[ scummvm-Patches-639699 ] SAM: Fix for graphics glitch

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Patches item #639699, was opened at 2002-11-17 17:15
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Torbjörn Andersson (eriktorbjorn)
Assigned to: Nobody/Anonymous (nobody)
Summary: SAM: Fix for graphics glitch

Initial Comment:
This patch fixes a graphics glitch at the Ball of Twine:

* Walk Sam to the foot of the stairs to the gondola
platform.

* Wait until Max stops walking. He should now be
standing in the parking lot.

* Walk Sam up the stairs. As the camera moves to the
right, you should see a partially drawn Max appear on
the right side of the screen.

This happens because Max is drawn with _xpos < 0, so he
"wraps around" to the right side.

It's possible/probable that it fixes other similar bugs
- I've made the change in all the codecs, not just the
one that causes the Sam & Max glitch - but this is the
only one I know how to trigger in any reliable way.

An alternative fix would probably be to make _xpos
unsigned. I'm not suggesting we actually do it this way
since it's not human-readable, but it could explain why
the code was reverse-engineered to only clip against
the right edge of the screen.

Oh, and the same thing probably applies to AKOS as
well, but I don't know of any test cases for it.


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