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lyra-engine
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Create a new crate! lyra-scene for representing a SceneGraph in an ECS world

This commit is contained in:
SeanOMik 2024-03-03 16:21:55 -05:00 committed by SeanOMik
parent b76832ec05
commit 8aae479df3
6 changed files with 447 additions and 1 deletions
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22
.vscode/launch.json vendored
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@ -83,6 +83,28 @@
},
"args": [],
"cwd": "${workspaceFolder}/lyra-ecs"
},
{
"type": "lldb",
"request": "launch",
"name": "Debug unit tests in executable 'lyra-scene'",
"cargo": {
"args": [
"test",
"--no-run",
"--lib",
"--package=lyra-scene",
//"command::tests::deferred_commands",
//"--",
//"--exact --nocapture"
],
"filter": {
"name": "lyra-scene",
"kind": "lib"
}
},
"args": [],
"cwd": "${workspaceFolder}/lyra-scene"
}
]
}

8
Cargo.lock generated
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@ -1855,6 +1855,14 @@ dependencies = [
"uuid",
]
[[package]]
name = "lyra-scene"
version = "0.1.0"
dependencies = [
"lyra-ecs",
"lyra-math",
]
[[package]]
name = "lyra-scripting"
version = "0.1.0"

2
Cargo.toml
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@ -10,7 +10,7 @@ members = [
"lyra-ecs",
"lyra-reflect",
"lyra-scripting",
"lyra-game", "lyra-math"]
"lyra-game", "lyra-math", "lyra-scene"]
[features]
scripting = ["dep:lyra-scripting"]

10
lyra-scene/Cargo.toml Normal file
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@ -0,0 +1,10 @@
[package]
name = "lyra-scene"
version = "0.1.0"
edition = "2021"
# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
[dependencies]
lyra-ecs = { path = "../lyra-ecs", features = [ "math" ] }
lyra-math = { path = "../lyra-math" }

305
lyra-scene/src/lib.rs Normal file
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@ -0,0 +1,305 @@
use std::{collections::VecDeque, ops::{Deref, DerefMut}};
use lyra_ecs::{query::Entities, relation::ChildOf, Bundle, Component, Entity, World};
// So we can use lyra_ecs::Component derive macro
pub(crate) mod lyra_engine {
pub(crate) mod ecs {
pub use lyra_ecs::*;
}
}
mod node;
use lyra_math::{Transform, Vec3};
pub use node::*;
/// A flag spawned on all scene node entities
#[derive(Component)]
pub struct SceneNodeFlag;
/// A flag spawned on only the scene root node
#[derive(Component)]
pub struct SceneNodeRoot;
enum MutCow<'a, T> {
Mut(&'a mut T),
Owned(T),
}
impl<'a, T> Deref for MutCow<'a, T> {
type Target = T;
fn deref(&self) -> &Self::Target {
match self {
MutCow::Mut(t) => t,
MutCow::Owned(t) => t,
}
}
}
impl<'a, T> DerefMut for MutCow<'a, T> {
fn deref_mut(&mut self) -> &mut Self::Target {
match self {
MutCow::Mut(t) => t,
MutCow::Owned(t) => t,
}
}
}
/// A SceneGraph is a Graph of nodes that represents the hierarchy of a scene.
///
/// This SceneGraph is special in the sense that it is literally just an ECS world with methods
/// implemented for it that make it easier to use for a SceneGraph.
//#[derive(Default)]
pub struct SceneGraph<'a> {
pub(crate) world: MutCow<'a, World>,
root_node: SceneNode,
}
impl<'a> SceneGraph<'a> {
/// Create a new SceneGraph with its own ECS World.
pub fn new() -> Self {
let mut world = World::new();
let e = world.spawn((Transform::from_translation(Vec3::new(0.0, 0.0, 0.0)), SceneNodeRoot));
let root = SceneNode::new(None, e);
Self {
world: MutCow::Owned(world),
root_node: root
}
}
/// Retrieve a SceneGraph from an ECS World.
