====== Generic File Format Data Types ======

**Generic File Format Data Types**


====== Intro ======

This is a generic list of data types encountered in **all** file formats. Not all of which will be used in a specific file format.

They are listed here, rather than repetitive typing in each of file format's documentation.

====== Endian ======

[[http://en.wikipedia.org/wiki/Endianness#Little-endian|Little endian]] byte order, lsb first for numeric values, text is stored in [[http://en.wikipedia.org/wiki/Endianness#Big-endian|Big endian]] byte order.

====== Data Types ======

^ Type ^ Description ^
| byte | unsigned 8 bit (1 byte) |
| char | signed 8 bit Ascii(utf8) character |
| char[] | fixed length string |
| tbool | byte (0 = false). |
| short | 16 bit signed short (2 bytes) |
| ushort | 16 bit **unsigned** short (2 bytes) |
| long | 32 bit signed integer (4 bytes) |
| ulong | 32 bit **unsigned** integer (4 bytes) |
| float | 32 bit IEEE-single precision floating point value (4 bytes) |
| double | 64 bit IEEE-double precision floating point value (8 bytes) |
| asciiz | Null terminated (0x00) variable length ascii string |
| asciiz... | zero or more concatenated asciiz strings |
| ascii | fixed length ascii string(UTF-8) |


====== XYPair ======

<code cpp>
XYPair
{
	ulong x,y; // normally associated with cell sizes
}
</code>


====== XYZTriplet ======

<code cpp>
XYZTriplet
{
	float    x,y,z;
}
</code>

Normally, this structure is associated with positional information.



====== RGBAColor ======

<code cpp>
RGBAColor
{
	byte r,g,b,a; // // 0xFF:FF:FF:FF means 'default'
}
</code>

  * RGBA colors correspond to Microsoft's D3DCOLORVALUE
  * They normally come in pairs inside the pew structures to reflect object and outline colors


====== String ======

<code cpp>
LenString
{
	ulong  Length;
	Asciiz Characters[[Length]];// null terminated regardless.
};
</code>

Length always =strlen(Characters)+1;

This is a pre-calculated convenience to reduce load times (and skip over the variable length block).


====== TransformMatrix[[4]][[3]] ======

This is the transform matrix as used by Microsoft DirectX. Known as row-vector format

In fact, the 'correct' matrix is actually 4 x 4, but the last column always represents 0,0,0,1 thus
<code>
M11, M12, M13 (0.0)
M21, M22, M23 (0.0)
M31, M32, M33 (0.0)
M41, M42, M43 (1.0)
</code>

And so is never stored. This identical matrix is used for WRP files (both formats) and RTM files.

In this documentation the above matrix is represented as XYZTriplets

<code cpp>
struct TransformMatrix
{
	XYZTriplet XYZ[[4]];
};
</code>

The last row:
<code>
M41..., or XYZ[[3]]...
</code>
corresponds to the position of the object.


====== ColumnFormat[[3]][[4]] ======

Pew files hold this data in Column, rather than row, vectors, as per OpenGL. Thus;

Wrp
<code>
ABC
DEF
GHI
JKL

Pew

ADGJ
BEHK
CFIL
</code>

And is repesent structurally as

<code cpp>
struct PewTransform
{
	float[[3]][[4]];
};
</code>


====== Note ======

Note that 'int' is not used in this documentation for the following reasons:

  * an 'int' is machine and compiler and language dependent. It is an arbitrary size SIGNED value.
  * with exceptions, BI use floats when requiring negative values.
  * almost all references to 'integers' in BI file formats are either positive-only offsets into memory, zero based indexes, and counts.
  * the incidence of true shorts and true integers in BI is quite rare. Exception -1 is a favourite, to indicate default