Easings

Sometimes you want to use fancy easing curves for various things in games. In the days of old this would have been a lot of math, and in modern times you'd probably use animation curves for it. I wrote a bit of code to act as a nice interface for animation curves.

Relevant Links

• itch.io

ease(val1, val2, f, curve_type)

This is the main function you'll want to use. It's basically a mirror of lerp where you specify the curve type.

Returns: number

Parameter	Type	Description
val1	real	The starting number you want to interpolate from.
val2	real	The final number you want to interpolate to.
f	real	The amount you want to interpolate by (usually a number between 0 and 1).
curve_type	Easings or string	The type of easing curve you want to use.

If you've ever used lerp before, which most of you probably have, the first three arguments are exactly the same.

curve_type can be either a member of the Easings enum or a string containing the name of the curve. See the chart below for reference.

easing_get(curve_type, f)

Returns: number

Parameter	Type	Description
curve_type	Easings or string	The type of easing curve you want to use.
f	real	The amount you want to interpolate by (usually a number between 0 and 1).

Like the above, but this function returns a value between (approximately) 0 and 1, without any min or max value.

global.animation_tween_names

If you want to attach nice, readable names to the easing curves (perhaps you want to show it to the user or something) there's a little global array with text strings corresponding to the members of the Easings enum.

Easing chart

String name	Enum name	Curve name
Linear	Easings.LINEAR	"linear"
Quadratic In	Easings.QUAD_I	"quad_i"
Quadratic Out	Easings.QUAD_O	"quad_o"
Quadratic In/Out	Easings.QUAD_IO	"quad_io"
Cubic In	Easings.CUBE_I	"cubic_i"
Cubic Out	Easings.CUBE_O	"cubic_o"
Cubic In/Out	Easings.CUBE_IO	"cubic_io"
Quartic In	Easings.QUART_I	"quart_i"
Quartic Out	Easings.QUART_O	"quart_o"
Quartic In/Out	Easings.QUART_IO	"quart_io"
Exponential In	Easings.EXP_I	"exp_i"
Exponential Out	Easings.EXP_O	"exp_o"
Exponential In/Out	Easings.EXP_IO	"exp_io"
Circular In	Easings.CIRC_I	"circ_i"
Circular Out	Easings.CIRC_O	"circ_o"
Circular In/Out	Easings.CIRC_IO	"circ_io"
Back In	Easings.BACK_I	"back_i"
Back Out	Easings.BACK_O	"back_o"
There and Back Again	Easings.BACK_IO	"back_io"
Elastic In	Easings.ELASTIC_I	"elastic_i"
Elastic Out	Easings.ELASTIC_O	"elastic_o"
Elastic In/Out	Easings.ELASTIC_IO	"elastic_io"
Bounce In	Easings.BOUNCE_I	"bounce_i"
Bounce Out	Easings.BOUNCE_O	"bounce_o"
Bounce In/Out	Easings.BOUNCE_IO	"bounce_io"
Fast to Slow	Easings.FAST_TO_SLOW	"fast_to_slow"
Mid to Slow	Easings.MID_TO_SLOW	"mid_slow"