Game stats that reset every frame, inspired by immediate mode rendering.

This makes it easy to implement temporary buffs/debuffs, and effects that change over time. Using a derive macro, stat resets are propagated to any stat fields, making it easy to compose stats into more complex objects.

# use immediate_stats::*;
#[derive(StatContainer)]
struct Speed(Stat);

fn main() {
    let mut speed = Speed(Stat::new(10)); // Set base speed to 10.
    
    loop {
        speed.0 *= 2.0; // Applies a multiplier to the final result.
        speed.0 += 5; // Adds a bonus to the final result.
        // The order does not matter, bonuses are always applied before multipliers.
        assert_eq!(speed.0.total(), 30); // (10 + 5) * 2 = 30

        speed.reset_modifiers(); // Reset speed back to 10.
    }
}

Bevy

There is build-in integration with the Bevy Engine via the bevy feature flag. This adds systems for resetting [StatContainer] components and resources.

use bevy_app::prelude::*;

use bevy_ecs::prelude::*;

use immediate_stats::*;

#[derive(StatContainer, Component, Resource, Default)] struct Speed(Stat);

fn main() { App::new() .add_plugins(( ImmediateStatsPlugin, ResetComponentPlugin::::new(), ResetResourcePlugin::::new(), )) .run(); }

### Bevy Butler

If you use [Bevy Butler](https://github.com/TGRCdev/bevy-butler/),
you can also use the `bevy_butler` feature flag.
This automatically registers the required system(s) using the `add_component` attribute
or the existing `insert_resource` macro.

# use bevy_app::prelude::*;
# use bevy_ecs::prelude::*;
# use immediate_stats::*;
# use bevy_butler::*;
fn main() {
    App::new().add_plugins((ImmediateStatsPlugin, MyPlugin)).run();
}

#[butler_plugin]
struct MyPlugin;

// `StatContainer` derive adds the `add_component` attribute
// and hooks into the existing `insert_resource` macro.
#[derive(StatContainer, Component, Resource, Default)]
#[add_component(plugin = MyPlugin)] // Adds `ResetComponentPlugin`
#[insert_resource(plugin = MyPlugin)] // Adds `ResetResourcePlugin`
struct Speed(Stat);

Version Compatibility