bevy/crates/bevy_animation/src/lib.rs
Nicola Papale c730d8c4cc
Fix animations resetting after repeat count (#10540)
# Objective

After #9002, it seems that "single shot" animations were broken. When
completing, they would reset to their initial value. Which is generally
not what you want.

- Fixes #10480

## Solution

Avoid `%`-ing the animation after the number of completions exceeds the
specified one. Instead, we early-return. This is also true when the
player is playing in reverse.

---

## Changelog

- Avoid resetting animations after `Repeat::Never` animation completion.
2023-11-14 01:59:36 +00:00

763 lines
26 KiB
Rust

//! Animation for the game engine Bevy
#![warn(missing_docs)]
#![allow(clippy::type_complexity)]
use std::ops::Deref;
use std::time::Duration;
use bevy_app::{App, Plugin, PostUpdate};
use bevy_asset::{Asset, AssetApp, Assets, Handle};
use bevy_core::Name;
use bevy_ecs::prelude::*;
use bevy_hierarchy::{Children, Parent};
use bevy_math::{Quat, Vec3};
use bevy_reflect::Reflect;
use bevy_render::mesh::morph::MorphWeights;
use bevy_time::Time;
use bevy_transform::{prelude::Transform, TransformSystem};
use bevy_utils::{tracing::warn, HashMap};
#[allow(missing_docs)]
pub mod prelude {
#[doc(hidden)]
pub use crate::{
AnimationClip, AnimationPlayer, AnimationPlugin, EntityPath, Keyframes, VariableCurve,
};
}
/// List of keyframes for one of the attribute of a [`Transform`].
#[derive(Reflect, Clone, Debug)]
pub enum Keyframes {
/// Keyframes for rotation.
Rotation(Vec<Quat>),
/// Keyframes for translation.
Translation(Vec<Vec3>),
/// Keyframes for scale.
Scale(Vec<Vec3>),
/// Keyframes for morph target weights.
///
/// Note that in `.0`, each contiguous `target_count` values is a single
/// keyframe representing the weight values at given keyframe.
///
/// This follows the [glTF design].
///
/// [glTF design]: https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#animations
Weights(Vec<f32>),
}
/// Describes how an attribute of a [`Transform`] or [`MorphWeights`] should be animated.
///
/// `keyframe_timestamps` and `keyframes` should have the same length.
#[derive(Reflect, Clone, Debug)]
pub struct VariableCurve {
/// Timestamp for each of the keyframes.
pub keyframe_timestamps: Vec<f32>,
/// List of the keyframes.
pub keyframes: Keyframes,
}
/// Path to an entity, with [`Name`]s. Each entity in a path must have a name.
#[derive(Reflect, Clone, Debug, Hash, PartialEq, Eq, Default)]
pub struct EntityPath {
/// Parts of the path
pub parts: Vec<Name>,
}
/// A list of [`VariableCurve`], and the [`EntityPath`] to which they apply.
#[derive(Asset, Reflect, Clone, Debug, Default)]
pub struct AnimationClip {
curves: Vec<Vec<VariableCurve>>,
paths: HashMap<EntityPath, usize>,
duration: f32,
}
impl AnimationClip {
#[inline]
/// [`VariableCurve`]s for each bone. Indexed by the bone ID.
pub fn curves(&self) -> &Vec<Vec<VariableCurve>> {
&self.curves
}
/// Gets the curves for a bone.
///
/// Returns `None` if the bone is invalid.
#[inline]
pub fn get_curves(&self, bone_id: usize) -> Option<&'_ Vec<VariableCurve>> {
self.curves.get(bone_id)
}
/// Gets the curves by it's [`EntityPath`].
///
/// Returns `None` if the bone is invalid.
