Re: [pygame]

[David Clark <silenus@telus.net>]

 > > I am trying to start coding to make games. How do you get the
 > > background pic to scroll? please give example. 

We've been playing with scrolling code in #pygame this morning, and
found out a few things.

First, it's very important that you .convert() any images you load. I
originally forgot to do this; after Pete rebuked me, my framerate
quadrupled :)

Second, you'll find that scrolling by 1 pixel at a time is unnecessary
- I tried scrolling in steps of four pixels, and it still looked
perfectly smooth.

Here's some code. This doesn't include the display-display blit
optimization Pete mentioned, but it still gets 80 fps unaccelerated in
X, and a whopping 550 fps fullscreen in Windows.

You'll find the image I used, twister.jpg, at:

http://pygame.seul.org/ftp/contrib/twister.jpg

Hope this helps.


<--------------------------------code---------------------------->

#! /usr/bin/env python

import pygame, pygame.image

pygame.init()

# create my display

display = pygame.display.set_mode((640, 480), pygame.HWSURFACE)

# load the background

background = pygame.image.load("twister.jpg").convert()

# create the viewport and boundary rects

backrect = pygame.Rect(background.get_rect())

viewport = pygame.Rect((0, 0, 640, 480))

# main loop

dirty = 1

while 1:
    framestart = pygame.time.get_ticks()
    
    # process input
    if pygame.event.peek(pygame.QUIT):
        break

    input = pygame.key.get_pressed()

    if input[pygame.K_ESCAPE]:
        break
    if input[pygame.K_LEFT]:
        if viewport.left > backrect.left:
            viewport.left -= 1
            dirty = 1
    if input[pygame.K_RIGHT]:
        if viewport.right < backrect.right:
            viewport.right += 1
            dirty = 1
    if input[pygame.K_UP]:
        if viewport.top > backrect.top:
            viewport.top -= 1
            dirty = 1
    if input[pygame.K_DOWN]:
        if viewport.bottom < backrect.bottom:
            viewport.bottom += 1
            dirty = 1

    # draw the image, if necessary

    if dirty:
        display.blit(background, (0, 0), viewport)
        pygame.display.update()
        dirty = 0

    frameend = pygame.time.get_ticks()

    fps = 1000 / ((frameend - framestart) or 1)
    print "FPS = " + str(fps)


<----------------------------code ends-------------------------->

 
-- 
David "Futility" Clark       |  How can this mean anything to me, when |
silenus@telus.net            |  I really don't feel anything at all?   |
------------------------------------------------------------------------

____________________________________
pygame mailing list
pygame-users@seul.org
http://pygame.seul.org