Introduction(3) — Silicon Graphics R1c

The IRIS Reference Manual 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.

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 Synopsis. A detailed description of the command, including function, side effect, and potential errors is given in the section called Description; related commands are listed under See Also.

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.

TEXT STRINGS

We have adopted the C convention of strings that end with a null character (ASCII 0) in Pascal. FORTRAN has a character data type that includes the length of the string.

POINTERS

Many of the Graphics Library commands return several values to the caller. The arguments to these commands are pointers: 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 var keyword to distinguish between value parameters and pointer arguments.

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.

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 MAXARRAY entries. The user can use some part of the array, or redefine MAXARRAY to a more realistic value.

BOOLEANS

Many of the commands have boolean arguments or return boolean vlues. These are declared as type Boolean in C and Pascal, and as logical in FORTRAN. We assume that FALSE is zero, and that TRUE ≠ FALSE.

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:

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;

Pascal
constMAXARRAY = 1023;
MAXRASTER = 4095;
typeByte = 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;