javax.media.j3d

Class View

java.lang.Object

javax.media.j3d.View

public class View
extends Object

The View object contains all parameters needed in rendering a three dimensional scene from one viewpoint. A view contains a list of Canvas3D objects that the view is rendered into. It exists outside of the scene graph, but attaches to a ViewPlatform leaf node object in the scene graph. It also contains a reference to a PhysicalBody and a PhysicalEnvironment object.

The View object is the main Java 3D object for controlling the Java 3D viewing model. All of the components that specify the view transform used to render to the 3D canvases are either contained in the View object or in objects that are referenced by the View object.

Java 3D allows applications to specify multiple simultaneously active View objects, each controlling its own set of canvases.

The Java 3D View object has several instance variables and methods, but most are calibration variables or user-helping functions. The viewing policies defined by the View object are described below.

Policies

The View object defines the following policies:

• View policy - informs Java 3D whether it should generate the view using the head-tracked system of transformations or the head-mounted system of transformations. These policies are attached to the Java 3D View object. There are two view policies:
• SCREEN_VIEW - specifies that Java 3D should compute a new viewpoint using the sequence of transforms appropriate to screen-based head-tracked display environments (fish-tank VR/portals/VR-desks). This is the default setting.
• HMD_VIEW - specifies that Java 3D should compute a new viewpoint using the sequence of transforms appropriate to head mounted display environments. This policy is not available in compatibility mode (see the setCompatibilityModeEnable method description).

• Projection policy - specifies whether Java 3D should generate a parallel projection or a perspective projection. This policy is attached to the Java 3D View object. There are two projection policies:
• PARALLEL_PROJECTION - specifies that a parallel projection transform is computed.
• PERSPECTIVE_PROJECTION - specifies that a perspective projection transform is computed. This is the default policy.

• Screen scale policy - specifies where the screen scale comes from. There are two screen scale policies:
• SCALE_SCREEN_SIZE - specifies that the scale is derived from the physical screen according to the following formula (this is the default mode):
screenScale = physicalScreenWidth / 2.0

• SCALE_EXPLICIT - pecifies that the scale is taken directly from the user-provided screenScale attribute (see the setScreenScale method description).

• Window resize policy - specifies how Java 3D modifies the view when users resize windows. When users resize or move windows, Java 3D can choose to think of the window as attached either to the physical world or to the virtual world. The window resize policy allows an application to specify how the view model will handle resizing requests. There are two window resize policies:
• VIRTUAL_WORLD - implies that the original image remains the same size on the screen but the user sees more or less of the virtual world depending on whether the window grew or shrank in size.
• PHYSICAL_WORLD - implies that the original image continues to fill the window in the same way using more or less pixels depending on whether the window grew or shrank in size.

• Window movement policy - specifies what part of the virtual world Java 3D draws as a function of window placement on the screen. There are two window movement policies:
• VIRTUAL_WORLD - implies that the image seen in the window changes as the position of the window shifts on the screen. (This mode acts as if the window were a window into the virtual world.)
• PHYSICAL_WORLD - implies that the image seen in the window remains the same no matter where the user positions the window on the screen.

• Window eyepoint policy - comes into effect in a non-head-tracked environment. The policy tells Java 3D how to construct a new view frustum based on changes in the field of view and in the Canvas3D's location on the screen. The policy only comes into effect when the application changes a parameter that can change the placement of the eyepoint relative to the view frustum. There are three window eyepoint policies:
• RELATIVE_TO_SCREEN - tells Java 3D to interpret the eye's position relative to the entire screen. No matter where an end user moves a window (a Canvas3D), Java 3D continues to interpret the eye's position relative to the screen. This implies that the view frustum changes shape whenever an end user moves the location of a window on the screen. In this mode, the field of view is read-only.
• RELATIVE_TO_WINDOW - specifies that Java 3D should interpret the eye's position information relative to the window (Canvas3D). No matter where an end user moves a window (a Canvas3D), Java 3D continues to interpret the eye's position relative to that window. This implies that the frustum remains the same no matter where the end user moves the window on the screen. In this mode, the field of view is read-only.
• RELATIVE_TO_FIELD_OF_VIEW - tells Java 3D that it should modify the eyepoint position so it is located at the appropriate place relative to the window to match the specified field of view. This implies that the view frustum will change whenever the application changes the field of view. In this mode, the eye position is read-only. This is the default setting.
• RELATIVE_TO_COEXISTENCE - tells Java 3D to interpret the eye's position in coexistence coordinates. In this mode, the eye position is taken from the view (rather than the Canvas3D) and transformed from coexistence coordinates to image plate coordinates for each Canvas3D. The resulting eye position is relative to the screen. As in RELATIVE_TO_SCREEN mode, this implies that the view frustum changes shape whenever an end user moves the location of a window on the screen. In this mode, the field of view is read-only.

• Front and back clip policies - specifies how Java 3D interprets clipping distances to both the near and far clip planes. The policies can contain one of four values specifying whether a distance measurement should be interpreted in the physical or the virtual world and whether that distance measurement should be interpreted relative to the physical eyepoint or the physical screen. The front and back clip policies are specified separately. The front clip policy determines where Java 3D places the front clipping plane. The back clip policy determines where Java 3D places the back clipping plane. The values for both front and back clipping planes are:
• VIRTUAL_EYE - specifies that the associated distance is from the eye and in units of virtual distance.
• PHYSICAL_EYE - specifies that the associated distance is from the eye and in units of physical distance (in meters). This is the default policy for both front and back clipping.
• VIRTUAL_SCREEN - specifies that the associated distance is from the screen and in units of virtual distance.
• PHYSICAL_SCREEN - specifies that the associated distance is from the screen and in units of physical distance (in meters).

• Visibility policy - specifies how visible and invisible objects are drawn. There are three visibility policies:
• VISIBILITY_DRAW_VISIBLE - only visible objects are drawn (this is the default).
• VISIBILITY_DRAW_INVISIBLE - only invisible objects are drawn.
• VISIBILITY_DRAW_ALL - both visible and invisible objects are drawn.

• Transparency sorting policy - specifies whether and how transparent objects are sorted. Sorting multiple transparent objects is necessary to avoid artifacts caused by overlapping transparent objects. There are two transparency sorting policies:
• TRANSPARENCY_SORT_NONE - no depth sorting of transparent objects is performed (this is the default). Transparent objects are drawn after opaque objects, but are not sorted from back to front.
• TRANSPARENCY_SORT_GEOMETRY - transparent objects are depth-sorted on a per-geometry basis. Each geometry object of each transparent Shape3D node is drawn from back to front. Note that this policy will not split geometry into smaller pieces, so intersecting or intertwined objects may not be sorted correctly. The method used for determining which geometry is closer is implementation dependent.

Projection and Clip Parameters

The projection and clip parameters determine the view model's field of view and the front and back clipping distances.

• Field of view - specifies the view model's horizontal field of view in radians, when in the default non-head-tracked mode. This value is ignored when the view model is operating in head-tracked mode, or when the Canvas3D's window eyepoint policy is set to a value other than the default setting of RELATIVE_TO_FIELD_OF_VIEW.
• Front clip distance - specifies the distance away from the clip origin, specified by the front clip policy variable, in the direction of gaze where objects stop disappearing. Objects closer than the clip origin (eye or screen) plus the front clip distance are not drawn. Measurements are done in the space (physical or virtual) that is specified by the associated front clip policy parameter.
• Back clip distance - specifies the distance away from the clip origin (specified by the back clip policy variable) in the direction of gaze where objects begin disappearing. Objects farther away from the clip origin (eye or screen) plus the back clip distance are not drawn. Measurements are done in the space (physical or virtual) that is specified by the associated back clip policy parameter. The View object's back clip distance is ignored if the scene graph contains an active Clip leaf node.

There are several considerations to take into account when choosing values for the front and back clip distances.

• The front clip distance must be greater than 0.0 in physical eye coordinates.
• The front clipping plane must be in front of the back clipping plane, that is, the front clip distance must be less than the back clip distance in physical eye coordinates.
• The front and back clip distances, in physical eye coordinates, must be less than the largest positive single-precision floating point value, Float.MAX_VALUE. In practice, since these physical eye coordinate distances are in meters, the values should be much less than that.
• The ratio of the back distance divided by the front distance, in physical eye coordinates, affects Z-buffer precision. This ratio should be less than about 3000 to accommodate 16-bit Z-buffers. Values of 100 to less than 1000 will produce better results.

Violating any of the above rules will result in undefined behavior. In many cases, no picture will be drawn.