#[inline]
pub fn get_curves_by_path(&self, path: &EntityPath) -> Option<&'_ Vec<VariableCurve>> {
self.paths.get(path).and_then(|id| self.curves.get(*id))
}
/// Duration of the clip, represented in seconds
#[inline]
pub fn duration(&self) -> f32 {
self.duration
}
/// Add a [`VariableCurve`] to an [`EntityPath`].
pub fn add_curve_to_path(&mut self, path: EntityPath, curve: VariableCurve) {
// Update the duration of the animation by this curve duration if it's longer
self.duration = self
.duration
.max(*curve.keyframe_timestamps.last().unwrap_or(&0.0));
if let Some(bone_id) = self.paths.get(&path) {
self.curves[*bone_id].push(curve);
} else {
let idx = self.curves.len();
self.curves.push(vec![curve]);
self.paths.insert(path, idx);
}
}
/// Whether this animation clip can run on entity with given [`Name`].
pub fn compatible_with(&self, name: &Name) -> bool {
self.paths.keys().any(|path| &path.parts[0] == name)
}
}
/// Repetition behavior of an animation.
#[derive(Reflect, Copy, Clone, Default)]
pub enum RepeatAnimation {
/// The animation will finish after running once.
#[default]
Never,
/// The animation will finish after running "n" times.
Count(u32),
/// The animation will never finish.
Forever,
}
#[derive(Reflect)]
struct PlayingAnimation {
repeat: RepeatAnimation,
speed: f32,
/// Total time the animation has been played.
///
/// Note: Time does not increase when the animation is paused or after it has completed.
elapsed: f32,
/// The timestamp inside of the animation clip.
///
/// Note: This will always be in the range [0.0, animation clip duration]
seek_time: f32,
animation_clip: Handle<AnimationClip>,
path_cache: Vec<Vec<Option<Entity>>>,
/// Number of times the animation has completed.
/// If the animation is playing in reverse, this increments when the animation passes the start.
completions: u32,
}
impl Default for PlayingAnimation {
fn default() -> Self {
Self {
repeat: RepeatAnimation::default(),
speed: 1.0,
elapsed: 0.0,
seek_time: 0.0,
animation_clip: Default::default(),
path_cache: Vec::new(),
completions: 0,
}
}
}
impl PlayingAnimation {
/// Check if the animation has finished, based on its repetition behavior and the number of times it has repeated.
///
/// Note: An animation with `RepeatAnimation::Forever` will never finish.
#[inline]
pub fn is_finished(&self) -> bool {
match self.repeat {
RepeatAnimation::Forever => false,
RepeatAnimation::Never => self.completions >= 1,
RepeatAnimation::Count(n) => self.completions >= n,
}
}
/// Update the animation given the delta time and the duration of the clip being played.
#[inline]
fn update(&mut self, delta: f32, clip_duration: f32) {
if self.is_finished() {
return;
}
self.elapsed += delta;
self.seek_time += delta * self.speed;
let over_time = self.speed > 0.0 && self.seek_time >= clip_duration;
let under_time = self.speed < 0.0 && self.seek_time < 0.0;
if over_time || under_time {
self.completions += 1;
if self.is_finished() {
return;
}
}
if self.seek_time >= clip_duration {
self.seek_time %= clip_duration;
}
// Note: assumes delta is never lower than -clip_duration
if self.seek_time < 0.0 {
self.seek_time += clip_duration;
}
}
/// Reset back to the initial state as if no time has elapsed.
fn replay(&mut self) {
self.completions = 0;
self.elapsed = 0.0;
self.seek_time = 0.0;
}
}
/// An animation that is being faded out as part of a transition
struct AnimationTransition {
/// The current weight. Starts at 1.0 and goes to 0.0 during the fade-out.
current_weight: f32,
/// How much to decrease `current_weight` per second
weight_decline_per_sec: f32,
/// The animation that is being faded out
animation: PlayingAnimation,
}
/// Animation controls
#[derive(Component, Default, Reflect)]
#[reflect(Component)]
pub struct AnimationPlayer {
paused: bool,
animation: PlayingAnimation,
// List of previous animations we're currently transitioning away from.