///
/// Returns `None` if the `root_entity` was not created from a `SceneGraph` that was later
/// inserted into another world with [`SceneGraph::into_world`].
pub fn from_world(world: &'a mut World, root_entity: Entity) -> Option<Self> {
if world.view_one::<(&SceneNodeRoot, &Transform)>(root_entity).get().is_none() {
None
} else {
Some(Self {
world: MutCow::Mut(world),
root_node: SceneNode::new(None, root_entity),
})
}
}
/// Create a new SceneGraph inside an existing ECS World.
pub fn new_from_world(world: &'a mut World) -> Self {
let root_en = world.spawn((Transform::from_translation(Vec3::new(0.0, 0.0, 0.0)), SceneNodeRoot));
let root = SceneNode::new(None, root_en);
Self {
world: MutCow::Mut(world),
root_node: root,
}
}
/// Consume the SceneGraph, inserting its internal world into the provided world.
///
/// The `into` World will contain all nodes of the SceneGraph. You could iterate through the
/// SceneGraph manually if you'd like. The root entity has a [`SceneNodeRoot`] flag component,
/// and a Transform component. The children nodes have a [`SceneNodeFlag`] component and a
/// Transform component. The transforms of the children will be local, you must find its world
/// transform by traversing up the hierarchy of the scene manually with the `ChildOf` relation.
///
/// Returns: the Entity of the root node in the provided world.
pub fn into_world(mut self, into: &mut World) -> Entity {
// first insert the root entity into the World.
let v = self.world.view_one::<&Transform>(self.root_node.entity());
let pos = *v.get().unwrap();
let new_root = into.spawn((pos, SceneNodeRoot));
// now process the children of the root node.
Self::traverse_inserting_into(&mut self.world, self.root_node.entity(), new_root, into);
new_root
}
/// Recursively traverse the `from` world, starting at `node_en`, inserting the
/// children entity into the world.
///
/// Parameters:
/// * `scene_world` - The world that the SceneGraph exists in
/// * `scene_en` - The entity of the parent entity inside of the `scene_world`.
/// * `parent_en` - The entity of the parent entity inside of the `into` world.
/// * `into` - The world to insert the SceneGraph world into.
fn traverse_inserting_into(scene_world: &mut World, scene_en: Entity, parent_en: Entity, into: &mut World) {
let v = scene_world.view::<(Entities, &Transform)>()
.relates_to::<ChildOf>(scene_en);
// unfortunately, the borrow checker exists, and wasn't happy that `scene_world` was
// immutably borrowed with the view (v), and being mutably borrowed in the
// recursive call.
let mut child_entities = VecDeque::new();
for ((child_scene_en, pos), _rel) in v.iter() {
let into_en = into.spawn((*pos, SceneNodeFlag));
into.add_relation(into_en, ChildOf, parent_en);
child_entities.push_back((child_scene_en, into_en));
}
while let Some((child_scene_en, into_en)) = child_entities.pop_front() {
Self::traverse_inserting_into(scene_world, child_scene_en, into_en, into);
}
}
/// Adds a node to the root node of the SceneGraph.
///
/// The spawned entity will have a `ChildOf` relation targeting the root node, the
/// `SceneNodeFlag` component is also added to the entity.
pub fn add_node<B: Bundle>(&mut self, local_transform: Transform, bundle: B) -> SceneNode {
let node = self.root_node.clone();
self.add_node_under(&node, local_transform, bundle)
}
/// Add a node under a parent node.
///
/// The spawned entity will have a `ChildOf` relation targeting the provided parent node,
/// the `SceneNodeFlag` component is also added to the entity.
pub fn add_node_under<B: Bundle>(&mut self, parent: &SceneNode, local_transform: Transform, bundle: B) -> SceneNode {
world_add_child_node(&mut self.world, parent, local_transform, bundle)
}
/// Traverses down the SceneGraph, calling `callback` with each SceneNode and its world transform.
