mirror of
https://github.com/trezor/trezor-firmware.git
synced 2024-11-22 23:48:12 +00:00
82 lines
2.9 KiB
Markdown
82 lines
2.9 KiB
Markdown
# Pareen
|
|
[](https://docs.rs/pareen)
|
|
[](https://github.com/leod/pareen/blob/master/LICENSE)
|
|
[](https://crates.io/crates/pareen)
|
|
|
|
Pareen is a small Rust library for *par*ameterized inbetw*een*ing.
|
|
The intended application is in game programming, where you sometimes have
|
|
two discrete game states between which you want to transition smoothly for
|
|
visualization purposes.
|
|
|
|
Pareen gives you tools for composing animations that are parameterized by
|
|
time (i.e. mappings from time to some animated value) without constantly
|
|
having to pass around time variables; it hides the plumbing, so that you
|
|
need to provide time only once: when evaluating the animation.
|
|
|
|
Animations are composed similarly to Rust's iterators, so no memory
|
|
allocations are necessary. The downside to this is that it is diffcult to store
|
|
pareen's animations. The recommended approach is to construct and evaluate
|
|
animations on the fly.
|
|
|
|
## Current Status
|
|
I consider `pareen` to be an experimental approach, and I'm not sure if I'm
|
|
still happy with it. Anyway, the integration of easing functions could use
|
|
some love. Contributions are very much welcome!
|
|
|
|
Unfortunately, it looks like heavily nested animations can cause an exponential
|
|
slowdown in compilation time. For now, boxing intermediate animations serves as
|
|
a workaround, but this comes with a decrease of both readability and efficiency.
|
|
|
|
## Examples
|
|
```rust
|
|
// An animation returning a constant value
|
|
let anim1 = pareen::constant(1.0f64);
|
|
|
|
// Animations can be evaluated at any time
|
|
let value = anim1.eval(0.5);
|
|
|
|
// Animations can be played in sequence
|
|
let anim2 = anim1.seq(0.7, pareen::prop(0.25) + 0.5);
|
|
|
|
// Animations can be composed and transformed in various ways
|
|
let anim3 = anim2
|
|
.lerp(pareen::circle().cos())
|
|
.scale_min_max(5.0, 10.0)
|
|
.backwards(1.0)
|
|
.squeeze(3.0, 0.5..=1.0);
|
|
|
|
let anim4 = pareen::cubic(&[1.0, 2.0, 3.0, 4.0]) - anim3;
|
|
|
|
let value = anim4.eval(1.0);
|
|
```
|
|
|
|
### Easer
|
|
Optionally, you can enable support for integrating easing functions from
|
|
[`easer`](https://docs.rs/easer/0.2.1/easer/index.html).
|
|
|
|
```rust
|
|
let first_anim = pareen::constant(2.0);
|
|
let second_anim = pareen::prop(1.0f32);
|
|
|
|
// Transition from first_anim to second_anim at time 0.5, applying cubic easing
|
|
// for 0.3 time units.
|
|
let anim = first_anim.seq_ease_in_out(
|
|
0.5,
|
|
easer::functions::Cubic,
|
|
0.3,
|
|
second_anim,
|
|
);
|
|
```
|
|
|
|
### Plots
|
|
There is an example that shows some animations as plots via
|
|
[RustGnuplot](https://github.com/SiegeLord/RustGnuplot) in
|
|
[examples/plots.rs](examples/plots.rs). Given that `gnuplot` has been
|
|
installed, it can be executed like this:
|
|
```bash
|
|
cargo run --example plots --feature easer
|
|
```
|
|
|
|
If everything works, you should see something like this:
|
|
|