Re: [pygame] my first game (so far)

["Patrick Mullen" <saluk64007@xxxxxxxxx>]

On Mon, Mar 17, 2008 at 6:50 PM, Lenard Lindstrom <len-l@xxxxxxxxx> wrote:
>  problems with the arrow keys that I could find. The only thing I
>  wondered about is that changing the direction the sprite faces also
>  makes it moving ahead one square.

Most rpgs I know of work this way, so Michael is working within the
standard.  Although maybe the standard is not so good :)

To Michael, I think you are making a great start with this, and the
code looks very clean and well designed.  Scrolling the screen can be
tricky if you have never done it before, but it is not too
complicated.  The biggest loss with screen scrolling is that (at least
if you are smooth scrolling) dirty rects basically go out the window -
the entire screen becomes the dirty rect when it is scrolling.

The main idea, is to have a camera offset value, and then every time
you draw you subtract that value from the x and y of what you are
drawing.  This way, most of your code doesn't have to be changed, as
you are working with the same coordinates for everything.  The only
code that has to change are the blits.

screen.blit(image,[x,y])
becomes
screen.blit(image,[x-cam_x,y-cam_y])

Test this step of the code, before you worry about scrolling, by
setting the cam_x and cam_y to different values.

Once you have this, you can detect where the player is going to be
drawn (player pos minus camera offset) to determine if the screen
should be scrolled.

Here's some pseudo code for that:
screen_x = player_x - cam_x
screen_y = player_y - cam_y
screen.blit(player,[screen_x,screen_y]
if screen_x>(screen_width-100):
   cam_x+=scroll_speed
if screen_x<100:
   cam_x-=scroll_speed
if screen_y>(screen_height-100):
   cam_y+=scroll_speed
if screen_y<100:
   cam_y-=scroll_speed

Then, the camera will scroll when the player is 100 pixels from any screen edge.

This is of course not directly applied to your project, but you should
be able to figure it out.

I hope to see more of this project in the future.  The world can never
have too many rpgs :)