71 lines
1.7 KiB
Rust
71 lines
1.7 KiB
Rust
use crate::GameState;
|
|
use bevy::prelude::*;
|
|
|
|
#[derive(Component)]
|
|
pub struct Trail {
|
|
points: Vec<Vec3>,
|
|
col_start: LinearRgba,
|
|
col_end: LinearRgba,
|
|
}
|
|
|
|
impl Trail {
|
|
pub fn new(points: usize, col_start: LinearRgba, col_end: LinearRgba) -> Self {
|
|
Self {
|
|
points: Vec::with_capacity(points),
|
|
col_start,
|
|
col_end,
|
|
}
|
|
}
|
|
|
|
pub fn with_pos(self, pos: Vec3) -> Self {
|
|
let mut trail = self;
|
|
trail.add(pos);
|
|
trail
|
|
}
|
|
|
|
pub fn add(&mut self, pos: Vec3) {
|
|
if self.points.len() >= self.points.capacity() {
|
|
self.points.pop();
|
|
}
|
|
self.points.insert(0, pos);
|
|
}
|
|
}
|
|
|
|
pub fn plugin(app: &mut App) {
|
|
app.add_systems(
|
|
FixedUpdate,
|
|
update_trail.run_if(in_state(GameState::Playing)),
|
|
);
|
|
}
|
|
|
|
fn update_trail(
|
|
mut query: Query<(Entity, &mut Trail, &Gizmo, &GlobalTransform)>,
|
|
global_transform: Query<&GlobalTransform>,
|
|
mut gizmo_assets: ResMut<Assets<GizmoAsset>>,
|
|
) -> Result {
|
|
for (e, mut trail, gizmo, pos) in query.iter_mut() {
|
|
trail.add(pos.translation());
|
|
|
|
let parent_transform = global_transform.get(e)?;
|
|
|
|
let Some(gizmo) = gizmo_assets.get_mut(gizmo.handle.id()) else {
|
|
continue;
|
|
};
|
|
|
|
gizmo.clear();
|
|
|
|
let lerp_denom = trail.points.len() as f32;
|
|
|
|
gizmo.linestrip_gradient(trail.points.iter().enumerate().map(|(i, pos)| {
|
|
(
|
|
GlobalTransform::from_translation(*pos)
|
|
.reparented_to(parent_transform)
|
|
.translation,
|
|
trail.col_start.mix(&trail.col_end, i as f32 / lerp_denom),
|
|
)
|
|
}));
|
|
}
|
|
|
|
Ok(())
|
|
}
|