Frame Start Time, Duration, and Number

There are five methods used to get information about system execution and performance:

getCurrentFrameStartTime returns the time at which the most recent rendering frame started.

getLastFrameDuration returns the duration, in milliseconds, of the most recently completed rendering frame.

getFrameNumber returns the frame number for this view.

getMaxFrameStartTimes retrieves the implementation-dependent maximum number of frames whose start times will be recorded by the system.

getFrameStartTimes copies the last k frame start time values into the user-specified array.

View Traversal and Behavior Scheduling

The following methods control the traversal, the rendering, and the execution of the behavior scheduler for this view:

startBehaviorScheduler starts the behavior scheduler running after it has been stopped.

stopBehaviorScheduler stops the behavior scheduler after all currently-scheduled behaviors are executed.

isBehaviorSchedulerRunning retrieves a flag that indicates whether the behavior scheduler is currently running.

startView starts traversing this view and starts the renderers associated with all canvases attached to this view.

stopView stops traversing this view after the current state of the scene graph is reflected on all canvases attached to this view.

isViewRunning returns a flag indicating whether the traverser is currently running on this view.

Note: The above six methods are heavy-weight methods intended for verification and image capture (recording). They are not intended to be used for flow control.

Scene Antialiasing

The following methods set and retrieve the scene antialiasing flag. Scene antialiasing is either enabled or disabled for this view. If enabled, the entire scene will be antialiased on each canvas in which scene antialiasing is available. Scene antialiasing is disabled by default.

setSceneAntialiasingEnable sets the scene antialiasing flag.

getSceneAntialiasingEnable returns the scene antialiasing flag.

Note that line and point antialiasing are independent of scene antialiasing. If antialiasing is enabled for lines and points, the lines and points will be antialiased prior to scene antialiasing. If scene antialiasing is disabled, antialiased lines and points will still be antialiased.

Note: Scene antialiasing is ignored in pure immediate mode, but is supported in mixed-immediate mode.

Depth Buffer

The following two methods enable and disable automatic freezing of the depth buffer for objects rendered during the transparent rendering pass (that is, objects rendered using alpha blending) for this view. If enabled, depth buffer writes are disabled during the transparent rendering pass regardless of the value of the depth-buffer-write-enable flag in the RenderingAttributes object for a particular node. This flag is enabled by default.

setDepthBufferFreezeTransparent enables depth buffer freezing.

getDepthBufferFreezeTransparent retrieves the depth buffer flag.

Transparent objects include BLENDED transparent primitives and antialiased lines and points. Transparent objects do not include opaque objects or primitives rendered with SCREEN_DOOR transparency.

Sensors

The following methods retrieve the sensor's location in the virtual world:

getSensorToVworld takes the sensor's last reading and generates a sensor-to-vworld coordinate system transform. This Transform3D object takes points in that sensor's local coordinate system and transforms them into virtual world coordinates.

getSensorHotSpotInVworld retrieves the specified sensor's last hotspot location in virtual world coordinates.

Compatibility Mode

A camera-based view model allows application programmers to think about the images displayed on the computer screen as if a virtual camera took those images. Such a view model allows application programmers to position and orient a virtual camera within a virtual scene, to manipulate some parameters of the virtual camera's lens (specify its field of view), and to specify the locations of the near and far clipping planes.

Java 3D allows applications to enable compatibility mode for room-mounted, non-head-tracked display environments, or to disable compatibility mode using the following methods. Camera-based viewing functions are only available in compatibility mode.

setCompatibilityModeEnable turns compatibility mode on or off. Compatibility mode is disabled by default.

getCompatabilityModeEnable returns the compatibility mode enable flag.

Use of these view-compatibility functions will disable some of Java 3D's view model features and limit the portability of Java 3D programs. These methods are primarily intended to help jump-start porting of existing applications.

Setting the Viewing Transform

The View object provides the following compatibility-mode methods that operate on the viewing transform.

setVpcToEc a compatibility mode method that specifies the ViewPlatform coordinates (VPC) to eye coordinates viewing transform.

getVpcToEc returns the VPC.

Setting the Projection Transform

The View object provides the following compatibility-mode methods that operate on the projection transform:

The setLeftProjection and setRightProjection methods specify a viewing frustum for the left and right eye that transforms points in eye coordinates to clipping coordinates.

The getLeftProjection and getRightProjection methods return the viewing frustum for the left and right eye.

Additional Information

For more information, see the Introduction to the Java 3D API and View Model documents.

See Also:

Canvas3D, PhysicalBody, PhysicalEnvironment, ViewPlatform, TransparencyAttributes

Field Summary

Fields

Modifier and Type	Field and Description
static int	CYCLOPEAN_EYE_VIEW Specifies that monoscopic view generated should be the view as seen from the 'center eye', the fictional eye half-way between the left and right eye.
static int	HMD_VIEW Specifies that the viewing environment for this view is a head-mounted display environment.
static int	LEFT_EYE_VIEW Specifies that monoscopic view generated should be the view as seen from the left eye.
static int	NOMINAL_FEET Specifies a policy whereby the origin of physical or virtual coordinates is relative to the position of the nominal feet.
static int	NOMINAL_HEAD Specifies a policy whereby the origin of physical or virtual coordinates is relative to the position of the nominal head.
static int	NOMINAL_SCREEN Specifies a policy whereby the origin of physical or virtual coordinates is relative to the screen.
static int	PARALLEL_PROJECTION Specifies that Java 3D should generate a parallel projection matrix for this View.
static int	PERSPECTIVE_PROJECTION Specifies that Java 3D should generate a perspective projection matrix for this View.
static int	PHYSICAL_EYE Specifies that the associated distance is measured from the eye in meters.
static int	PHYSICAL_SCREEN Specifies that the associated distance is measured from the screen in meters.
static int	PHYSICAL_WORLD Policy for resizing and moving windows.
static int	RELATIVE_TO_COEXISTENCE Policy for placing the eyepoint in non-head-tracked modes.
static int	RELATIVE_TO_FIELD_OF_VIEW Policy for placing the eyepoint in non-head-tracked modes.
static int	RELATIVE_TO_SCREEN Policy for placing the eyepoint in non-head-tracked modes.
static int	RELATIVE_TO_WINDOW Policy for placing the eyepoint in non-head-tracked modes.
static int	RIGHT_EYE_VIEW Specifies that monoscopic view generated should be the view as seen from the right eye.
static int	SCALE_EXPLICIT Specifies that the screen scale for this view is taken directly from the user-provided screenScale parameter.
static int	SCALE_SCREEN_SIZE Specifies that the screen scale for this view is derived from the physical screen size.
static int	SCREEN_VIEW Specifies that the viewing environment for this view is a standard screen-based display environment.
static int	TRANSPARENCY_SORT_GEOMETRY Policy that specifies that transparent objects are sorted from back to front on a per-geometry basis.
static int	TRANSPARENCY_SORT_NONE Policy that specifies that no sorting of transparent objects is done.
static int	VIRTUAL_EYE Specifies that the associated distance is measured from the eye in virtual world coordinates.
static int	VIRTUAL_SCREEN Specifies that the associated distance is measured from the screen in virtual world coordinates.
static int	VIRTUAL_WORLD Policy for resizing and moving windows.
static int	VISIBILITY_DRAW_ALL Policy that specifies that both visible and invisible objects should be drawn.
static int	VISIBILITY_DRAW_INVISIBLE Policy that specifies that only invisible objects should be drawn.
static int	VISIBILITY_DRAW_VISIBLE Policy that specifies that only visible objects should be drawn.

Constructor Summary

Constructors

Constructor and Description
View() Constructs a View object with default parameters.

