SCUMM z-planes

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Rum Rogers
Posts: 2
Joined: Wed Mar 30, 2016 1:54 pm

SCUMM z-planes

Post by Rum Rogers » Wed Mar 30, 2016 7:08 pm

Hi guys,
while fiddling with old SCUMM games resources I noticed they often use a bitmask in order to describe which chunks of the backgrounds should stay in foreground.
I was surprised, since I imagined they had separate sprites for those "layers".
I'm wondering if they did image-cropping at run time and added the chunks depending on the z-order (seems pretty unlikely) or they used a "subtractive" approach, that is avoiding to display the pixels which were hidden by objects.
In any case I assume they actually had direct access to the pixel matrix to do something like this without separate sprites...
Am I missing something here?
Does anybody know how SCUMM did manage those chunks internally (or at least, how does ScummVM treat them?).
I also know AGS does something similar with bitmasks.
Just curious.
Thanks! :)

Rum Rogers
Posts: 2
Joined: Wed Mar 30, 2016 1:54 pm

Post by Rum Rogers » Sat Jul 16, 2016 1:58 pm

Sorry for double posting but...nothing at all?

MrPunchy
Posts: 127
Joined: Mon Nov 06, 2006 2:04 pm

Post by MrPunchy » Sat Jan 27, 2018 1:22 am

Gluxe?

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