Spaces, tabs, and new lines are all considered white space in a SLIDE file. One or more white space characters are used to separate tokens in a SLIDE file.
There are two ways of specifying comments in a SLIDE file. The
first type is a simple line comment which is designated by the
# symbol. When this character is encountered by the
parser, all characters which follow it until the next new line will be
ignored. For example:
# This is a line comment
The other type of comment is a region comment which is similar to
comments in C. These comments regions are demarked by
(* *). Unlike the C language, SLIDE region
comments can be arbitrarily nested. The following are correct
examples of region comments:
(* This is
a region
comment *)
(* These (* are (* nested *) *) (* region *) comments *)
(* This will (* cause a nesting ERROR *)
| Type | Examples | BNF |
|---|---|---|
| Integers | 10$SLF_ON$SLF_FRAME |
[0-9]+ |
| Floats | 11.0-1e-11.0E5$SLF_PI$SLF_TIME |
[-]?([0-9]*[.])?[0-9]+([eE][-+]?[0-9]+)? |
| Tcl Macro Values | %{ expr sin($SLF_PI/6) }% |
%{ <Tcl expr> }% |
| Tcl Dynamic Values | { expr sin($SLF_TIME) } |
{ <Tcl expr> } |
| Pairs | 1.0 { expr 2.0 } |
float float |
| Triples | { expr 1.0 } 2.0 %{ expr 3.0 }% |
float float float |
| Strings | "This is sphere: \"s29\"" |
["]([\]["]|.)*["] |
| Identifiers | gLeft_Arm_3 |
[A-Za-z_][A-Za-z_0-9]* |
| Id Lists | p0 p1 p2 |
id* |
| Paths | camgCam.iCam.camgBody.iHead.iLeftEye.cam |
(node_id[.](inst_id[.])+)?node_id |
Integers are used for the enumerated values of the SLIDE flag types. Integers are also used as values for specific fields like the zslices field of the sphere primitive.
Most fields take floating point precision values. SLIDE follows the C conventions for representing floating point numbers.
Tcl macro values are abitrary Tcl expressions demarked by
%{ }%. These values are computed exactly once
during initialization and can be treated as floating point or integer
constants.
Tcl dynamic values are abitrary Tcl expressions demarked by
{ }. These values are computed once per frame and
can be treated as varying floating point or integer values.
2D primitives, like windows and viewports, have fields which take a pair of floating point values separated by white space, like the size field.
3D primitives have fields which take a vector valued triple of floating point values separated by white space. An example is the coordinate vector of a SLIDE point.
Certain fields can take on C style string constant values. These string constants are contained within double quotation marks ("") where back-slashes (\) are used to escape special characters.
Most SLIDE primitives are given identifiers, so that other primitives can refer to them. These identifiers are defined by the same rules as C variable identifiers, where the name must begin with a letter or an underscore followed by zero or more letters, numbers, or underscores.
In SLIDE, references to other entities are usually made in identifier lists. This is simply a list of identifiers separated by white space. An example is the point id list in the face construct.
Paths are used to refer to a particular instance within a scene
graph. It is not possible to use a single identifier because entities
can be instanced multiple times. The only way to uniquely refer to a
particular instance is by defining a traversal pathway down the
directed acyclic graph (DAG) which is the scene graph. A path can be
a single node identifier like cam. A path can also be
the identifier of a node at which to begin the traversal followed by
one or more instance identifiers which tell which branches to take
along the traversal and terminated with the primitive's node
identifier which can be used to verify the path
(gBody.iHead.iLeftEye.cam).