From:	don_rogers AT my-deja DOT com
Newsgroups:	comp.os.msdos.djgpp
Subject:	Allegro: scroll_screen problems
Date:	Sun, 08 Aug 1999 03:36:43 GMT
Organization:	Deja.com - Share what you know. Learn what you don't.
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To:	djgpp AT delorie DOT com
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Reply-To:	djgpp AT delorie DOT com

  Could someone please help me with this problem.
I am new to Allegro so I decided to keep it
simple, just draw some shapes on the screen
(virtual) and then scroll around a bit. So,

	set_gfx_mode(GFX_AUTODETECT,800,600,0,0);
	.
	.
	set_pallete(desktop_pallete);
	set_clip(screen,VIRTUAL_W,VIRTUAL_H);
	draw some shapes on 1024x4096 virtual
        screen
	.
	.
	scroll_screen(50,0);

Everything moved over just as I had expected.
But when,

	'
	'
	scroll_screen(0,50)

shapes on the screen move diagonally instead of
vertically!?

If instead of shapes I draw a line diagonally
across the screen, top-left to bottom-right,
and then scroll_screen(0,50), I get two lines,
one across the upper-right and one across the
lower-left corners of the screen.

What am I doing wrong?



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