public final class SpringForce


Spring Force defines the characteristics of the spring being used in the animation.

By configuring the stiffness and damping ratio, callers can create a spring with the look and feel suits their use case. Stiffness corresponds to the spring constant. The stiffer the spring is, the harder it is to stretch it, the faster it undergoes dampening.

Spring damping ratio describes how oscillations in a system decay after a disturbance. When damping ratio >1* (i.e. over-damped), the object will quickly return to the rest position without overshooting. If damping ratio equals to 1 (i.e. critically damped), the object will return to equilibrium within the shortest amount of time. When damping ratio is less than 1 (i.e. under-damped), the mass tends to overshoot, and return, and overshoot again. Without any damping (i.e. damping ratio = 0), the mass will oscillate forever.

Summary

Constants

static final float

Damping ratio for a very bouncy spring.

static final float

Damping ratio for a spring with low bounciness.

static final float

Damping ratio for a medium bouncy spring.

static final float

Damping ratio for a spring with no bounciness.

static final float
STIFFNESS_HIGH = 10000.0f

Stiffness constant for extremely stiff spring.

static final float
STIFFNESS_LOW = 200.0f

Stiffness constant for a spring with low stiffness.

static final float

Stiffness constant for medium stiff spring.

static final float

Stiffness constant for a spring with very low stiffness.

Public constructors

Creates a spring force.

SpringForce(float finalPosition)

Creates a spring with a given final rest position.

Public methods

float

Returns the damping ratio of the spring.

float

Returns the rest position of the spring.

float

Gets the stiffness of the spring.

SpringForce
setDampingRatio(@FloatRange(from = 0.0) float dampingRatio)

Spring damping ratio describes how oscillations in a system decay after a disturbance.

SpringForce
setFinalPosition(float finalPosition)

Sets the rest position of the spring.

SpringForce
setStiffness(@FloatRange(from = 0.0, fromInclusive = false) float stiffness)

Sets the stiffness of a spring.

Constants

DAMPING_RATIO_HIGH_BOUNCY

Added in 1.0.0
public static final float DAMPING_RATIO_HIGH_BOUNCY = 0.2f

Damping ratio for a very bouncy spring. Note for under-damped springs (i.e. damping ratio <1), the lower the damping ratio, the more bouncy the spring.

DAMPING_RATIO_LOW_BOUNCY

Added in 1.0.0
public static final float DAMPING_RATIO_LOW_BOUNCY = 0.75f

Damping ratio for a spring with low bounciness. Note for under-damped springs (i.e. damping ratio <1), the lower the damping ratio, the higher the bounciness.

DAMPING_RATIO_MEDIUM_BOUNCY

Added in 1.0.0
public static final float DAMPING_RATIO_MEDIUM_BOUNCY = 0.5f

Damping ratio for a medium bouncy spring. This is also the default damping ratio for spring force. Note for under-damped springs (i.e. damping ratio <1), the lower the damping ratio, the more bouncy the spring.

DAMPING_RATIO_NO_BOUNCY

Added in 1.0.0
public static final float DAMPING_RATIO_NO_BOUNCY = 1.0f

Damping ratio for a spring with no bounciness. This damping ratio will create a critically damped spring that returns to equilibrium within the shortest amount of time without oscillating.

STIFFNESS_HIGH

Added in 1.0.0
public static final float STIFFNESS_HIGH = 10000.0f

Stiffness constant for extremely stiff spring.

STIFFNESS_LOW

Added in 1.0.0
public static final float STIFFNESS_LOW = 200.0f

Stiffness constant for a spring with low stiffness.

STIFFNESS_MEDIUM

Added in 1.0.0
public static final float STIFFNESS_MEDIUM = 1500.0f

Stiffness constant for medium stiff spring. This is the default stiffness for spring force.

STIFFNESS_VERY_LOW

Added in 1.0.0
public static final float STIFFNESS_VERY_LOW = 50.0f

Stiffness constant for a spring with very low stiffness.

Public constructors

SpringForce

Added in 1.0.0
public SpringForce()

Creates a spring force. Note that final position of the spring must be set through setFinalPosition before the spring animation starts.

SpringForce

Added in 1.0.0
public SpringForce(float finalPosition)

Creates a spring with a given final rest position.

Parameters
float finalPosition

final position of the spring when it reaches equilibrium

Public methods

getDampingRatio

Added in 1.0.0
public float getDampingRatio()

Returns the damping ratio of the spring.

Returns
float

damping ratio of the spring

getFinalPosition

Added in 1.0.0
public float getFinalPosition()

Returns the rest position of the spring.

Returns
float

rest position of the spring

getStiffness

Added in 1.0.0
public float getStiffness()

Gets the stiffness of the spring.

Returns
float

the stiffness of the spring

setDampingRatio

Added in 1.0.0
public SpringForce setDampingRatio(@FloatRange(from = 0.0) float dampingRatio)

Spring damping ratio describes how oscillations in a system decay after a disturbance.

When damping ratio >1 (over-damped), the object will quickly return to the rest position without overshooting. If damping ratio equals to 1 (i.e. critically damped), the object will return to equilibrium within the shortest amount of time. When damping ratio is less than 1 (i.e. under-damped), the mass tends to overshoot, and return, and overshoot again. Without any damping (i.e. damping ratio = 0), the mass will oscillate forever.

Default damping ratio is DAMPING_RATIO_MEDIUM_BOUNCY.

Parameters
@FloatRange(from = 0.0) float dampingRatio

damping ratio of the spring, it should be non-negative

Returns
SpringForce

the spring force that the given damping ratio is set on

Throws
java.lang.IllegalArgumentException

if the {@param dampingRatio} is negative.

setFinalPosition

Added in 1.0.0
public SpringForce setFinalPosition(float finalPosition)

Sets the rest position of the spring.

Parameters
float finalPosition

rest position of the spring

Returns
SpringForce

the spring force that the given final position is set on

setStiffness

Added in 1.0.0
public SpringForce setStiffness(@FloatRange(from = 0.0, fromInclusive = false) float stiffness)

Sets the stiffness of a spring. The more stiff a spring is, the more force it applies to the object attached when the spring is not at the final position. Default stiffness is STIFFNESS_MEDIUM.

Parameters
@FloatRange(from = 0.0, fromInclusive = false) float stiffness

non-negative stiffness constant of a spring

Returns
SpringForce

the spring force that the given stiffness is set on

Throws
java.lang.IllegalArgumentException

if the given spring stiffness is not positive