bevy/assets/scenes/load_scene_example.scn.ron

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(De) serialize resources in scenes (#6846) # Objective Co-Authored-By: davier [bricedavier@gmail.com](mailto:bricedavier@gmail.com) Fixes #3576. Adds a `resources` field in scene serialization data to allow de/serializing resources that have reflection enabled. ## Solution Most of this code is taken from a previous closed PR: https://github.com/bevyengine/bevy/pull/3580. Most of the credit goes to @Davier , what I did was mostly getting it to work on the latest main branch of Bevy, along with adding a few asserts in the currently existing tests to be sure everything is working properly. This PR changes the scene format to include resources in this way: ``` ( resources: { // List of resources here, keyed by resource type name. }, entities: [ // Previous scene format here ], ) ``` An example taken from the tests: ``` ( resources: { "bevy_scene::serde::tests::MyResource": ( foo: 123, ), }, entities: { // Previous scene format here }, ) ``` For this, a `resources` fields has been added on the `DynamicScene` and the `DynamicSceneBuilder` structs. The latter now also has a method named `extract_resources` to properly extract the existing resources registered in the local type registry, in a similar way to `extract_entities`. --- ## Changelog Added: Reflect resources registered in the type registry used by dynamic scenes will now be properly de/serialized in scene data. ## Migration Guide Since the scene format has been changed, the user may not be able to use scenes saved prior to this PR due to the `resources` scene field being missing. ~~To preserve backwards compatibility, I will try to make the `resources` fully optional so that old scenes can be loaded without issue.~~ ## TODOs - [x] I may have to update a few doc blocks still referring to dynamic scenes as mere container of entities, since they now include resources as well. - [x] ~~I want to make the `resources` key optional, as specified in the Migration Guide, so that old scenes will be compatible with this change.~~ Since this would only be trivial for ron format, I think it might be better to consider it in a separate PR/discussion to figure out if it could be done for binary serialization too. - [x] I suppose it might be a good idea to add a resources in the scene example so that users will quickly notice they can serialize resources just like entities. --------- Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2023-03-20 21:17:02 +00:00
resources: {
"scene::ResourceA": (
score: 2,
),
},
entities: {
0: (
bevy_scene: Use map for scene `components` (#6345) # Objective Currently scenes define components using a list: ```rust [ ( entity: 0, components: [ { "bevy_transform::components::transform::Transform": ( translation: ( x: 0.0, y: 0.0, z: 0.0 ), rotation: (0.0, 0.0, 0.0, 1.0), scale: ( x: 1.0, y: 1.0, z: 1.0 ), ), }, { "my_crate::Foo": ( text: "Hello World", ), }, { "my_crate::Bar": ( baz: 123, ), }, ], ), ] ``` However, this representation has some drawbacks (as pointed out by @Metadorius in [this](https://github.com/bevyengine/bevy/pull/4561#issuecomment-1202215565) comment): 1. Increased nesting and more characters (minor effect on overall size) 2. More importantly, by definition, entities cannot have more than one instance of any given component. Therefore, such data is best stored as a map— where all values are meant to have unique keys. ## Solution Change `components` to store a map of components rather than a list: ```rust [ ( entity: 0, components: { "bevy_transform::components::transform::Transform": ( translation: ( x: 0.0, y: 0.0, z: 0.0 ), rotation: (0.0, 0.0, 0.0, 1.0), scale: ( x: 1.0, y: 1.0, z: 1.0 ), ), "my_crate::Foo": ( text: "Hello World", ), "my_crate::Bar": ( baz: 123 ), }, ), ] ``` #### Code Representation This change only affects the scene format itself. `DynamicEntity` still stores its components as a list. The reason for this is that storing such data as a map is not really needed since: 1. The "key" of each value is easily found by just calling `Reflect::type_name` on it 2. We should be generating such structs using the `World` itself which upholds the one-component-per-entity rule One could in theory create manually create a `DynamicEntity` with duplicate components, but this isn't something I think we should focus on in this PR. `DynamicEntity` can be broken in other ways (i.e. storing a non-component in the components list), and resolving its issues can be done in a separate PR. --- ## Changelog * The scene format now uses a map to represent the collection of components rather than a list ## Migration Guide The scene format now uses a map to represent the collection of components. Scene files will need to update from the old list format. <details> <summary>Example Code</summary> ```rust // OLD [ ( entity: 0, components: [ { "bevy_transform::components::transform::Transform": ( translation: ( x: 0.0, y: 0.0, z: 0.0 ), rotation: (0.0, 0.0, 0.0, 1.0), scale: ( x: 1.0, y: 1.0, z: 1.0 ), ), }, { "my_crate::Foo": ( text: "Hello World", ), }, { "my_crate::Bar": ( baz: 123, ), }, ], ), ] // NEW [ ( entity: 0, components: { "bevy_transform::components::transform::Transform": ( translation: ( x: 0.0, y: 0.0, z: 0.0 ), rotation: (0.0, 0.0, 0.0, 1.0), scale: ( x: 1.0, y: 1.0, z: 1.0 ), ), "my_crate::Foo": ( text: "Hello World", ), "my_crate::Bar": ( baz: 123 ), }, ), ] ``` </details>
2022-10-27 01:46:33 +00:00
components: {
"bevy_transform::components::transform::Transform": (
translation: (
x: 0.0,
y: 0.0,
z: 0.0
