animation player (#4375)

# Objective

- Add a basic animation player
  - Single track
  - Not generic, can only animate `Transform`s
  - With plenty of possible optimisations available
  - Close-ish to https://github.com/bevyengine/rfcs/pull/49
- https://discord.com/channels/691052431525675048/774027865020039209/958820063148929064

## Solution

- Can play animations
  - looping or not
- Can pause animations
- Can seek in animation
- Can alter speed of animation
- I also removed the previous gltf animation example

https://user-images.githubusercontent.com/8672791/161051887-e79283f0-9803-448a-93d0-5f7a62acb02d.mp4

CREDITS.md

@@ -21,5 +21,6 @@
 * Ground tile from [Kenney's Tower Defense Kit](https://www.kenney.nl/assets/tower-defense-kit) (CC0 1.0 Universal)
 * Game icons from [Kenney's Game Icons](https://www.kenney.nl/assets/game-icons) (CC0 1.0 Universal)
 * Space ships from [Kenny's Simple Space Kit](https://www.kenney.nl/assets/simple-space) (CC0 1.0 Universal)
-* glTF animated triangle from [glTF Sample Models](https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/AnimatedTriangle) (CC0 1.0 Universal)
+* glTF animated fox from [glTF Sample Models](https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/Fox)
-* glTF box animated from [glTF Sample Models](https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/BoxAnimated) ([CC BY 4.0](https://creativecommons.org/licenses/by/4.0/) - by [Cesium](https://cesium.com))
+  * Low poly fox [by PixelMannen](https://opengameart.org/content/fox-and-shiba) (CC0 1.0 Universal)
+  * Rigging and animation [by @tomkranis on Sketchfab](https://sketchfab.com/models/371dea88d7e04a76af5763f2a36866bc) ([CC-BY 4.0](https://creativecommons.org/licenses/by/4.0/))

Cargo.toml

@@ -17,6 +17,7 @@ members = ["crates/*", "examples/ios", "tools/ci", "errors"]
 
 [features]
 default = [
+  "animation",
   "bevy_audio",
   "bevy_gilrs",
   "bevy_winit",
@@ -43,6 +44,7 @@ render = [
 ]
 
 # Optional bevy crates
+bevy_animation = ["bevy_internal/bevy_animation"]
 bevy_audio = ["bevy_internal/bevy_audio"]
 bevy_core_pipeline = ["bevy_internal/bevy_core_pipeline"]
 bevy_dynamic_plugin = ["bevy_internal/bevy_dynamic_plugin"]
@@ -98,6 +100,9 @@ bevy_ci_testing = ["bevy_internal/bevy_ci_testing"]
 # Enable the "debug asset server" for hot reloading internal assets
 debug_asset_server = ["bevy_internal/debug_asset_server"]
 
+# Enable animation support, and glTF animation loading
+animation = ["bevy_internal/animation"]
+
 [dependencies]
 bevy_dylib = { path = "crates/bevy_dylib", version = "0.7.0-dev", default-features = false, optional = true }
 bevy_internal = { path = "crates/bevy_internal", version = "0.7.0-dev", default-features = false }
@@ -183,10 +188,6 @@ path = "examples/3d/lighting.rs"
 name = "load_gltf"
 path = "examples/3d/load_gltf.rs"
 
-[[example]]
-name = "manual_gltf_animation_player"
-path = "examples/3d/manual_gltf_animation_player.rs"
-
 [[example]]
 name = "many_cubes"
 path = "examples/3d/many_cubes.rs"
@@ -236,6 +237,10 @@ name = "wireframe"
 path = "examples/3d/wireframe.rs"
 
 # Animation
+[[example]]
+name = "animated_fox"
+path = "examples/animation/animated_fox.rs"
+
 [[example]]
 name = "custom_skinned_mesh"
 path = "examples/animation/custom_skinned_mesh.rs"

assets/models/animated/AnimatedTriangle.gltf

@@ -1,118 +0,0 @@
-{
-  "scene" : 0,
-  "scenes" : [
-    {
-      "nodes" : [ 0 ]
-    }
-  ],
-  
-  "nodes" : [
-    {
-      "mesh" : 0,
-      "rotation" : [ 0.0, 0.0, 0.0, 1.0 ]
-    }
-  ],
-  
-  "meshes" : [
-    {
-      "primitives" : [ {
-        "attributes" : {
-          "POSITION" : 1
-        },
-        "indices" : 0
-      } ]
-    }
-  ],
-  
-  "animations": [
-    {
-      "samplers" : [
-        {
-          "input" : 2,
-          "interpolation" : "LINEAR",
-          "output" : 3
-        }
-      ],
-      "channels" : [ {
-        "sampler" : 0,
-        "target" : {
-          "node" : 0,
-          "path" : "rotation"
-        }
-      } ]
-    }
-  ],
-
-  "buffers" : [
-    {
-      "uri" : "data:application/octet-stream;base64,AAABAAIAAAAAAAAAAAAAAAAAAAAAAIA/AAAAAAAAAAAAAAAAAACAPwAAAAA=",
-      "byteLength" : 44
-    },
-    {
-      "uri" : "data:application/octet-stream;base64,AAAAAAAAgD4AAAA/AABAPwAAgD8AAAAAAAAAAAAAAAAAAIA/AAAAAAAAAAD0/TQ/9P00PwAAAAAAAAAAAACAPwAAAAAAAAAAAAAAAPT9ND/0/TS/AAAAAAAAAAAAAAAAAACAPw==",
-      "byteLength" : 100
-    }
-  ],
-  "bufferViews" : [
-    {
-      "buffer" : 0,
-      "byteOffset" : 0,
-      "byteLength" : 6,
-      "target" : 34963
-    },
-    {
-      "buffer" : 0,
-      "byteOffset" : 8,
-      "byteLength" : 36,
-      "target" : 34962
-    },
-    {
-      "buffer" : 1,
-      "byteOffset" : 0,
-      "byteLength" : 100
-    }
-  ],
-  "accessors" : [
-    {
-      "bufferView" : 0,
-      "byteOffset" : 0,
-      "componentType" : 5123,
-      "count" : 3,
-      "type" : "SCALAR",
-      "max" : [ 2 ],
-      "min" : [ 0 ]
-    },
-    {
-      "bufferView" : 1,
-      "byteOffset" : 0,
-      "componentType" : 5126,
-      "count" : 3,
-      "type" : "VEC3",
-      "max" : [ 1.0, 1.0, 0.0 ],
-      "min" : [ 0.0, 0.0, 0.0 ]
-    },
-    {
-      "bufferView" : 2,
-      "byteOffset" : 0,
-      "componentType" : 5126,
-      "count" : 5,
-      "type" : "SCALAR",
-      "max" : [ 1.0 ],
-      "min" : [ 0.0 ]
-    },
-    {
-      "bufferView" : 2,
-      "byteOffset" : 20,
-      "componentType" : 5126,
-      "count" : 5,
-      "type" : "VEC4",
-      "max" : [ 0.0, 0.0, 1.0, 1.0 ],
-      "min" : [ 0.0, 0.0, 0.0, -0.707 ]
-    }
-  ],
-  
-  "asset" : {
-    "version" : "2.0"
-  }
-  
-}

