SECTION 9.5
801
3D Artwork
3D Reference Dictionaries
It is possible for more than one 3D annotation to be associated with the same 3D
artwork. For example, several annotations might show different views of the same
object. There are two ways in which this association can occur, as determined by
the annotation’s
3DD
entry (see Table 9.33):
•
If the
3DD
entry specifies a 3D stream, the annotation has its own run-time in-
stance of the 3D artwork. Any changes to the artwork are reflected only in this
annotation. Other annotations that refer to the same stream have separate run-
time instances.
•
If the
3DD
entry specifies a 3D reference dictionary (whose entries are shown
in Table 9.38), the annotation shares a run-time instance of the 3D artwork
with all other annotations that specify the same reference dictionary. Any
changes to the artwork are reflected in all such annotations.
TABLE 9.38 Entries in a 3D reference dictionary
KEY
TYPE
VALUE
Type
name
stream
(Optional)
The type of PDF object that this dictionary describes; if present,
must be
3DRef
for a 3D reference dictionary.
(Required)
The 3D stream (see Section 9.5.2, “3D Streams”) containing the
specification of the 3D artwork.
3DD
the same 3D artwork. Object 100 (Annotation 1) has its own run-time instance of
the 3D stream (object 200); object 101(Annotation 2) and object 102 (Annotation
3) share a run-time instance through the 3D reference dictionary (object 201).
Example 9.2
100 0 obj
<< /Type /Annot
/Subtype /3D
/3DD 200 0 R
>>
endobj
101 0 obj
<< /Type /Annot
/Subtype /3D
% 3D annotation 1
% Reference to the 3D stream containing the 3D artwork
% 3D annotation 2