From: "Stefan Viljoen" Newsgroups: comp.os.msdos.djgpp Subject: Re: Allegro: scroll_screen problems Date: Sun, 8 Aug 1999 22:43:45 +0300 Organization: The South African Internet Exchange Lines: 33 Message-ID: <7okqg4$7lc$3@ctb-nnrp1.saix.net> References: <7oiu0a$vqa$1 AT nnrp1 DOT deja DOT com> NNTP-Posting-Host: pc36-01-p26.nt.saix.net X-Trace: ctb-nnrp1.saix.net 934145348 7852 155.239.194.26 (8 Aug 1999 20:49:08 GMT) X-Complaints-To: abuse AT saix DOT net NNTP-Posting-Date: 8 Aug 1999 20:49:08 GMT X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 5.00.2014.211 X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2014.211 To: djgpp AT delorie DOT com DJ-Gateway: from newsgroup comp.os.msdos.djgpp Reply-To: djgpp AT delorie DOT com ----- Original Message ----- From: Newsgroups: comp.os.msdos.djgpp Sent: Sunday, August 08, 1999 6:36 AM Subject: Allegro: scroll_screen problems > 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, I have heard that some of the functions that do scrolling can be hardware dependant when used - this means that something that Shawn & contributors to Allegro designed to go vertically and did work on their particular SVGA setups might not neccessarily go vertically on yours - I thus implemented software scrolling using oversized bitmaps when I wanted to do scrolling a while ago. You might want to try this - IMHO it is more reliable than hardware scrolling due to the various hardware setups your program might have to run on. Basically what I did was to set up a large "source" bitmap that is twice as large as the physical screen, then use a "sliding" bitmap 'window' onto that source bitmap to blit to the actual screen - implemented correctly it gives a nice, smooth scrolling or sliding effect. This message courtesy of RylanNet rylan AT intekom DOT co DOT za http://home.intekom.com/rylan/ -- StarWars for ever!.