crates/bevy_animation/Cargo.toml

@@ -0,0 +1,21 @@
+[package]
+name = "bevy_animation"
+version = "0.7.0-dev"
+edition = "2021"
+description = "Provides animation functionality for Bevy Engine"
+homepage = "https://bevyengine.org"
+repository = "https://github.com/bevyengine/bevy"
+license = "MIT OR Apache-2.0"
+keywords = ["bevy"]
+
+[dependencies]
+# bevy
+bevy_app = { path = "../bevy_app", version = "0.7.0-dev" }
+bevy_asset = { path = "../bevy_asset", version = "0.7.0-dev" }
+bevy_core = { path = "../bevy_core", version = "0.7.0-dev" }
+bevy_math = { path = "../bevy_math", version = "0.7.0-dev" }
+bevy_reflect = { path = "../bevy_reflect", version = "0.7.0-dev", features = ["bevy"] }
+bevy_utils = { path = "../bevy_utils", version = "0.7.0-dev" }
+bevy_ecs = { path = "../bevy_ecs", version = "0.7.0-dev" }
+bevy_transform = { path = "../bevy_transform", version = "0.7.0-dev" }
+bevy_hierarchy = { path = "../bevy_hierarchy", version = "0.7.0-dev" }

crates/bevy_animation/src/lib.rs

@@ -0,0 +1,284 @@
+//! Animation for the game engine Bevy
+
+#![warn(missing_docs)]
+
+use std::ops::Deref;
+
+use bevy_app::{App, CoreStage, Plugin};
+use bevy_asset::{AddAsset, Assets, Handle};
+use bevy_core::{Name, Time};
+use bevy_ecs::{
+    change_detection::DetectChanges,
+    entity::Entity,
+    prelude::Component,
+    reflect::ReflectComponent,
+    schedule::ParallelSystemDescriptorCoercion,
+    system::{Query, Res},
+};
+use bevy_hierarchy::{Children, HierarchySystem};
+use bevy_math::{Quat, Vec3};
+use bevy_reflect::{Reflect, TypeUuid};
+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(Clone, Debug)]
+pub enum Keyframes {
+    /// Keyframes for rotation.
+    Rotation(Vec<Quat>),
+    /// Keyframes for translation.
+    Translation(Vec<Vec3>),
+    /// Keyframes for scale.
+    Scale(Vec<Vec3>),
+}
+
+/// Describes how an attribute of a [`Transform`] should be animated.
+///
+/// `keyframe_timestamps` and `keyframes` should have the same length.
+#[derive(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(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(Clone, TypeUuid, Debug, Default)]
+#[uuid = "d81b7179-0448-4eb0-89fe-c067222725bf"]
+pub struct AnimationClip {
+    curves: HashMap<EntityPath, Vec<VariableCurve>>,
+    duration: f32,
+}
+
+impl AnimationClip {
+    #[inline]
+    /// Hashmap of the [`VariableCurve`]s per [`EntityPath`].
+    pub fn curves(&self) -> &HashMap<EntityPath, Vec<VariableCurve>> {
+        &self.curves
+    }
+
+    /// 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));
+        self.curves.entry(path).or_default().push(curve);
+    }
+}
+
+/// Animation controls
+#[derive(Component, Reflect)]
+#[reflect(Component)]
+pub struct AnimationPlayer {
+    paused: bool,
+    repeat: bool,
+    speed: f32,
+    elapsed: f32,
+    animation_clip: Handle<AnimationClip>,
+}
+
+impl Default for AnimationPlayer {
+    fn default() -> Self {
+        Self {
+            paused: false,
+            repeat: false,
+            speed: 1.0,
+            elapsed: 0.0,
+            animation_clip: Default::default(),
+        }
+    }
+}
+
+impl AnimationPlayer {
+    /// Start playing an animation, resetting state of the player
+    pub fn play(&mut self, handle: Handle<AnimationClip>) -> &mut Self {
+        *self = Self {
+            animation_clip: handle,
+            ..Default::default()
+        };
+        self
+    }
+
+    /// Set the animation to repeat
+    pub fn repeat(&mut self) -> &mut Self {
+        self.repeat = true;
+        self
+    }
+
+    /// Stop the animation from repeating
+    pub fn stop_repeating(&mut self) -> &mut Self {
+        self.repeat = false;
+        self
+    }
+
+    /// 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.speed
+    }
+
+    /// Set the speed of the animation playback
+    pub fn set_speed(&mut self, speed: f32) -> &mut Self {
+        self.speed = speed;
+        self
+    }
+
+    /// Time elapsed playing the animation
+    pub fn elapsed(&self) -> f32 {
+        self.elapsed
+    }
+
+    /// Seek to a specific time in the animation
+    pub fn set_elapsed(&mut self, elapsed: f32) -> &mut Self {
+        self.elapsed = elapsed;
+        self
+    }
+}
+
+/// System that will play all animations, using any entity with a [`AnimationPlayer`]
+/// and a [`Handle<AnimationClip>`] as an animation root
+pub fn animation_player(
+    time: Res<Time>,
+    animations: Res<Assets<AnimationClip>>,
+    mut animation_players: Query<(Entity, &mut AnimationPlayer)>,
+    names: Query<&Name>,
+    mut transforms: Query<&mut Transform>,
+    children: Query<&Children>,
+) {
+    for (entity, mut player) in animation_players.iter_mut() {
+        if let Some(animation_clip) = animations.get(&player.animation_clip) {
