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https://github.com/bevyengine/bevy
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320d53c1d2
# Objective Enhance the [custom skinned mesh example](https://bevyengine.org/examples/animation/custom-skinned-mesh/) to show some variety and clarify what the transform does to the mesh. ## Solution https://github.com/user-attachments/assets/c919db74-6e77-4f33-ba43-0f40a88042b3 Add variety and clarity with the following changes: - vary transform changes, - use a UV texture, - and show transform changes via gizmos. (Maybe it'd be worth turning on wireframe rendering to show what happens to the mesh. I think it'd be nice visually but might make the code a little noisy.) ## Testing I exercised it on my x86 macOS computer. It'd be good to have it validated on Windows, Linux, and WASM. --- ## Showcase - Custom skinned mesh example varies the transforms changes and uses a UV test texture.
235 lines
8 KiB
Rust
235 lines
8 KiB
Rust
//! Skinned mesh example with mesh and joints data defined in code.
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//! Example taken from <https://github.com/KhronosGroup/glTF-Tutorials/blob/master/gltfTutorial/gltfTutorial_019_SimpleSkin.md>
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use std::f32::consts::*;
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use bevy::{
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math::ops,
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prelude::*,
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render::{
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mesh::{
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skinning::{SkinnedMesh, SkinnedMeshInverseBindposes},
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Indices, PrimitiveTopology, VertexAttributeValues,
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},
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render_asset::RenderAssetUsages,
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},
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};
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use rand::{Rng, SeedableRng};
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use rand_chacha::ChaCha8Rng;
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fn main() {
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App::new()
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.add_plugins(DefaultPlugins)
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.insert_resource(AmbientLight {
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brightness: 3000.0,
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..default()
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})
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.add_systems(Startup, setup)
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.add_systems(Update, joint_animation)
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.run();
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}
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/// Used to mark a joint to be animated in the [`joint_animation`] system.
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#[derive(Component)]
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struct AnimatedJoint(isize);
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/// Construct a mesh and a skeleton with 2 joints for that mesh,
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/// and mark the second joint to be animated.
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/// It is similar to the scene defined in `models/SimpleSkin/SimpleSkin.gltf`
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fn setup(
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mut commands: Commands,
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asset_server: Res<AssetServer>,
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mut meshes: ResMut<Assets<Mesh>>,
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mut materials: ResMut<Assets<StandardMaterial>>,
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mut skinned_mesh_inverse_bindposes_assets: ResMut<Assets<SkinnedMeshInverseBindposes>>,
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) {
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// Create a camera
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commands.spawn((
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Camera3d::default(),
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Transform::from_xyz(2.5, 2.5, 9.0).looking_at(Vec3::ZERO, Vec3::Y),
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));
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// Create inverse bindpose matrices for a skeleton consists of 2 joints
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let inverse_bindposes = skinned_mesh_inverse_bindposes_assets.add(vec![
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Mat4::from_translation(Vec3::new(-0.5, -1.0, 0.0)),
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Mat4::from_translation(Vec3::new(-0.5, -1.0, 0.0)),
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]);
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// Create a mesh
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let mesh = Mesh::new(
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PrimitiveTopology::TriangleList,
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RenderAssetUsages::RENDER_WORLD,
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)
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// Set mesh vertex positions
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.with_inserted_attribute(
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Mesh::ATTRIBUTE_POSITION,
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vec![
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[0.0, 0.0, 0.0],
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[1.0, 0.0, 0.0],
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[0.0, 0.5, 0.0],
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[1.0, 0.5, 0.0],
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[0.0, 1.0, 0.0],
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[1.0, 1.0, 0.0],
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[0.0, 1.5, 0.0],
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[1.0, 1.5, 0.0],
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[0.0, 2.0, 0.0],
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[1.0, 2.0, 0.0],
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],
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)
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// Add UV coordinates that map the left half of the texture since its a 1 x
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// 2 rectangle.
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.with_inserted_attribute(
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Mesh::ATTRIBUTE_UV_0,
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vec![
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[0.0, 0.00],
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[0.5, 0.00],
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[0.0, 0.25],
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[0.5, 0.25],
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[0.0, 0.50],
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[0.5, 0.50],
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[0.0, 0.75],
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[0.5, 0.75],
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[0.0, 1.00],
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[0.5, 1.00],
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],
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)
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// Set mesh vertex normals
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.with_inserted_attribute(Mesh::ATTRIBUTE_NORMAL, vec![[0.0, 0.0, 1.0]; 10])
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// Set mesh vertex joint indices for mesh skinning.
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// Each vertex gets 4 indices used to address the `JointTransforms` array in the vertex shader
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// as well as `SkinnedMeshJoint` array in the `SkinnedMesh` component.
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// This means that a maximum of 4 joints can affect a single vertex.
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.with_inserted_attribute(
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Mesh::ATTRIBUTE_JOINT_INDEX,
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// Need to be explicit here as [u16; 4] could be either Uint16x4 or Unorm16x4.
