BS Contact J Specification
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BS Contact J Specification |
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The field and event specification is taken from the VRML 97 specification with the following exceptions:
3.1 Introduction
3.1.1 Table of contents
3.1.2 Description
3.2 SFBool
3.3 SFColor and MFColor
3.4 SFFloat and MFFloat
3.5 SFImage
3.6 SFInt32 and MFInt32
3.7 SFNode and MFNode
3.8 SFRotation and MFRotation
3.9 SFString and MFString
3.10 SFTime and MFTime
3.11 SFVec2f and MFVec2f
3.12 SFVec3f and MFVec3f
This clause describes the syntax and general semantics of fields and events, the elemental data types used by VRML nodes to define objects (see 6, Node reference). Nodes are composed of fields and events (see 4, Concepts). The types defined in this annex are used by both fields and events.
There are two general classes of fields and events: fields and events that contain a single value (where a value may be a single number, a vector, or even an image), and fields and events that contain an ordered list of multiple values. Single-valued fields and events have names that begin with SF.Multiple-valued fields and events have names that begin with MF.
Multiple-valued fields/events are written as an ordered list of values enclosed in square brackets and separated by whitespace. If the field or event has zero values, only the square brackets ("[ ]") are written. The last value may optionally be followed by whitespace. If the field has exactly one value, the brackets may be omitted. 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 ]
The SFBool field or event specifies a single boolean value. SFBools are written as TRUE or FALSE. For example,
fooBool FALSE
is an SFBool field, fooBool, defining a FALSE value.
The initial value of an SFBool eventOut is FALSE.
The SFColor field or event specifies one RGB (red-green-blue) colour triple. MFColor specifies zero or more RGB triples. Each colour is written to the VRML file as an RGB triple of floating point numbers in ISO C floating point format (see 2.[ISOC]) 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 colours red, green, and blue.
The initial value of an SFColor eventOut is (0 0 0). The initial value of an MFColor eventOut is [ ].
The SFFloat field or event specifies one single-precision floating point number. MFFloat specifies zero or more single-precision floating point numbers. SFFloats and MFFloats are written to the VRML file in ISO C floating point format (see 2.[ISOC]). For example:
fooFloat [ 3.1415926, 12.5e-3, .0001 ]
is an MFFloat field, fooFloat, containing three floating point values.
The initial value of an SFFloat eventOut is 0.0. The initial value of an MFFloat eventOut is [ ].
The SFImage field is not supported in Core X3D.
The SFInt32 field and event specifies one 32-bit integer. The MFInt32 field and event specifies zero or more 32-bit integers. SFInt32 and MFInt32 fields and events are written to the VRML 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.
The initial value of an SFInt32 eventOut is 0. The initial value of an MFInt32 eventOut is [ ].
The SFNode field and event specifies a VRML node. The MFNode field and event specifies zero or more nodes. The following example illustrates valid syntax for an MFNode field, fooNode, defining four nodes:
fooNode [ Transform { translation 1 0 0 }
DEF CUBE Box { }
USE CUBE
USE SOME_OTHER_NODE ]
The SFNode field and event may contain the keyword NULL to indicate that it is empty.
The initial value of an SFNode eventOut is NULL. The initial value of an MFNode eventOut is [ ].
The SFRotation field and event specifies one arbitrary rotation. The MFRotation field and event specifies zero or more arbitrary rotations. An SFRotation is written to the VRML file as four ISO C floating point values (see 2.[ISOC]) separated by whitespace. The first three values specify a normalized rotation axis vector about which the rotation takes place. The fourth value specifies the amount of right-handed rotation about that axis in radians. For example, an SFRotation containing a PI radians rotation about the Y axis is:
fooRot 0.0 1.0 0.0 3.14159265
The 3x3 matrix representation of a rotation (x y z a) is
[ tx2+c txy+sz txz-sy
txy-sz ty2+c tyz+sx
txz+sy tyz-sx tz2+c ]
where c = cos(a), s = sin(a), and t = 1-c
The initial value of an SFRotation eventOut is (0 0 1 0). The initial value of an MFRotation eventOut is [ ].
The SFString and MFString fields and events contain strings formatted with the UTF-8 universal character set (see 2.[UTF8]). SFString specifies a single string. The MFString specifies zero or more strings. Strings are written to the VRML file as a sequence of UTF-8 octets enclosed in double quotes (e.g., "string").
Any characters (including linefeeds and '#') may appear within the quotes. A double quote character within the string is preceded with a backslash. A backslash character within the string is also preceded with a backslash forming two backslashes. For example:
fooString [ "One, Two, Three", "He said, \"Immel did it!\"" ]
is an MFString field, fooString, with two valid strings.
The initial value of an SFString eventOut is "" (the empty string). The initial value of an MFString eventOut is [ ].
The SFTime field or event specifies a single time value. The MFTime field or event specifies zero or more time values. Time values are written to the VRML file as a double-precision floating point number in ISO C floating point format (see 2.[ISOC]). Time values are specified as the number of seconds from a specific time origin. Typically, SFTime fields and events represent the number of seconds since Jan 1, 1970, 00:00:00 GMT. For example:
fooTime 0.0
is an SFTime field, fooTime, representing a time of 0.0 seconds.
The initial value of an SFTime eventOut is -1. The initial value of an MFTime eventOut is [ ].
The SFVec2f field or event specifies a two-dimensional (2D) vector. An MFVec2f field or event specifies zero or more 2D vectors. SFVec2f's and MFVec2f's are written to the VRML file as a pair of ISO C floating point values (see 2.[ISOC]) separated by whitespace. For example:
fooVec2f [ 42 666, 7 94 ]
is an MFVec2f field, fooVec2f, with two valid vectors.
The initial value of an SFVec2f eventOut is (0 0). The initial value of an MFVec2f eventOut is [ ].
The SFVec3f field or event specifies a three-dimensional (3D) vector. An MFVec3f field or event specifies zero or more 3D vectors. SFVec3f's and MFVec3f's are written to the VRML file as three ISO C floating point values (see 2.[ISOC]) separated by whitespace. For example:
fooVec3f [ 1 42 666, 7 94 0 ]
is an MFVec3f field, fooVec3f, with two valid vectors.
The initial value of an SFVec3f eventOut is (0 0 0). The initial value of an MFVec3f eventOut is [ ].