Method Summary

Methods

Modifier and Type	Method and Description
void	addCanvas3D(Canvas3D canvas3D) Adds the given Canvas3D at the end of the list.
void	attachViewPlatform(ViewPlatform vp) Attach viewPlatform structure to this view.
Enumeration<Canvas3D>	getAllCanvas3Ds() Gets the enumeration object of all the Canvas3Ds.
double	getBackClipDistance() Returns the view model's back clip distance.
int	getBackClipPolicy() Returns the view model's current back clip policy.
Canvas3D	getCanvas3D(int index) Gets the Canvas3D at the specified index position.
boolean	getCoexistenceCenteringEnable() Retrieves the coexistenceCentering enable flag.
boolean	getCompatibilityModeEnable() Retrieves the compatibility mode enable flag.
long	getCurrentFrameStartTime() This method returns the time at which the most recent rendering frame started.
boolean	getDepthBufferFreezeTransparent() Retrieves the current value of the depth buffer freeze transparent flag for this view.
double	getFieldOfView() Returns the current field of view.
long	getFrameNumber() This method returns the frame number for this view.
long	getFrameStartTimes(long[] times) Copies the last k frame start time values into the user-specified array.
double	getFrontClipDistance() Returns the view model's front clip distance.
int	getFrontClipPolicy() Returns the view model's current front clip policy.
long	getLastFrameDuration() This method returns the duration, in milliseconds, of the most recently completed rendering frame.
void	getLeftManualEyeInCoexistence(javax.vecmath.Point3d position) Retrieves the position of the user-specified, manual left eye in coexistence coordinates and copies that value into the object provided.
void	getLeftProjection(Transform3D projection) Compatibility mode method that retrieves the current compatibility mode projection transform for the left eye and places it into the specified object.
boolean	getLocalEyeLightingEnable() Retrieves a flag that indicates whether or not local eye lighting is enabled for this view.
static int	getMaxFrameStartTimes() Retrieves the implementation-dependent maximum number of frames whose start times will be recorded by the system.
long	getMinimumFrameCycleTime() Retrieves the minimum frame cycle time, in milliseconds, for this view.
int	getMonoscopicViewPolicy() Deprecated. As of Java 3D version 1.2, replaced by Canvas3D.getMonoscopicViewPolicy
PhysicalBody	getPhysicalBody() Returns a reference to the view model's PhysicalBody object.
PhysicalEnvironment	getPhysicalEnvironment() Returns a reference to the view model's PhysicalEnvironment object.
int	getProjectionPolicy() Retrieves the current projection policy for this View.
void	getRightManualEyeInCoexistence(javax.vecmath.Point3d position) Retrieves the position of the user-specified, manual right eye in coexistence coordinates and copies that value into the object provided.
void	getRightProjection(Transform3D projection) Compatibility mode method that retrieves the current compatibility mode projection transform for the right eye and places it into the specified object.
boolean	getSceneAntialiasingEnable() Returns a flag that indicates whether or not scene antialiasing is enabled for this view.
double	getScreenScale() Returns the current screen scale value
int	getScreenScalePolicy() Returns the current screen scale policy, one of: SCALE_SCREEN_SIZE or SCALE_EXPLICIT.
void	getSensorHotspotInVworld(Sensor sensor, javax.vecmath.Point3d position) Retrieves the position of the specified Sensor's hotspot in virtual-world coordinates and copies that value into the position provided.
void	getSensorHotspotInVworld(Sensor sensor, javax.vecmath.Point3f position) Retrieves the position of the specified Sensor's hotspot in virtual-world coordinates and copies that value into the position provided.
void	getSensorToVworld(Sensor sensor, Transform3D t) Computes the sensor to virtual-world transform and copies that value into the transform provided.
boolean	getTrackingEnable() Returns a status flag indicating whether or not head tracking is enabled.
int	getTransparencySortingPolicy() Retrieves the current transparency sorting policy.
void	getUserHeadToVworld(Transform3D t) Retrieves the user-head to virtual-world transform and copies that value into the transform provided.
boolean	getUserHeadToVworldEnable() Returns a status flag indicating whether or not Java 3D is continuously updating the userHeadToVworldEnable transform.
ViewPlatform	getViewPlatform() Retrieves the currently attached ViewPlatform object
int	getViewPolicy() Retrieves the current view computation policy for this View.
int	getVisibilityPolicy() Retrieves the current visibility policy.
void	getVpcToEc(Transform3D vpcToEc) Compatibility mode method that retrieves the current ViewPlatform Coordinates (VPC) system to Eye Coordinates (EC) transform and copies it into the specified object.
int	getWindowEyepointPolicy() Returns the current window eyepoint policy, one of: RELATIVE_TO_SCREEN, RELATIVE_TO_WINDOW, RELATIVE_TO_FIELD_OF_VIEW or RELATIVE_TO_COEXISTENCE.
int	getWindowMovementPolicy() Returns the current window movement policy, one of: VIRTUAL_WORLD or PHYSICAL_WORLD.
int	getWindowResizePolicy() Returns the current window resize policy, one of: VIRTUAL_WORLD or PHYSICAL_WORLD.
int	indexOfCanvas3D(Canvas3D canvas3D) Retrieves the index of the specified Canvas3D in this View's list of Canvas3Ds
void	insertCanvas3D(Canvas3D canvas3D, int index) Inserts the Canvas3D at the given index position.
boolean	isBehaviorSchedulerRunning() Retrieves a flag that indicates whether the behavior scheduler is currently running.
boolean	isViewRunning() Retrieves a flag that indicates whether the traverser is currently running on this view.
int	numCanvas3Ds() Returns the number of Canvas3Ds in this View.
void	removeAllCanvas3Ds() Removes all Canvas3Ds from this View.
void	removeCanvas3D(Canvas3D canvas3D) Removes the specified Canvas3D from this View's list of Canvas3Ds.
void	removeCanvas3D(int index) Removes the Canvas3D from the given index position.
void	renderOnce() Renders one frame for a stopped View.
void	repaint() Requests that this View be scheduled for rendering as soon as possible.
void	setBackClipDistance(double distance) Sets the view model's back clip distance.
void	setBackClipPolicy(int policy) Sets the view model's back clip policy, the policy Java 3D uses in computing where to place the back clip plane.
void	setCanvas3D(Canvas3D canvas3D, int index) Sets given Canvas3D at the given index position.
void	setCoexistenceCenteringEnable(boolean flag) Sets the coexistenceCentering enable flag to true or false.
void	setCompatibilityModeEnable(boolean flag) Sets the compatibility mode enable flag to true or false.
void	setDepthBufferFreezeTransparent(boolean flag) Enables or disables automatic freezing of the depth buffer for objects rendered during the transparent rendering pass (i.e., objects rendered using alpha blending) for this view.
void	setFieldOfView(double fieldOfView) Sets the field of view used to compute the projection transform.
void	setFrontClipDistance(double distance) Sets the view model's front clip distance.
void	setFrontClipPolicy(int policy) Sets the view model's front clip policy, the policy Java 3D uses in computing where to place the front clip plane.
void	setLeftManualEyeInCoexistence(javax.vecmath.Point3d position) Sets the position of the manual left eye in coexistence coordinates.
void	setLeftProjection(Transform3D projection) Compatibility mode method that specifies a viewing frustum for the left eye that transforms points in Eye Coordinates (EC) to Clipping Coordinates (CC).
void	setLocalEyeLightingEnable(boolean flag) Sets a flag that indicates whether the local eyepoint is used in lighting calculations for perspective projections.
void	setMinimumFrameCycleTime(long minimumTime) Sets the minimum frame cycle time, in milliseconds, for this view.
void	setMonoscopicViewPolicy(int policy) Deprecated. As of Java 3D version 1.2, replaced by Canvas3D.setMonoscopicViewPolicy
void	setPhysicalBody(PhysicalBody physicalBody) Sets the view model's physical body to the PhysicalBody object provided.
void	setPhysicalEnvironment(PhysicalEnvironment physicalEnvironment) Sets the view model's physical environment to the PhysicalEnvironment object provided.
void	setProjectionPolicy(int policy) Sets the projection policy for this View.
void	setRightManualEyeInCoexistence(javax.vecmath.Point3d position) Sets the position of the manual right eye in coexistence coordinates.
void	setRightProjection(Transform3D projection) Compatibility mode method that specifies a viewing frustum for the right eye that transforms points in Eye Coordinates (EC) to Clipping Coordinates (CC).
void	setSceneAntialiasingEnable(boolean flag) Enables or disables scene antialiasing for this view.
void	setScreenScale(double scale) Sets the screen scale value for this view.
void	setScreenScalePolicy(int policy) Sets the screen scale policy for this view.
void	setTrackingEnable(boolean flag) Turns head tracking on or off for this view.
void	setTransparencySortingPolicy(int policy) Sets the transparency sorting policy for this view.
void	setUserHeadToVworldEnable(boolean flag) Turns on or off the continuous updating of the userHeadToVworld transform.
void	setViewPolicy(int policy) Sets the policy for view computation.
void	setVisibilityPolicy(int policy) Sets the visibility policy for this view.
void	setVpcToEc(Transform3D vpcToEc) Compatibility mode method that specifies the ViewPlatform Coordinates (VPC) to Eye Coordinates (EC) transform.
void	setWindowEyepointPolicy(int policy) Sets the view model's window eyepoint policy.
void	setWindowMovementPolicy(int policy) Sets the window movement policy.
void	setWindowResizePolicy(int policy) Sets the window resize policy.
void	startBehaviorScheduler() Starts the behavior scheduler running after it has been stopped.
void	startView() Starts traversing this view, and starts the renderers associated with all canvases attached to this view.
long[]	stopBehaviorScheduler() Stops the behavior scheduler after all currently scheduled behaviors are executed.
void	stopView() Stops traversing the scene graph for this view after the current state of the scene graph is reflected on all canvases attached to this view.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

NOMINAL_HEAD

public static final int NOMINAL_HEAD

Specifies a policy whereby the origin of physical or virtual coordinates is relative to the position of the nominal head. When used as a view attach policy, this sets the origin of view platform coordinates to be at the eyepoint.