// Usually this is empty, when transitioning between animations, there is
// one entry. When another animation transition happens while a transition
// is still ongoing, then there can be more than one entry.
// Once a transition is finished, it will be automatically removed from the list
#[reflect(ignore)]
transitions: Vec<AnimationTransition>,
}
impl AnimationPlayer {
/// Start playing an animation, resetting state of the player.
/// This will use a linear blending between the previous and the new animation to make a smooth transition.
pub fn start(&mut self, handle: Handle<AnimationClip>) -> &mut Self {
self.animation = PlayingAnimation {
animation_clip: handle,
..Default::default()
};
// We want a hard transition.
// In case any previous transitions are still playing, stop them
self.transitions.clear();
self
}
/// Start playing an animation, resetting state of the player.
/// This will use a linear blending between the previous and the new animation to make a smooth transition.
pub fn start_with_transition(
&mut self,
handle: Handle<AnimationClip>,
transition_duration: Duration,
) -> &mut Self {
let mut animation = PlayingAnimation {
animation_clip: handle,
..Default::default()
};
std::mem::swap(&mut animation, &mut self.animation);
// Add the current transition. If other transitions are still ongoing,
// this will keep those transitions running and cause a transition between
// the output of that previous transition to the new animation.
self.transitions.push(AnimationTransition {
current_weight: 1.0,
weight_decline_per_sec: 1.0 / transition_duration.as_secs_f32(),
animation,
});
self
}
/// Start playing an animation, resetting state of the player, unless the requested animation is already playing.
/// If `transition_duration` is set, this will use a linear blending
/// between the previous and the new animation to make a smooth transition
pub fn play(&mut self, handle: Handle<AnimationClip>) -> &mut Self {
if !self.is_playing_clip(&handle) || self.is_paused() {
self.start(handle);
}
self
}
/// Start playing an animation, resetting state of the player, unless the requested animation is already playing.
/// This will use a linear blending between the previous and the new animation to make a smooth transition
pub fn play_with_transition(
&mut self,
handle: Handle<AnimationClip>,
transition_duration: Duration,
) -> &mut Self {
if !self.is_playing_clip(&handle) || self.is_paused() {
self.start_with_transition(handle, transition_duration);
}
self
}
/// Handle to the animation clip being played.
pub fn animation_clip(&self) -> &Handle<AnimationClip> {
&self.animation.animation_clip
}
/// Check if the given animation clip is being played.
pub fn is_playing_clip(&self, handle: &Handle<AnimationClip>) -> bool {
self.animation_clip() == handle
}
/// Check if the playing animation has finished, according to the repetition behavior.
pub fn is_finished(&self) -> bool {
self.animation.is_finished()
}
/// Sets repeat to [`RepeatAnimation::Forever`].
///
/// See also [`Self::set_repeat`].
pub fn repeat(&mut self) -> &mut Self {
self.animation.repeat = RepeatAnimation::Forever;
self
}
/// Set the repetition behaviour of the animation.
pub fn set_repeat(&mut self, repeat: RepeatAnimation) -> &mut Self {
self.animation.repeat = repeat;
self
}
/// Repetition behavior of the animation.
pub fn repeat_mode(&self) -> RepeatAnimation {
self.animation.repeat
}
/// Number of times the animation has completed.
pub fn completions(&self) -> u32 {
self.animation.completions
}
/// Check if the animation is playing in reverse.
pub fn is_playback_reversed(&self) -> bool {
self.animation.speed < 0.0
}
/// Pause the animation
pub fn pause(&mut self) {
self.paused = true;
}
/// Unpause the animation
pub fn resume(&mut self) {
self.paused = false;
}
/// Is the animation paused
pub fn is_paused(&self) -> bool {
self.paused
}
/// Speed of the animation playback
pub fn speed(&self) -> f32 {
self.animation.speed
}
/// Set the speed of the animation playback
pub fn set_speed(&mut self, speed: f32) -> &mut Self {
self.animation.speed = speed;
self
}
/// Time elapsed playing the animation
pub fn elapsed(&self) -> f32 {
self.animation.elapsed
}
/// Seek time inside of the animation. Always within the range [0.0, clip duration].
