javax.media.j3d
Class Alpha

java.lang.Object
  |
  +--javax.media.j3d.SceneGraphObject
        |
        +--javax.media.j3d.NodeComponent
              |
              +--javax.media.j3d.Alpha

public class Alpha

extends NodeComponent

The alpha NodeComponent object provides common methods for converting a time value into an alpha value (a value in the range 0 to 1). The Alpha object is effectively a function of time that generates alpha values in the range [0,1] when sampled: f(t) = [0,1]. A primary use of the Alpha object is to provide alpha values for Interpolator behaviors. The function f(t) and the characteristics of the Alpha object are determined by user-definable parameters:

loopCount -- This is the number of times to run this Alpha; a value of -1 specifies that the Alpha loops indefinitely.

triggerTime -- This is the time in milliseconds since the start time that this object first triggers. If (startTime + triggerTime >= currentTime) then the Alpha object starts running.

phaseDelayDuration -- This is an additional number of milliseconds to wait after triggerTime before actually starting this Alpha.

mode -- This can be set to INCREASING_ENABLE, DECREASING_ENABLE, or the Or'ed value of the two. INCREASING_ENABLE activates the increasing Alpha parameters listed below; DECREASING_ENABLE activates the decreasing Alpha parameters listed below.

Increasing Alpha parameters:

increasingAlphaDuration -- This is the period of time during which Alpha goes from zero to one.

increasingAlphaRampDuration -- This is the period of time during which the Alpha step size increases at the beginning of the increasingAlphaDuration and, correspondingly, decreases at the end of the increasingAlphaDuration. This parameter is clamped to half of increasingAlphaDuration. When this parameter is non-zero, one gets constant acceleration while it is in effect; constant positive acceleration at the beginning of the ramp and constant negative acceleration at the end of the ramp. If this parameter is zero, then the effective velocity of the Alpha value is constant and the acceleration is zero (ie, a linearly increasing alpha ramp).

alphaAtOneDuration -- This is the period of time that Alpha stays at one.

Decreasing Alpha parameters:

decreasingAlphaDuration -- This is the period of time during which Alpha goes from one to zero.

decreasingAlphaRampDuration -- This is the period of time during which the Alpha step size increases at the beginning of the decreasingAlphaDuration and, correspondingly, decreases at the end of the decreasingAlphaDuration. This parameter is clamped to half of decreasingAlphaDuration. When this parameter is non-zero, one gets constant acceleration while it is in effect; constant positive acceleration at the beginning of the ramp and constant negative acceleration at the end of the ramp. If this parameter is zero, the effective velocity of the Alpha value is constant and the acceleration is zero (i.e., a linearly-decreasing alpha ramp).

alphaAtZeroDuration -- This is the period of time that Alpha stays at zero.

See Also:

Interpolator

Field Summary

static int	DECREASING_ENABLE Specifies that the decreasing component of the alpha is used
static int	INCREASING_ENABLE Specifies that the increasing component of the alpha is used.

Constructor Summary

Alpha()
Constructs an Alpha object with default parameters.

Alpha(int loopCount, int mode, long triggerTime, long phaseDelayDuration, long increasingAlphaDuration, long increasingAlphaRampDuration, long alphaAtOneDuration, long decreasingAlphaDuration, long decreasingAlphaRampDuration, long alphaAtZeroDuration)
This constructor takes all of the Alpha user-definable parameters.

Alpha(int loopCount, long increasingAlphaDuration)
This constructor takes only the loopCount and increasingAlphaDuration as parameters and assigns the default values to all of the other parameters.

Alpha(int loopCount, long triggerTime, long phaseDelayDuration, long increasingAlphaDuration, long increasingAlphaRampDuration, long alphaAtOneDuration)
Constructs a new Alpha object that assumes that the mode is INCREASING_ENABLE.

