Path: chuka.playstation.co.uk!scea!peter_alau@playstation.sony.com From: Elliott Lee Newsgroups: scee.yaroze.programming.2d_graphics Subject: Re: Scrolling backgrounds Date: Wed, 08 Jul 1998 10:34:51 -0700 Organization: Cisco Systems Lines: 26 Message-ID: <35A3ADBB.72164A44@jps.net> References: <6nvfvm$9o1@chuka.playstation.co.uk> Reply-To: tenchi@jps.net NNTP-Posting-Host: dhcp-m-62-247.cisco.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Mailer: Mozilla 4.03 [en] (Win95; U) A cheezy-yet-effective way to create a scrolling background (as long as it is going one direction only) is to use a star field function and substitute semi-trans clouds for the stars. Vary the speed and size, too? That might be faster than computing the next line(s)...? Mark Green wrote: > > I am trying to create a 2D scrolling cloud-type background that is > automatically generated by an algorithm. I have the algorithm to generate > the next line to be scrolled on given the previous line, but I am having > some problem making the scrolling itself happen. > It would seem to make sense that I should hold the background somewhere > in video RAM, scroll and update it there then copy it to the frame buffer. > Unfortunately this seems to be very inefficient (requiring two full-screen > blits per frame, one to scroll the buffer and another to copy it to the frame > buffer) and will not work with the non-blocking operations anyway since the > scroll must be assured complete before the copy can take place. > I am sure that there is a more efficient way of doing this type of thing > but it is eluding me at the moment :) Can anyoone give me any pointers? -- Mata ne, ... ... - e! ::' tenchi@shell.jps.net ':: (Protocol) :: ACiD -/- ACS -/- pHluid -/- Yaroze -/- Nemesis :: (Tenchikun) ::. http://www.jps.net/tenchi .:: ''' '''