///
/// The traversal does not include the root scene node.
pub fn traverse_down<F>(&self, mut callback: F)
where
F: FnMut(&SceneNode, Transform),
{
self.traverse_down_from(self.root_node.clone(), &mut callback);
}
/// Traverses down the SceneGraph from a starting node, calling `callback` with each
/// SceneNode and its world transform.
fn traverse_down_from<F>(&self, start: SceneNode, callback: &mut F)
where
F: FnMut(&SceneNode, Transform),
{
let v = self.world.view::<(Entities, &Transform)>()
.relates_to::<ChildOf>(start.entity());
for ((e, _), _rel) in v.iter() {
let node = SceneNode::new(Some(start.entity()), e);
let world_pos = node.world_transform(self);
callback(&node, world_pos);
self.traverse_down_from(node, callback);
}
}
}
/// Add a node under a parent node.
///
/// The spawned entity will have a `ChildOf` relation targeting the provided parent node,
/// the `SceneNodeFlag` component is also added to the entity.
pub(crate) fn world_add_child_node<B: Bundle>(world: &mut World, parent: &SceneNode, local_transform: Transform, bundle: B) -> SceneNode {
let e = world.spawn(bundle);
world.insert(e, (SceneNodeFlag, local_transform));
world.add_relation(e, ChildOf, parent.entity());
SceneNode::new(Some(parent.entity()), e)
}
#[cfg(test)]
pub mod tests {
use lyra_ecs::{query::Entities, relation::ChildOf, Component, World};
use lyra_math::{Transform, Vec3};
use crate::{lyra_engine, SceneGraph, SceneNodeRoot};
#[derive(Component)]
pub struct FakeMesh;
#[test]
fn single_node_hierarchy() {
let mut scene = SceneGraph::new();
let a = scene.add_node(Transform::from_translation(Vec3::new(10.0, 10.0, 10.0)), FakeMesh);
assert!(a.parent(&scene).unwrap() == scene.root_node);
}
#[test]
fn double_node_hierarchy() {
let mut scene = SceneGraph::new();
let a = scene.add_node(Transform::from_translation(Vec3::new(10.0, 10.0, 10.0)), FakeMesh);
assert!(a.parent(&scene).unwrap() == scene.root_node);
let b = a.add_node(&mut scene, Transform::from_translation(Vec3::new(50.0, 50.0, 50.0)), FakeMesh);
assert!(b.parent(&scene).unwrap() == a);
}
#[test]
fn traverse_down() {
let v2s = vec![Vec3::new(10.0, 10.0, 10.0), Vec3::new(50.0, 50.0, 50.0)];
let mut scene = SceneGraph::new();
let a = scene.add_node(Transform::from_translation(v2s[0]), FakeMesh);
assert!(a.parent(&scene).unwrap() == scene.root_node);
let b = a.add_node(&mut scene, Transform::from_translation(v2s[1]), FakeMesh);
assert!(b.parent(&scene).unwrap() == a);
let mut idx = 0;
scene.traverse_down(|_e, pos| {
if idx == 0 {
assert_eq!(pos, Transform::from_translation(v2s[idx]));
} else if idx == 1 {
let t = v2s.iter().sum();
assert_eq!(pos, Transform::from_translation(t));
}
idx += 1;
});
}
#[test]
fn inserting_and_from_world() {
let v2s = vec![Vec3::new(10.0, 10.0, 10.0), Vec3::new(50.0, 50.0, 50.0)];
let mut scene = SceneGraph::new();
let a = scene.add_node(Transform::from_translation(v2s[0]), FakeMesh);
assert!(a.parent(&scene).unwrap() == scene.root_node);
let b = a.add_node(&mut scene, Transform::from_translation(v2s[1]), FakeMesh);
assert!(b.parent(&scene).unwrap() == a);
let mut other_world = World::new();
let root = scene.into_world(&mut other_world);
// check all of the entities inside of the World
let (root_pos, _) = other_world.view_one::<(&Transform, &SceneNodeRoot)>(root).get().unwrap();
assert_eq!(*root_pos, Transform::from_xyz(0.0, 0.0, 0.0));
let ((child_en, child_pos), _) = other_world.view::<(Entities, &Transform)>()
.relates_to::<ChildOf>(root).iter().next().unwrap();
assert_eq!(*child_pos, Transform::from_translation(v2s[0]));
let ((_, childchild_pos), _) = other_world.view::<(Entities, &Transform)>()
.relates_to::<ChildOf>(child_en).iter().next().unwrap();
assert_eq!(*childchild_pos, Transform::from_translation(v2s[1]));
drop(root_pos);
drop(child_pos);
drop(childchild_pos);
// Now get the SceneGraph inside the World and use the nice utility tools to traverse it.
