A Primer to Programming in Desmos
2024 autumn
Did you know you can develop games in Desmos?
Aw yeah, Desmos is so much more than just a graphical calculator. In fact, you can create animations, interfaces, or even entire programs. It’s kinda like Scratch↗ – you can create anything you want, if you try hard enough!
Desmos in Action
The singular feature which makes programming in Desmos possible is actions. The Desmos article↗> explains them far better than I could, so have a read of that if you’re not familiar with them.
Critically, actions give us the ability to mutate state. If you think about variables:
We can set them to particular values; we can change them (manually) with a slider; we can even keep them oscillating by animating the slider. What we can’t do (without actions) is use Desmos itself to change their values. We either have to type in a new value, drag the slider, or …wait for the slider to momentarily hit the value we wanted. Not exactly ideal for programming!
Actions, then, give us a programmatic way to alter variables. Check it out:
When we run the action, it updates the value of the variable. Now let’s pull a JavaScript and assign this expression to an identifier:
Now we can use $a()$ anywhere to run this action. And since it’s pretty much just a function, we can of course add parameters too:
Lo and behold, what have we here? Might as well just be a function / procedure / method / whatever you wanna call it.
So, we’ve got variables, and we’ve got functions to change them. All we’re missing now is the logic to control how we go about that!