pub fn seek_time(&self) -> f32 {
self.animation.seek_time
}
/// Seek to a specific time in the animation.
pub fn seek_to(&mut self, seek_time: f32) -> &mut Self {
self.animation.seek_time = seek_time;
self
}
/// Reset the animation to its initial state, as if no time has elapsed.
pub fn replay(&mut self) {
self.animation.replay();
}
}
fn entity_from_path(
root: Entity,
path: &EntityPath,
children: &Query<&Children>,
names: &Query<&Name>,
path_cache: &mut Vec<Option<Entity>>,
) -> Option<Entity> {
// PERF: finding the target entity can be optimised
let mut current_entity = root;
path_cache.resize(path.parts.len(), None);
let mut parts = path.parts.iter().enumerate();
// check the first name is the root node which we already have
let Some((_, root_name)) = parts.next() else {
return None;
};
if names.get(current_entity) != Ok(root_name) {
return None;
}
for (idx, part) in parts {
let mut found = false;
let children = children.get(current_entity).ok()?;
if let Some(cached) = path_cache[idx] {
if children.contains(&cached) {
if let Ok(name) = names.get(cached) {
if name == part {
current_entity = cached;
found = true;
}
}
}
}
if !found {
for child in children.deref() {
if let Ok(name) = names.get(*child) {
if name == part {
// Found a children with the right name, continue to the next part
current_entity = *child;
path_cache[idx] = Some(*child);
found = true;
break;
}
}
}
}
if !found {
warn!("Entity not found for path {:?} on part {:?}", path, part);
return None;
}
}
Some(current_entity)
}
/// Verify that there are no ancestors of a given entity that have an [`AnimationPlayer`].
fn verify_no_ancestor_player(
player_parent: Option<&Parent>,
parents: &Query<(Has<AnimationPlayer>, Option<&Parent>)>,
) -> bool {
let Some(mut current) = player_parent.map(Parent::get) else {
return true;
};
loop {
let Ok((has_player, parent)) = parents.get(current) else {
return true;
};
if has_player {
return false;
}
if let Some(parent) = parent {
current = parent.get();
} else {
return true;
}
}
}
/// System that will play all animations, using any entity with a [`AnimationPlayer`]
/// and a [`Handle<AnimationClip>`] as an animation root
#[allow(clippy::too_many_arguments)]
pub fn animation_player(
time: Res<Time>,
animations: Res<Assets<AnimationClip>>,
children: Query<&Children>,
names: Query<&Name>,
transforms: Query<&mut Transform>,
morphs: Query<&mut MorphWeights>,
parents: Query<(Has<AnimationPlayer>, Option<&Parent>)>,
mut animation_players: Query<(Entity, Option<&Parent>, &mut AnimationPlayer)>,
) {
animation_players
.par_iter_mut()
.for_each(|(root, maybe_parent, mut player)| {
update_transitions(&mut player, &time);
run_animation_player(
root,
player,
&time,
&animations,
&names,
&transforms,
&morphs,
maybe_parent,
&parents,
&children,
);
});
}
#[allow(clippy::too_many_arguments)]
fn run_animation_player(
root: Entity,
mut player: Mut<AnimationPlayer>,
time: &Time,
animations: &Assets<AnimationClip>,
names: &Query<&Name>,
transforms: &Query<&mut Transform>,
morphs: &Query<&mut MorphWeights>,
maybe_parent: Option<&Parent>,
parents: &Query<(Has<AnimationPlayer>, Option<&Parent>)>,
children: &Query<&Children>,
) {
let paused = player.paused;
// Continue if paused unless the `AnimationPlayer` was changed
// This allow the animation to still be updated if the player.elapsed field was manually updated in pause
if paused && !player.is_changed() {
return;
}
// Apply the main animation
apply_animation(
1.0,
&mut player.animation,
paused,
root,
time,
animations,
names,
transforms,
morphs,
maybe_parent,
parents,
children,
);
// Apply any potential fade-out transitions from previous animations
for AnimationTransition {
current_weight,
animation,
..
