Path: chuka.playstation.co.uk!news
From: Philip Gooch <philg@easynet.co.uk>
Newsgroups: scee.yaroze.beginners,scee.yaroze.programming.codewarrior,scee.yaroze.programming.2d_graphics
Subject: Still strugglin' with the basics: broken sprite code (long)
Date: Wed, 15 Jul 1998 10:09:40 +0100
Organization: PlayStation Net Yaroze (SCEE)
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Xref: chuka.playstation.co.uk scee.yaroze.beginners:408 scee.yaroze.programming.codewarrior:297 scee.yaroze.programming.2d_graphics:432

Hello everyone

You know how it is when you use other people's code to do the basics and
it works fine so you don't try and tinker with it?

Except when you do because you want to do things slightly differently,
and then you totally screw it up but can't see what's going wrong?

Or you decide to try and write something from scratch, having fully
understood the examples you've copied from?

Well, I'm having a nightmare. I'm just trying to display a sprite, but
I'm taking stuff from the tuto0.c sample Sony code so that I can load
images into the frame buffer in one function, and link them to a sprite
in another.

What happens is that when I run the program I get the Yaroze boot-up
screen, then the screen flashes briefly before returning to the boot-up
screen. What's weird is that in Codewarrior, if I change my data address
in Linker Settings from the default 0x00000000 to 0x80140000, I get a
very large (700K) executable, except this time the screen goes black and
I get a line of garbage along the bottom.

Would someone be kind enough to have a look at my source code and tell
me what I'm doing wrong. I was up till 4.30 this morning trying to
figure it out. The TIM file is only about 2K (96*48 pixels)

Thanks

Phil

Here it is:
(my batch file is
local dload redcars.tim 80100000
local load ny.pxe
go)

#include <libps.h>
#include "asssert.h"

#define PLAYER_TIM   0x80100000
#define SCREEN_WIDTH  512
#define SCREEN_HEIGHT  256
#define MAX_SPRITES  1
#define OT_LENGTH   1


// globals

GsIMAGE gPlayerTextureInfo;
GsSPRITE gPlayerSprite;
GsOT gOrderTable[2];
PACKET GpuPacketArea[2][MAX_SPRITES*24];

// prototypes
void InitGraphics();
void LoadTimData(u_long address, GsIMAGE *textureInfo);
void LinkSpritetoTimData(GsSPRITE *sprite, GsIMAGE *textureInfo);
void InitSprite(GsSPRITE *sprite);


void main()
{

 int activeBuffer;


 InitGraphics();

 while (1)
 {
  activeBuffer = GsGetActiveBuff();

  GsSetWorkBase((PACKET *)GpuPacketArea[activeBuffer]);

  GsClearOt(0, 0, &gOrderTable[activeBuffer]);

  GsSortFastSprite(&gPlayerSprite, &gOrderTable[activeBuffer], 0);

  DrawSync(0);

  VSync(0);

  GsSwapDispBuff();

  GsSortClear(34,34,34, &gOrderTable[activeBuffer]);

  GsDrawOt(&gOrderTable[activeBuffer]);
 }

}

void InitGraphics()
{
 GsOT_TAG OTTags[2][1<<OT_LENGTH];

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

 GsDefDispBuff(0, 0, 0, SCREEN_HEIGHT);

 SetVideoMode( MODE_PAL );

 gOrderTable[0].length = OT_LENGTH;
 gOrderTable[0].org = OTTags[0];
 gOrderTable[1].length = OT_LENGTH;
 gOrderTable[1].org = OTTags[0];

 LoadTimData(PLAYER_TIM, &gPlayerTextureInfo);
 LinkSpritetoTimData(&gPlayerSprite, &gPlayerTextureInfo);

}


void LoadTimData(u_long address, GsIMAGE *textureInfo)
{

 RECT rect;
 GsGetTimInfo( (u_long *)(address + 4), textureInfo);

 // Load image into frame buffer
 rect.x = textureInfo->px;
 rect.y = textureInfo->py;
 rect.w = textureInfo->pw;   // width in 16-bit words (NOT pixels)
 rect.h = textureInfo->ph;
 LoadImage(&rect, textureInfo->pixel);

 /*printf("image x %d\n", textureInfo->px);
 printf("image y %d\n", textureInfo->py);
 printf("image w %d\n", textureInfo->pw);
 printf("image h %d\n", textureInfo->ph);*/

 /* pmode takes these values (binary):
 0000 4 bit, no clut
 1000 4 bit, clut
 0001 8 bit, no clut
 1001 8 bit, clut
 0010 16 bit
 0011 24 bit
 */

 // Load the CLUT into the frame buffer, if it has one
 if (textureInfo->pmode & 0x8)
 {
  rect.x = textureInfo->cx;       // x pos in frame buffer
  rect.y = textureInfo->cy;       // y pos in frame buffer
  rect.w = textureInfo->cw;       // width of CLUT
  rect.h = textureInfo->ch;       // height of CLUT
  LoadImage(&rect, textureInfo->clut);    // load data into frame buffer

  /*printf("clut x %d\n", textureInfo->cx);
  printf("clut y %d\n", textureInfo->cy);
  printf("clut w %d\n", textureInfo->cw);
  printf("clut h %d\n", textureInfo->ch);*/
 }

 DrawSync(0);
}

void LinkSpritetoTimData(GsSPRITE *sprite, GsIMAGE *textureInfo)
{
 int pixelsPerWord, texturePage;

 InitSprite(sprite);

 // Get texture page ID
 texturePage = GetTPage(textureInfo->pmode & 0x7, 0, textureInfo->px,
textureInfo->py);

 // Work out bit depth (number of pixels per word)
 switch (textureInfo->pmode & 0x7)
 {
  case 0:
   pixelsPerWord = 4; // 4 bit
    break;
  case 1:
   pixelsPerWord = 2; // 8 bit
    break;
  case 2:
   pixelsPerWord = 1; // 16 bit
  default:
   // unexpected pmode value
   pixelsPerWord = 0;
   printf("Unexpected pmode value\n");
   assert(0);
    break;
 }

 sprite->attribute = 0 + (1<<6) + (textureInfo->pmode & 0x7) << 24 +
(1<<30) + (1<<31);
 sprite->tpage = texturePage;
 sprite->cx = textureInfo->cx;     // CLUT x axis position
 sprite->cy = textureInfo->cy;     // CLUT y axis positio
}

// give sprite default values
void InitSprite(GsSPRITE *sprite)
{
 sprite->attribute = 0;
 sprite->x = 32;
 sprite->y = 32;
 sprite->w = 32;        // don't want to display whole TIM, just the
first 32*48 segment
 sprite->h = 48;
 sprite->tpage = 0;
 sprite->u = 0;
 sprite->v = 0;
 sprite->cx = 0;
 sprite->cy = 0;
 sprite->r = 128;
 sprite->g = 128;
 sprite->b = 128;
 sprite->mx = 0;
 sprite->my = 0;
 sprite->scalex = ONE;  // ONE = 4096
 sprite->scaley = ONE;
 sprite->rotate = 0;
}