Re: [pygame] Fixed aspect ratio scaling

[Phil Hassey <philhassey@xxxxxxxxx>]

Casey,

Can you paste that into the pygame cookbook - it's a pretty nice bit of code :)

Phil

Casey Duncan <casey@xxxxxxxxxxx> wrote:
>  On May 31, 2007, at 1:03 AM, John Eriksson wrote:
>
> > Hi,
> >
> > Does anyone know about a good solution on the stretching problem when
> > running in fullscreen mode on a widescreen monitor?
> >
> > For windows users having an nvidia driver it's possible to set "Fixed
> > aspect ratio scaling" as an option for the display causing the
> > widescreen to have black borders at the sides.
> >
> > But are there any platform independent solutions to this?
> >
> > I guess it might be possible to solve this using code, creating a
> > correct sized display and then blitt the game screen to it's centered.
> >
> > But this (I guess) can
>  cause some performance loss. And I don't  
> > know if
> > it's even possible to detect the best screen resolution to use.
> > As far as I know there are no way to determine the current screen
> > resolution (to calculate the monitors aspect ratio) of the system?
>
> Is the problem that your game expects a fixed-resolution and  
> therefore a fixed aspect ratio? Regardless if your game demands a  
> fixed aspect ratio then on some monitors you must either letter-box  
> the screen or stretch everything to fit. You seem to be hinting at  
> doing the latter, but that causes undesireable distortion (i.e.,  
> circles become ovals, etc).
>
> Here is my suggested solution to this problem:
>
> - Make your game resolution independent. That is, distances in the  
> game are independent of pixel size.
>
> - Make either the horizontal or vertical screen distance fixed,  
> perhaps matching it to the "ideal" screen size (e.g., 1280 or
>  1600)
>
> - At game startup let pygame pick the resolution by default or allow  
> it to be overridden by user preference. Figure out the scale by  
> dividing the fixed screen distance by the actual screen resolution.  
> Then scale all of your graphics accordingly. If you are using sprite  
> images, rotozoom works excellent (just zoom everything at load-time)  
> and is very fast.
>
> You get several benefits from this:
>
> - You can pretty easily implement a zoom in/out feature by varying  
> the fixed screen distance.
>
> - Users can select lower resolutions to trade quality for performance  
> or vice versa. Some resolutions may be letterboxed, but the user can  
> decide if this is objectionable, many times it isn't.
>
> To get at the screen resolution use the surface object returned from  
> pygame.display.set_mode(), call get_rect() on it to figure out the  
> screen res.
>
> Here is some code I wrote to select the screen res from four
>  user  
> resolution settings: max, high, med and low. It is intended to pick  
> sizes that fit the aspect ratio of the screen in fullscreen mode,  
> where possible. It also favors portrait orientation (for those of us  
> with pivoting monitors).
>
> screen_sizes = {
>  'max': ((0, 100000), (1280, 1024)),
>  'high': ((650, 800), (1024, 768)),
>  'med': ((500, 649), (800, 600)),
>  'low': ((400, 499), (640, 480))
> }
> (min_height, max_height), window_size = screen_sizes[resolution]
> if fullscreen:
>  modes = pygame.display.list_modes()
>  # Choose the first mode with a height in the desired range
>  for mode in modes:
>   if min_height <= mode[1] <= max_height and mode[0] > mode[1]:
>    break
>  else:
>   mode = modes[0]
>   print "Could not find ideal display mode, using", mode
>  screen = pygame.display.set_mode(mode, FULLSCREEN)
> else:
>  screen = pygame.display.set_mode(window_size)
> screen_rect =
>  screen.get_rect()
>
> hth,
>
> -Casey

---

Shape Yahoo! in your own image.  
Join our Network Research Panel today!