See Also:

ViewPlatform.setViewAttachPolicy(int), PhysicalEnvironment.setCoexistenceCenterInPworldPolicy(int), Constant Field Values

NOMINAL_FEET

public static final int NOMINAL_FEET

Specifies a policy whereby the origin of physical or virtual coordinates is relative to the position of the nominal feet. When used as a view attach policy, this sets the origin of view platform coordinates to be at the ground plane.

See Also:

ViewPlatform.setViewAttachPolicy(int), PhysicalEnvironment.setCoexistenceCenterInPworldPolicy(int), Constant Field Values

NOMINAL_SCREEN

public static final int NOMINAL_SCREEN

Specifies a policy whereby the origin of physical or virtual coordinates is relative to the screen. When used as a view attach policy, this sets the origin of view platform coordinates to be at the center of the window or screen, in effect, allowing the user to view objects from an optimal viewpoint.

See Also:

ViewPlatform.setViewAttachPolicy(int), PhysicalEnvironment.setCoexistenceCenterInPworldPolicy(int), Constant Field Values

SCALE_SCREEN_SIZE

public static final int SCALE_SCREEN_SIZE

Specifies that the screen scale for this view is derived from the physical screen size. This scale factor is computed as follows:

physical_screen_width / 2.0

This allows an application to define a world in a normalized [-1,1] space and view it on a screen of any size.

See Also:

setScreenScalePolicy(int), Constant Field Values

SCALE_EXPLICIT

public static final int SCALE_EXPLICIT

Specifies that the screen scale for this view is taken directly from the user-provided screenScale parameter.

See Also:

setScreenScalePolicy(int), setScreenScale(double), Constant Field Values

VIRTUAL_SCREEN

public static final int VIRTUAL_SCREEN

Specifies that the associated distance is measured from the screen in virtual world coordinates. Policy for interpreting clip plane distances. Used in specifying the policy in frontClipPolicy and backClipPolicy.

See Also:

setFrontClipPolicy(int), setBackClipPolicy(int), Constant Field Values

PHYSICAL_SCREEN

public static final int PHYSICAL_SCREEN

Specifies that the associated distance is measured from the screen in meters. Policy for interpreting clip plane distances. Used in specifying the policy in frontClipPolicy and backClipPolicy.

See Also:

setFrontClipPolicy(int), setBackClipPolicy(int), Constant Field Values

VIRTUAL_EYE

public static final int VIRTUAL_EYE

Specifies that the associated distance is measured from the eye in virtual world coordinates. Policy for interpreting clip plane distances. Used in specifying the policy in frontClipPolicy and backClipPolicy.

See Also:

setFrontClipPolicy(int), setBackClipPolicy(int), Constant Field Values

PHYSICAL_EYE

public static final int PHYSICAL_EYE

Specifies that the associated distance is measured from the eye in meters. Policy for interpreting clip plane distances. Used in specifying the policy in frontClipPolicy and backClipPolicy. This is the default policy for both front and back clipping.

See Also:

setFrontClipPolicy(int), setBackClipPolicy(int), Constant Field Values

VIRTUAL_WORLD

public static final int VIRTUAL_WORLD

Policy for resizing and moving windows. Used in specifying windowResizePolicy and windowMovementPolicy. VIRTUAL_WORLD specifies that the associated action takes place in the virtual world as well as in the physical world.

See Also:

setWindowResizePolicy(int), setWindowMovementPolicy(int), Constant Field Values

PHYSICAL_WORLD

public static final int PHYSICAL_WORLD

Policy for resizing and moving windows. Used in specifying windowResizePolicy and windowMovementPolicy. PHYSICAL_WORLD specifies that the specified action takes place only in the physical world.

See Also:

setWindowResizePolicy(int), setWindowMovementPolicy(int), Constant Field Values

RELATIVE_TO_SCREEN

public static final int RELATIVE_TO_SCREEN

Policy for placing the eyepoint in non-head-tracked modes. Specifies that Java 3D should interpret the given fixed eyepoint position as relative to the entire screen. This implies that the view frustum shape will change whenever a user moves the location of a window on the screen.

See Also:

setWindowEyepointPolicy(int), Constant Field Values

RELATIVE_TO_WINDOW

public static final int RELATIVE_TO_WINDOW

Policy for placing the eyepoint in non-head-tracked modes. Specifies that Java 3D should interpret the given fixed-eyepoint position as relative to the window.

See Also:

setWindowEyepointPolicy(int), Constant Field Values

RELATIVE_TO_FIELD_OF_VIEW

public static final int RELATIVE_TO_FIELD_OF_VIEW

Policy for placing the eyepoint in non-head-tracked modes. Specifies that Java 3D should modify the position of the eyepoint to match any changes in field of view; the view frustum will change whenever the application program changes the field of view.

NOTE: when this policy is specified, the Z coordinate of the derived eyepoint is used in place of nominalEyeOffsetFromNominalScreen.

See Also:

setWindowEyepointPolicy(int), Constant Field Values

RELATIVE_TO_COEXISTENCE

public static final int RELATIVE_TO_COEXISTENCE

Policy for placing the eyepoint in non-head-tracked modes. Specifies that Java 3D should interpret the fixed eyepoint position in the view as relative to the origin of coexistence coordinates. This eyepoint is transformed from coexistence coordinates to image plate coordinates for each Canvas3D. As in RELATIVE_TO_SCREEN mode, this implies that the view frustum shape will change whenever a user moves the location of a window on the screen.

Since:

Java 3D 1.2

See Also:

setWindowEyepointPolicy(int), Constant Field Values

LEFT_EYE_VIEW

public static final int LEFT_EYE_VIEW

Specifies that monoscopic view generated should be the view as seen from the left eye.

See Also:

Canvas3D.setMonoscopicViewPolicy(int), Constant Field Values

RIGHT_EYE_VIEW

public static final int RIGHT_EYE_VIEW

Specifies that monoscopic view generated should be the view as seen from the right eye.

See Also:

Canvas3D.setMonoscopicViewPolicy(int), Constant Field Values

CYCLOPEAN_EYE_VIEW

public static final int CYCLOPEAN_EYE_VIEW

Specifies that monoscopic view generated should be the view as seen from the 'center eye', the fictional eye half-way between the left and right eye.

See Also:

Canvas3D.setMonoscopicViewPolicy(int), Constant Field Values

SCREEN_VIEW

public static final int SCREEN_VIEW

Specifies that the viewing environment for this view is a standard screen-based display environment. In this mode, Java 3D will compute new viewpoints using that sequence of transforms appropriate to screen-based, display environments, that may or may not include head tracking (e.g., a monoscopic screen, fish-tank VR, portals, VR-desks). This is the default mode.

See Also:

setViewPolicy(int), Constant Field Values

HMD_VIEW

public static final int HMD_VIEW

Specifies that the viewing environment for this view is a head-mounted display environment. In this mode, Java 3D will compute new viewpoints using that sequence of transforms appropriate to head-mounted display environments. These environments are generally head-tracked.

See Also:

setViewPolicy(int), Constant Field Values

PARALLEL_PROJECTION

public static final int PARALLEL_PROJECTION

Specifies that Java 3D should generate a parallel projection matrix for this View.

See Also:

setProjectionPolicy(int), Constant Field Values

PERSPECTIVE_PROJECTION

public static final int PERSPECTIVE_PROJECTION

Specifies that Java 3D should generate a perspective projection matrix for this View. This is the default mode.

See Also:

setProjectionPolicy(int), Constant Field Values

VISIBILITY_DRAW_VISIBLE

public static final int VISIBILITY_DRAW_VISIBLE

Policy that specifies that only visible objects should be drawn. This is the default mode.

Since:

Java 3D 1.2

See Also:

setVisibilityPolicy(int), Constant Field Values

VISIBILITY_DRAW_INVISIBLE

public static final int VISIBILITY_DRAW_INVISIBLE

Policy that specifies that only invisible objects should be drawn.

Since:

Java 3D 1.2

See Also:

setVisibilityPolicy(int), Constant Field Values

VISIBILITY_DRAW_ALL

public static final int VISIBILITY_DRAW_ALL

Policy that specifies that both visible and invisible objects should be drawn.

Since:

Java 3D 1.2

See Also:

setVisibilityPolicy(int), Constant Field Values

TRANSPARENCY_SORT_NONE

public static final int TRANSPARENCY_SORT_NONE

Policy that specifies that no sorting of transparent objects is done. This is the default mode.

