Path: chuka.playstation.co.uk!news
From: "Greg Cook" <gjc53@student.canterbury.ac.nz>
Newsgroups: scee.yaroze.freetalk.english
Subject: Re: Packet Explanation
Date: Sat, 24 Nov 2001 19:17:32 +1300
Organization: PlayStation Net Yaroze (SCEE)
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Message-ID: <9tne1e$dq916@www.netyaroze-europe.com>
References: <9tkp3s$dq91@www.netyaroze-europe.com> <9tlh4b$dq95@www.netyaroze-europe.com>
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Thanks alot for the explanantion Alex.

Heres some code i've written today, as you can see im just starting out...

Ive got a few questions scattered in that code as comments, maybe you can
answer some

like i said this is the first code i wrote and got working today, though i
understand a good portion of it, theres alot im not sure of,

also just say i press select and start to quit the program..

how would i clear the screen, put the words " thanks for checking me oout"
and then quit the program?

thanks alot for your help and patience.

Greg


******************************************

#include <libps.h>
#include "pad.c"


/*=========================== Defines ==================================*/
#define SCREEN_WIDTH  320
#define SCREEN_HEIGHT  256
#define SPRITE_COUNT (1+1)
#define OT_LENGTH 1

GsOT WorldOT[2];

// the ordering tables units thought i really still dont get what they are.

GsOT_TAG WorldTags[2][1<<OT_LENGTH];

static PACKET packetArea[2][SPRITE_COUNT*sizeof(GsSPRITE)];  // GPU PACKETS
AREA

int ContinuePlaying = 1;
int x = 0;
int y = 0;
/*=========================== Protypes =================================*/

void main (void);
void InitialiseScreen(void);
void GetPadInput(void);

/*=========================== Code Starts =========================*/

void main (void)
{
 int buffNumber;

    InitialiseScreen();
 buffNumber = GsGetActiveBuff();

      while(ContinuePlaying)
        {

            GetPadInput();

            // not sure about the (PACKET*) part, but as i understand it
   // it is type casting (PACKET*) but whats the *? pointer?

   GsSetWorkBase((PACKET*)packetArea[buffNumber]);

         GsClearOt(0,0,&WorldOT[buffNumber]);

   DrawSync(0);

   VSync(0);

   ResetGraph(1);

   GsSwapDispBuff();

            GsSortClear(0,0,0,&WorldOT[buffNumber]);

   GsDrawOt(&WorldOT[buffNumber]);

   buffNumber = buffNumber^1;

   FntFlush(-1);

    }

 ResetGraph(0);
}

void InitialiseScreen(void)
{
    int x;
    int something;

    PadInit();
 SetVideoMode(MODE_PAL);

 // why is this set at 4? hmmm good question...  how did you work that value
out?
 // i know what the 4 means, non interlaced etc,but how did you get 4?

    GsInitGraph(SCREEN_WIDTH,SCREEN_HEIGHT,4,0,0);

    GsDefDispBuff(0,0,0,SCREEN_HEIGHT);

    for(x=0;x<2;x++)
 {
  WorldOT[x].length = OT_LENGTH; // set OT length

        // still unsure about this..  whats exactly is WorldTags[x]

  WorldOT[x].org = WorldTags[x]; // link in the OT units

        GsClearOt(0,0,&WorldOT[x]);
  }

     // where do some of these magic numbers come from...

  FntLoad(960,256);
  FntOpen(10,80,256,200,0,512);
 }

void GetPadInput(void)
{
    u_long padStatus;


 // PadRead() gets the status from the controller.
 padStatus = PadRead();

  if (padStatus & PADstart && padStatus & PADselect)  // Quit Program
     {
     ContinuePlaying = 0;
     }

  if (padStatus & PADLleft)
  {
   x = x - 1 ;
  }

  if (padStatus & PADLright)
  {
   x = x + 1;
  }

     if (padStatus & PADLdown)
  {
   y = y - 1 ;
  }

  if (padStatus & PADLup)
  {
   y = y + 1;
  }

    FntPrint("X : %d\n", x);

 FntPrint("Y : %d\n", y);
}
----- Original Message -----
From: "Alex Herbert" <alex@herbs.dabsol.co.uk>
Newsgroups: scee.yaroze.freetalk.english
Sent: Saturday, November 24, 2001 2:00 AM
Subject: Re: Packet Explanation


> Hi Greg,
>
> The packet area is just a chuck of memory, so as long as it's big enough
to
> hold all the packets you create then fine.  It doesn't really matter how
you
> define it but declaring an array seems to be the most common way.
>
> The NO_SPRITES*sizeof(GsSPRITE) method seems logical at first as this
would
> suggest that the packet area is the correct size to hold the number of
> sprite packets as defined by NO_SPRITES.  However this is wrong as the
size
> of the GsSPRITE structure has nothing to do with the size of the packets
> created.  For this reason I wouldn't advise doing it this way.
>
> The PACKETMAX*24 method makes a little more sense to me as 24 is an
average
> size for a GPU packet.  Some are bigger, some are smaller but 24 is good
as
> a rough guide.  As for how a value for PACKETMAX is chosen, well that's up
> to the programmer to decide.  Picking a value of 2048 for example is
saying
> that you definitely won't be sorting more than 2048 items (roughly) into
the
> OT.
>
> Or you could just declare it like this:
>
> #define    PACKETAREA_SIZE    32768        // 32Kbytes
> PACKET    packetarea[2][PACKETAREA_SIZE];
>
> and just specify the number of bytes required.  Choosing a big(ish) number
> like 32K is a good starting place.  This number can then be refined
> throughout development as you get a better idea of how much space is
> actually required.  Calling GsGetWorkBase() after sorting all your objects
> (i.e. just before you call GsDrawOt) will return the address of the next
> free byte in the packet area (one byte beyond the used area).  So, simply
> subtracting the start address of the packet area will tell you how much
> memory is being used.  Sorted!
>
> Alternatively, instead of declaring an array for the packet workspace, you
> could assign memory from the heap at run-time using malloc().  Or if
> memory's getting tight, you could set the address of the packet workspaces
> to the area of memory where you loaded your TIMs.  Once the TIMs have been
> loaded into VRAM the chances are that you don't need the copies in main
RAM
> any more, so overwriting them with GPU packets isn't a problem.  At the
end
> of the day it's up to you to use the method which you feel is the most
> appropriate.
>
> Alex
>
>
> "Greg Cook" <gjc53@student.canterbury.ac.nz> wrote in message
> news:9tkp3s$dq91@www.netyaroze-europe.com...
> > Ok well ive been working through various beginner tutes, and have been
> > reading the beginners forum to get some help and explain some things.
> >
> > But i have a question about Packets.  In most tutes there are two
distinct
> > ways to define the Packet Area and im unsure which is the correct way to
> do
> > it..
> >
> > 1.
> >
> > #define NO_SPRITES 1
> >
> > static PACKET packetarea[2] [NO_SPRITES*sizeof(GSPRITE)];
> >
> > 2.
> >
> > #define PACKETMAX 2048
> > #define PACKETMAX2 (PACKETMAX*24)
> >
> > static PACKET packetarea[2][PACKETMAX2];
> >
> > so which one is correct? and in the second version where does the magic
> > number 2048 come from? i assume the 24 is something to do with the size
of
> > the items in the structure... but is 2048 just a magic number as i have
> seen
> > it defined as 1024 and various other sizes...........
> >
> > ok well yet another question from me..
> >
> > thanks guys
> >
> > Greg
> >
> >
> >
> >
>
>