SpringAnimation Class Reference

#import <spring_animation.h>

Inheritance diagram for SpringAnimation:

Instance Methods
(instancetype)	- initWithStiffness:damping:mass:initialVelocity:fromValue:toValue:
(double)	- curveFunction:

Properties
double	stiffness
double	damping
double	mass
double	initialVelocity
double	fromValue
double	toValue
double	zeta [implementation]
double	omega0 [implementation]
double	omega1 [implementation]
double	v0 [implementation]

Detailed Description

Definition at line 23 of file spring_animation.h.

Method Documentation

curveFunction:

- (double) curveFunction:

(double)

t

Definition at line 20 of file spring_animation.mm.

                       :(double)t {
  const double x0 = _toValue - _fromValue;
 
  double y;
  if (_zeta < 1) {
    // Under damped.
    const double envelope = exp(-_zeta * _omega0 * t);
    y = _toValue - envelope * (((_v0 + _zeta * _omega0 * x0) / _omega1) * sin(_omega1 * t) +
                               x0 * cos(_omega1 * t));
  } else {
    // Critically damped.
    const double envelope = exp(-_omega0 * t);
    y = _toValue - envelope * (x0 + (_v0 + _omega0 * x0) * t);
  }
 
  return y;
}

initWithStiffness:damping:mass:initialVelocity:fromValue:toValue:

- (instancetype) initWithStiffness:		(double)	stiffness
damping:		(double)	damping
mass:		(double)	mass
initialVelocity:		(double)	initialVelocity
fromValue:		(double)	fromValue
toValue:		(double)	toValue

Definition at line 20 of file spring_animation.mm.

                                 :(double)stiffness
                          damping:(double)damping
                             mass:(double)mass
                  initialVelocity:(double)initialVelocity
                        fromValue:(double)fromValue
                          toValue:(double)toValue {
  self = [super init];
  if (self) {
    _stiffness = stiffness;
    _damping = damping;
    _mass = mass;
    _initialVelocity = initialVelocity;
    _fromValue = fromValue;
    _toValue = toValue;
 
    _zeta = _damping / (2 * sqrt(_stiffness * _mass));  // Damping ratio.
    _omega0 = sqrt(_stiffness / _mass);             // Undamped angular frequency of the oscillator.
    _omega1 = _omega0 * sqrt(1.0 - _zeta * _zeta);  // Exponential decay.
    _v0 = -_initialVelocity;
  }
  return self;
}

Property Documentation

damping

- (double) damping

readnonatomicassign

Definition at line 35 of file spring_animation.h.

fromValue

- (double) fromValue

readwritenonatomicassign

Definition at line 38 of file spring_animation.h.

initialVelocity

- (double) initialVelocity

readnonatomicassign

Definition at line 37 of file spring_animation.h.

mass

- (double) mass

readnonatomicassign

Definition at line 36 of file spring_animation.h.

omega0

- (double) omega0

readwritenonatomicassignimplementation

Definition at line 18 of file spring_animation.mm.

omega1

- (double) omega1

readwritenonatomicassignimplementation

Definition at line 19 of file spring_animation.mm.

stiffness

- (double) stiffness

readnonatomicassign

Definition at line 34 of file spring_animation.h.

toValue

- (double) toValue

readwritenonatomicassign

Definition at line 39 of file spring_animation.h.

v0

- (double) v0

readwritenonatomicassignimplementation

Definition at line 20 of file spring_animation.mm.

zeta

- (double) zeta

readwritenonatomicassignimplementation

Definition at line 17 of file spring_animation.mm.

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The documentation for this class was generated from the following files:

• third_party/spring_animation/spring_animation.h
• third_party/spring_animation/spring_animation.mm