1 chapter 10 behavior and interaction to understand dynamic behaviors in graphics to understand...

1Zhang & Liang, Computer Graphics Using Java 2D and 3D (c) 2007 Pearson Education, Inc. All rights reserved.

Chapter 10 Behavior and Interaction

To understand dynamic behaviors in graphics To understand Java 3D Behavior and

WakeupCondition classes To apply Behavior nodes in scene graphs To use mouse behaviors To use key navigator behaviors To use view platform behaviors To combine picking and behaviors


Dynamic 3D Scenes

3D graphics is not limited to static content There are two common types of dynamic

change in a scene– Interaction allows the user to control the

changes– Animation generates changes under the control

of the program


Behavior

Java3D uses behavior to facilitate dynamics in a scene graph

Behavior is a leaf node– Defines actions to be taken when the behavior

is activated (waked-up)– Behavior is triggered by wakeup conditions

For interactions, triggers are user generated For animation, triggers are time-based


Behavior Execution Cycles


Behavior

During the initialization of the Behavior object, it sets a WakeupCondition object.

When the wakeup condition occurs, it will awaken the Behavior by calling its processStimulus.

After executing the custom code in processStimulus, a wakeup condition can be set again by calling the wakeupOn method.

The process will then repeat indefinitely.


Behavior Classes Behavior

– abstract

– extends Leaf

Two methodsvoid initialize()

void processStimulus ( Enumeration wakeupCriteria)


WakeupCondition

Serve as signals to trigger different behaviors under different circumstances

WakeupCriterion– Many subclasses for different kinds of triggers

time, AWT events, collisions, transform changes, …

Subclasses that are used to create combinations of conditions


Wakeup Condition


Combining Wakeup Criteria

Subclasses of WakeupConditionWakeupAnd(WakeupCriterion[] criteria)WakeupOr(WakeupCriterion[] criteria)WakeupOrOfAnds(WakeupAnd[] criteriaAnds)WakeupAndOfOrs(WakeupOr[] criteriaOrs)


Combining Wakeup Criteria

WakeupCriterion[] criteria1

= {new WakeupOnElapsedTime(10000)};

WakeupCriterion[] criteria2 =

{new WakeupOnElapsedFrames(5),

new WakeupOnCollisionEntry(node)};

WakeupAnd[] ands = {new WakeupAnd( criteria1), new WakeupAnd(criteria2)};

WakeupOrOfAnds condition = new WakeupOrOfAnds( ands);


Scheduling Bounds

Each Behavior has a scheduling bounds Behavior is active only if the scheduling

bounds intersects the view platform Set scheduling bounds with

setSchedulingBounds( Bounds bounds)

setSchedulingBoundingLeaf( BoundingLeaf bounds)


Implement Custom Behavior Define a subclass of Behavior class and override

the initialize and processStimulus methods. Set the appropriate wakeup condition in the

initialize method. If necessary set the wakeup condition again in processStimulus.

Create an instance of the custom Behavior class and add it to the scene graph as a leaf.

Set the influence bound for the behavior object.


Example: Clock.java


Classes for Interaction

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Mouse Behavior Mouse behavior classes

– Operate on a TransformGroup– Triggered by WakeUpOnAWTEvent

Three classes for rotation, translation and zoom

Constructors take– TransformGroup– Component– TransformGroup and Component

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Mouse Behaviors

MouseRotate: drag the mouse with the left button down.

MouseTranslate: drag the mouse with the right button down.

MouseZoom: drag the mouse with the middle button down – Drag left button down while holding the Alt

key if there is no middle mouse button

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MoveGlobe.java

Contains a texture-mapped sphere and a set of coordinate axes

Three behaviors for rotation, translation and zoom– All applied to the TransformGroup above the

sphere– Axes don't change

Notice the event handling is all hidden inside the Behavior objects

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Using Keys for Interaction

KeyNavigationBehavior operates on a TransformGroup

Similar constructors to the mouse behavior


KeyNavigatorBehavior

<left>, <right>: Rotate left/right <up>, <down>: Translate forward/backward Alt-<left>, Alt-<right>: Translate left/right PgUp, PgDn: Rotate up/down Alt-PgUp, Alt-PgDn: Translate up/down -: Reduce back clip distance +: Reset back clip distance =: Reset


View Platform Behavior OrbitBehavior allows user to interact with

the view platform using the mouse– One class supports rotation, translation and zoom– Behavior is applied to the TransformGroup of

the view platform Constructors

– OrbitBehavior()– OrbitBehavior(Canvas3D cv)– OrbitBehavior(Canvas3D cv, int flags)

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MoveView.java

Similar to MoveGlobe except the view platform is moved rather than the globe itself– Direction of apparent motion is reversed– Axes move too


Picking and Mouse Behavior PickMouseBehavior has three subclasses

– PickRotateBehavior– PickTranslateBehavior– PickZoomBehavior

Changes apply only to picked object Constructor

PickRotateBehavior rotator = new PickRotateBehavior(cv, root, bounds);

root.addChild(rotator);

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TestPickBehavior

Behaviors are applied to the BranchGroup containing the objects

Behaviors need reference to the canvas and the scheduling bounds

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Data Visualization

The possibility of interacting with a 3D scene provides a powerful tool for studying 3D data sets– Reorienting the scene gives different views of

the data Improves perception of 3D nature of the data

– Ability to select subsets of the data allows refinment of the view


DataViewer.java

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Using Pick Intersections

Use PickCanvas to pick based on mouse coordinates

All data points are in same 3D object as vertices– need to find the intersection with the pick volume to

select individual pointsPickIntersection inter = results[i].getIntersection(0);Point3d pt = inter.getClosestVertexCoordinates();int[] ind = inter.getPrimitiveCoordinateIndices();

1 chapter 10 behavior and interaction to understand dynamic behaviors in graphics to understand...

Documents

d behavior

behavior object

behavior nodes

behavior java3d

wakeup condition slide

scene graph behavior

timebased slide

program slide