+            // 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 player.paused && !player.is_changed() {
+                continue;
+            }
+            if !player.paused {
+                player.elapsed += time.delta_seconds() * player.speed;
+            }
+            let mut elapsed = player.elapsed;
+            if player.repeat {
+                elapsed %= animation_clip.duration;
+            }
+            if elapsed < 0.0 {
+                elapsed += animation_clip.duration;
+            }
+            'entity: for (path, curves) in &animation_clip.curves {
+                // PERF: finding the target entity can be optimised
+                let mut current_entity = entity;
+                // Ignore the first name, it is the root node which we already have
+                for part in path.parts.iter().skip(1) {
+                    let mut found = false;
+                    if let Ok(children) = children.get(current_entity) {
+                        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;
+                                    found = true;
+                                    break;
+                                }
+                            }
+                        }
+                    }
+                    if !found {
+                        warn!("Entity not found for path {:?} on part {:?}", path, part);
+                        continue 'entity;
+                    }
+                }
+                if let Ok(mut transform) = transforms.get_mut(current_entity) {
+                    for curve in curves {
+                        // 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(&elapsed).unwrap())
+                        {
+                            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 = (elapsed - 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
+                                transform.rotation = Quat::from_array(rot_start.normalize().into())
+                                    .slerp(Quat::from_array(rot_end.normalize().into()), lerp);
+                            }
+                            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 = result;
+                            }
+                            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 = result;
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
+
+/// Adds animation support to an app
+#[derive(Default)]
+pub struct AnimationPlugin {}
+
+impl Plugin for AnimationPlugin {
+    fn build(&self, app: &mut App) {
+        app.add_asset::<AnimationClip>()
+            .register_type::<AnimationPlayer>()
+            .add_system_to_stage(
+                CoreStage::PostUpdate,
+                animation_player
+                    .before(TransformSystem::TransformPropagate)
+                    .after(HierarchySystem::ParentUpdate),
+            );
+    }
+}

crates/bevy_gltf/Cargo.toml

@@ -10,19 +10,20 @@ keywords = ["bevy"]
 
 [dependencies]
 # bevy
+bevy_animation = { path = "../bevy_animation", version = "0.7.0-dev", optional = true }
 bevy_app = { path = "../bevy_app", version = "0.7.0-dev" }
 bevy_asset = { path = "../bevy_asset", version = "0.7.0-dev" }
 bevy_core = { path = "../bevy_core", version = "0.7.0-dev" }
 bevy_ecs = { path = "../bevy_ecs", version = "0.7.0-dev" }
 bevy_hierarchy = { path = "../bevy_hierarchy", version = "0.7.0-dev" }
+bevy_log = { path = "../bevy_log", version = "0.7.0-dev" }
+bevy_math = { path = "../bevy_math", version = "0.7.0-dev" }
 bevy_pbr = { path = "../bevy_pbr", version = "0.7.0-dev" }
 bevy_reflect = { path = "../bevy_reflect", version = "0.7.0-dev", features = ["bevy"] }
 bevy_render = { path = "../bevy_render", version = "0.7.0-dev" }
+bevy_scene = { path = "../bevy_scene", version = "0.7.0-dev" }
 bevy_transform = { path = "../bevy_transform", version = "0.7.0-dev" }
 bevy_utils = { path = "../bevy_utils", version = "0.7.0-dev" }
-bevy_math = { path = "../bevy_math", version = "0.7.0-dev" }
-bevy_scene = { path = "../bevy_scene", version = "0.7.0-dev" }
-bevy_log = { path = "../bevy_log", version = "0.7.0-dev" }
 
 # other
 gltf = { version = "1.0.0", default-features = false, features = [

crates/bevy_gltf/src/lib.rs

@@ -1,5 +1,5 @@
-use bevy_ecs::{prelude::Component, reflect::ReflectComponent};
+#[cfg(feature = "bevy_animation")]
-use bevy_math::{Quat, Vec3};
+use bevy_animation::AnimationClip;
 use bevy_utils::HashMap;
 
 mod loader;
@@ -8,7 +8,7 @@ pub use loader::*;
 use bevy_app::prelude::*;
 use bevy_asset::{AddAsset, Handle};
 use bevy_pbr::StandardMaterial;
-use bevy_reflect::{Reflect, TypeUuid};
+use bevy_reflect::TypeUuid;
 use bevy_render::mesh::Mesh;
 use bevy_scene::Scene;
 
