Twerp - Script for GMS2

JUST A HEADS UP -------------------
With the addition of Animation Curves, this script is kinda unnecessary now. I'll leave it up for those who still prefer using a single script to defining and using animcurves, but I've personally stopped using twerp.

We had a good run, buddy.
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Twerp is an easing function for GameMaker Studio 2 that functions similar to the lerp() function, but allows you to select from many easing algorithms to augment how the value changes over time.

Here is how I typically use twerp:
You need 4 things to start, often defined in the create event.
1. A start value.
2. An end value.
3. A length for the transition from start to end (typically in steps)
4. And a timer to keep track of how long the current transition has been going.

So my create event might look like this:

timer = 0;
length = room_speed * 2;
start = 50;
end = 150;

Then my Step Event:

timer++;
x = twerp(TwerpType.inout_cubic, start, end, timer / length);

And it's really that simple.