Since:

Java 3D 1.3

See Also:

setTransparencySortingPolicy(int), Constant Field Values

TRANSPARENCY_SORT_GEOMETRY

public static final int TRANSPARENCY_SORT_GEOMETRY

Policy that specifies that transparent objects are sorted from back to front on a per-geometry basis.

Since:

Java 3D 1.3

See Also:

setTransparencySortingPolicy(int), Constant Field Values

Constructor Detail

View

public View()

Constructs a View object with default parameters. The default values are as follows:

view policy : SCREEN_VIEW
projection policy : PERSPECTIVE_PROJECTION
screen scale policy : SCALE_SCREEN_SIZE
window resize policy : PHYSICAL_WORLD
window movement policy : PHYSICAL_WORLD
window eyepoint policy : RELATIVE_TO_FIELD_OF_VIEW
monoscopic view policy : CYCLOPEAN_EYE_VIEW
front clip policy : PHYSICAL_EYE
back clip policy : PHYSICAL_EYE
visibility policy : VISIBILITY_DRAW_VISIBLE
transparency sorting policy : TRANSPARENCY_SORT_NONE
coexistenceCentering flag : true
compatibility mode : false
left projection : identity
right projection : identity
vpc to ec transform : identity
physical body : null
physical environment : null
screen scale : 1.0
field of view : PI/4
left manual eye in coexistence : (-0.033, 0.0, 0.4572)
right manual eye in coexistence : (0.033, 0.0, 0.4572)
front clip distance : 0.1
back clip distance : 10.0
tracking enable : false
user head to vworld enable : false
list of Canvas3D objects : empty
depth buffer freeze transparent : true
scene antialiasing : false
local eye lighting : false
view platform : null
behavior scheduler running : true
view running : true
minimum frame cycle time : 0

Method Detail

setViewPolicy

public void setViewPolicy(int policy)

Sets the policy for view computation. This variable specifies how Java 3D uses its transforms in computing new viewpoints.

• SCREEN_VIEW specifies that Java 3D should compute a new viewpoint using the sequence of transforms appropriate to screen-based head-tracked display environments (fish-tank VR/portals/VR-desks).
• HMD_VIEW specifies that Java 3D should compute a new viewpoint using the sequence of transforms appropriate to head mounted display environments.

The default view policy is SCREEN_VIEW.

Parameters:

policy - the new policy, one of SCREEN_VIEW or HMD_VIEW

Throws:

IllegalArgumentException - if policy is a value other than SCREEN_VIEW or HMD_VIEW

IllegalStateException - if the specified policy is HMD_VIEW and if any canvas associated with this view is a stereo canvas with a monoscopicEyePolicy of CYCLOPEAN_EYE_VIEW

getViewPolicy

public int getViewPolicy()

Retrieves the current view computation policy for this View.

Returns:

one of: SCREEN_VIEW or HMD_VIEW.

setProjectionPolicy

public void setProjectionPolicy(int policy)

Sets the projection policy for this View. This variable specifies the type of projection transform that will be generated. A value of PARALLEL_PROJECTION specifies that a parallel projection transform is generated. A value of PERSPECTIVE_PROJECTION specifies that a perspective projection transform is generated. The default projection policy is PERSPECTIVE.

Parameters:

policy - the new policy, one of PARALLEL_PROJECTION or PERSPECTIVE_PROJECTION

Throws:

IllegalArgumentException - if policy is a value other than PARALLEL_PROJECTION or PERSPECTIVE_PROJECTION

getProjectionPolicy

public int getProjectionPolicy()

Retrieves the current projection policy for this View.

Returns:

one of: PARALLEL_PROJECTION or PERSPECTIVE_PROJECTION.

setScreenScalePolicy

public void setScreenScalePolicy(int policy)

Sets the screen scale policy for this view. This policy specifies how the screen scale is derived. The value is either SCALE_SCREEN_SIZE or SCALE_EXPLICIT. A value of SCALE_SCREEN_SIZE specifies that the scale is derived from the size of the physical screen. A value of SCALE_EXPLICIT specifies that the scale is taken directly from the screenScale parameter. The default screen scale policy is SCALE_SCREEN_SIZE.

Parameters:

policy - the new policy, one of SCALE_SCREEN_SIZE or SCALE_EXPLICIT.

getScreenScalePolicy

public int getScreenScalePolicy()

Returns the current screen scale policy, one of: SCALE_SCREEN_SIZE or SCALE_EXPLICIT.

Returns:

the current screen scale policy

setWindowResizePolicy

public void setWindowResizePolicy(int policy)

Sets the window resize policy. This variable specifies how Java 3D modifies the view when users resize windows. The variable can contain one of VIRTUAL_WORLD or PHYSICAL_WORLD. A value of VIRTUAL_WORLD implies that the original image remains the same size on the screen but the user sees more or less of the virtual world depending on whether the window grew or shrank in size. A value of PHYSICAL_WORLD implies that the original image continues to fill the window in the same way using more or less pixels depending on whether the window grew or shrank in size. The default window resize policy is PHYSICAL_WORLD.

Parameters:

policy - the new policy, one of VIRTUAL_WORLD or PHYSICAL_WORLD

getWindowResizePolicy

public int getWindowResizePolicy()

Returns the current window resize policy, one of: VIRTUAL_WORLD or PHYSICAL_WORLD.

Returns:

the current window resize policy

setWindowMovementPolicy

public void setWindowMovementPolicy(int policy)

Sets the window movement policy. This variable specifies what part of the virtual world Java 3D draws as a function of window placement on the screen. The variable can contain one of VIRTUAL_WORLD or PHYSICAL_WORLD. A value of VIRTUAL_WORLD implies that the image seen in the window changes as the position of the window shifts on the screen. (This mode acts as if the window were a window into the virtual world.) A value of PHYSICAL_WORLD implies that the image seen in the window remains the same no matter where the user positions the window on the screen. The default window movement policy is PHYSICAL_WORLD.

Parameters:

policy - the new policy, one of VIRTUAL_WORLD or PHYSICAL_WORLD

getWindowMovementPolicy

public int getWindowMovementPolicy()

Returns the current window movement policy, one of: VIRTUAL_WORLD or PHYSICAL_WORLD.

Returns:

the current window movement policy

setWindowEyepointPolicy

public void setWindowEyepointPolicy(int policy)

Sets the view model's window eyepoint policy. This variable specifies how Java 3D handles the predefined eye point in a non-head-tracked environment. The variable can contain one of:

• RELATIVE_TO_SCREEN, Java 3D should interpret the given fixed-eyepoint position as relative to the screen (this implies that the view frustum shape will change whenever a user moves the location of a window on the screen).
• RELATIVE_TO_WINDOW, Java 3D should interpret the given fixed-eyepoint position as relative to the window. In this mode, the X and Y values are taken as the center of the window and the Z value is taken from the canvas eyepoint position.
• RELATIVE_TO_FIELD_OF_VIEW, Java 3D should modify the position of the eyepoint to match any changes in field of view (the view frustum will change whenever the application program changes the field of view).
• RELATIVE_TO_COEXISTENCE, Java 3D should interpret the eye's position in coexistence coordinates. In this mode, the eye position is taken from the view (rather than the Canvas3D) and transformed from coexistence coordinates to image plate coordinates for each Canvas3D. The resulting eye position is relative to the screen (this implies that the view frustum shape will change whenever a user moves the location of a window on the screen).

The default window eyepoint policy is RELATIVE_TO_FIELD_OF_VIEW.

Parameters:

policy - the new policy, one of RELATIVE_TO_SCREEN, RELATIVE_TO_WINDOW, RELATIVE_TO_FIELD_OF_VIEW, or RELATIVE_TO_COEXISTENCE

getWindowEyepointPolicy

public int getWindowEyepointPolicy()

Returns the current window eyepoint policy, one of: RELATIVE_TO_SCREEN, RELATIVE_TO_WINDOW, RELATIVE_TO_FIELD_OF_VIEW or RELATIVE_TO_COEXISTENCE.

Returns:

the current window eyepoint policy

setMonoscopicViewPolicy

public void setMonoscopicViewPolicy(int policy)

Deprecated. As of Java 3D version 1.2, replaced by Canvas3D.setMonoscopicViewPolicy

getMonoscopicViewPolicy

public int getMonoscopicViewPolicy()

Deprecated. As of Java 3D version 1.2, replaced by Canvas3D.getMonoscopicViewPolicy

setCoexistenceCenteringEnable

public void setCoexistenceCenteringEnable(boolean flag)

Sets the coexistenceCentering enable flag to true or false. If the coexistenceCentering flag is true, the center of coexistence in image plate coordinates, as specified by the trackerBaseToImagePlate transform, is translated to the center of either the window or the screen in image plate coordinates, according to the value of windowMovementPolicy.