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VertexAttributeValues::Uint16x4(vec![
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[0, 0, 0, 0],
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[0, 0, 0, 0],
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[0, 1, 0, 0],
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[0, 1, 0, 0],
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[0, 1, 0, 0],
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[0, 1, 0, 0],
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[0, 1, 0, 0],
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[0, 1, 0, 0],
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[0, 1, 0, 0],
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[0, 1, 0, 0],
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]),
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)
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// Set mesh vertex joint weights for mesh skinning.
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// Each vertex gets 4 joint weights corresponding to the 4 joint indices assigned to it.
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// The sum of these weights should equal to 1.
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.with_inserted_attribute(
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Mesh::ATTRIBUTE_JOINT_WEIGHT,
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vec![
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[1.00, 0.00, 0.0, 0.0],
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[1.00, 0.00, 0.0, 0.0],
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[0.75, 0.25, 0.0, 0.0],
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[0.75, 0.25, 0.0, 0.0],
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[0.50, 0.50, 0.0, 0.0],
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[0.50, 0.50, 0.0, 0.0],
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[0.25, 0.75, 0.0, 0.0],
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[0.25, 0.75, 0.0, 0.0],
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[0.00, 1.00, 0.0, 0.0],
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[0.00, 1.00, 0.0, 0.0],
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],
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)
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// Tell bevy to construct triangles from a list of vertex indices,
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// where each 3 vertex indices form an triangle.
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.with_inserted_indices(Indices::U16(vec![
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0, 1, 3, 0, 3, 2, 2, 3, 5, 2, 5, 4, 4, 5, 7, 4, 7, 6, 6, 7, 9, 6, 9, 8,
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]));
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let mesh = meshes.add(mesh);
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// We're seeding the PRNG here to make this example deterministic for testing purposes.
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// This isn't strictly required in practical use unless you need your app to be deterministic.
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let mut rng = ChaCha8Rng::seed_from_u64(42);
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for i in -5..5 {
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// Create joint entities
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let joint_0 = commands
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.spawn(Transform::from_xyz(
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i as f32 * 1.5,
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0.0,
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// Move quads back a small amount to avoid Z-fighting and not
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// obscure the transform gizmos.
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-(i as f32 * 0.01).abs(),
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))
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.id();
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let joint_1 = commands.spawn((AnimatedJoint(i), Transform::IDENTITY)).id();
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// Set joint_1 as a child of joint_0.
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commands.entity(joint_0).add_children(&[joint_1]);
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// Each joint in this vector corresponds to each inverse bindpose matrix in `SkinnedMeshInverseBindposes`.
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let joint_entities = vec![joint_0, joint_1];
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// Create skinned mesh renderer. Note that its transform doesn't affect the position of the mesh.
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commands.spawn((
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Mesh3d(mesh.clone()),
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MeshMaterial3d(materials.add(StandardMaterial {
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base_color: Color::srgb(
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rng.gen_range(0.0..1.0),
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rng.gen_range(0.0..1.0),
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rng.gen_range(0.0..1.0),
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),
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base_color_texture: Some(asset_server.load("textures/uv_checker_bw.png")),
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..default()
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})),
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SkinnedMesh {
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inverse_bindposes: inverse_bindposes.clone(),
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joints: joint_entities,
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},
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));
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}
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}
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/// Animate the joint marked with [`AnimatedJoint`] component.
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fn joint_animation(
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time: Res<Time>,
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mut query: Query<(&mut Transform, &AnimatedJoint)>,
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mut gizmos: Gizmos,
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) {
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for (mut transform, animated_joint) in &mut query {
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match animated_joint.0 {
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-5 => {
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transform.rotation =
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Quat::from_rotation_x(FRAC_PI_2 * ops::sin(time.elapsed_seconds()));
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}
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-4 => {
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transform.rotation =
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Quat::from_rotation_y(FRAC_PI_2 * ops::sin(time.elapsed_seconds()));
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}
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-3 => {
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transform.rotation =
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Quat::from_rotation_z(FRAC_PI_2 * ops::sin(time.elapsed_seconds()));
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}
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-2 => {
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transform.scale.x = ops::sin(time.elapsed_seconds()) + 1.0;
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}
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-1 => {
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transform.scale.y = ops::sin(time.elapsed_seconds()) + 1.0;
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}
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0 => {
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transform.translation.x = 0.5 * ops::sin(time.elapsed_seconds());
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transform.translation.y = ops::cos(time.elapsed_seconds());
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}
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1 => {
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transform.translation.y = ops::sin(time.elapsed_seconds());
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transform.translation.z = ops::cos(time.elapsed_seconds());
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}
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2 => {
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transform.translation.x = ops::sin(time.elapsed_seconds());
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}
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3 => {
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transform.translation.y = ops::sin(time.elapsed_seconds());
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transform.scale.x = ops::sin(time.elapsed_seconds()) + 1.0;
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}
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_ => (),
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}
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// Show transform
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let mut axis = *transform;
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axis.translation.x += animated_joint.0 as f32 * 1.5;
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gizmos.axes(axis, 1.0);
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}
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}
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