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//! Hierarchy and transform propagation stress test.
//!
//! Running this example:
//!
//! ```
//! cargo r --release --example transform_hierarchy <configuration name>
//! ```
//!
//! | Configuration | Description |
//! | -------------------- | ----------------------------------------------------------------- |
//! | `large_tree` | A fairly wide and deep tree. |
//! | `wide_tree` | A shallow but very wide tree. |
//! | `deep_tree` | A deep but not very wide tree. |
//! | `chain` | A chain. 2500 levels deep. |
//! | `update_leaves` | Same as `large_tree`, but only leaves are updated. |
//! | `update_shallow` | Same as `large_tree`, but only the first few levels are updated. |
//! | `humanoids_active` | 4000 active humanoid rigs. |
//! | `humanoids_inactive` | 4000 humanoid rigs. Only 10 are active. |
//! | `humanoids_mixed` | 2000 active and 2000 inactive humanoid rigs. |
use bevy::prelude::*;
use rand::Rng;
/// pre-defined test configurations with name
const CONFIGS: [(&str, Cfg); 9] = [
(
"large_tree",
Cfg {
test_case: TestCase::NonUniformTree {
depth: 18,
branch_width: 8,
},
update_filter: UpdateFilter {
probability: 0.5,
min_depth: 0,
max_depth: u32::MAX,
},
},
),
(
"wide_tree",
Cfg {
test_case: TestCase::Tree {
depth: 3,
branch_width: 500,
},
update_filter: UpdateFilter {
probability: 0.5,
min_depth: 0,
max_depth: u32::MAX,
},
},
),
(
"deep_tree",
Cfg {
test_case: TestCase::NonUniformTree {
depth: 25,
branch_width: 2,
},
update_filter: UpdateFilter {
probability: 0.5,
min_depth: 0,
max_depth: u32::MAX,
},
},
),
(
"chain",
Cfg {
test_case: TestCase::Tree {
depth: 2500,
branch_width: 1,
},
update_filter: UpdateFilter {
probability: 0.5,
min_depth: 0,
max_depth: u32::MAX,
},
},
),
(
"update_leaves",
Cfg {
test_case: TestCase::Tree {
depth: 18,
branch_width: 2,
},
update_filter: UpdateFilter {
probability: 0.5,
min_depth: 17,
max_depth: u32::MAX,
},
},
),
(
"update_shallow",
Cfg {
test_case: TestCase::Tree {
depth: 18,
branch_width: 2,
},
update_filter: UpdateFilter {
probability: 0.5,
min_depth: 0,
max_depth: 8,
},
},
),
(
"humanoids_active",
Cfg {
test_case: TestCase::Humanoids {
active: 4000,
inactive: 0,
},
update_filter: UpdateFilter {
probability: 1.0,
min_depth: 0,
max_depth: u32::MAX,
},
},
),
(
"humanoids_inactive",
Cfg {
test_case: TestCase::Humanoids {
active: 10,
inactive: 3990,
},
update_filter: UpdateFilter {
probability: 1.0,
min_depth: 0,
max_depth: u32::MAX,
},
},
),
(
"humanoids_mixed",
Cfg {
test_case: TestCase::Humanoids {
active: 2000,
inactive: 2000,
},
update_filter: UpdateFilter {
probability: 1.0,
min_depth: 0,
max_depth: u32::MAX,
},
},
),
];
fn print_available_configs() {
println!("available configurations:");
for (name, _) in CONFIGS {
println!(" {name}");
}
}
fn main() {
// parse cli argument and find the selected test configuration
let cfg: Cfg = match std::env::args().nth(1) {
Some(arg) => match CONFIGS.iter().find(|(name, _)| *name == arg) {
Some((name, cfg)) => {
println!("test configuration: {name}");
cfg.clone()
}
None => {
println!("test configuration \"{arg}\" not found.\n");
print_available_configs();
return;
}
},
None => {
println!("missing argument: <test configuration>\n");
print_available_configs();
return;
}
};
println!("\n{cfg:#?}");
App::new()
.insert_resource(cfg)
.add_plugins((MinimalPlugins, TransformPlugin))
.add_systems(Startup, setup)
// Updating transforms *must* be done before `PostUpdate`
// or the hierarchy will momentarily be in an invalid state.