By default, coexistenceCentering is enabled. It should be disabled if the trackerBaseToImagePlate calibration transform is set to a value other than the identity (for example, when rendering to multiple screens or when head tracking is enabled). This flag is ignored for HMD mode, or when the coexistenceCenterInPworldPolicy is not NOMINAL_SCREEN.

Parameters:

flag - the new coexistenceCentering enable flag

Since:

Java 3D 1.2

getCoexistenceCenteringEnable

public boolean getCoexistenceCenteringEnable()

Retrieves the coexistenceCentering enable flag.

Returns:

the current coexistenceCentering enable flag

Since:

Java 3D 1.2

setCompatibilityModeEnable

public void setCompatibilityModeEnable(boolean flag)

Sets the compatibility mode enable flag to true or false. Compatibility mode is disabled by default.

Parameters:

flag - the new compatibility mode enable flag

getCompatibilityModeEnable

public boolean getCompatibilityModeEnable()

Retrieves the compatibility mode enable flag.

Returns:

the current compatibility mode enable flag

setLeftProjection

public void setLeftProjection(Transform3D projection)

Compatibility mode method that specifies a viewing frustum for the left eye that transforms points in Eye Coordinates (EC) to Clipping Coordinates (CC). If compatibility mode is disabled, then this transform is not used; the actual projection is derived from other values. In monoscopic mode, only the left eye projection matrix is used.

Parameters:

projection - the new left eye projection transform

Throws:

RestrictedAccessException - if compatibility mode is disabled.

setRightProjection

public void setRightProjection(Transform3D projection)

Compatibility mode method that specifies a viewing frustum for the right eye that transforms points in Eye Coordinates (EC) to Clipping Coordinates (CC). If compatibility mode is disabled, then this transform is not used; the actual projection is derived from other values. In monoscopic mode, the right eye projection matrix is ignored.

Parameters:

projection - the new right eye projection transform

Throws:

RestrictedAccessException - if compatibility mode is disabled.

getLeftProjection

public void getLeftProjection(Transform3D projection)

Compatibility mode method that retrieves the current compatibility mode projection transform for the left eye and places it into the specified object.

Parameters:

projection - the Transform3D object that will receive the projection

Throws:

RestrictedAccessException - if compatibility mode is disabled.

getRightProjection

public void getRightProjection(Transform3D projection)

Compatibility mode method that retrieves the current compatibility mode projection transform for the right eye and places it into the specified object.

Parameters:

projection - the Transform3D object that will receive the projection

Throws:

RestrictedAccessException - if compatibility mode is disabled.

setVpcToEc

public void setVpcToEc(Transform3D vpcToEc)

Compatibility mode method that specifies the ViewPlatform Coordinates (VPC) to Eye Coordinates (EC) transform. If compatibility mode is disabled, then this transform is derived from other values and is read-only.

Parameters:

vpcToEc - the new VPC to EC transform

Throws:

RestrictedAccessException - if compatibility mode is disabled.

BadTransformException - if the transform is not affine.

getVpcToEc

public void getVpcToEc(Transform3D vpcToEc)

Compatibility mode method that retrieves the current ViewPlatform Coordinates (VPC) system to Eye Coordinates (EC) transform and copies it into the specified object.

Parameters:

vpcToEc - the object that will receive the vpcToEc transform.

Throws:

RestrictedAccessException - if compatibility mode is disabled.

setPhysicalBody

public void setPhysicalBody(PhysicalBody physicalBody)

Sets the view model's physical body to the PhysicalBody object provided. Java 3D uses the parameters in the PhysicalBody to ensure accurate image and sound generation when in head-tracked mode.

Parameters:

physicalBody - the new PhysicalBody object

getPhysicalBody

public PhysicalBody getPhysicalBody()

Returns a reference to the view model's PhysicalBody object.

Returns:

the view object's PhysicalBody object

setPhysicalEnvironment

public void setPhysicalEnvironment(PhysicalEnvironment physicalEnvironment)

Sets the view model's physical environment to the PhysicalEnvironment object provided.

Parameters:

physicalEnvironment - the new PhysicalEnvironment object

getPhysicalEnvironment

public PhysicalEnvironment getPhysicalEnvironment()

Returns a reference to the view model's PhysicalEnvironment object.

Returns:

the view object's PhysicalEnvironment object

setScreenScale

public void setScreenScale(double scale)

Sets the screen scale value for this view. This is used when the screen scale policy is SCALE_EXPLICIT. The default value is 1.0 (i.e., unscaled).

Parameters:

scale - the new screen scale

getScreenScale

public double getScreenScale()

Returns the current screen scale value

Returns:

the current screen scale value

setFieldOfView

public void setFieldOfView(double fieldOfView)

Sets the field of view used to compute the projection transform. This is used when head tracking is disabled and when the Canvas3D's windowEyepointPolicy is RELATIVE_TO_FIELD_OF_VIEW.

Parameters:

fieldOfView - the new field of view in radians

getFieldOfView

public double getFieldOfView()

Returns the current field of view.

Returns:

the current field of view in radians

setLeftManualEyeInCoexistence

public void setLeftManualEyeInCoexistence(javax.vecmath.Point3d position)

Sets the position of the manual left eye in coexistence coordinates. This value determines eye placement when a head tracker is not in use and the application is directly controlling the eye position in coexistence coordinates. This value is ignored when in head-tracked mode or when the windowEyePointPolicy is not RELATIVE_TO_COEXISTENCE.

Parameters:

position - the new manual left eye position

Since:

Java 3D 1.2

setRightManualEyeInCoexistence

public void setRightManualEyeInCoexistence(javax.vecmath.Point3d position)

Sets the position of the manual right eye in coexistence coordinates. This value determines eye placement when a head tracker is not in use and the application is directly controlling the eye position in coexistence coordinates. This value is ignored when in head-tracked mode or when the windowEyePointPolicy is not RELATIVE_TO_COEXISTENCE.

Parameters:

position - the new manual right eye position

Since:

Java 3D 1.2

getLeftManualEyeInCoexistence

public void getLeftManualEyeInCoexistence(javax.vecmath.Point3d position)

Retrieves the position of the user-specified, manual left eye in coexistence coordinates and copies that value into the object provided.

Parameters:

position - the object that will receive the position

Since:

Java 3D 1.2

getRightManualEyeInCoexistence

public void getRightManualEyeInCoexistence(javax.vecmath.Point3d position)

Retrieves the position of the user-specified, manual right eye in coexistence coordinates and copies that value into the object provided.

Parameters:

position - the object that will receive the position

Since:

Java 3D 1.2

setFrontClipDistance

public void setFrontClipDistance(double distance)

Sets the view model's front clip distance. This value specifies the distance away from the eyepoint in the direction of gaze where objects stop disappearing. Objects closer to the eye than the front clip distance are not drawn. The default value is 0.1 meters.

There are several considerations that need to be taken into account when choosing values for the front and back clip distances.

• The front clip distance must be greater than 0.0 in physical eye coordinates.
• The front clipping plane must be in front of the back clipping plane, that is, the front clip distance must be less than the back clip distance in physical eye coordinates.
• The front and back clip distances, in physical eye coordinates, must be less than the largest positive single-precision floating point value, Float.MAX_VALUE. In practice, since these physical eye coordinate distances are in meters, the values should be much less than that.
• The ratio of the back distance divided by the front distance, in physical eye coordinates, affects Z-buffer precision. This ratio should be less than about 3000 in order to accommodate 16-bit Z-buffers. Values of 100 to less than 1000 will produce better results.

Violating any of the above rules will result in undefined behavior. In many cases, no picture will be drawn.

Parameters:

distance - the new front clip distance

See Also:

setBackClipDistance(double)

getFrontClipDistance

public double getFrontClipDistance()

Returns the view model's front clip distance.

Returns:

the current front clip distance

setBackClipDistance

public void setBackClipDistance(double distance)

Sets the view model's back clip distance. The parameter specifies the distance from the eyepoint in the direction of gaze to where objects begin disappearing. Objects farther away from the eye than the back clip distance are not drawn. The default value is 10.0 meters.

There are several considerations that need to be taken into account when choosing values for the front and back clip distances. These are enumerated in the description of setFrontClipDistance.

Note that this attribute is only used if there is no Clip node that is in scope of the view platform associated with this view.

Parameters:

distance - the new back clip distance

See Also:

setFrontClipDistance(double), Clip.setBackDistance(double)

getBackClipDistance

public double getBackClipDistance()

Returns the view model's back clip distance.