@@ -22,9 +22,7 @@ impl Plugin for GltfPlugin {
             .add_asset::<Gltf>()
             .add_asset::<GltfNode>()
             .add_asset::<GltfPrimitive>()
-            .add_asset::<GltfMesh>()
+            .add_asset::<GltfMesh>();
-            .add_asset::<GltfAnimation>()
-            .register_type::<GltfAnimatedNode>();
     }
 }
 
@@ -41,8 +39,10 @@ pub struct Gltf {
     pub nodes: Vec<Handle<GltfNode>>,
     pub named_nodes: HashMap<String, Handle<GltfNode>>,
     pub default_scene: Option<Handle<Scene>>,
-    pub animations: Vec<Handle<GltfAnimation>>,
+    #[cfg(feature = "bevy_animation")]
-    pub named_animations: HashMap<String, Handle<GltfAnimation>>,
+    pub animations: Vec<Handle<AnimationClip>>,
+    #[cfg(feature = "bevy_animation")]
+    pub named_animations: HashMap<String, Handle<AnimationClip>>,
 }
 
 /// A glTF node with all of its child nodes, its [`GltfMesh`] and
@@ -69,52 +69,3 @@ pub struct GltfPrimitive {
     pub mesh: Handle<Mesh>,
     pub material: Option<Handle<StandardMaterial>>,
 }
-
-/// Interpolation method for an animation. Part of a [`GltfNodeAnimation`].
-#[derive(Clone, Debug)]
-pub enum GltfAnimationInterpolation {
-    Linear,
-    Step,
-    CubicSpline,
-}
-
-/// How a property of a glTF node should be animated. The property and its value can be found
-/// through the [`GltfNodeAnimationKeyframes`] attribute.
-#[derive(Clone, Debug)]
-pub struct GltfNodeAnimation {
-    pub keyframe_timestamps: Vec<f32>,
-    pub keyframes: GltfNodeAnimationKeyframes,
-    pub interpolation: GltfAnimationInterpolation,
-}
-
-/// A glTF animation, listing how each node (by its index) that is part of it should be animated.
-#[derive(Default, Clone, TypeUuid, Debug)]
-#[uuid = "d81b7179-0448-4eb0-89fe-c067222725bf"]
-pub struct GltfAnimation {
-    pub node_animations: HashMap<usize, Vec<GltfNodeAnimation>>,
-}
-
-/// Key frames of an animation.
-#[derive(Clone, Debug)]
-pub enum GltfNodeAnimationKeyframes {
-    Rotation(Vec<Quat>),
-    Translation(Vec<Vec3>),
-    Scale(Vec<Vec3>),
-}
-
-impl Default for GltfNodeAnimation {
-    fn default() -> Self {
-        Self {
-            keyframe_timestamps: Default::default(),
-            keyframes: GltfNodeAnimationKeyframes::Translation(Default::default()),
-            interpolation: GltfAnimationInterpolation::Linear,
-        }
-    }
-}
-
-/// A glTF node that is part of an animation, with its index.
-#[derive(Component, Debug, Clone, Reflect, Default)]
-#[reflect(Component)]
-pub struct GltfAnimatedNode {
-    pub index: usize,
-}

crates/bevy_gltf/src/loader.rs

@@ -1,4 +1,6 @@
 use anyhow::Result;
+#[cfg(feature = "bevy_animation")]
+use bevy_animation::{AnimationClip, AnimationPlayer, EntityPath, Keyframes, VariableCurve};
 use bevy_asset::{
     AssetIoError, AssetLoader, AssetPath, BoxedFuture, Handle, LoadContext, LoadedAsset,
 };
@@ -33,15 +35,12 @@ use bevy_utils::{HashMap, HashSet};
 use gltf::{
     mesh::Mode,
     texture::{MagFilter, MinFilter, WrappingMode},
-    Material, Primitive,
+    Material, Node, Primitive,
 };
 use std::{collections::VecDeque, path::Path};
 use thiserror::Error;
 
-use crate::{
+use crate::{Gltf, GltfNode};
-    Gltf, GltfAnimatedNode, GltfAnimation, GltfAnimationInterpolation, GltfNode, GltfNodeAnimation,
-    GltfNodeAnimationKeyframes,
-};
 
 /// An error that occurs when loading a glTF file.
 #[derive(Error, Debug)]
@@ -129,18 +128,30 @@ async fn load_gltf<'a, 'b>(
         }
     }
 
+    #[cfg(feature = "bevy_animation")]
+    let paths = {
+        let mut paths = HashMap::<usize, Vec<Name>>::new();
+        for scene in gltf.scenes() {
+            for node in scene.nodes() {
+                paths_recur(node, &[], &mut paths);
+            }
+        }
+        paths
+    };
+
+    #[cfg(feature = "bevy_animation")]
+    let (animations, named_animations) = {
         let mut animations = vec![];
         let mut named_animations = HashMap::default();
-    let mut animated_nodes = HashSet::default();
         for animation in gltf.animations() {
-        let mut gltf_animation = GltfAnimation::default();
+            let mut animation_clip = AnimationClip::default();
             for channel in animation.channels() {
-            let interpolation = match channel.sampler().interpolation() {
+                match channel.sampler().interpolation() {
-                gltf::animation::Interpolation::Linear => GltfAnimationInterpolation::Linear,
+                    gltf::animation::Interpolation::Linear => (),
-                gltf::animation::Interpolation::Step => GltfAnimationInterpolation::Step,
+                    other => warn!(
-                gltf::animation::Interpolation::CubicSpline => {
+                        "Animation interpolation {:?} is not supported, will use linear",
-                    GltfAnimationInterpolation::CubicSpline
+                        other
-                }
+                    ),
                 };
                 let node = channel.target().node();
                 let reader = channel.reader(|buffer| Some(&buffer_data[buffer.index()]));
@@ -148,27 +159,25 @@ async fn load_gltf<'a, 'b>(
                     match inputs {
                         gltf::accessor::Iter::Standard(times) => times.collect(),
                         gltf::accessor::Iter::Sparse(_) => {
-                        warn!("sparse accessor not supported for animation sampler input");
+                            warn!("Sparse accessor not supported for animation sampler input");
                             continue;
                         }
                     }
                 } else {
-                warn!("animations without a sampler input are not supported");
+                    warn!("Animations without a sampler input are not supported");
                     return Err(GltfError::MissingAnimationSampler(animation.index()));
                 };
 