let scene = SceneGraph::from_world(&mut other_world, root)
.expect("Failed to get SceneGraph from World!");
let mut idx = 0;
scene.traverse_down(|_e, pos| {
if idx == 0 {
assert_eq!(pos, Transform::from_translation(v2s[idx]));
} else if idx == 1 {
let t = v2s.iter().sum();
assert_eq!(pos, Transform::from_translation(t));
}
idx += 1;
});
}
}

101
lyra-scene/src/node.rs Normal file
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@ -0,0 +1,101 @@
use lyra_ecs::{query::Entities, relation::{ChildOf, RelationOriginComponent}, Bundle, Entity};
use lyra_math::Transform;
use crate::SceneGraph;
#[derive(Clone, PartialEq, Eq)]
pub struct SceneNode {
//world: WorldLock,
parent: Option<Entity>,
entity: Entity
}
impl SceneNode {
pub fn new(parent: Option<Entity>, entity: Entity) -> Self {
Self {
parent,
entity,
}
}
/// If this node has a parent, retrieves the parent node from the SceneGraph.
pub fn parent(&self, graph: &SceneGraph) -> Option<SceneNode> {
if let Some(parent) = self.parent {
let v = graph.world.view_one::<&RelationOriginComponent<ChildOf>>(parent);
let p_parent = if let Some(pp) = v.get() {
Some(pp.target())
} else { None };
Some(SceneNode::new(p_parent, parent))
} else {
None
}
}
pub fn parent_entity(&self) -> Option<Entity> {
self.parent
}
pub fn children(&self, graph: &SceneGraph) -> Vec<SceneNode> {
let v = graph.world.view::<Entities>()
.relates_to::<ChildOf>(self.entity);
v.into_iter().map(|(e, _)| SceneNode::new(Some(self.entity), e)).collect()
}
pub fn entity(&self) -> Entity {
self.entity
}
/// Add a child node to this node.
///
/// The spawned entity backing the scene node will have a `ChildOf` relation targeting
/// the provided parent node, the `SceneNodeFlag` component is also added to the entity.
pub fn add_node<B: Bundle>(&self, graph: &mut SceneGraph, local_transform: Transform, bundle: B) -> SceneNode {
graph.add_node_under(self, local_transform, bundle)
}
pub fn local_transform(&self, graph: &SceneGraph) -> Transform {
let v = graph.world.view_one::<&Transform>(self.entity);
let t = v.get().expect("Somehow the SceneNode is missing its Transform!");
t.clone()
}
/// Retrieves the world transform of the Node.
///
/// This traverses up the SceneGraph from this node.
pub fn world_transform(&self, graph: &SceneGraph) -> Transform {
match self.parent(graph) {
Some(parent) => {
let pt = parent.world_transform(graph);
pt + self.local_transform(graph)
},
None => {
self.local_transform(graph)
}
}
}
}
#[cfg(test)]
mod tests {
use lyra_math::{Transform, Vec3};
use crate::{tests::FakeMesh, SceneGraph};
#[test]
fn node_world_transform() {
let mut scene = SceneGraph::new();
let a = scene.add_node(Transform::from_translation(Vec3::new(10.0, 10.0, 10.0)), FakeMesh);
assert!(a.parent(&scene).unwrap() == scene.root_node);
let b = a.add_node(&mut scene, Transform::from_translation(Vec3::new(50.0, 50.0, 50.0)), FakeMesh);
assert!(b.parent(&scene).unwrap() == a);
let wrld_tran = b.world_transform(&scene);
assert_eq!(wrld_tran, Transform::from_translation(Vec3::new(60.0, 60.0, 60.0)));
}
}