} in &mut player.transitions
{
apply_animation(
*current_weight,
animation,
paused,
root,
time,
animations,
names,
transforms,
morphs,
maybe_parent,
parents,
children,
);
}
}
/// Update `weights` based on weights in `keyframe` with a linear interpolation
/// on `key_lerp`.
fn lerp_morph_weights(weights: &mut [f32], keyframe: impl Iterator<Item = f32>, key_lerp: f32) {
let zipped = weights.iter_mut().zip(keyframe);
for (morph_weight, keyframe) in zipped {
*morph_weight += (keyframe - *morph_weight) * key_lerp;
}
}
/// Extract a keyframe from a list of keyframes by index.
///
/// # Panics
///
/// When `key_index * target_count` is larger than `keyframes`
///
/// This happens when `keyframes` is not formatted as described in
/// [`Keyframes::Weights`]. A possible cause is [`AnimationClip`] not being
/// meant to be used for the [`MorphWeights`] of the entity it's being applied to.
fn get_keyframe(target_count: usize, keyframes: &[f32], key_index: usize) -> &[f32] {
let start = target_count * key_index;
let end = target_count * (key_index + 1);
&keyframes[start..end]
}
#[allow(clippy::too_many_arguments)]
fn apply_animation(
weight: f32,
animation: &mut PlayingAnimation,
paused: bool,
root: Entity,
time: &Time,
animations: &Assets<AnimationClip>,
names: &Query<&Name>,
transforms: &Query<&mut Transform>,
morphs: &Query<&mut MorphWeights>,
maybe_parent: Option<&Parent>,
parents: &Query<(Has<AnimationPlayer>, Option<&Parent>)>,
children: &Query<&Children>,
) {
if let Some(animation_clip) = animations.get(&animation.animation_clip) {
// We don't return early because seek_to() may have been called on the animation player.
animation.update(
if paused { 0.0 } else { time.delta_seconds() },
animation_clip.duration,
);
if animation.path_cache.len() != animation_clip.paths.len() {
animation.path_cache = vec![Vec::new(); animation_clip.paths.len()];
}
if !verify_no_ancestor_player(maybe_parent, parents) {
warn!("Animation player on {:?} has a conflicting animation player on an ancestor. Cannot safely animate.", root);
return;
}
let mut any_path_found = false;
for (path, bone_id) in &animation_clip.paths {
let cached_path = &mut animation.path_cache[*bone_id];
let curves = animation_clip.get_curves(*bone_id).unwrap();
let Some(target) = entity_from_path(root, path, children, names, cached_path) else {
continue;
};
any_path_found = true;
// SAFETY: The verify_no_ancestor_player check above ensures that two animation players cannot alias
// any of their descendant Transforms.
//
// The system scheduler prevents any other system from mutating Transforms at the same time,
// so the only way this fetch can alias is if two AnimationPlayers are targeting the same bone.
// This can only happen if there are two or more AnimationPlayers are ancestors to the same
// entities. By verifying that there is no other AnimationPlayer in the ancestors of a
// running AnimationPlayer before animating any entity, this fetch cannot alias.