                 let keyframes = if let Some(outputs) = reader.read_outputs() {
                     match outputs {
                         gltf::animation::util::ReadOutputs::Translations(tr) => {
-                        GltfNodeAnimationKeyframes::Translation(tr.map(Vec3::from).collect())
+                            Keyframes::Translation(tr.map(Vec3::from).collect())
                         }
                         gltf::animation::util::ReadOutputs::Rotations(rots) => {
-                        GltfNodeAnimationKeyframes::Rotation(
+                            Keyframes::Rotation(rots.into_f32().map(Quat::from_array).collect())
-                            rots.into_f32().map(Quat::from_array).collect(),
-                        )
                         }
                         gltf::animation::util::ReadOutputs::Scales(scale) => {
-                        GltfNodeAnimationKeyframes::Scale(scale.map(Vec3::from).collect())
+                            Keyframes::Scale(scale.map(Vec3::from).collect())
                         }
                         gltf::animation::util::ReadOutputs::MorphTargetWeights(_) => {
                             warn!("Morph animation property not yet supported");
@@ -176,30 +185,38 @@ async fn load_gltf<'a, 'b>(
                         }
                     }
                 } else {
-                warn!("animations without a sampler output are not supported");
+                    warn!("Animations without a sampler output are not supported");
                     return Err(GltfError::MissingAnimationSampler(animation.index()));
                 };
 
-            gltf_animation
+                if let Some(path) = paths.get(&node.index()) {
-                .node_animations
+                    animation_clip.add_curve_to_path(
-                .entry(node.index())
+                        EntityPath {
-                .or_default()
+                            parts: path.clone(),
-                .push(GltfNodeAnimation {
+                        },
+                        VariableCurve {
                             keyframe_timestamps,
                             keyframes,
-                    interpolation,
+                        },
-                });
+                    );
-            animated_nodes.insert(node.index());
+                } else {
+                    warn!(
+                        "Animation ignored for node {}: part of its hierarchy is missing a name",
+                        node.index()
+                    );
+                }
             }
             let handle = load_context.set_labeled_asset(
                 &format!("Animation{}", animation.index()),
-            LoadedAsset::new(gltf_animation),
+                LoadedAsset::new(animation_clip),
             );
             if let Some(name) = animation.name() {
                 named_animations.insert(name.to_string(), handle.clone());
             }
             animations.push(handle);
         }
+        (animations, named_animations)
+    };
 
     let mut meshes = vec![];
     let mut named_meshes = HashMap::default();
@@ -436,7 +453,6 @@ async fn load_gltf<'a, 'b>(
                         parent,
                         load_context,
                         &buffer_data,
-                        &animated_nodes,
                         &mut node_index_to_entity_map,
                         &mut entity_to_skin_index_map,
                     );
@@ -450,6 +466,13 @@ async fn load_gltf<'a, 'b>(
             return Err(err);
         }
 
+        #[cfg(feature = "bevy_animation")]
+        if !animations.is_empty() {
+            world
+                .entity_mut(*node_index_to_entity_map.get(&0).unwrap())
+                .insert(AnimationPlayer::default());
+        }
+
         for (&entity, &skin_index) in &entity_to_skin_index_map {
             let mut entity = world.entity_mut(entity);
             let skin = gltf.skins().nth(skin_index).unwrap();
@@ -486,13 +509,26 @@ async fn load_gltf<'a, 'b>(
         named_materials,
         nodes,
         named_nodes,
+        #[cfg(feature = "bevy_animation")]
         animations,
+        #[cfg(feature = "bevy_animation")]
         named_animations,
     }));
 
     Ok(())
 }
 
+fn paths_recur(node: Node, current_path: &[Name], paths: &mut HashMap<usize, Vec<Name>>) {
+    if let Some(name) = node.name() {
+        let mut path = current_path.to_owned();
+        path.push(Name::new(name.to_string()));
+        for child in node.children() {
+            paths_recur(child, &path, paths);
+        }
+        paths.insert(node.index(), path);
+    }
+}
+
 /// Loads a glTF texture as a bevy [`Image`] and returns it together with its label.
 async fn load_texture<'a>(
     gltf_texture: gltf::Texture<'a>,
@@ -633,7 +669,6 @@ fn load_node(
     world_builder: &mut WorldChildBuilder,
     load_context: &mut LoadContext,
     buffer_data: &[Vec<u8>],
-    animated_nodes: &HashSet<usize>,
     node_index_to_entity_map: &mut HashMap<usize, Entity>,
     entity_to_skin_index_map: &mut HashMap<Entity, usize>,
 ) -> Result<(), GltfError> {
@@ -643,12 +678,6 @@ fn load_node(
         Mat4::from_cols_array_2d(&transform.matrix()),
     )));
 
-    if animated_nodes.contains(&gltf_node.index()) {
-        node.insert(GltfAnimatedNode {
-            index: gltf_node.index(),
-        });
-    }
-
     if let Some(name) = gltf_node.name() {
         node.insert(Name::new(name.to_string()));
     }
@@ -798,7 +827,6 @@ fn load_node(
                 parent,
                 load_context,
                 buffer_data,
-                animated_nodes,
                 node_index_to_entity_map,
                 entity_to_skin_index_map,
             ) {

crates/bevy_internal/Cargo.toml

@@ -53,6 +53,9 @@ webgl = ["bevy_pbr/webgl", "bevy_render/webgl"]
 # enable systems that allow for automated testing on CI
 bevy_ci_testing = ["bevy_app/bevy_ci_testing", "bevy_render/ci_limits"]
 
