The Virtual Reality Modeling Language Specification

6. Field Reference

Version 2.0, Official Draft #3, ISO/IEC 14772

July 15, 1996

6.1 Introduction

6.2 SFBool

6.3 SFColor and MF Color

6.4 SFFloat and MFFloat

6.5 SFImage

6.6 SFInt32 and MFInt32

6.7 SFNode and MFNode

6.8 SFRotation and SFRotation

6.9 SFString and MFString

6.10 SFTime

6.11 SFVec2f and MFVec2f

6.12 SFVec3f and MFVec3f

6.1 Introduction

There are two general classes of fields; fields that contain a single value (where a value may be a single number, a vector, or even an image), and fields that contain multiple values. Single-valued fields all have names that begin with SF, multiple-valued fields have names that begin with MF. Each field type defines the format for the values it writes.

Multiple-valued fields are written as a series of values enclosed in square brackets, and separated by whitespace (e.g. commas). If the field has zero values then only the square brackets ("[]") are written. The last value may optionally be followed by whitespace (e.g. comma). If the field has exactly one value, the brackets may be omitted and just the value written. For example, all of the following are valid for a multiple-valued MFInt32 field named foo containing the single integer value 1:

   foo 1
   foo [1,]
   foo [ 1 ]

6.2 SFBool

A field containing a single boolean value. SFBools are written as TRUE or FALSE. For example,

    fooBool FALSE

is an SFBool field, fooBool, defining a FALSE value.

6.3 SFColor/MFColor

Fields containing zero or more RGB colors. SFColor contains zero or one RGB and MFColor contains zero or more RGB colors. Each color is written to file as an RGB triple of floating point numbers in ANSI C floating point format, in the range 0.0 to 1.0. For example:

   fooColor [ 1.0 0. 0.0, 0 1 0, 0 0 1 ]

is an MFColor field, fooColor, containing the three primary colors red, green, and blue.

6.4 SFFloat/MFFloat

Fields that contain one (SFFloat) or zero or more (MFFloat) single-precision floating point number. SFFloats are written to file in ANSI C floating point format. For example:

    fooFloat [ 3.1415926, 12.5e-3, .0001 ]

is an MFFloat field, fooFloat, containing three floating point values values.

6.5 SFImage

The SFImage field defines a single uncompressed 2-dimensional pixel image. SFImage fields are written to file as three integers representing the width, height and number of components in the image, followed by width*height hexadecimal values representing the pixels in the image, separated by whitespace:

     fooImage <width> <height> <num components> <pixels values>

A one-component image contains one-byte hexadecimal values representing the intensity of the image. For example, 0xFF is full intensity, 0x00 is no intensity. A two-component image puts the intensity in the first (high) byte and the alpha (opacity) in the second (low) byte. Pixels in a three-component image have the red component in the first (high) byte, followed by the green and blue components (0xFF0000 is red). Four-component images put the alpha byte after red/green/blue (0x0000FF80 is semi-transparent blue). A value of 0x00 is completely transparent, 0xFF is completely opaque.

Each pixel is read as a single unsigned number. For example, a 3-component pixel with value 0x0000FF may also be written as 0xFF or 255 (decimal). Pixels are specified from left to right, bottom to top. The first hexadecimal value is the lower left pixel and the last value is the upper right pixel.

For example,

    fooImage 1 2 1 0xFF 0x00

is a 1 pixel wide by 2 pixel high one-component (i.e. greyscale) image, with the bottom pixel white and the top pixel black. And:

   fooImage 2 4 3 0xFF0000 0xFF00 0 0 0 0 0xFFFFFF 0xFFFF00
                  # red    green  black.. white    yellow

is a 2 pixel wide by 4 pixel high RGB image, with the bottom left pixel red, the bottom right pixel green, the two middle rows of pixels black, the top left pixel white, and the top right pixel yellow.

6.6 SFInt32/MFInt32

The SFInt32 field contains zero or one 32-bit integer, and the MFInt32 field contains zero or more 32-bit integers. S/FFInt32 fields are written to file as an integer in decimal or hexadecimal (beginning with '0x') format. For example:

    fooInt32 [ 17, -0xE20, -518820 ]

is an MFInt32 field containing three values.

6.7 SFNode/MFNode

The SFNode field contains zero or one nodes, and the MFNode field syntax is just the node that it contain. For example, this is valid syntax for an MFNode field, fooNode:

    fooNode [ Transform { translation 1 0 0 }
              DEF CUBE Box { }
              USE CUBE
              USE SOME_OTHER_NODE ]

The S/MFNode fields may also contain the keyword NULL to indicate that it is empty.

6.8 SFRotation/MFRotation

The SFRotation field contains zero or one arbitrary rotation, and the MFRotation field contains zero or more arbitrary rotations. S/MFRotations are written to file as four floating point values separated by whitespace. The 4 values represent an axis of rotation followed by the amount of right-handed rotation about that axis, in radians. For example, an SFRotation containing a 180 degree rotation about the Y axis is:

    fooRot 0 1 0  3.14159265

6.9 SFString/MFString

The SFString and MFString fields contain strings formatted with the UTF-8 universal character set (ISO/IEC 10646-1:1993, SFString contains zero or one string, and the MFString contains zero or more strings. Strings are written to file as a sequence of UTF-8 octets enclosed in double quotes (e.g. "string").

Due to the drastic changes in Korean Jamo language, the character set of the UTF-8 will be based on ISO 10646-1:1993 plus pDAM 1 - 5 (including the Korean changes). The text strings are stored in visual order.

Any characters (including newlines and '#') may appear within the quotes. To include a double quote character within the string, precede it with a backslash. To include a backslash character within the string, type two backslashes. For example:

    fooString [ "One, Two, Three", "He said, \"Immel did it!\"" ]

is a MFString field, fooString, with two valid strings.

6.10 SFTime/MFTime

Field containing a single time value. Each time value is written to file as a double-precision floating point number in ANSI C floating point format. An absolute SFTime is the number of seconds since Jan 1, 1970 GMT.

6.11 SFVec2f/MFVec2f

Field containing a two-dimensional vector. SFVec2fs are written to file as a pair of floating point values separated by whitespace. For example:

    fooVec2f [ 42 666, 7 94 ]

is a MFString field, fooVec2f, with two valid vectors.

6.12 SFVec3f/MFVec3f

Field containing a three-dimensional vector. SFVec3fs are written to file as three floating point values separated by whitespace. For example:

    fooVec3f [ 1 42 666, 7 94 0 ]

is a MFString field, fooVec3f, with two valid vectors.

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