.TH Introduction 3 "R1c" "Silicon Graphics"
The \f2IRIS Reference Manual\f1 contains detailed descriptions
of the commands in the Graphics Library.  Each command begins on a new page.
The pages are arranged in alphabetical order with both a page number and the
command name in the upper outside corner of the page.
.PP
Each command description defines the number, order, and types of all arguments
to the commands.  C, FORTRAN, and Pascal descriptions are provided
under the heading \f3Synopsis\f1.
A detailed description of the command, including function, side effect,
and potential errors is given in the section called \f3Description\f1;
related commands are listed under \f3See Also\f1.
.PP
Some of the commands come in several flavors, depending on the number
and type of the arguments.  Coordinate data can be 2D or 3D, and can be
floating point numbers or integers.  The default is 3D floating point data.
Integer data and 2D points are specified with suffixes: "i" for integer
and "2" for 2D.  All four forms are shown for
each language.
.SH TEXT STRINGS
We have adopted the C convention of strings that end with a null
character (ASCII 0) in Pascal.  FORTRAN has a \f3character\f1 
data type that includes the length of the string.
.SH POINTERS
Many of the Graphics Library commands return several values to the caller.
The arguments to these commands are \f2pointers\f1: addresses of memory
locations.  In C, they are declared as pointer variables by prefixing the
variable name with an asterisk in the declaration.  FORTRAN passes all
parameters by reference, so no special declaration is necessary.  Pascal
uses the 
.I var
keyword to distinguish between value parameters and
pointer arguments. 
.SH PASCAL ARRAYS
Pascal normally copies all arguments to a subroutine,
including arrays.  In the interest of efficiency, we have declared
all array arguments to be reference parameters: an address to the data
will be passed to the subroutine, rather than the data itself.
.PP
Furthermore, the Pascal language forces the size of the array to be part
of the type of the array.  Many Graphics Library commands 
accept variable-length arrays.  Therefore, we have defined oversized
arrays with 
.I MAXARRAY
entries.  The user can use some part of the
array, or redefine 
.I MAXARRAY
to a more realistic value.
.SH BOOLEANS
Many of the commands have boolean arguments or return boolean vlues.
These are declared as type 
.I Boolean
in C and Pascal, and
as 
.I logical
in FORTRAN.  We assume that 
.I FALSE
is zero, and that 
.I TRUE
\(!=
.I FALSE.
.SH TYPE DECLARATIONS
We have constructed type declarations for C and Pascal
wherever they add to the readability
of the code.  Here are the type definitions:
.nf
.TP \w'FORTRAN\ \ \ 'u
C
#define FALSE 0
#define TRUE !FALSE

typedef unsigned char Byte;
typedef Byte Boolean;
typedef short Angle;
typedef unsigned short Screen;
typedef long Icoord;
typedef float Coord;
typedef char *String;
typedef float Matrix[4][4];

typedef unsigned short Device;

typedef unsigned short Colorindex;
typedef unsigned short RGBvalue;

typedef unsigned short Linestyle;
typedef Byte Texture[16];
typedef unsigned short Cursor[16];
typedef struct {
	unsigned short offset;	/* 2 bytes */
	Byte w,h;		/* 2 bytes */
	char xoff,yoff;		/* 2 bytes */
	short width;		/* 2 bytes */
} Fontchar;

typedef long Object;
typedef long Tag;
typedef long Offset;

.nf
.TP \w'FORTRAN\ \ \ 'u
Pascal
const	MAXARRAY = 1023;
	MAXRASTER = 4095;

type	Byte = 0..255;
	Short = -32768..32767;
	UnsignedShort = Short;
	Angle = integer;
	Screencoord = -2048..2047;
	Icoord = integer;
	Coord = real;
	String = packed array [0..127] of char;
	Matrix = array [0..3, 0..3] of real;

	Device = Short;

	Colorindex = Short;
	RGBvalue = 0..255;

	Linestyle = Short;
	Texture = array [0..15] of Byte;
	Cursor = array [0..15] of Short;
	Fontchar = record 
			offst: Short;	
			w, h: Byte;
			xoff, yoff: -128..127;
	 		xinc: Short;
		end;

	Object = integer;
	Tag = integer;
	Offset = integer;

	Coord4array = array [0..MAXARRAY, 0..3] of Coord;
	Coord3array = array [0..MAXARRAY, 0..2] of Coord;
	Coord2array = array [0..MAXARRAY, 0..1] of Coord;
	Icoord3array = array [0..MAXARRAY, 0..2] of Icoord;
	Icoord2array = array [0..MAXARRAY, 0..1] of Icoord;
	Screenarray = array [0..MAXARRAY, 0..2] of Screencoord;

	Boolarray = array [0..MAXARRAY] of Boolean;
	Colorarray = array [0..MAXARRAY] of Colorindex;
	RGBarray = array [0..MAXARRAY] of RGBvalue;

	Objarray = array [0..127] of Object;
	Fntchrarray = array [0..127] of Fontchar;
	Fontraster = array [0..MAXRASTER] of Byte;