CHAPTER 9
804
Multimedia Features
9.5.3 3D Views
Beginning with PDF 1.6, a
3D view
(or simply
view)
specifies parameters to be
applied to the virtual camera associated with a 3D annotation. These parameters
may include orientation and position of the camera, details regarding the projec-
tion of camera coordinates into the annotation’s target coordinate system, and a
description of the background on which the artwork is to be drawn. Starting with
PDF 1.7, specific views can also specify how 3D artwork is rendered, colored, lit,
and cross-sectioned, without the use of embedded JavaScript. Specific views can
also specify which nodes (three-dimensional areas) of 3D artwork are included in
a view and whether those nodes are opaque or invisible.
Users can manipulate views by performing interactive operations such as free ro-
tation and translation. In addition, 3D artwork can contain a set of predefined
views that the author deems to be of particular interest. For example, a mechani-
cal drawing of a part may have specific views showing the top, bottom, left, right,
front, and back of an object.
A 3D stream may contain a list of named preset views of the 3D artwork, as spec-
ified by the
VA
entry, which is an array of 3D view dictionaries. The entries in a
3D view dictionary are shown in Table 9.39.
TABLE 9.39 Entries in a 3D view dictionary
KEY
TYPE
VALUE
Type
name
text string
text string
(Optional)
The type of PDF object that this dictionary describes; if present,
must be
3DView
for a 3D view dictionary.
(Required)
The external name of the view, suitable for presentation in a user in-
terface.
(Optional)
The internal name of the view, used to refer to the view from other
objects, such as the go-to-3D-view action (see “Go-To-3D-View Actions” on
(Optional)
A name specifying the entry to use for the 3D camera-to-world
transformation matrix. The following values are supported:
M
U3D
XN
IN
MS
name
Indicates that the
C2W
entry specifies the matrix
Indicates that the
U3DPath
entry in the 3D stream object is
used for the matrix. This value reflects the sole supported value
of the
Subtype
entry in the 3D stream dictionary.
If omitted, the view specified in the 3D artwork is used.