Path: chuka.playstation.co.uk!scea!greg_labrec@interactive.sony.com
From: Jorge Freitas <jfreitas@netcom.ca>
Newsgroups: scea.yaroze.programming.3d_graphics
Subject: Creating a TMD on the fly
Date: Wed, 28 May 1997 07:59:19 -0400
Organization: SCEA Net Yaroze News
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I'm trying to create a TMD object in memory, with the intention of
creating a landscape object on the fly.  I have no difficulty displaying
objects comverted using RSDLINK, but I can't get this TMD code to work. 
The code is supposed to create a single triangle, flat shaded.

I've used tables to store some of the information, expecting the
compiler to place them sequencially in RAM without any padding, and I've
set the FIXP flag in the header FLAGs denoting a real address for the
Object pointers.

The description of the TMD File Format is a bit confusing, the order of
the items is shown as MSB and LSB of 32 bit data (what the document
calls a WORD(?) ), so the ordering of the all the structures might be
reversed?

I'm not sure if the library calls expect the primitives, vertecies, and
normals tables to appear sequencially, or if the library code uses the
pointers in the Object structure to reference the tables (which would
seem correct )?

After examining a TMD of a single triangle I created using RSDLINK, I
duplicated the TMD in Build_TMD().  I tried reversing the order of the
vertex indecies in the Primitive, reversing the normal, patting my head
and jumping up and down on one foot, and nothing seems to help. 
Hopefully I've simply forgotten to set a FLAG or something, I don't
think my structures or concept is flawed?

Jorge
jfreitas@netcom.ca

--------------------------------
 Here's the code and structures
--------------------------------

typedef struct
{
	long int ID;
	long int FLAGS;
	long int NOBJ;
}TMD_Header;

typedef struct
{
	TMD_Header header;						//remove this for multiple object TMD

	unsigned long int *vert_top;
	unsigned long int n_vert;
	unsigned long int *normal_top;
	unsigned long int n_normal;
	unsigned long int *primitive_top;
	unsigned long int n_primitive;
	long int scale;
}TMD_Object;

typedef struct
{
	char olen;
	char ilen;
	char flag;
	char mode;
}TMD_Primitive;

typedef struct					//specifically for flat shaded triangle
{
	unsigned char r;
	unsigned char g;
	unsigned char b;
	unsigned char pad;

	unsigned short int n;

	unsigned short int v0;
	unsigned short int v1;
	unsigned short int v2;
}TMD_Packet;

typedef struct
{
	short int vx;
	short int vy;
	short int vz;
	short int pad;
}TMD_Vertex;

typedef struct
{
	short int nx;
	short int ny;
	short int nz;
	short int pad;
}TMD_Normal;

//
//
//

TMD_Object Test_Object;
TMD_Primitive Primitive_Table[ 1 ];		//packets must appear directly
after
TMD_Packet Packet_Table[ 1 ];				//the primitive table, and the tables
TMD_Vertex Vertex_Table[ 3 ];				//are sized so as to appear immediately
TMD_Normal Normal_Table[ 1 ];				//one after the other in memory

/************
* Build_TMD *
************/
void Build_TMD( void )
{
	Test_Object.header.ID = 0x41;
	Test_Object.header.FLAGS = 1;
	Test_Object.header.NOBJ = 1;

	Test_Object.vert_top = (unsigned long int *)&Vertex_Table;
	Test_Object.n_vert = 3;
	Test_Object.normal_top = (unsigned long int *)&Normal_Table;
	Test_Object.n_normal = 1;
	Test_Object.primitive_top = (unsigned long int *)&Primitive_Table;
	Test_Object.n_primitive = 1;
	Test_Object.scale = 0;

	Vertex_Table[ 0 ].vx = 0;
	Vertex_Table[ 0 ].vy = -1;
	Vertex_Table[ 0 ].vz = 0;
	Vertex_Table[ 0 ].pad = 0;

	Vertex_Table[ 1 ].vx = -1;
	Vertex_Table[ 1 ].vy = 1;
	Vertex_Table[ 1 ].vz = 0;
	Vertex_Table[ 1 ].pad = 0;

	Vertex_Table[ 2 ].vx = 1;
	Vertex_Table[ 2 ].vy = 1;
	Vertex_Table[ 2 ].vz = 0;
	Vertex_Table[ 2 ].pad = 0;

	Normal_Table[ 0 ].nx = 0;
	Normal_Table[ 0 ].ny = 0;
	Normal_Table[ 0 ].nz = -1;
	Normal_Table[ 0 ].pad = 0;

	Primitive_Table[ 0 ].olen = 4;
	Primitive_Table[ 0 ].ilen = 3;
	Primitive_Table[ 0 ].flag = 0;
	Primitive_Table[ 0 ].mode = 0x20;

	Packet_Table[ 0 ].r = 0xc8;
	Packet_Table[ 0 ].g = 0xc8;
	Packet_Table[ 0 ].b = 0xc8;
	Packet_Table[ 0 ].pad = 0;
	Packet_Table[ 0 ].n = 0;
	Packet_Table[ 0 ].v0 = 0;
	Packet_Table[ 0 ].v1 = 2;
	Packet_Table[ 0 ].v2 = 1;
}