+# Enable animation support, and glTF animation loading
+animation = ["bevy_animation", "bevy_gltf/bevy_animation"]
+
 [dependencies]
 # bevy
 bevy_app = { path = "../bevy_app", version = "0.7.0-dev" }
@@ -72,6 +75,7 @@ bevy_utils = { path = "../bevy_utils", version = "0.7.0-dev" }
 bevy_window = { path = "../bevy_window", version = "0.7.0-dev" }
 bevy_tasks = { path = "../bevy_tasks", version = "0.7.0-dev" }
 # bevy (optional)
+bevy_animation = { path = "../bevy_animation", optional = true, version = "0.7.0-dev" }
 bevy_audio = { path = "../bevy_audio", optional = true, version = "0.7.0-dev" }
 bevy_core_pipeline = { path = "../bevy_core_pipeline", optional = true, version = "0.7.0-dev" }
 bevy_gltf = { path = "../bevy_gltf", optional = true, version = "0.7.0-dev" }

crates/bevy_internal/src/default_plugins.rs

@@ -68,6 +68,9 @@ impl PluginGroup for DefaultPlugins {
 
         #[cfg(feature = "bevy_gilrs")]
         group.add(bevy_gilrs::GilrsPlugin::default());
+
+        #[cfg(feature = "bevy_animation")]
+        group.add(bevy_animation::AnimationPlugin::default());
     }
 }
 

crates/bevy_internal/src/lib.rs

@@ -85,6 +85,12 @@ pub mod window {
     pub use bevy_window::*;
 }
 
+#[cfg(feature = "bevy_animation")]
+pub mod animation {
+    //! Provides types and plugins for animations.
+    pub use bevy_animation::*;
+}
+
 #[cfg(feature = "bevy_audio")]
 pub mod audio {
     //! Provides types and plugins for audio playback.

crates/bevy_internal/src/prelude.rs

@@ -11,6 +11,10 @@ pub use bevy_derive::{bevy_main, Deref, DerefMut};
 #[cfg(feature = "bevy_audio")]
 pub use crate::audio::prelude::*;
 
+#[doc(hidden)]
+#[cfg(feature = "bevy_animation")]
+pub use crate::animation::prelude::*;
+
 #[doc(hidden)]
 #[cfg(feature = "bevy_core_pipeline")]
 pub use crate::core_pipeline::prelude::*;

