Path: chuka.playstation.co.uk!scea!greg_labrec@interactive.sony.com
From: Scott Cartier <dsyaroze@concentric.net>
Newsgroups: scea.yaroze.programming.2d_graphics
Subject: Background flicker
Date: Mon, 18 Aug 1997 22:24:55 -0700
Organization: SCEA News Server
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Message-ID: <33F92E27.19B4@concentric.net>
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I'm having trouble with my background.  It flickers - like it's
only being drawn every other frame.  I'm using 640x480 and when 
I switch to low resolution it works fine.  I'm wondering if 
there is something obvious I'm doing wrong.  Here's a general
outline of my program.  Is there anything that jumps out as
being incorrect (assuming I've initialized the cells and map
data)?

  #define H_RES 640
  #define V_RES 480

  u_short backgnd_array[64 * 64];  // Max of 64 by 64 background
  GsCELL backgnd_cells[2];         // Only 2 cells for now
  GsMAP backgnd_map;
  GsBG backgnd;
  u_long backgnd_workarea[(((H_RES >> 4) + 1) * ((V_RES >> 4) + 1 + 1) *
6 + 4) * 2 + 2];

  backgnd.attribute = 0;
  backgnd.x = 0;
  backgnd.y = 0;
  backgnd.w = H_RES;
  backgnd.h = V_RES;
  backgnd.scrollx = 0;
  backgnd.scrolly = 0;
  backgnd.r = backgnd.g = backgnd.b = 0x80;
  backgnd.map = map;
  backgnd.mx = backgnd.my = 0;
  backgnd.scalex = backgnd.scaley = ONE;
  backgnd.rotate = 0;

  GsInitFixBg16(&backgnd, backgnd_workarea);

  while (pad_state[PAD_SELECT] == 0) {  // Main loop

    activeBuff = GsGetActiveBuff();
    GsSetWorkBase((PACKET *)GpuPacketArea[activeBuff]);
    GsClearOt(0, 0, &WorldOT[activeBuff]);

    pad_read();

    GsSortFixBg16(&backgnd,
backgnd_workarea[activeBuff],                   WorldOT[activeBuff],
OT_BACKGND);

    cnt = VSync(0);
    ResetGraph(1);
    GsSwapDispBuff();
    GsSortClear(0, 0, 0, &WorldOT[activeBuff]);
    GsDrawOt(&WorldOT[activeBuff]);
  }

Scott