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Ferrous-Solitaire/solitaire_engine/src/card_animation/animation.rs
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chore(engine): apply rustfmt after dead-code removals
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-07-09 15:02:15 -07:00

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//! `CardAnimation` component and the system that drives it.
//!
//! # Design
//!
//! `CardAnimation` is a **drop-in upgrade** for the existing linear `CardAnim`.
//! It targets `Transform` (the current sprite-based architecture). Swapping to
//! Bevy UI requires only changing the four write lines in `advance_card_animations`
//! to write `Style.left` / `Style.top` via a `Style` component query instead.
//!
//! # Z-lift
//!
//! During motion, `translation.z` follows a parabolic arc:
//!
//! ```text
//! z(t) = lerp(start_z, end_z, t) + z_lift × sin(t × π)
//! ```
//!
//! The sine term is 0 at `t = 0` and `t = 1` and peaks at `t = 0.5`, so the
//! card "floats up" in the middle of its travel and lands at its correct rest z.
//!
//! # Coexistence with `CardAnim`
//!
//! `CardAnimation` and the legacy `CardAnim` can coexist in the same world but
//! **must never be on the same entity** — both write to `Transform`. When
//! migrating, replace `CardAnim` insertions with `CardAnimation` insertions and
//! register `CardAnimationPlugin` alongside `AnimationPlugin`.
use std::f32::consts::PI;
use bevy::prelude::*;
use bevy::window::RequestRedraw;
use super::curves::{MotionCurve, sample_curve};
use super::timing::compute_duration;
use crate::pause_plugin::PausedResource;
// ---------------------------------------------------------------------------
// Component
// ---------------------------------------------------------------------------
/// Curve-based card animation.
///
/// Drives `Transform` XY translation via a [`MotionCurve`], with optional
/// z-lift and scale interpolation. Removes itself when the animation completes.
#[derive(Component, Debug, Clone)]
pub struct CardAnimation {
/// 2-D start position (world space).
pub start: Vec2,
/// 2-D destination (world space).
pub end: Vec2,
/// Seconds elapsed since the delay expired.
pub elapsed: f32,
/// Total animation duration in seconds (excluding delay).
pub duration: f32,
/// Easing curve applied to the interpolation factor.
pub curve: MotionCurve,
/// Seconds to wait before starting movement.
pub delay: f32,
/// Z coordinate at animation start (used for parabolic lift calculation).
pub start_z: f32,
/// Z coordinate at animation end — the card's resting z after completion.
pub end_z: f32,
/// Extra Z added at the midpoint of motion (`z(0.5) = base_z + z_lift`).
/// Set to 0.0 to disable the depth arc.
pub z_lift: f32,
/// Transform scale at `t = 0`.
pub scale_start: f32,
/// Transform scale at `t = 1`.
pub scale_end: f32,
}
impl CardAnimation {
/// Convenience constructor: slide from `start` to `end` with auto-computed
/// duration based on pixel distance. No z-lift or scale change.
pub fn slide(start: Vec2, start_z: f32, end: Vec2, end_z: f32, curve: MotionCurve) -> Self {
Self {
start,
end,
elapsed: 0.0,
duration: compute_duration(start.distance(end)),
curve,
delay: 0.0,
start_z,
end_z,
z_lift: 0.0,
scale_start: 1.0,
scale_end: 1.0,
}
}
/// Sets the pre-animation delay in seconds.
#[must_use]
pub fn with_delay(mut self, secs: f32) -> Self {
self.delay = secs;
self
}
/// Overrides the auto-computed duration.
#[must_use]
pub fn with_duration(mut self, secs: f32) -> Self {
self.duration = secs;
self
}
/// Enables the parabolic z-lift arc with the given peak offset.
#[must_use]
pub fn with_z_lift(mut self, lift: f32) -> Self {
self.z_lift = lift;
self
}
/// Interpolates `Transform.scale` from `start` to `end` over the animation.
#[must_use]
pub fn with_scale(mut self, start: f32, end: f32) -> Self {
self.scale_start = start;
self.scale_end = end;
self
}
/// Returns the current interpolated XY position without advancing time.
pub fn current_xy(&self) -> Vec2 {
if self.duration <= 0.0 {
return self.end;
}
let t = (self.elapsed / self.duration).clamp(0.0, 1.0);
let s = sample_curve(self.curve, t);
self.start.lerp(self.end, s)
}
}
// ---------------------------------------------------------------------------
// System
// ---------------------------------------------------------------------------
/// Advances all [`CardAnimation`] components each frame.