Method Summary

boolean	finished() Query to test if this alpha object is past its activity window, that is, if it has finished looping.
long	getAlphaAtOneDuration() Retrieves this alpha's alphaAtOneDuration.
long	getAlphaAtZeroDuration() Retrieves this alpha's alphaAtZeroDuration.
long	getDecreasingAlphaDuration() Retrieves this alpha's decreasingAlphaDuration.
long	getDecreasingAlphaRampDuration() Retrieves this alpha's decreasingAlphaRampDuration.
long	getIncreasingAlphaDuration() Retrieves this alpha's increasingAlphaDuration.
long	getIncreasingAlphaRampDuration() Retrieves this alpha's increasingAlphaRampDuration.
int	getLoopCount() Retrieves this alpha's loopCount.
int	getMode() Retrieves this alpha's mode.
long	getPauseTime() Returns the time at which this alpha was paused.
long	getPhaseDelayDuration() Retrieves this alpha's phaseDelayDuration.
long	getStartTime() Retrieves this alpha's startTime, the base for all relative time specifications; the default value for startTime is the system start time.
long	getTriggerTime() Retrieves this alpha's triggerTime.
boolean	isPaused() Returns true if this alpha object is paused.
void	pause() Pauses this alpha object.
void	pause(long time) Pauses this alpha object as of the specified time.
void	resume() Resumes this alpha object.
void	resume(long time) Resumes this alpha object as of the specified time.
void	setAlphaAtOneDuration(long alphaAtOneDuration) Set this alpha object's alphaAtOneDuration to the specified value.
void	setAlphaAtZeroDuration(long alphaAtZeroDuration) Set this alpha object's alphaAtZeroDuration to the specified value.
void	setDecreasingAlphaDuration(long decreasingAlphaDuration) Set this alpha's decreasingAlphaDuration to that specified in the argument.
void	setDecreasingAlphaRampDuration(long decreasingAlphaRampDuration) Set this alpha's decreasingAlphaRampDuration to that specified in the argument.
void	setIncreasingAlphaDuration(long increasingAlphaDuration) Set this alpha's increasingAlphaDuration to that specified in the argument.
void	setIncreasingAlphaRampDuration(long increasingAlphaRampDuration) Set this alpha's increasingAlphaRampDuration to that specified in the argument.
void	setLoopCount(int loopCount) Set this alpha's loopCount to that specified in the argument.
void	setMode(int mode) Set this alpha's mode to that specified in the argument.
void	setPhaseDelayDuration(long phaseDelayDuration) Set this alpha's phaseDelayDuration to that specified in the argument.
void	setStartTime(long startTime) Sets this alpha's startTime to that specified in the argument; startTime sets the base (or zero) for all relative time computations; the default value for startTime is the system start time.
void	setTriggerTime(long triggerTime) Set this alpha's triggerTime to that specified in the argument.
float	value() This method returns a value between 0.0 and 1.0 inclusive, based on the current time and the time-to-alpha parameters established for this alpha.
float	value(long atTime) This method returns a value between 0.0 and 1.0 inclusive, based on the specified time and the time-to-alpha parameters established for this alpha.

Methods inherited from class javax.media.j3d.NodeComponent

cloneNodeComponent, cloneNodeComponent, duplicateNodeComponent, duplicateNodeComponent, getDuplicateOnCloneTree, setDuplicateOnCloneTree

Methods inherited from class javax.media.j3d.SceneGraphObject

clearCapability, clearCapabilityIsFrequent, duplicateSceneGraphObject, getCapability, getCapabilityIsFrequent, getUserData, isCompiled, isLive, setCapability, setCapabilityIsFrequent, setUserData, updateNodeReferences

Methods inherited from class java.lang.Object

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

Field Detail

INCREASING_ENABLE

public static final int INCREASING_ENABLE

Specifies that the increasing component of the alpha is used.

