vona.time

Class Interpolator

java.lang.Object

vona.time.Interpolator

Direct Known Subclasses:

TrapezoidInterpolator

public class Interpolator
extends java.lang.Object

Vona's utils: a time-based interpolator.

Interpolates a currentValue() from start to end over the time period duration according to clock.

Default impl is simple linear interpolation.

Copyright (C) 2004 Marsette A. Vona, III

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

Author:

Marsette (Marty) A. Vona, III

Field Summary

Fields

Modifier and Type	Field and Description
Clock	clock The time base to use for this interpolation.
(package private) static java.lang.String	cvsid CVS id.
double	distance end-start.
double	duration The duration of this interpolation.
double	end The ending value for this interpolation.
double	start The starting value for this interpolation.
protected double	startTime The start time of the current interpolation, or NaN if no current interpolation.
static Clock	wallClock A default time base.

Constructor Summary

Constructors

Constructor and Description
Interpolator(Clock clock, double start, double end, double duration) Create a new Interpolator.
Interpolator(double start, double end, double duration) Covers Interpolator(Clock, double, double, double) but always uses wallClock.

Method Summary

Methods

Modifier and Type	Method and Description
double	currentValue() Get the current value of the interpolation.
protected double	currentValue(double when) Hook for subclasses to implement different interpolation schemes.
void	reset() Reset this Interpolator.

Methods inherited from class java.lang.Object

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

Field Detail

cvsid

static final java.lang.String cvsid

CVS id.

See Also:

Constant Field Values

clock

public final Clock clock

The time base to use for this interpolation.

start

public final double start

The starting value for this interpolation.

end

public final double end

The ending value for this interpolation.

distance

public final double distance

end-start.

duration

public final double duration

The duration of this interpolation.

startTime

protected double startTime

The start time of the current interpolation, or NaN if no current interpolation.

wallClock

public static final Clock wallClock

A default time base.

Constructor Detail

Interpolator

public Interpolator(Clock clock,
            double start,
            double end,
            double duration)

Create a new Interpolator.

Parameters:

clock - the time base, if null then use wallClock

start - the initial value

end - the final falue

duration - the duration in seconds according to clock

Interpolator

public Interpolator(double start,
            double end,
            double duration)

Covers Interpolator(Clock, double, double, double) but always uses wallClock.

Method Detail

currentValue

public double currentValue()

Get the current value of the interpolation.

The first call to this method after construction or a reset() returns start and initiates the interpolation. Subsequent calls will return the interpolated value at the time of call until duration has expired according to clock, after which time all calls will return end until the next reset().

Returns:

the current value of the interpolation

currentValue

protected double currentValue(double when)

Hook for subclasses to implement different interpolation schemes.

currentValue() calls this to compute intermediate values between start and end.

Parameters:

when - the time in seconds according to clock since the start of the interpolation

Returns:

the value of the interpolation at when

reset

public void reset()

Reset this Interpolator.

May be called at any time.