///
/// Skipped while the game is paused. On completion the component is removed
/// and `Transform` is snapped to the exact destination to prevent floating-point
/// drift.
pub(crate) fn advance_card_animations(
mut commands: Commands,
time: Res<Time>,
paused: Option<Res<PausedResource>>,
mut q: Query<(Entity, &mut Transform, &mut CardAnimation)>,
mut redraw: MessageWriter<RequestRedraw>,
) {
if paused.is_some_and(|p| p.0) {
return;
}
// Keep the winit event loop awake while any animation (including one
// still in its delay phase) needs per-frame ticks. Without this,
// Android's reactive_low_power focused_mode only wakes at its 100 ms
// ceiling and card slides render at ~10 fps.
if !q.is_empty() {
redraw.write(RequestRedraw);
}
let dt = time.delta_secs();
for (entity, mut transform, mut anim) in &mut q {
// Honour pre-animation delay.
if anim.delay > 0.0 {
anim.delay = (anim.delay - dt).max(0.0);
continue;
}
// Zero-duration: instant snap.
if anim.duration <= 0.0 {
transform.translation = anim.end.extend(anim.end_z);
transform.scale = Vec3::splat(anim.scale_end);
commands.entity(entity).remove::<CardAnimation>();
continue;
}
anim.elapsed += dt;
let t = (anim.elapsed / anim.duration).min(1.0);
let s = sample_curve(anim.curve, t);
// --- XY via curve ---
let xy = anim.start.lerp(anim.end, s);
transform.translation.x = xy.x;
transform.translation.y = xy.y;
// --- Z: linear base interpolation + parabolic lift arc ---
//
// The sine arch is 0 at t=0 and t=1, peaking at t=0.5.
// This keeps the card's resting Z correct at both ends.
let base_z = anim.start_z + (anim.end_z - anim.start_z) * t;
let lift = anim.z_lift * (t * PI).sin();
transform.translation.z = base_z + lift;
// --- Scale ---
let scale = anim.scale_start + (anim.scale_end - anim.scale_start) * s;
transform.scale = Vec3::splat(scale);
// --- Completion ---
if t >= 1.0 {
transform.translation = anim.end.extend(anim.end_z);
transform.scale = Vec3::splat(anim.scale_end);
commands.entity(entity).remove::<CardAnimation>();
}
}
}
// ---------------------------------------------------------------------------
// Tests
// ---------------------------------------------------------------------------
#[cfg(test)]
mod tests {
use super::*;
fn make_anim(start: Vec2, end: Vec2, elapsed: f32, duration: f32) -> CardAnimation {
CardAnimation {
start,
end,
elapsed,
duration,
curve: MotionCurve::Responsive, // linear-ish for easy assertion
delay: 0.0,
start_z: 0.0,
end_z: 0.0,
z_lift: 0.0,
scale_start: 1.0,
scale_end: 1.0,
}
}
#[test]
fn current_xy_at_start() {
let anim = make_anim(Vec2::ZERO, Vec2::new(100.0, 0.0), 0.0, 1.0);
let pos = anim.current_xy();
assert!(
pos.x < 5.0,
"at t=0 position should be near start, got {pos:?}"
);
}
#[test]
fn current_xy_at_end() {
let anim = make_anim(Vec2::ZERO, Vec2::new(100.0, 0.0), 1.0, 1.0);
let pos = anim.current_xy();
assert!(
(pos.x - 100.0).abs() < 1e-3,
"at t=1 position should be at end, got {pos:?}"
);
}
#[test]
fn current_xy_zero_duration_returns_end() {
let anim = make_anim(Vec2::ZERO, Vec2::new(50.0, 0.0), 0.0, 0.0);
let pos = anim.current_xy();
assert!(
(pos.x - 50.0).abs() < 1e-3,
"zero-duration must return end immediately, got {pos:?}"
);
}
#[test]
fn slide_constructor_auto_computes_duration() {
let start = Vec2::ZERO;
let end = Vec2::new(300.0, 0.0);
let anim = CardAnimation::slide(start, 0.0, end, 0.0, MotionCurve::SmoothSnap);
let distance = 300.0_f32;
let expected = compute_duration(distance);
assert!(
(anim.duration - expected).abs() < 1e-5,
"slide() duration mismatch: got {}, expected {}",
anim.duration,
expected
);
}
#[test]
fn with_delay_sets_delay() {
let anim = CardAnimation::slide(Vec2::ZERO, 0.0, Vec2::ONE, 0.0, MotionCurve::SmoothSnap)
.with_delay(0.5);
assert!((anim.delay - 0.5).abs() < 1e-6);
}
#[test]
fn with_z_lift_sets_z_lift() {
let anim = CardAnimation::slide(Vec2::ZERO, 0.0, Vec2::ONE, 0.0, MotionCurve::SmoothSnap)
.with_z_lift(12.0);
assert!((anim.z_lift - 12.0).abs() < 1e-6);
}
}