awoo

Animate and schedule code.

This crate provides a very simple mechanism to animate some code. Consider:

let mut time = 0.; // time that passes
let a = 0.;
let b = 1.;
let c = 2.;

// main loop of our application
loop {
  if time < a {
    // do something until time passes a point in time a
  } else if time < b {
    // do something until time passes a point in time b
  } else if time < c {
    // do something until time passes a point in time c
  } // etc. etc.

  // time advances here
  time += 0.1;

  if time >= c {
    break
  }
}

That might sound surprising to you, but a lot of demoscene productions are written with that kind of if / else if blocks. It’s pretty bad and ugly though, I agree. For several reasons:

• It doesn’t compose at all. If you want to do something in between α and β, you will have to break the whole block and change every timings.
• Dynamic branching will get worse and worse as time passes, since you’re going to make more and more tests.
• The code is just ugly!

Instead of writing that kind of code, we can do better:

use awoo::window::Window;

let pre_alpha = Window::new(0., 1.); // do something until time passes 1.
let pre_beta = Window::new(1., 2.); // do something until time passes 2.
let pre_gamma = Window::new(2., 3.); // do something until time passes 3.

By default, Window<T> is just a window of time T. We can map actions to completely do the same thing as above:

let pre_alpha = Window::new(0., 1.).map(|time| println!("time is {}", time));

The type of that MappedWindow<_> is determined by what you return from your closure in the map call. Once all windows are created, you can schedule them:

use awoo::scheduler::RandomAccessScheduler;
use awoo::time::simple::SimpleF32TimeGenerator;

let mut scheduler = RandomAccessScheduler::new(
  SimpleF32TimeGenerator::new(0., 0.1), // a generator that generates linear time starting at 0 and incrementing by 0.1
  vec![pre_alpha, pre_beta, pre_gamma] // our mapped windows
).unwrap();

scheduler.schedule();

What’s interesting is that we can get the windows from a file, for instance, and map them on the fly.