Struct Step 

pub struct Step<'a> {
    pub player: &'a mut Player,
    pub intent: &'a Intent,
    pub terrain: &'a mut dyn Terrain,
    pub tuning: &'a Tuning,
    pub moves: &'a mut Moves,
    pub events: &'a mut Vec<Event>,
    pub others: &'a [Rect],
    pub dt: f32,
    pub scale: i32,
}

What an Ability gets to work with in one step.

Fields

player: &'a mut Player

The body.

intent: &'a Intent

This step’s input.

terrain: &'a mut dyn Terrain

The world around it; changes count from here on, in this step too.

tuning: &'a Tuning

The movement feel.

moves: &'a mut Moves

The built-in moves allowed this step: clear some in Ability::before. Changes in Ability::after come too late for this step (and the next starts from Moves::ALL again).

events: &'a mut Vec<Event>

This step’s events so far; push yours (Event::Custom).

others: &'a [Rect]

The other characters’ bodies on the same terrain (a crate::Party), as the step started for those yet to move and as they ended up for those already moved; empty for a character on its own.

dt: f32

The step’s length in seconds (super::DT).

scale: i32

Pixels of the game’s terrain per unit (super::World::scale; 1 without a Builder::scale). Everything in the step is in units, but a terrain of the game’s own reached through find_mut answers in its pixels: ask it with rect.scaled(s.scale).