title: Gravity in pygame
body: <p>I'm making a platform game with pygame, and I would like to add gravity to it.
  Right now I only have a picture which moves when I press the arrow keys, and my next step would be gravity. Here's my code:</p>
  
  <pre><code>import pygame, sys
  from pygame.locals import *
  
  pygame.init()
  
  FPS = 30
  fpsClock = pygame.time.Clock()
  
  DISPLAYSURF = pygame.display.set_mode((400, 300), 0, 32)
  pygame.display.set_caption("Jadatja")
  
  WHITE = (255, 255, 255)
  catImg = pygame.image.load("images/cat.png")
  catx = 10
  caty = 10
  movingRight = False
  movingDown = False
  movingLeft = False
  movingUp = False
  
  while True: #main game loop
  
      #update
      for event in pygame.event.get():
      if event.type == KEYDOWN:
          if event.key == K_RIGHT:
              #catx += 5
              movingRight = True
              movingLeft = False
          elif event.key == K_DOWN:
              #caty += 5
              movingDown = True
              movingUp = False
          elif event.key == K_LEFT:
              #catx -= 5
              movingLeft = True
              movingRight = False
          elif event.key == K_UP:
              #caty -= 5
              movingUp = True
              movingDown = False
  
      if event.type == KEYUP:
          if event.key == K_RIGHT:
              movingRight = False
          if event.key == K_DOWN:
              movingDown = False
          if event.key == K_LEFT:
              movingLeft = False
          if event.key == K_UP:
              movingUp = False
  
  
      #actually make the player move
      if movingRight == True:
          catx += 5
      if movingDown == True:
          caty += 5
      if movingLeft == True:
          catx -= 5
      if movingUp == True:
          caty -= 5
  
  
      #exit
      for event in pygame.event.get():
          if event.type == KEYUP:
              if event.key == K_ESCAPE:
                  pygame.quit()
                  sys.exit()
  
          if event.type == QUIT:
              pygame.quit()
              sys.exit()
  
      #draw
      DISPLAYSURF.fill(WHITE)
      DISPLAYSURF.blit(catImg, (catx, caty))
  
  
  
      pygame.display.update()
      fpsClock.tick(FPS)
  </code></pre>
  
  <p>I'm not 100% sure if this code is as smooth as I think it is, but I hope you guys can make something of it.</p>
  
  <p>Thanks</p>