Object Scale/Paste Into Background

[Steven M]

I've got a SHMUP prototype in motion. The game is strictly monochrome and the player's bullets change the landscape. Black bullets leave black space on the screen, white bullets leave white space (using the 'Paste into background' command). It's almost like Ikaruga crossed with MSPaint. This system works fine so far.

Now I've got a system set up where scrolling the mouse wheel changes a global value in proportion to the direction of the scroll. This global value affects the scale of the player's bullets. This system isn't working quite as fine.

WHAT I WANT:

The player should be able to quickly cover the screen in large swathes of enlarged bullets - if the player has the global value set to 5, then fires across the screen, there should be large bullet backdrops on the screen. If the global value is set to something like 1, the backdrops should be comparatively small.

WHAT HAPPENS:

The player fires bullets of a size according to the global value. However the sprite that is pasted into the background remains the default (i.e. small) size. Thus a 5-value spreadshot results in tiny pellet backdrops.

I'm not sure how to fix this, since enforcing the scale of the bullet in the same event list as 'paste backdrop etc' doesn't change things. Any suggestions would be appreciated. If that all still sounds a bit complicated I've uploaded the source code so you can get a better look at the problem. (*White bullets have a larger separate sprite to the default, so don't be fooled if you try messing with the mouse wheel and white sprite.)