Scratch

One of the main points of scrolling is that whatever is displayed on the screen has no relation to the actual "position" of the objects.  You'll need to make "absolute position" variables for all your sprites (just call them Position.X and Position.Y, or something like that).  You can define that 0,0 is the bottom left-hand corner of the entire area, including what's not on screen.  When you initialize a tank, you send it coordinates to the Position.X and Position.Y user-created variables, not the default x and y position (blue). 

For example, the tank on the left might have a starting position of (10, 100), and the one on the right might have something like (1000, 100).  The actual drawing process would involve taking the camera x and y values -- these are also variables, representing what part of the terrain you're looking at -- and then sending the sprites to ((Camera.X) - (Position.X), (Camera.Y) - (Position.Y)).  If you adjust the values of Camera.X and Camera.Y, the entire viewing screen will move around. 

So, for a basic sprite that is supposed to scroll:

when gf clicked
forever
go to x: ((Scroll.X) - (Position.X)) y: ((Scroll.Y) - (Position.Y))
end

This means that you can't use certain movement commands: move (_) steps, change x by (_), etc.  You have to replace them with custom commands.  Here's a workaround for move (_) steps.

change [Position.X v] by (([cos v] of ((90) - (direction))) * (steps))
change [Position.Y v] by (([sin v] of ((90) - (direction))) * (steps))

Last edited by amcerbu (2012-08-30 01:54:41)

It didn't seem to work quite right, not sure what happened. It seemed very odd, like it wasn't supposed to happen.    Unfortunately, I'll have to revert to my back-up plan for the competition, but I'll still need this script for later.

Last edited by sonicfan12p (2012-08-30 21:40:27)