examples/3d/manual_gltf_animation_player.rs

@@ -1,230 +0,0 @@
-use bevy::{
-    core::FixedTimestep,
-    gltf::*,
-    math::{const_quat, const_vec3},
-    prelude::*,
-    scene::InstanceId,
-};
-
-/// This illustrates loading animations from GLTF files and manually playing them.
-/// Note that a higher level animation api is in the works. This exists to illustrate how to
-/// read and build a custom GLTF animator, not to illustrate a final Bevy animation api.
-fn main() {
-    App::new()
-        .add_plugins(DefaultPlugins)
-        .insert_resource(AmbientLight {
-            color: Color::WHITE,
-            brightness: 1.0,
-        })
-        .add_startup_system(setup)
-        .add_system_set(
-            SystemSet::new()
-                .with_run_criteria(FixedTimestep::step(10.0))
-                .with_system(switch_scene),
-        )
-        .add_system(setup_scene_once_loaded)
-        .add_system(gltf_animation_driver)
-        .run();
-}
-
-struct Example {
-    model_name: &'static str,
-    camera_transform: Transform,
-    speed: f32,
-}
-impl Example {
-    const fn new(model_name: &'static str, camera_transform: Transform, speed: f32) -> Self {
-        Self {
-            model_name,
-            camera_transform,
-            speed,
-        }
-    }
-}
-
-// const ANIMATIONS: [(&str, Transform, f32); 3] = [
-const ANIMATIONS: [Example; 3] = [
-    // https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/AnimatedTriangle
-    Example::new(
-        "models/animated/AnimatedTriangle.gltf",
-        Transform {
-            translation: const_vec3!([0.0, 0.0, 3.0]),
-            rotation: const_quat!([0.0, 0.0, 0.0, 1.0]),
-            scale: const_vec3!([1.0; 3]),
-        },
-        0.12,
-    ),
-    // https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/BoxAnimated
-    Example::new(
-        "models/animated/BoxAnimated.gltf",
-        Transform {
-            translation: const_vec3!([4.0, 2.0, 4.0]),
-            rotation: const_quat!([-0.08, 0.38, 0.03, 0.92]),
-            scale: const_vec3!([1.0; 3]),
-        },
-        0.4,
-    ),
-    Example::new(
-        "models/animated/animations.gltf",
-        Transform {
-            translation: const_vec3!([-10.0, 5.0, -3.0]),
-            rotation: const_quat!([0.16, 0.69, 0.16, -0.69]),
-            scale: const_vec3!([1.0; 3]),
-        },
-        2.5,
-    ),
-];
-
-struct CurrentScene {
-    instance_id: InstanceId,
-    animation: Handle<GltfAnimation>,
-    speed: f32,
-}
-
-struct CurrentAnimation {
-    start_time: f64,
-    animation: GltfAnimation,
-}
-
-fn setup(
-    mut commands: Commands,
-    asset_server: Res<AssetServer>,
-    mut scene_spawner: ResMut<SceneSpawner>,
-) {
-    // Insert a resource with the current scene information
-    commands.insert_resource(CurrentScene {
-        // Its instance id, to be able to check that it's loaded
-        instance_id: scene_spawner
-            .spawn(asset_server.load(&format!("{}#Scene0", ANIMATIONS[0].model_name))),
-        // The handle to the first animation
-        animation: asset_server.load(&format!("{}#Animation0", ANIMATIONS[0].model_name)),
-        // The animation speed modifier
-        speed: ANIMATIONS[0].speed,
-    });
-
-    // Add a camera
-    commands.spawn_bundle(PerspectiveCameraBundle {
-        transform: ANIMATIONS[0].camera_transform,
-        ..Default::default()
-    });
-
-    // Add a directional light
-    commands.spawn_bundle(DirectionalLightBundle::default());
-}
-
-// Switch the scene to the next one every 10 seconds
-fn switch_scene(
-    mut commands: Commands,
-    scene_root: Query<Entity, (Without<Camera>, Without<DirectionalLight>, Without<Parent>)>,
-    mut camera: Query<&mut Transform, With<Camera>>,
-    mut current: Local<usize>,
-    mut current_scene: ResMut<CurrentScene>,
-    asset_server: Res<AssetServer>,
-    mut scene_spawner: ResMut<SceneSpawner>,
-) {
-    *current = (*current + 1) % ANIMATIONS.len();
-
-    // Despawn the existing scene, then start loading the next one
-    commands.entity(scene_root.single()).despawn_recursive();
-    current_scene.instance_id = scene_spawner
-        .spawn(asset_server.load(&format!("{}#Scene0", ANIMATIONS[*current].model_name)));
-    current_scene.animation =
-        asset_server.load(&format!("{}#Animation0", ANIMATIONS[*current].model_name));
-    current_scene.speed = ANIMATIONS[*current].speed;
-
-    // Update the camera position
-    *camera.single_mut() = ANIMATIONS[*current].camera_transform;
-
-    // Reset the current animation
-    commands.remove_resource::<CurrentAnimation>();
-}
-
-// Setup the scene for animation once it is loaded, by adding the animation to a resource with
-// the start time.
-fn setup_scene_once_loaded(
-    mut commands: Commands,
-    scene_spawner: Res<SceneSpawner>,
-    current_scene: Res<CurrentScene>,
-    time: Res<Time>,
-    mut done: Local<bool>,
-    animations: Res<Assets<GltfAnimation>>,
-) {
-    // If the current scene resource has changed, start waiting for it to be loaded
-    if current_scene.is_changed() {
-        *done = false;
-    }
-    // Once the scene and the animation are loaded, start the animation
-    if !*done && scene_spawner.instance_is_ready(current_scene.instance_id) {
-        if let Some(animation) = animations.get(&current_scene.animation) {
-            *done = true;
-            commands.insert_resource(CurrentAnimation {
-                start_time: time.seconds_since_startup(),
-                animation: animation.clone(),
-            })
-        }
-    }
-}
-
-// This animation driver is not made to work in the general case. It will work with only one
-// animation per scene, and will ignore the specified interpolation method to only do linear.
-fn gltf_animation_driver(
-    mut animated: Query<(&mut Transform, &GltfAnimatedNode)>,
-    current_animation: Option<Res<CurrentAnimation>>,
-    current_scene: Res<CurrentScene>,
-    time: Res<Time>,
-) {
-    if let Some(current_animation) = current_animation {
-        let elapsed = (time.seconds_since_startup() - current_animation.start_time) as f32
-            * current_scene.speed;
-        for (mut transform, node) in animated.iter_mut() {
-            let node_animations = current_animation
-                .animation
-                .node_animations
-                .get(&node.index)
-                .unwrap();
-            for node_animation in node_animations.iter() {
-                let mut keyframe_timestamps = node_animation.keyframe_timestamps.iter().enumerate();
-                let mut step_start = keyframe_timestamps.next().unwrap();
-                if elapsed < *step_start.1 {
-                    continue;
-                }
-                for next in keyframe_timestamps {
-                    if *next.1 > elapsed {
-                        break;
-                    }
-                    step_start = next;
-                }
-                if step_start.0 == node_animation.keyframe_timestamps.len() - 1 {
-                    continue;
-                }
-
-                let step_end = node_animation.keyframe_timestamps[step_start.0 + 1];
-                let lerp = (elapsed - *step_start.1) / (step_end - step_start.1);
-                match &node_animation.keyframes {
-                    GltfNodeAnimationKeyframes::Rotation(keyframes) => {
-                        let rot_start = keyframes[step_start.0];
-                        let mut rot_end = keyframes[step_start.0 + 1];
-                        if rot_end.dot(rot_start) < 0.0 {
-                            rot_end = -rot_end;
-                        }
-                        let result = Quat::from_array(rot_start.normalize().into())
-                            .slerp(Quat::from_array(rot_end.normalize().into()), lerp);
-                        transform.rotation = result;
-                    }
-                    GltfNodeAnimationKeyframes::Translation(keyframes) => {
-                        let translation_start = keyframes[step_start.0];
-                        let translation_end = keyframes[step_start.0 + 1];
-                        let result = translation_start.lerp(translation_end, lerp);
-                        transform.translation = result;
-                    }
-                    GltfNodeAnimationKeyframes::Scale(keyframes) => {
-                        let scale_start = keyframes[step_start.0];
-                        let scale_end = keyframes[step_start.0 + 1];
-                        let result = scale_start.lerp(scale_end, lerp);
-                        transform.scale = result;
-                    }
-                }
-            }
-        }
-    }
-}

examples/README.md

@@ -105,7 +105,6 @@ Example | File | Description
 `3d_scene` | [`3d/3d_scene.rs`](./3d/3d_scene.rs) | Simple 3D scene with basic shapes and lighting
 `lighting` | [`3d/lighting.rs`](./3d/lighting.rs) | Illustrates various lighting options in a simple scene
 `load_gltf` | [`3d/load_gltf.rs`](./3d/load_gltf.rs) | Loads and renders a gltf file as a scene
-`manual_gltf_animation_player` | [`3d/manual_gltf_animation_player.rs`](./3d/manual_gltf_animation_player.rs) | Loads and manually renders a gltf file with animations
 `many_cubes` | [`3d/many_cubes.rs`](./3d/many_cubes.rs) | Simple benchmark to test per-entity draw overhead
 `msaa` | [`3d/msaa.rs`](./3d/msaa.rs) | Configures MSAA (Multi-Sample Anti-Aliasing) for smoother edges
 `orthographic` | [`3d/orthographic.rs`](./3d/orthographic.rs) | Shows how to create a 3D orthographic view (for isometric-look games or CAD applications)
@@ -123,6 +122,7 @@ Example | File | Description
 
