module Eagle::Ease

Overview

Easing curves: functions that reshape progress from 0..1 so motion speeds up, slows down, overshoots or bounces instead of moving at a constant rate.

You usually pass an easing to a tween by name, as in ease: :quad_out. Call the functions directly when you animate something by hand.

Which one to pick:

_out curves start fast and settle, which suits things arriving: UI sliding in, a camera stopping.
_in curves start slow and accelerate, which suits things leaving.
_in_out curves are slow at both ends, which suits back-and-forth motion.
#back_out overshoots a little and comes back. It makes buttons and popups feel springy.
#bounce_out and #elastic_out are playful, for landing items and wobbling icons.

t = 0.5_f32
Ease.quad_out(t)   # => 0.75, already three quarters of the way there
Ease.by_name(:bounce_out).call(t)

eagle/core/tween.cr

#back_in(t : Float32) : Float32
Pulls back slightly before moving forward, like winding up.
#back_out(t : Float32) : Float32
Overshoots the target slightly, then settles back.
#bounce_in(t : Float32) : Float32
Bounces at the start instead of the end.
#bounce_out(t : Float32) : Float32
Bounces against the target like a dropped ball.
#by_name(name : Symbol) : Proc(Float32, Float32)
Looks up an easing by symbol, such as :quad_out.
#cubic_in(t : Float32) : Float32
Like #quad_in, but stronger.
#cubic_in_out(t : Float32) : Float32
Like #quad_in_out, but stronger.
#cubic_out(t : Float32) : Float32
Like #quad_out, but stronger.
#elastic_out(t : Float32) : Float32
Overshoots and wobbles like a spring before settling.
#expo_in(t : Float32) : Float32
Almost still, then a sudden rush at the end.
#expo_out(t : Float32) : Float32
Very fast start with a long, soft landing.
#linear(t : Float32) : Float32
Constant speed.
#quad_in(t : Float32) : Float32
Starts slow and speeds up (t²).
#quad_in_out(t : Float32) : Float32
Slow at both ends.
#quad_out(t : Float32) : Float32
Starts fast and slows to a stop.
#sine_in(t : Float32) : Float32
Gentle acceleration following a quarter sine wave.
#sine_in_out(t : Float32) : Float32
Gentle at both ends, good for breathing and hovering motion.
#sine_out(t : Float32) : Float32
Gentle deceleration.

def back_in(t : Float32) : Float32 #

Pulls back slightly before moving forward, like winding up.

def back_out(t : Float32) : Float32 #

Overshoots the target slightly, then settles back. Great for popups.

def bounce_in(t : Float32) : Float32 #

Bounces at the start instead of the end.

def bounce_out(t : Float32) : Float32 #

Bounces against the target like a dropped ball.

def by_name(name : Symbol) : Proc(Float32, Float32) #

Looks up an easing by symbol, such as :quad_out. Raises ArgumentError for unknown names.

def cubic_in(t : Float32) : Float32 #

Like #quad_in, but stronger.

def cubic_in_out(t : Float32) : Float32 #

Like #quad_in_out, but stronger.

def cubic_out(t : Float32) : Float32 #

Like #quad_out, but stronger.

def elastic_out(t : Float32) : Float32 #

Overshoots and wobbles like a spring before settling.

def expo_in(t : Float32) : Float32 #

Almost still, then a sudden rush at the end.

def expo_out(t : Float32) : Float32 #

Very fast start with a long, soft landing.

def linear(t : Float32) : Float32 #

Constant speed.

def quad_in(t : Float32) : Float32 #

Starts slow and speeds up (t²).

def quad_in_out(t : Float32) : Float32 #

Slow at both ends.

def quad_out(t : Float32) : Float32 #

Starts fast and slows to a stop. A good default for most UI motion.

def sine_in(t : Float32) : Float32 #

Gentle acceleration following a quarter sine wave.

def sine_in_out(t : Float32) : Float32 #

Gentle at both ends, good for breathing and hovering motion.

def sine_out(t : Float32) : Float32 #

Gentle deceleration.