Returns:

the current back clip distance

getUserHeadToVworld

public void getUserHeadToVworld(Transform3D t)

Retrieves the user-head to virtual-world transform and copies that value into the transform provided.

Parameters:

t - the Transform3D object that will receive the transform

setFrontClipPolicy

public void setFrontClipPolicy(int policy)

Sets the view model's front clip policy, the policy Java 3D uses in computing where to place the front clip plane. The variable can contain one of:

• VIRTUAL_EYE, to specify that the associated distance is from the eye and in units of virtual distance
• PHYSICAL_EYE, to specify that the associated distance is from the eye and in units of physical distance (meters)
• VIRTUAL_SCREEN, to specify that the associated distance is from the screen and in units of virtual distance
• PHYSICAL_SCREEN, to specify that the associated distance is from the screen and in units of physical distance (meters)

The default front clip policy is PHYSICAL_EYE.

Parameters:

policy - the new policy, one of PHYSICAL_EYE, PHYSICAL_SCREEN, VIRTUAL_EYE, or VIRTUAL_SCREEN

getFrontClipPolicy

public int getFrontClipPolicy()

Returns the view model's current front clip policy.

Returns:

one of: VIRTUAL_EYE, PHYSICAL_EYE, VIRTUAL_SCREEN, or PHYSICAL_SCREEN

setBackClipPolicy

public void setBackClipPolicy(int policy)

Sets the view model's back clip policy, the policy Java 3D uses in computing where to place the back clip plane. The variable can contain one of:

• VIRTUAL_EYE, to specify that the associated distance is from the eye and in units of virtual distance
• PHYSICAL_EYE, to specify that the associated distance is from the eye and in units of physical distance (meters)
• VIRTUAL_SCREEN, to specify that the associated distance is from the screen and in units of virtual distance
• PHYSICAL_SCREEN, to specify that the associated distance is from the screen and in units of physical distance (meters)

The default back clip policy is PHYSICAL_EYE.

Parameters:

policy - the new policy, one of PHYSICAL_EYE, PHYSICAL_SCREEN, VIRTUAL_EYE, or VIRTUAL_SCREEN

getBackClipPolicy

public int getBackClipPolicy()

Returns the view model's current back clip policy.

Returns:

one of: VIRTUAL_EYE, PHYSICAL_EYE, VIRTUAL_SCREEN, or PHYSICAL_SCREEN

setVisibilityPolicy

public void setVisibilityPolicy(int policy)

Sets the visibility policy for this view. This attribute is one of:

• VISIBILITY_DRAW_VISIBLE, to specify that only visible objects are drawn.
• VISIBILITY_DRAW_INVISIBLE, to specify that only invisible objects are drawn.
• VISIBILITY_DRAW_ALL, to specify that both visible and invisible objects are drawn.

The default visibility policy is VISIBILITY_DRAW_VISIBLE.

Parameters:

policy - the new policy, one of VISIBILITY_DRAW_VISIBLE, VISIBILITY_DRAW_INVISIBLE, or VISIBILITY_DRAW_ALL.

Since:

Java 3D 1.2

See Also:

RenderingAttributes.setVisible(boolean)

getVisibilityPolicy

public int getVisibilityPolicy()

Retrieves the current visibility policy.

Returns:

one of: VISIBILITY_DRAW_VISIBLE, VISIBILITY_DRAW_INVISIBLE, or VISIBILITY_DRAW_ALL.

Since:

Java 3D 1.2

setTransparencySortingPolicy

public void setTransparencySortingPolicy(int policy)

Sets the transparency sorting policy for this view. This attribute is one of:

• TRANSPARENCY_SORT_NONE, to specify that no depth sorting of transparent objects is performed. Transparent objects are drawn after opaque objects, but are not sorted from back to front.
• TRANSPARENCY_SORT_GEOMETRY, to specify that transparent objects are depth-sorted on a per-geometry basis. Each geometry object of each transparent Shape3D node is drawn from back to front. Note that this policy will not split geometry into smaller pieces, so intersecting or intertwined objects may not be sorted correctly.

The default policy is TRANSPARENCY_SORT_NONE.

Parameters:

policy - the new policy, one of TRANSPARENCY_SORT_NONE or TRANSPARENCY_SORT_GEOMETRY.

Since:

Java 3D 1.3

getTransparencySortingPolicy

public int getTransparencySortingPolicy()

Retrieves the current transparency sorting policy.

Returns:

one of: TRANSPARENCY_SORT_NONE or TRANSPARENCY_SORT_GEOMETRY.

Since:

Java 3D 1.3

setTrackingEnable

public void setTrackingEnable(boolean flag)

Turns head tracking on or off for this view.

Parameters:

flag - specifies whether head tracking is enabled or disabled for this view

getTrackingEnable

public boolean getTrackingEnable()

Returns a status flag indicating whether or not head tracking is enabled.

Returns:

a flag telling whether head tracking is enabled

setUserHeadToVworldEnable

public void setUserHeadToVworldEnable(boolean flag)

Turns on or off the continuous updating of the userHeadToVworld transform.

Parameters:

flag - enables or disables continuous updating

getUserHeadToVworldEnable

public boolean getUserHeadToVworldEnable()

Returns a status flag indicating whether or not Java 3D is continuously updating the userHeadToVworldEnable transform.

Returns:

a flag indicating if continuously updating userHeadToVworld

getSensorToVworld

public void getSensorToVworld(Sensor sensor,
                     Transform3D t)

Computes the sensor to virtual-world transform and copies that value into the transform provided. The computed transforms takes points in the sensor's coordinate system and produces the point's corresponding value in virtual-world coordinates.

Parameters:

sensor - the sensor in question

t - the object that will receive the transform

getSensorHotspotInVworld

public void getSensorHotspotInVworld(Sensor sensor,
                            javax.vecmath.Point3f position)

Retrieves the position of the specified Sensor's hotspot in virtual-world coordinates and copies that value into the position provided. This value is derived from other values and is read-only.

Parameters:

sensor - the sensor in question

position - the variable that will receive the position

getSensorHotspotInVworld

public void getSensorHotspotInVworld(Sensor sensor,
                            javax.vecmath.Point3d position)

Retrieves the position of the specified Sensor's hotspot in virtual-world coordinates and copies that value into the position provided. This value is derived from other values and is read-only.

Parameters:

sensor - the sensor in question

position - the variable that will receive the position

setCanvas3D

public void setCanvas3D(Canvas3D canvas3D,
               int index)

Sets given Canvas3D at the given index position.

Parameters:

canvas3D - the given Canvas3D to be set

index - the position to be set

Throws:

IllegalStateException - if the specified canvas is a stereo canvas with a monoscopicEyePolicy of CYCLOPEAN_EYE_VIEW, and the viewPolicy for this view is HMD_VIEW

IllegalSharingException - if the specified canvas is associated with another view

getCanvas3D

public Canvas3D getCanvas3D(int index)

Gets the Canvas3D at the specified index position.

Parameters:

index - the position from which to get Canvas3D object

Returns:

the Canvas3D at the sprcified index position

getAllCanvas3Ds

public Enumeration<Canvas3D> getAllCanvas3Ds()

Gets the enumeration object of all the Canvas3Ds.

Returns:

the enumeration object of all the Canvas3Ds.

numCanvas3Ds

public int numCanvas3Ds()

Returns the number of Canvas3Ds in this View.

Returns:

the number of Canvas3Ds in this View

Since:

Java 3D 1.2

addCanvas3D

public void addCanvas3D(Canvas3D canvas3D)

Adds the given Canvas3D at the end of the list.

Parameters:

canvas3D - the Canvas3D to be added

Throws:

IllegalStateException - if the specified canvas is a stereo canvas with a monoscopicEyePolicy of CYCLOPEAN_EYE_VIEW, and the viewPolicy for this view is HMD_VIEW

IllegalSharingException - if the specified canvas is associated with another view

insertCanvas3D

public void insertCanvas3D(Canvas3D canvas3D,
                  int index)

Inserts the Canvas3D at the given index position.

Parameters:

canvas3D - the Canvas3D to be inserted

index - the position to be inserted at

Throws:

IllegalStateException - if the specified canvas is a stereo canvas with a monoscopicEyePolicy of CYCLOPEAN_EYE_VIEW, and the viewPolicy for this view is HMD_VIEW

IllegalSharingException - if the specified canvas is associated with another view

removeCanvas3D

public void removeCanvas3D(int index)

Removes the Canvas3D from the given index position.

Parameters:

index - the position of Canvas3D object to be removed

indexOfCanvas3D

public int indexOfCanvas3D(Canvas3D canvas3D)

Retrieves the index of the specified Canvas3D in this View's list of Canvas3Ds

Parameters:

canvas3D - the Canvas3D to be looked up.

