      direction[i] = direction[i] * -1

  # randomly change the color directon on occasion
  if randint(0,511) == 128:
      for i in range(3):
         direction[i] = choice((-1,1))