javax.media.j3d
Class Billboard

java.lang.Object
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  +--javax.media.j3d.SceneGraphObject
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        +--javax.media.j3d.Node
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              +--javax.media.j3d.Leaf
                    |
                    +--javax.media.j3d.Behavior
                          |
                          +--javax.media.j3d.Billboard

public class Billboard

extends Behavior

The Billboard behavior node operates on the TransformGroup node to cause the local +z axis of the TransformGroup to point at the viewer's eye position. This is done regardless of the transforms above the specified TransformGroup node in the scene graph.

If the alignment mode is ROTATE_AXIS, then the rotation will be around the specified axis. If the alignment mode is ROTATE_ABOUT_POINT, then the rotation will be about the specfied point, with an additional rotation to align the +y axis of the TransformGroup with the +y axis in the View.

Billboard nodes provide the most benefit for complex, roughly-symmetric objects. A typical use might consist of a quadrilateral that contains a texture of a tree.

Field Summary

static int	ROTATE_ABOUT_AXIS Specifies that rotation should be about the specified axis.
static int	ROTATE_ABOUT_POINT Specifies that rotation should be about the specified point and that the children's Y-axis should match the view object's Y-axis.

Fields inherited from class javax.media.j3d.Node

ALLOW_AUTO_COMPUTE_BOUNDS_READ, ALLOW_AUTO_COMPUTE_BOUNDS_WRITE, ALLOW_BOUNDS_READ, ALLOW_BOUNDS_WRITE, ALLOW_COLLIDABLE_READ, ALLOW_COLLIDABLE_WRITE, ALLOW_LOCAL_TO_VWORLD_READ, ALLOW_PICK, ALLOW_PICKABLE_READ, ALLOW_PICKABLE_WRITE, ENABLE_COLLISION_REPORTING, ENABLE_PICK_REPORTING

Constructor Summary

Billboard()
Constructs a Billboard node with default parameters.

Billboard(TransformGroup tg)
Constructs a Billboard node with default parameters that operates on the specified TransformGroup node.

Billboard(TransformGroup tg, int mode, Point3f point)
Constructs a Billboard node with the specified rotation point and mode that operates on the specified TransformGroup node.

Billboard(TransformGroup tg, int mode, Vector3f axis)
Constructs a Billboard node with the specified axis and mode that operates on the specified TransformGroup node.

Method Summary

Node	cloneNode(boolean forceDuplicate) Creates a new instance of the node.
void	duplicateNode(Node originalNode, boolean forceDuplicate) Copies all node information from originalNode into the current node.
void	getAlignmentAxis(Vector3f axis) Gets the alignment axis and sets the parameter to this value
int	getAlignmentMode() Gets the alignment mode.
void	getRotationPoint(Point3f point) Gets the rotation point and sets the parameter to this value
TransformGroup	getTarget() Returns a copy of the transformGroup associated with this BillBoard;
void	initialize() Initialize method that sets up initial wakeup criteria.
void	processStimulus(java.util.Enumeration criteria) Process stimulus method that computes appropriate transform.
void	setAlignmentAxis(float x, float y, float z) Sets the alignment axis.
void	setAlignmentAxis(Vector3f axis) Sets the alignment axis.
void	setAlignmentMode(int mode) Sets the alignment mode.
void	setRotationPoint(float x, float y, float z) Sets the rotate point.
void	setRotationPoint(Point3f point) Sets the rotation point.
void	setTarget(TransformGroup tg) Sets the tranformGroup for this Billboard object.
void	updateNodeReferences(NodeReferenceTable referenceTable) Callback used to allow a node to check if any scene graph objects referenced by that node have been duplicated via a call to cloneTree.

Methods inherited from class javax.media.j3d.Behavior

getEnable, getSchedulingBoundingLeaf, getSchedulingBounds, getView, postId, setEnable, setSchedulingBoundingLeaf, setSchedulingBounds, wakeupOn

Methods inherited from class javax.media.j3d.Node

cloneTree, cloneTree, cloneTree, getBounds, getBoundsAutoCompute, getCollidable, getLocalToVworld, getLocalToVworld, getParent, getPickable, setBounds, setBoundsAutoCompute, setCollidable, setPickable

Methods inherited from class javax.media.j3d.SceneGraphObject

clearCapability, duplicateSceneGraphObject, getCapability, getUserData, isCompiled, isLive, setCapability, setUserData

Methods inherited from class java.lang.Object

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

Field Detail

ROTATE_ABOUT_AXIS

public static final int ROTATE_ABOUT_AXIS

Specifies that rotation should be about the specified axis.

ROTATE_ABOUT_POINT

public static final int ROTATE_ABOUT_POINT

Specifies that rotation should be about the specified point and that the children's Y-axis should match the view object's Y-axis.

Constructor Detail

Billboard

public Billboard()

Constructs a Billboard node with default parameters. The default values are as follows:

alignment mode : ROTATE_ABOUT_AXIS
alignment axis : Y-axis (0,1,0)
rotation point : (0,0,1)
target transform group: null

Billboard

public Billboard(TransformGroup tg)

Constructs a Billboard node with default parameters that operates on the specified TransformGroup node. The default alignment mode is ROTATE_ABOUT_AXIS rotation with the axis pointing along the Y axis.

Parameters:

tg - the TransformGroup node that this Billboard node operates upon

Billboard

public Billboard(TransformGroup tg,
                 int mode,
                 Vector3f axis)

Constructs a Billboard node with the specified axis and mode that operates on the specified TransformGroup node.