Returns:

the index of the specified Canvas3D; returns -1 if the object is not in the list.

Since:

Java 3D 1.3

removeCanvas3D

public void removeCanvas3D(Canvas3D canvas3D)

Removes the specified Canvas3D from this View's list of Canvas3Ds. If the specified object is not in the list, the list is not modified.

Parameters:

canvas3D - the Canvas3D to be removed.

removeAllCanvas3Ds

public void removeAllCanvas3Ds()

Removes all Canvas3Ds from this View.

Since:

Java 3D 1.3

getCurrentFrameStartTime

public long getCurrentFrameStartTime()

This method returns the time at which the most recent rendering frame started. It is defined as the number of milliseconds since January 1, 1970 00:00:00 GMT. Since multiple canvases might be attached to this View, the start of a frame is defined as the point in time just prior to clearing any canvas attached to this view.

Returns:

the time at which the most recent rendering frame started

getLastFrameDuration

public long getLastFrameDuration()

This method returns the duration, in milliseconds, of the most recently completed rendering frame. The time taken to render all canvases attached to this view is measured. This duration is computed as the difference between the start of the most recently completed frame and the end of that frame. Since multiple canvases might be attached to this View, the start of a frame is defined as the point in time just prior to clearing any canvas attached to this view--before preRender is called for any canvas. Similarly, the end of a frame is defined as the point in time just after swapping the buffer for all canvases--after postSwap is called for all canvases. Note that since the frame duration is measured from start to stop for this view only, the value returned is not the same as frame rate; it measures only the rendering time for this view.

Returns:

the duration, in milliseconds, of the most recently completed rendering frame

getFrameNumber

public long getFrameNumber()

This method returns the frame number for this view. The frame number starts at 0 and is incremented at the start of each frame--prior to clearing all the canvases attached to this view.

Returns:

the current frame number for this view

getMaxFrameStartTimes

public static int getMaxFrameStartTimes()

Retrieves the implementation-dependent maximum number of frames whose start times will be recorded by the system. This value is guaranteed to be at least 10 for all implementations of the Java 3D API.

Returns:

the maximum number of frame start times recorded

getFrameStartTimes

public long getFrameStartTimes(long[] times)

Copies the last k frame start time values into the user-specified array. The most recent frame start time is copied to location 0 of the array, the next most recent frame start time is copied into location 1 of the array, and so forth. If times.length is smaller than maxFrameStartTimes, then only the last times.length values are copied. If times.length is greater than maxFrameStartTimes, then all array elements after index maxFrameStartTimes-1 are set to 0.

Returns:

the frame number of the most recent frame in the array

See Also:

setMinimumFrameCycleTime(long)

setMinimumFrameCycleTime

public void setMinimumFrameCycleTime(long minimumTime)

Sets the minimum frame cycle time, in milliseconds, for this view. The Java 3D renderer will ensure that the time between the start of each successive frame is at least the specified number of milliseconds. The default value is 0.

Parameters:

minimumTime - the minimum number of milliseconds between successive frames

Throws:

IllegalArgumentException - if minimumTime < 0

Since:

Java 3D 1.2

See Also:

getFrameStartTimes(long[])

getMinimumFrameCycleTime

public long getMinimumFrameCycleTime()

Retrieves the minimum frame cycle time, in milliseconds, for this view.

Returns:

the minimum frame cycle time for this view.

Since:

Java 3D 1.2

See Also:

getFrameStartTimes(long[])

setDepthBufferFreezeTransparent

public void setDepthBufferFreezeTransparent(boolean flag)

Enables or disables automatic freezing of the depth buffer for objects rendered during the transparent rendering pass (i.e., objects rendered using alpha blending) for this view. If enabled, depth buffer writes will be disabled during the transparent rendering pass regardless of the value of the depth buffer write enable flag in the RenderingAttributes object for a particular node. This flag is enabled by default.

Parameters:

flag - indicates whether automatic freezing of the depth buffer for transparent/antialiased objects is enabled.

See Also:

RenderingAttributes.setDepthBufferWriteEnable(boolean)

getDepthBufferFreezeTransparent

public boolean getDepthBufferFreezeTransparent()

Retrieves the current value of the depth buffer freeze transparent flag for this view.

Returns:

a flag that indicates whether or not the depth buffer is automatically frozen during the transparent rendering pass.

setSceneAntialiasingEnable

public void setSceneAntialiasingEnable(boolean flag)

Enables or disables scene antialiasing for this view. If enabled, the entire scene will be antialiased on each canvas in which scene antialiasing is available. Scene antialiasing is disabled by default.

NOTE: Scene antialiasing is ignored in pure immediate mode, but is supported in mixed-immediate mode.

Parameters:

flag - indicates whether scene antialiasing is enabled

See Also:

Canvas3D.queryProperties()

getSceneAntialiasingEnable

public boolean getSceneAntialiasingEnable()

Returns a flag that indicates whether or not scene antialiasing is enabled for this view.

Returns:

a flag that indicates whether scene antialiasing is enabled

setLocalEyeLightingEnable

public void setLocalEyeLightingEnable(boolean flag)

Sets a flag that indicates whether the local eyepoint is used in lighting calculations for perspective projections. If this flag is set to true, the view vector is calculated per-vertex based on the direction from the actual eyepoint to the vertex. If this flag is set to false, a single view vector is computed from the eyepoint to the center of the view frustum. This is called infinite eye lighting. Local eye lighting is disabled by default, and is ignored for parallel projections.

Parameters:

flag - indicates whether local eye lighting is enabled

getLocalEyeLightingEnable

public boolean getLocalEyeLightingEnable()

Retrieves a flag that indicates whether or not local eye lighting is enabled for this view.

Returns:

a flag that indicates whether local eye lighting is enabled

attachViewPlatform

public void attachViewPlatform(ViewPlatform vp)

Attach viewPlatform structure to this view.

Parameters:

vp - the viewPlatform to be attached

getViewPlatform

public ViewPlatform getViewPlatform()

Retrieves the currently attached ViewPlatform object

Returns:

the currently attached ViewPlatform

stopBehaviorScheduler

public final long[] stopBehaviorScheduler()

Stops the behavior scheduler after all currently scheduled behaviors are executed. Any frame-based behaviors scheduled to wake up on the next frame will be executed at least once before the behavior scheduler is stopped.

NOTE: This is a heavy-weight method intended for verification and image capture (recording); it is not intended to be used for flow control.

Returns:

a pair of integers that specify the beginning and ending time (in milliseconds since January 1, 1970 00:00:00 GMT) of the behavior scheduler's last pass

Throws:

IllegalStateException - if this method is called from a Behavior method or from any Canvas3D render callback method

startBehaviorScheduler

public final void startBehaviorScheduler()

Starts the behavior scheduler running after it has been stopped.

Throws:

IllegalStateException - if this method is called from a Behavior method or from any Canvas3D render callback method

isBehaviorSchedulerRunning

public final boolean isBehaviorSchedulerRunning()

Retrieves a flag that indicates whether the behavior scheduler is currently running.

Returns:

true if the behavior scheduler is running, false otherwise

Throws:

IllegalStateException - if this method is called from a Behavior method or from any Canvas3D render callback method

stopView

public final void stopView()

Stops traversing the scene graph for this view after the current state of the scene graph is reflected on all canvases attached to this view. The renderers associated with these canvases are also stopped.

NOTE: This is a heavy-weight method intended for verification and image capture (recording); it is not intended to be used for flow control.

Throws:

IllegalStateException - if this method is called from a Behavior method or from any Canvas3D render callback method

startView

public final void startView()

Starts traversing this view, and starts the renderers associated with all canvases attached to this view.

Throws:

IllegalStateException - if this method is called from a Behavior method or from any Canvas3D render callback method

isViewRunning

public final boolean isViewRunning()

Retrieves a flag that indicates whether the traverser is currently running on this view.

Returns:

true if the traverser is running, false otherwise

Throws:

IllegalStateException - if this method is called from a Behavior method or from any Canvas3D render callback method

renderOnce

public void renderOnce()

Renders one frame for a stopped View. Functionally, this method is equivalent to startView() followed by stopview(), except that it is atomic, which guarantees that only one frame is rendered.

Throws:

IllegalStateException - if this method is called from a Behavior method or from any Canvas3D render callback, or if the view is currently running.

Since:

Java 3D 1.2

repaint

public void repaint()

Requests that this View be scheduled for rendering as soon as possible. The repaint method may return before the frame has been rendered. If the view is stopped, or if the view is continuously running (for example, due to a free-running interpolator), this method will have no effect. Most applications will not need to call this method, since any update to the scene graph or to viewing parameters will automatically cause all affected views to be rendered.

Since:

Java 3D 1.2