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From: buffa@sardaigne.inria.fr (Michel Buffa)
Newsgroups: rec.games.programmer,comp.sys.amiga.tech
Subject: Re: Animation Speed & Redraw
Message-ID: <1990Sep7.094337@sardaigne.inria.fr>
Date: 8 Sep 90 07:07:37 GMT
References: <4275@crash.cts.com>
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Organization: Inria Sofia Antipolis
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In article <4275@crash.cts.com>, uzun@pnet01.cts.com (Roger Uzun) writes:
> 
> Most all developers on the amiga, who develop for the amiga, make
> use of hardware sprites

FALSE. Look at most of the arcade games on the amiga. Each object is more than
4 colors (or even 16 in some of them). Only games like datastorm use hardware
sprites. Battle squadron doesn't use sprites. Silkworm doesn't use sprites
(The object are too numerous and too long to be sprites, Turrican doesn't use
sprites: same method as the one used in blood money, see explanations later)

> Blood Money uses mostly all sprites.

FALSE ! I read a bunch of article in THE ONE (an english magasine), all
written by the author of blood money, and he said that there was NO SPRITE at
all in blood money. Only Blitter Objects. I recommend reading this magazine:
it contains each month some technical articles written by an author of some
famous games. During six months they gave almost the entire code of Menace,
with full explanations.

> With the older agnus, I think you cannot blit a 320X200X4 bit screen
> is a single pass, but I forget for sure.  

Why do you want to do it in a single pass. The blitter is fast enough to do 
several operations during each vbl (60 times/second)

in blood money, the following technique is used (read in the magazine)

   the scrolling uses both the blitter and the copper. The copper is used to
   scroll one line every 1/50s, and every 50/16s, the blitter is used to map
   only a row or a column, with 16x16 basic squares of background.

   Before pasting an object on the scroll, the followings steps are achieved:

   -restore previous portions of background (where the objects were in the
   previous frame)

   -calculate new positions of the objects, test collisions

   -save what will be behind the object you are going to paste in the current
   frame. (a special "save buffer" is associated to each object)

   -paste the new objects on the background

Everything is done with the blitter and the copper (the copper avoids to
redraw the full background evry frame, so the blitter is used only to animate
the objects, and each 16 frames to map a row or a column in the scrolling
background. 

>