Path: chuka.playstation.co.uk!scea!greg_labrec@interactive.sony.com
From: "Nelson Santos" <nsantos@total.net>
Newsgroups: scee.yaroze.programming.2d_graphics
Subject: Jerky graphics
Date: 19 Jun 1997 05:13:34 GMT
Organization: SCEA Net Yaroze News
Lines: 48
Message-ID: <01bc7c89$6c62a860$6c37eccd@nsantos>
NNTP-Posting-Host: ppp-annex-0626.mtl.total.net
X-Newsreader: Microsoft Internet News 4.70.1155

Hello all,

Does anyone know what is wrong with my game loop:

-------------------------------------------------------------
         for(;;)                            // Game loop
         {
            Pad1 = PadRead(1);
            MovePlayer(Pad1);

            if(NumHeroBullets > 0)
               MoveHeroBullets();

            Buffer = GsGetActiveBuff();
            GsSetWorkBase((PACKET *)Packet[Buffer]);
            GsClearOt(0,0,&OrdTab[Buffer]);

            GsSortFastSprite(&Hero, &OrdTab[Buffer], 0);
            if(NumHeroBullets > 0)
            {
               for(i=0 ; i < NumHeroBullets ; i += 1)
                  GsSortFastSprite(&HeroBullets[i], &OrdTab[Buffer], 0);
            }
            DrawSync(0);
            VSync(0);
            GsSwapDispBuff();
            GsSortClear(0, 0, 0, &OrdTab[Buffer]);
            GsDrawOt(&OrdTab[Buffer]);

            if (GameOver == TRUE) break;
         }
------------------------------------------------------------

This is a slimmed down version of my game loop.  Whenever the ship fires
any bullets (therefore having more than one sprite), the animation becomes
choppy.  However, if I place a printf statement anywhere in the loop before
the "if(NumHeroBullets > 0)" or after the "GsDrawOt(&OrdTab[Buffer]);", no
more jerkiness!  With the printf statement in there I can have several
sprites at once with no jerkiness.  Without the printf however, 2 sprites
makes the display jerky.

Why?  I did follow all the steps in the proper order didn't I?

Please help.

Nelson.