Parameters:

tg - the TransformGroup node that this Billboard node operates upon

mode - alignment mode, one of ROTATE_AXIS or ROTATE_ABOUT_POINT

axis - the ray about which the billboard rotates

Billboard

public Billboard(TransformGroup tg,
                 int mode,
                 Point3f point)

Constructs a Billboard node with the specified rotation point and mode that operates on the specified TransformGroup node.

Parameters:

tg - the TransformGroup node that this Billboard node operates upon

mode - alignment mode, one of ROTATE_AXIS or ROTATE_ABOUT_POINT

point - the position about which the billboard rotates

Method Detail

setAlignmentMode

public final void setAlignmentMode(int mode)

Sets the alignment mode.

Parameters:

mode - one of: ROTATE_ABOUT_AXIS or ROTATE_ABOUT_POINT

getAlignmentMode

public final int getAlignmentMode()

Gets the alignment mode.

Returns:

one of: ROTATE_ABOUT_AXIS or ROTATE_ABOUT_POINT

setAlignmentAxis

public final void setAlignmentAxis(Vector3f axis)

Sets the alignment axis.

Parameters:

axis - the ray about which the billboard rotates

setAlignmentAxis

public final void setAlignmentAxis(float x,
                                   float y,
                                   float z)

Sets the alignment axis.

Parameters:

x - the x component of the ray about which the billboard rotates

y - the y component of the ray about which the billboard rotates

z - the z component of the ray about which the billboard rotates

getAlignmentAxis

public final void getAlignmentAxis(Vector3f axis)

Gets the alignment axis and sets the parameter to this value

Parameters:

axis - the vector that will contain the ray about which the billboard rotates

setRotationPoint

public final void setRotationPoint(Point3f point)

Sets the rotation point.

Parameters:

point - the point about which the billboard rotates

setRotationPoint

public final void setRotationPoint(float x,
                                   float y,
                                   float z)

Sets the rotate point.

Parameters:

x - the x component of the point about which the billboard rotates

y - the y component of the point about which the billboard rotates

z - the z component of the point about which the billboard rotates

getRotationPoint

public final void getRotationPoint(Point3f point)

Gets the rotation point and sets the parameter to this value

Parameters:

point - the position that the Billboard rotates about

setTarget

public final void setTarget(TransformGroup tg)

Sets the tranformGroup for this Billboard object.

Parameters:

tg - the transformGroup node which replaces the current transformGroup node for this Billboard

getTarget

public final TransformGroup getTarget()

Returns a copy of the transformGroup associated with this BillBoard;

Returns:

the TranformGroup for this Billboard

initialize

public void initialize()

Initialize method that sets up initial wakeup criteria.

Overrides:

initialize in class Behavior

processStimulus

public void processStimulus(java.util.Enumeration criteria)

Process stimulus method that computes appropriate transform.

Overrides:

processStimulus in class Behavior

Parameters:

criteria - an enumeration of the criteria that caused the stimulus

cloneNode

public Node cloneNode(boolean forceDuplicate)

Creates a new instance of the node. This routine is called by cloneTree to duplicate the current node.

Overrides:

cloneNode in class Node

Parameters:

forceDuplicate - when set to true, causes the duplicateOnCloneTree flag to be ignored. When false, the value of each node's duplicateOnCloneTree variable determines whether NodeComponent data is duplicated or copied.

See Also:

Node.cloneTree(), Node.cloneNode(boolean), Node.duplicateNode(javax.media.j3d.Node, boolean), NodeComponent.setDuplicateOnCloneTree(boolean)

duplicateNode

public void duplicateNode(Node originalNode,
                          boolean forceDuplicate)

Copies all node information from originalNode into the current node. This method is called from the cloneNode method which is, in turn, called by the cloneTree method.

For any NodeComponent objects contained by the object being duplicated, each NodeComponent object's duplicateOnCloneTree value is used to determine whether the NodeComponent should be duplicated in the new node or if just a reference to the current node should be placed in the new node. This flag can be overridden by setting the forceDuplicate parameter in the cloneTree method to true.

Overrides:

duplicateNode in class Behavior

Parameters:

originalNode - the original node to duplicate.

forceDuplicate - when set to true, causes the duplicateOnCloneTree flag to be ignored. When false, the value of each node's duplicateOnCloneTree variable determines whether NodeComponent data is duplicated or copied.

See Also:

Group.cloneNode(boolean), Node.duplicateNode(javax.media.j3d.Node, boolean), Node.cloneTree(), NodeComponent.setDuplicateOnCloneTree(boolean)

updateNodeReferences

public void updateNodeReferences(NodeReferenceTable referenceTable)

Callback used to allow a node to check if any scene graph objects referenced by that node have been duplicated via a call to cloneTree. This method is called by cloneTree after all nodes in the sub-graph have been duplicated. The cloned Leaf node's method will be called and the Leaf node can then look up any object references by using the getNewObjectReference method found in the NodeReferenceTable object. If a match is found, a reference to the corresponding object in the newly cloned sub-graph is returned. If no corresponding reference is found, either a DanglingReferenceException is thrown or a reference to the original object is returned depending on the value of the allowDanglingReferences parameter passed in the cloneTree call.

Overrides:

updateNodeReferences in class Behavior

Parameters:

referenceTable - a NodeReferenceTableObject that contains the getNewObjectReference method needed to search for new object instances.

See Also:

NodeReferenceTable, Node.cloneTree(), DanglingReferenceException