 Example | File | Description
 --- | --- | ---
+`animated_fox` | [`animation/animated_fox.rs`](./animation/animated_fox.rs) | Plays an animation from a skinned glTF.
 `custom_skinned_mesh` | [`animation/custom_skinned_mesh.rs`](./animation/custom_skinned_mesh.rs) | Skinned mesh example with mesh and joints data defined in code.
 `gltf_skinned_mesh` | [`animation/gltf_skinned_mesh.rs`](./animation/gltf_skinned_mesh.rs) | Skinned mesh example with mesh and joints data loaded from a glTF file.
 

examples/animation/animated_fox.rs

@@ -0,0 +1,127 @@
+use bevy::prelude::*;
+
+fn main() {
+    App::new()
+        .add_plugins(DefaultPlugins)
+        .insert_resource(AmbientLight {
+            color: Color::WHITE,
+            brightness: 1.0,
+        })
+        .add_startup_system(setup)
+        .add_system(setup_scene_once_loaded)
+        .add_system(keyboard_animation_control)
+        .run();
+}
+
+struct Animations(Vec<Handle<AnimationClip>>);
+
+fn setup(
+    mut commands: Commands,
+    asset_server: Res<AssetServer>,
+    mut scene_spawner: ResMut<SceneSpawner>,
+    mut meshes: ResMut<Assets<Mesh>>,
+    mut materials: ResMut<Assets<StandardMaterial>>,
+) {
+    // Insert a resource with the current scene information
+    commands.insert_resource(Animations(vec![
+        asset_server.load("models/animated/Fox.glb#Animation2"),
+        asset_server.load("models/animated/Fox.glb#Animation1"),
+        asset_server.load("models/animated/Fox.glb#Animation0"),
+    ]));
+
+    // Camera
+    commands.spawn_bundle(PerspectiveCameraBundle {
+        transform: Transform::from_xyz(100.0, 100.0, 150.0)
+            .looking_at(Vec3::new(0.0, 20.0, 0.0), Vec3::Y),
+        ..Default::default()
+    });
+
+    // Plane
+    commands.spawn_bundle(PbrBundle {
+        mesh: meshes.add(Mesh::from(shape::Plane { size: 500000.0 })),
+        material: materials.add(Color::rgb(0.3, 0.5, 0.3).into()),
+        ..default()
+    });
+
+    // Light
+    commands.spawn_bundle(DirectionalLightBundle {
+        transform: Transform::from_rotation(Quat::from_euler(
+            EulerRot::ZYX,
+            0.0,
+            1.0,
+            -std::f32::consts::FRAC_PI_4,
+        )),
+        directional_light: DirectionalLight {
+            shadows_enabled: true,
+            ..default()
+        },
+        ..default()
+    });
+
+    // Fox
+    scene_spawner.spawn(asset_server.load("models/animated/Fox.glb#Scene0"));
+
+    println!("Animation controls:");
+    println!("  - spacebar: play / pause");
+    println!("  - arrow up / down: speed up / slow down animation playback");
+    println!("  - arrow left / right: seek backward / forward");
+    println!("  - return: change animation");
+}
+
+// Once the scene is loaded, start the animation
+fn setup_scene_once_loaded(
+    animations: Res<Animations>,
+    mut player: Query<&mut AnimationPlayer>,
+    mut done: Local<bool>,
+) {
+    if !*done {
+        if let Ok(mut player) = player.get_single_mut() {
+            player.play(animations.0[0].clone_weak()).repeat();
+            *done = true;
+        }
+    }
+}
+
+fn keyboard_animation_control(
+    keyboard_input: Res<Input<KeyCode>>,
+    mut animation_player: Query<&mut AnimationPlayer>,
+    animations: Res<Animations>,
+    mut current_animation: Local<usize>,
+) {
+    if let Ok(mut player) = animation_player.get_single_mut() {
+        if keyboard_input.just_pressed(KeyCode::Space) {
+            if player.is_paused() {
+                player.resume();
+            } else {
+                player.pause();
+            }
+        }
+
+        if keyboard_input.just_pressed(KeyCode::Up) {
+            let speed = player.speed();
+            player.set_speed(speed * 1.2);
+        }
+
+        if keyboard_input.just_pressed(KeyCode::Down) {
+            let speed = player.speed();
+            player.set_speed(speed * 0.8);
+        }
+
+        if keyboard_input.just_pressed(KeyCode::Left) {
+            let elapsed = player.elapsed();
+            player.set_elapsed(elapsed - 0.1);
+        }
+
+        if keyboard_input.just_pressed(KeyCode::Right) {
+            let elapsed = player.elapsed();
+            player.set_elapsed(elapsed + 0.1);
+        }
+
+        if keyboard_input.just_pressed(KeyCode::Return) {
+            *current_animation = (*current_animation + 1) % animations.0.len();
+            player
+                .play(animations.0[*current_animation].clone_weak())
+                .repeat();
+        }
+    }
+}