See Also:

Constant Field Values

DECREASING_ENABLE

public static final int DECREASING_ENABLE

Specifies that the decreasing component of the alpha is used

See Also:

Constant Field Values

Constructor Detail

Alpha

public Alpha()

Constructs an Alpha object with default parameters. The default values are as follows:

loopCount : -1
mode : INCREASING_ENABLE
startTime : system start time
triggerTime : 0
phaseDelayDuration : 0
increasingAlphaDuration : 1000
increasingAlphaRampDuration : 0
alphaAtOneDuration : 0
decreasingAlphaDuration : 0
decreasingAlphaRampDuration : 0
alphaAtZeroDuration : 0
isPaused : false
pauseTime : 0

Alpha

public Alpha(int loopCount,
             int mode,
             long triggerTime,
             long phaseDelayDuration,
             long increasingAlphaDuration,
             long increasingAlphaRampDuration,
             long alphaAtOneDuration,
             long decreasingAlphaDuration,
             long decreasingAlphaRampDuration,
             long alphaAtZeroDuration)

This constructor takes all of the Alpha user-definable parameters.

Parameters:

loopCount - number of times to run this alpha; a value of -1 specifies that the alpha loops indefinitely

mode - indicates whether the increasing alpha parameters or the decreasing alpha parameters or both are active. This parameter accepts the following values, INCREASING_ENABLE or DECREASING_ENABLE, which may be ORed together to specify that both are active. The increasing alpha parameters are increasingAlphaDuration, increasingAlphaRampDuration, and alphaAtOneDuration. The decreasing alpha parameters are decreasingAlphaDuration, decreasingAlphaRampDuration, and alphaAtZeroDuration.

triggerTime - time in milliseconds since the start time that this object first triggers

phaseDelayDuration - number of milliseconds to wait after triggerTime before actually starting this alpha

increasingAlphaDuration - period of time during which alpha goes from zero to one

increasingAlphaRampDuration - period of time during which the alpha step size increases at the beginning of the increasingAlphaDuration and, correspondingly, decreases at the end of the increasingAlphaDuration. This value is clamped to half of increasingAlphaDuration. NOTE: a value of zero means that the alpha step size remains constant during the entire increasingAlphaDuration.

alphaAtOneDuration - period of time that alpha stays at one

decreasingAlphaDuration - period of time during which alpha goes from one to zero

decreasingAlphaRampDuration - period of time during which the alpha step size increases at the beginning of the decreasingAlphaDuration and, correspondingly, decreases at the end of the decreasingAlphaDuration. This value is clamped to half of decreasingAlphaDuration. NOTE: a value of zero means that the alpha step size remains constant during the entire decreasingAlphaDuration.

alphaAtZeroDuration - period of time that alpha stays at zero

Alpha

public Alpha(int loopCount,
             long triggerTime,
             long phaseDelayDuration,
             long increasingAlphaDuration,
             long increasingAlphaRampDuration,
             long alphaAtOneDuration)

Constructs a new Alpha object that assumes that the mode is INCREASING_ENABLE.

Parameters:

loopCount - number of times to run this alpha; a value of -1 specifies that the alpha loops indefinitely.

triggerTime - time in milliseconds since the start time that this object first triggers

phaseDelayDuration - number of milliseconds to wait after triggerTime before actually starting this alpha

increasingAlphaDuration - period of time during which alpha goes from zero to one

increasingAlphaRampDuration - period of time during which the alpha step size increases at the beginning of the increasingAlphaDuration and, correspondingly, decreases at the end of the increasingAlphaDuration. This value is clamped to half of increasingAlphaDuration. NOTE: a value of zero means that the alpha step size remains constant during the entire increasingAlphaDuration.

alphaAtOneDuration - period of time that alpha stays at one

Alpha

public Alpha(int loopCount,
             long increasingAlphaDuration)

This constructor takes only the loopCount and increasingAlphaDuration as parameters and assigns the default values to all of the other parameters.

Parameters:

loopCount - number of times to run this alpha; a value of -1 specifies that the alpha loops indefinitely

increasingAlphaDuration - period of time during which alpha goes from zero to one

Method Detail

pause

public void pause()

Pauses this alpha object. The current system time when this method is called will be used in place of the actual current time when calculating subsequent alpha values. This has the effect of freezing the interpolator at the time the method is called.