//
// This means only the AnimationPlayers closest to the root of the hierarchy will be able
// to run their animation. Any players in the children or descendants will log a warning
// and do nothing.
let Ok(mut transform) = (unsafe { transforms.get_unchecked(target) }) else {
continue;
};
let mut morphs = unsafe { morphs.get_unchecked(target) };
for curve in curves {
// Some curves have only one keyframe used to set a transform
if curve.keyframe_timestamps.len() == 1 {
match &curve.keyframes {
Keyframes::Rotation(keyframes) => {
transform.rotation = transform.rotation.slerp(keyframes[0], weight);
}
Keyframes::Translation(keyframes) => {
transform.translation =
transform.translation.lerp(keyframes[0], weight);
}
Keyframes::Scale(keyframes) => {
transform.scale = transform.scale.lerp(keyframes[0], weight);
}
Keyframes::Weights(keyframes) => {
if let Ok(morphs) = &mut morphs {
let target_count = morphs.weights().len();
lerp_morph_weights(
morphs.weights_mut(),
get_keyframe(target_count, keyframes, 0).iter().copied(),
weight,
);
}
}
}
continue;
}
// Find the current keyframe
// PERF: finding the current keyframe can be optimised
let step_start = match curve
.keyframe_timestamps
.binary_search_by(|probe| probe.partial_cmp(&animation.seek_time).unwrap())
{
Ok(n) if n >= curve.keyframe_timestamps.len() - 1 => continue, // this curve is finished
Ok(i) => i,
Err(0) => continue, // this curve isn't started yet
Err(n) if n > curve.keyframe_timestamps.len() - 1 => continue, // this curve is finished
Err(i) => i - 1,
};
let ts_start = curve.keyframe_timestamps[step_start];
let ts_end = curve.keyframe_timestamps[step_start + 1];
let lerp = (animation.seek_time - ts_start) / (ts_end - ts_start);
// Apply the keyframe
match &curve.keyframes {
Keyframes::Rotation(keyframes) => {
let rot_start = keyframes[step_start];
let mut rot_end = keyframes[step_start + 1];
// Choose the smallest angle for the rotation
if rot_end.dot(rot_start) < 0.0 {
rot_end = -rot_end;
}
// Rotations are using a spherical linear interpolation
let rot = rot_start.normalize().slerp(rot_end.normalize(), lerp);
transform.rotation = transform.rotation.slerp(rot, weight);
}
Keyframes::Translation(keyframes) => {
let translation_start = keyframes[step_start];
let translation_end = keyframes[step_start + 1];
let result = translation_start.lerp(translation_end, lerp);
transform.translation = transform.translation.lerp(result, weight);
}
Keyframes::Scale(keyframes) => {
let scale_start = keyframes[step_start];
let scale_end = keyframes[step_start + 1];
let result = scale_start.lerp(scale_end, lerp);
transform.scale = transform.scale.lerp(result, weight);
}
Keyframes::Weights(keyframes) => {
if let Ok(morphs) = &mut morphs {
let target_count = morphs.weights().len();
let morph_start = get_keyframe(target_count, keyframes, step_start);
let morph_end = get_keyframe(target_count, keyframes, step_start + 1);
let result = morph_start
.iter()
.zip(morph_end)
.map(|(a, b)| *a + lerp * (*b - *a));
lerp_morph_weights(morphs.weights_mut(), result, weight);
}
}
}
}
}
if !any_path_found {
warn!("Animation player on {root:?} did not match any entity paths.");
}
}
}
fn update_transitions(player: &mut AnimationPlayer, time: &Time) {
player.transitions.retain_mut(|animation| {
animation.current_weight -= animation.weight_decline_per_sec * time.delta_seconds();
animation.current_weight > 0.0
});
}
/// Adds animation support to an app
#[derive(Default)]
pub struct AnimationPlugin;
impl Plugin for AnimationPlugin {
fn build(&self, app: &mut App) {
app.init_asset::<AnimationClip>()
.register_asset_reflect::<AnimationClip>()
.register_type::<AnimationPlayer>()
.add_systems(
PostUpdate,
animation_player.before(TransformSystem::TransformPropagate),
);
}
}