| The Screen3D Object contains all information about a particular screen.
All Canvas3D objects on the same physical screen (display device)
refer to the same Screen3D object. Note that Screen3D has no public
constructors--it is obtained from the Canvas3D via the getScreen3D
method.
Default values for Screen3D parameters are as follows:
physical screen width : 0.0254/90.0 * screen width (in pixels)
physical screen height : 0.0254/90.0 * screen height (in pixels)
tracker base to image plate transform : identity
head tracker to left image plate transform : identity
head tracker to right image plate transform : identity
off-screen size : (0,0)
Offscreen Rendering
New for Java 3D 1.2, an off-screen rendering mode allows rendering
to a memory image, which is possibly larger than the screen. The
setSize and getSize methods are defined specifically for this
mode. Note that the off-screen size, physical width, and physical height
must be set prior to rendering
to the associated off-screen canvas. Failure to do so will result
in an exception.
Calibration Parameters
The Screen3D object must be calibrated with the coexistence volume.
The Screen3D class provides several methods for defining the
calibration parameters.
Measured Parameters
The screen's (image plate's) physical width and height (in meters)
is set once, typically by a browser, calibration program, system
administrator, or system calibrator, not by an applet. These values
must be determined by measuring the display's active image width
and height. In the case of a head-mounted display, this should be
the display's apparent width and height at the focal plane. These
values are defined by the setPhysicalScreenWidth and
setPhysicalScreenHeight methods.
Head-tracker Coordinate System
If head tracking is enabled, one of two parameters need to be specified:
- If the view policy is SCREEN_VIEW, the tracker-base-to-image-plate
coordinate system must be specified (setTrackerBaseToImagePlate method).
This coordinate system must be recalibrated whenever the image
plate moves relative to the tracker.
- If the view policy is HMD_VIEW, the head-tracker-to-left-image-plate
and head-tracker-to-right-image-plate coordinate systems must be
specified (setHeadTrackerToLeftImagePlate and
setHeadTrackerToRightImagePlate methods).
Additional Information
For more information, see the
Introduction to the Java 3D API and
View Model
documents.
See Also: Canvas3D
See Also: Canvas3D.getScreen3D | 