Since:

Java 3D 1.3

pause

public void pause(long time)

Pauses this alpha object as of the specified time. The specified time will be used in place of the actual current time when calculating subsequent alpha values. This has the effect of freezing the interpolator at the specified time. Note that specifying a time in the future (that is, a time greater than System.currentTimeMillis()) will cause the alpha to immediately advance to that point before pausing. Similarly, specifying a time in the past (that is, a time less than System.currentTimeMillis()) will cause the alpha to immediately revert to that point before pausing.

Parameters:

time - the time at which to pause the alpha

Throws:

java.lang.IllegalArgumentException - if time <= 0

Since:

Java 3D 1.3

resume

public void resume()

Resumes this alpha object. If the alpha object was paused, the difference between the current time and the pause time will be used to adjust the startTime of this alpha. The equation is as follows:

startTime += System.currentTimeMillis() - pauseTime

Since the alpha object is no longer paused, this has the effect of resuming the interpolator as of the current time. If the alpha object is not paused when this method is called, then this method does nothing--the start time is not adjusted in this case.

Since:

Java 3D 1.3

resume

public void resume(long time)

Resumes this alpha object as of the specified time. If the alpha object was paused, the difference between the specified time and the pause time will be used to adjust the startTime of this alpha. The equation is as follows:

startTime += time - pauseTime

Since the alpha object is no longer paused, this has the effect of resuming the interpolator as of the specified time. If the alpha object is not paused when this method is called, then this method does nothing--the start time is not adjusted in this case.

Parameters:

time - the time at which to resume the alpha

Throws:

java.lang.IllegalArgumentException - if time <= 0

Since:

Java 3D 1.3

isPaused

public boolean isPaused()

Returns true if this alpha object is paused.

Returns:

true if this alpha object is paused, false otherwise

Since:

Java 3D 1.3

getPauseTime

public long getPauseTime()

Returns the time at which this alpha was paused.

Returns:

the pause time; returns 0 if this alpha is not paused

Since:

Java 3D 1.3

value

public float value()

This method returns a value between 0.0 and 1.0 inclusive, based on the current time and the time-to-alpha parameters established for this alpha. If this alpha object is paused, the value will be based on the pause time rather than the current time. This method will return the starting alpha value if the alpha has not yet started (that is, if the current time is less than startTime + triggerTime + phaseDelayDuration). This method will return the ending alpha value if the alpha has finished (that is, if the loop count has expired).

Returns:

a value between 0.0 and 1.0 based on the current time

value

public float value(long atTime)

This method returns a value between 0.0 and 1.0 inclusive, based on the specified time and the time-to-alpha parameters established for this alpha. This method will return the starting alpha value if the alpha has not yet started (that is, if the specified time is less than startTime + triggerTime + phaseDelayDuration). This method will return the ending alpha value if the alpha has finished (that is, if the loop count has expired).

Parameters:

atTime - The time for which we wish to compute alpha

Returns:

a value between 0.0 and 1.0 based on the specified time

getStartTime

public long getStartTime()

Retrieves this alpha's startTime, the base for all relative time specifications; the default value for startTime is the system start time.

Returns:

this alpha's startTime.

setStartTime

public void setStartTime(long startTime)

Sets this alpha's startTime to that specified in the argument; startTime sets the base (or zero) for all relative time computations; the default value for startTime is the system start time.

Parameters:

startTime - the new startTime value

getLoopCount

public int getLoopCount()

Retrieves this alpha's loopCount.

Returns:

this alpha's loopCount.

setLoopCount

public void setLoopCount(int loopCount)

Set this alpha's loopCount to that specified in the argument.

Parameters:

loopCount - the new loopCount value

getMode

public int getMode()

Retrieves this alpha's mode.

Returns:

this alpha's mode: any combination of INCREASING_ENABLE and DECREASING_ENABLE

setMode

public void setMode(int mode)

Set this alpha's mode to that specified in the argument.