.add_systems(Update, update)
.run();
}
/// test configuration
#[derive(Resource, Debug, Clone)]
struct Cfg {
/// which test case should be inserted
test_case: TestCase,
/// which entities should be updated
update_filter: UpdateFilter,
}
#[allow(unused)]
#[derive(Debug, Clone)]
enum TestCase {
/// a uniform tree, exponentially growing with depth
Tree {
/// total depth
depth: u32,
/// number of children per node
branch_width: u32,
},
/// a non uniform tree (one side is deeper than the other)
/// creates significantly less nodes than `TestCase::Tree` with the same parameters
NonUniformTree {
/// the maximum depth
depth: u32,
/// max number of children per node
branch_width: u32,
},
/// one or multiple humanoid rigs
Humanoids {
/// number of active instances (uses the specified [`UpdateFilter`])
active: u32,
/// number of inactive instances (always inactive)
inactive: u32,
},
}
/// a filter to restrict which nodes are updated
#[derive(Debug, Clone)]
struct UpdateFilter {
/// starting depth (inclusive)
min_depth: u32,
/// end depth (inclusive)
max_depth: u32,
/// probability of a node to get updated (evaluated at insertion time, not during update)
/// 0 (never) .. 1 (always)
probability: f32,
}
/// update component with some per-component value
#[derive(Component)]
struct UpdateValue(f32);
/// update positions system
fn update(time: Res<Time>, mut query: Query<(&mut Transform, &mut UpdateValue)>) {
for (mut t, mut u) in &mut query {
u.0 += time.delta_seconds() * 0.1;
set_translation(&mut t.translation, u.0);
}
}
/// set translation based on the angle `a`
fn set_translation(translation: &mut Vec3, a: f32) {
translation.x = a.cos() * 32.0;
translation.y = a.sin() * 32.0;
}
fn setup(mut commands: Commands, cfg: Res<Cfg>) {
warn!(include_str!("warning_string.txt"));
let mut cam = Camera2dBundle::default();
cam.transform.translation.z = 100.0;
commands.spawn(cam);
let result = match cfg.test_case {
TestCase::Tree {
depth,
branch_width,
} => {
let tree = gen_tree(depth, branch_width);
spawn_tree(&tree, &mut commands, &cfg.update_filter, default())
}
TestCase::NonUniformTree {
depth,
branch_width,
} => {
let tree = gen_non_uniform_tree(depth, branch_width);
spawn_tree(&tree, &mut commands, &cfg.update_filter, default())
}
TestCase::Humanoids { active, inactive } => {
let mut result = InsertResult::default();
let mut rng = rand::thread_rng();
for _ in 0..active {
result.combine(spawn_tree(
&HUMANOID_RIG,
&mut commands,
&cfg.update_filter,
Transform::from_xyz(
rng.gen::<f32>() * 500.0 - 250.0,
rng.gen::<f32>() * 500.0 - 250.0,
0.0,
),
));
}
for _ in 0..inactive {
result.combine(spawn_tree(
&HUMANOID_RIG,
&mut commands,
&UpdateFilter {
// force inactive by setting the probability < 0
probability: -1.0,
..cfg.update_filter
},
Transform::from_xyz(
rng.gen::<f32>() * 500.0 - 250.0,
rng.gen::<f32>() * 500.0 - 250.0,
0.0,
),
));
}
result
}
};
println!("\n{result:#?}");
}
/// overview of the inserted hierarchy
#[derive(Default, Debug)]
struct InsertResult {
/// total number of nodes inserted
inserted_nodes: usize,
/// number of nodes that get updated each frame
active_nodes: usize,
/// maximum depth of the hierarchy tree
maximum_depth: usize,
}
impl InsertResult {
fn combine(&mut self, rhs: Self) -> &mut Self {
self.inserted_nodes += rhs.inserted_nodes;
self.active_nodes += rhs.active_nodes;
self.maximum_depth = self.maximum_depth.max(rhs.maximum_depth);
self
}
}
/// spawns a tree defined by a parent map (excluding root)
/// the parent map must be ordered (parent must exist before child)
fn spawn_tree(
parent_map: &[usize],
commands: &mut Commands,
update_filter: &UpdateFilter,
root_transform: Transform,
) -> InsertResult {
// total count (# of nodes + root)
let count = parent_map.len() + 1;
#[derive(Default, Clone, Copy)]
struct NodeInfo {
child_count: u32,
depth: u32,
}
// node index -> entity lookup list
let mut ents: Vec<Entity> = Vec::with_capacity(count);
let mut node_info: Vec<NodeInfo> = vec![default(); count];
for (i, &parent_idx) in parent_map.iter().enumerate() {
// assert spawn order (parent must be processed before child)
assert!(parent_idx <= i, "invalid spawn order");
node_info[parent_idx].child_count += 1;
}
// insert root
ents.push(commands.spawn(TransformBundle::from(root_transform)).id());
let mut result = InsertResult::default();
let mut rng = rand::thread_rng();
// used to count through the number of children (used only for visual layout)
let mut child_idx: Vec<u16> = vec![0; count];
// insert children
for (current_idx, &parent_idx) in parent_map.iter().enumerate() {
