| 1 |
be read by the program getinfo.
|
| 2 |
|
| 3 |
2. Scene Description
|
| 4 |
|
| 5 |
A scene description file represents a three-dimensional
|
| 6 |
physical environment in Cartesian (rectilinear) world coor-
|
| 7 |
dinates. It is stored as ascii text, with the following
|
| 8 |
basic format:
|
| 9 |
|
| 10 |
# comment
|
| 11 |
|
| 12 |
modifier type identifier
|
| 13 |
n S1 S2 S3 ... Sn
|
| 14 |
0
|
| 15 |
m R1 R2 R3 ... Rm
|
| 16 |
|
| 17 |
! command
|
| 18 |
|
| 19 |
...
|
| 20 |
|
| 21 |
|
| 22 |
A comment line begins with a pound sign, `#'.
|
| 23 |
|
| 24 |
The scene description primitives all have the same gen-
|
| 25 |
eral format, and can be either surfaces or modifiers. A
|
| 26 |
primitive has a modifier, a type, and an identifier. A
|
| 27 |
modifier is either the identifier of a previously defined
|
| 28 |
primitive, or void. An identifier can be any string (ie.
|
| 29 |
sequence of non-blank characters). The arguments associated
|
| 30 |
with a primitive can be strings or real numbers. The first
|
| 31 |
integer following the identifier is the number of string
|
| 32 |
arguments, and it is followed by the arguments themselves.
|
| 33 |
The next integer is the number of integer arguments, and is
|
| 34 |
followed by the integer arguments. (There are currently no
|
| 35 |
primitives that use them, however.) The next integer is the
|
| 36 |
real argument count, and it is followed by the real argu-
|
| 37 |
ments.
|
| 38 |
|
| 39 |
A line beginning with an exclamation point, `!', is
|
| 40 |
interpreted as a command. It is executed by the shell, and
|
| 41 |
its output is read as input to the program. The command
|
| 42 |
must not try to read from its standard input, or confusion
|
| 43 |
will result.
|
| 44 |
|
| 45 |
Blank space is generally ignored, except as a separa-
|
| 46 |
tor. The exception is the newline character after a command
|
| 47 |
or comment. Commands, comments and primitives may appear in
|
| 48 |
any combination, so long as they are not intermingled.
|
| 49 |
|
| 50 |
2.1. Primitive Types
|
| 51 |
|
| 52 |
Primitives can be surfaces, materials, textures or pat-
|
| 53 |
terns. Materials modify surfaces, textures and patterns
|
| 54 |
modify textures, patterns and materials.
|
| 55 |
|
| 56 |
2.1.1. Surfaces
|
| 57 |
|
| 58 |
A scene description will consist mostly of surfaces.
|
| 59 |
The basic types are given below.
|
| 60 |
|
| 61 |
|
| 62 |
|
| 63 |
|
| 64 |
|
| 65 |
|
| 66 |
|
| 67 |
|
| 68 |
- 201 -
|