Parameters:

mode - indicates whether the increasing alpha parameters or the decreasing alpha parameters or both are active. This parameter accepts the following values, INCREASING_ENABLE or DECREASING_ENABLE, which may be ORed together to specify that both are active. The increasing alpha parameters are increasingAlphaDuration, increasingAlphaRampDuration, and alphaAtOneDuration. The decreasing alpha parameters are decreasingAlphaDuration, decreasingAlphaRampDuration, and alphaAtZeroDuration.

getTriggerTime

public long getTriggerTime()

Retrieves this alpha's triggerTime.

Returns:

this alpha's triggerTime.

setTriggerTime

public void setTriggerTime(long triggerTime)

Set this alpha's triggerTime to that specified in the argument.

Parameters:

triggerTime - the new triggerTime

getPhaseDelayDuration

public long getPhaseDelayDuration()

Retrieves this alpha's phaseDelayDuration.

Returns:

this alpha's phaseDelayDuration.

setPhaseDelayDuration

public void setPhaseDelayDuration(long phaseDelayDuration)

Set this alpha's phaseDelayDuration to that specified in the argument.

Parameters:

phaseDelayDuration - the new phaseDelayDuration

getIncreasingAlphaDuration

public long getIncreasingAlphaDuration()

Retrieves this alpha's increasingAlphaDuration.

Returns:

this alpha's increasingAlphaDuration.

setIncreasingAlphaDuration

public void setIncreasingAlphaDuration(long increasingAlphaDuration)

Set this alpha's increasingAlphaDuration to that specified in the argument.

Parameters:

increasingAlphaDuration - the new increasingAlphaDuration

getIncreasingAlphaRampDuration

public long getIncreasingAlphaRampDuration()

Retrieves this alpha's increasingAlphaRampDuration.

Returns:

this alpha's increasingAlphaRampDuration.

setIncreasingAlphaRampDuration

public void setIncreasingAlphaRampDuration(long increasingAlphaRampDuration)

Set this alpha's increasingAlphaRampDuration to that specified in the argument.

Parameters:

increasingAlphaRampDuration - the new increasingAlphaRampDuration

getAlphaAtOneDuration

public long getAlphaAtOneDuration()

Retrieves this alpha's alphaAtOneDuration.

Returns:

this alpha's alphaAtOneDuration.

setAlphaAtOneDuration

public void setAlphaAtOneDuration(long alphaAtOneDuration)

Set this alpha object's alphaAtOneDuration to the specified value.

Parameters:

alphaAtOneDuration - the new alphaAtOneDuration

getDecreasingAlphaDuration

public long getDecreasingAlphaDuration()

Retrieves this alpha's decreasingAlphaDuration.

Returns:

this alpha's decreasingAlphaDuration.

setDecreasingAlphaDuration

public void setDecreasingAlphaDuration(long decreasingAlphaDuration)

Set this alpha's decreasingAlphaDuration to that specified in the argument.

Parameters:

decreasingAlphaDuration - the new decreasingAlphaDuration

getDecreasingAlphaRampDuration

public long getDecreasingAlphaRampDuration()

Retrieves this alpha's decreasingAlphaRampDuration.

Returns:

this alpha's decreasingAlphaRampDuration.

setDecreasingAlphaRampDuration

public void setDecreasingAlphaRampDuration(long decreasingAlphaRampDuration)

Set this alpha's decreasingAlphaRampDuration to that specified in the argument.

Parameters:

decreasingAlphaRampDuration - the new decreasingAlphaRampDuration

getAlphaAtZeroDuration

public long getAlphaAtZeroDuration()

Retrieves this alpha's alphaAtZeroDuration.

Returns:

this alpha's alphaAtZeroDuration.

setAlphaAtZeroDuration

public void setAlphaAtZeroDuration(long alphaAtZeroDuration)

Set this alpha object's alphaAtZeroDuration to the specified value.

Parameters:

alphaAtZeroDuration - the new alphaAtZeroDuration

finished

public boolean finished()

Query to test if this alpha object is past its activity window, that is, if it has finished looping.

Returns:

true if no longer looping, false otherwise