let current_idx = current_idx + 1;
// separation factor to visually separate children (0..1)
let sep = child_idx[parent_idx] as f32 / node_info[parent_idx].child_count as f32;
child_idx[parent_idx] += 1;
// calculate and set depth
// this works because it's guaranteed that we have already iterated over the parent
let depth = node_info[parent_idx].depth + 1;
let info = &mut node_info[current_idx];
info.depth = depth;
// update max depth of tree
result.maximum_depth = result.maximum_depth.max(depth.try_into().unwrap());
// insert child
let child_entity = {
let mut cmd = commands.spawn_empty();
// check whether or not to update this node
let update = (rng.gen::<f32>() <= update_filter.probability)
&& (depth >= update_filter.min_depth && depth <= update_filter.max_depth);
if update {
cmd.insert(UpdateValue(sep));
result.active_nodes += 1;
}
let transform = {
let mut translation = Vec3::ZERO;
// use the same placement fn as the `update` system
// this way the entities won't be all at (0, 0, 0) when they don't have an `Update` component
set_translation(&mut translation, sep);
Transform::from_translation(translation)
};
// only insert the components necessary for the transform propagation
cmd.insert(TransformBundle::from(transform));
cmd.id()
};
commands
.get_or_spawn(ents[parent_idx])
.add_child(child_entity);
ents.push(child_entity);
}
result.inserted_nodes = ents.len();
result
}
/// generate a tree `depth` levels deep, where each node has `branch_width` children
fn gen_tree(depth: u32, branch_width: u32) -> Vec<usize> {
// calculate the total count of branches
let mut count: usize = 0;
for i in 0..(depth - 1) {
count += TryInto::<usize>::try_into(branch_width.pow(i)).unwrap();
}
// the tree is built using this pattern:
// 0, 0, 0, ... 1, 1, 1, ... 2, 2, 2, ... (count - 1)
(0..count)
.flat_map(|i| std::iter::repeat(i).take(branch_width.try_into().unwrap()))
.collect()
}
/// recursive part of [`gen_non_uniform_tree`]
fn add_children_non_uniform(
tree: &mut Vec<usize>,
parent: usize,
mut curr_depth: u32,
max_branch_width: u32,
) {
for _ in 0..max_branch_width {
tree.push(parent);
curr_depth = curr_depth.checked_sub(1).unwrap();
if curr_depth == 0 {
return;
}
add_children_non_uniform(tree, tree.len(), curr_depth, max_branch_width);
}
}
/// generate a tree that has more nodes on one side that the other
/// the deepest hierarchy path is `max_depth` and the widest branches have `max_branch_width` children
fn gen_non_uniform_tree(max_depth: u32, max_branch_width: u32) -> Vec<usize> {
let mut tree = Vec::new();
add_children_non_uniform(&mut tree, 0, max_depth, max_branch_width);
tree
}
/// parent map for a decently complex humanoid rig (based on mixamo rig)
const HUMANOID_RIG: [usize; 67] = [
// (0: root)
0, // 1: hips
1, // 2: spine
2, // 3: spine 1
3, // 4: spine 2
4, // 5: neck
5, // 6: head
6, // 7: head top
6, // 8: left eye
6, // 9: right eye
4, // 10: left shoulder
10, // 11: left arm
11, // 12: left forearm
12, // 13: left hand
13, // 14: left hand thumb 1
14, // 15: left hand thumb 2
15, // 16: left hand thumb 3
16, // 17: left hand thumb 4
13, // 18: left hand index 1
18, // 19: left hand index 2
19, // 20: left hand index 3
20, // 21: left hand index 4
13, // 22: left hand middle 1
22, // 23: left hand middle 2
23, // 24: left hand middle 3
24, // 25: left hand middle 4
13, // 26: left hand ring 1
26, // 27: left hand ring 2
27, // 28: left hand ring 3
28, // 29: left hand ring 4
13, // 30: left hand pinky 1
30, // 31: left hand pinky 2
31, // 32: left hand pinky 3
32, // 33: left hand pinky 4
4, // 34: right shoulder
34, // 35: right arm
35, // 36: right forearm
36, // 37: right hand
37, // 38: right hand thumb 1
38, // 39: right hand thumb 2
39, // 40: right hand thumb 3
40, // 41: right hand thumb 4
37, // 42: right hand index 1
42, // 43: right hand index 2
43, // 44: right hand index 3
44, // 45: right hand index 4
37, // 46: right hand middle 1
46, // 47: right hand middle 2
47, // 48: right hand middle 3
48, // 49: right hand middle 4
37, // 50: right hand ring 1
50, // 51: right hand ring 2
51, // 52: right hand ring 3
52, // 53: right hand ring 4
37, // 54: right hand pinky 1
54, // 55: right hand pinky 2
55, // 56: right hand pinky 3
56, // 57: right hand pinky 4
1, // 58: left upper leg
58, // 59: left leg
59, // 60: left foot
60, // 61: left toe base
61, // 62: left toe end
1, // 63: right upper leg
63, // 64: right leg
64, // 65: right foot
65, // 66: right toe base
66, // 67: right toe end
];