bevy_reflect: Improve serialization format even more (#5723) > Note: This is rebased off #4561 and can be viewed as a competitor to that PR. See `Comparison with #4561` section for details. # Objective The current serialization format used by `bevy_reflect` is both verbose and error-prone. Taking the following structs[^1] for example: ```rust // -- src/inventory.rs #[derive(Reflect)] struct Inventory { id: String, max_storage: usize, items: Vec<Item> } #[derive(Reflect)] struct Item { name: String } ``` Given an inventory of a single item, this would serialize to something like: ```rust // -- assets/inventory.ron { "type": "my_game::inventory::Inventory", "struct": { "id": { "type": "alloc::string::String", "value": "inv001", }, "max_storage": { "type": "usize", "value": 10 }, "items": { "type": "alloc::vec::Vec<alloc::string::String>", "list": [ { "type": "my_game::inventory::Item", "struct": { "name": { "type": "alloc::string::String", "value": "Pickaxe" }, }, }, ], }, }, } ``` Aside from being really long and difficult to read, it also has a few "gotchas" that users need to be aware of if they want to edit the file manually. A major one is the requirement that you use the proper keys for a given type. For structs, you need `"struct"`. For lists, `"list"`. For tuple structs, `"tuple_struct"`. And so on. It also ***requires*** that the `"type"` entry come before the actual data. Despite being a map— which in programming is almost always orderless by default— the entries need to be in a particular order. Failure to follow the ordering convention results in a failure to deserialize the data. This makes it very prone to errors and annoyances. ## Solution Using #4042, we can remove a lot of the boilerplate and metadata needed by this older system. Since we now have static access to type information, we can simplify our serialized data to look like: ```rust // -- assets/inventory.ron { "my_game::inventory::Inventory": ( id: "inv001", max_storage: 10, items: [ ( name: "Pickaxe" ), ], ), } ``` This is much more digestible and a lot less error-prone (no more key requirements and no more extra type names). Additionally, it is a lot more familiar to users as it follows conventional serde mechanics. For example, the struct is represented with `(...)` when serialized to RON. #### Custom Serialization Additionally, this PR adds the opt-in ability to specify a custom serde implementation to be used rather than the one created via reflection. For example[^1]: ```rust // -- src/inventory.rs #[derive(Reflect, Serialize)] #[reflect(Serialize)] struct Item { #[serde(alias = "id")] name: String } ``` ```rust // -- assets/inventory.ron { "my_game::inventory::Inventory": ( id: "inv001", max_storage: 10, items: [ ( id: "Pickaxe" ), ], ), }, ``` By allowing users to define their own serialization methods, we do two things: 1. We give more control over how data is serialized/deserialized to the end user 2. We avoid having to re-define serde's attributes and forcing users to apply both (e.g. we don't need a `#[reflect(alias)]` attribute). ### Improved Formats One of the improvements this PR provides is the ability to represent data in ways that are more conventional and/or familiar to users. Many users are familiar with RON so here are some of the ways we can now represent data in RON: ###### Structs ```js { "my_crate::Foo": ( bar: 123 ) } // OR { "my_crate::Foo": Foo( bar: 123 ) } ``` <details> <summary>Old Format</summary> ```js { "type": "my_crate::Foo", "struct": { "bar": { "type": "usize", "value": 123 } } } ``` </details> ###### Tuples ```js { "(f32, f32)": (1.0, 2.0) } ``` <details> <summary>Old Format</summary> ```js { "type": "(f32, f32)", "tuple": [ { "type": "f32", "value": 1.0 }, { "type": "f32", "value": 2.0 } ] } ``` </details> ###### Tuple Structs ```js { "my_crate::Bar": ("Hello World!") } // OR { "my_crate::Bar": Bar("Hello World!") } ``` <details> <summary>Old Format</summary> ```js { "type": "my_crate::Bar", "tuple_struct": [ { "type": "alloc::string::String", "value": "Hello World!" } ] } ``` </details> ###### Arrays It may be a bit surprising to some, but arrays now also use the tuple format. This is because they essentially _are_ tuples (a sequence of values with a fixed size), but only allow for homogenous types. Additionally, this is how RON handles them and is probably a result of the 32-capacity limit imposed on them (both by [serde](https://docs.rs/serde/latest/serde/trait.Serialize.html#impl-Serialize-for-%5BT%3B%2032%5D) and by [bevy_reflect](https://docs.rs/bevy/latest/bevy/reflect/trait.GetTypeRegistration.html#impl-GetTypeRegistration-for-%5BT%3B%2032%5D)). ```js { "[i32; 3]": (1, 2, 3) } ``` <details> <summary>Old Format</summary> ```js { "type": "[i32; 3]", "array": [ { "type": "i32", "value": 1 }, { "type": "i32", "value": 2 }, { "type": "i32", "value": 3 } ] } ``` </details> ###### Enums To make things simple, I'll just put a struct variant here, but the style applies to all variant types: ```js { "my_crate::ItemType": Consumable( name: "Healing potion" ) } ``` <details> <summary>Old Format</summary> ```js { "type": "my_crate::ItemType", "enum": { "variant": "Consumable", "struct": { "name": { "type": "alloc::string::String", "value": "Healing potion" } } } } ``` </details> ### Comparison with #4561 This PR is a rebased version of #4561. The reason for the split between the two is because this PR creates a _very_ different scene format. You may notice that the PR descriptions for either PR are pretty similar. This was done to better convey the changes depending on which (if any) gets merged first. If #4561 makes it in first, I will update this PR description accordingly. --- ## Changelog * Re-worked serialization/deserialization for reflected types * Added `TypedReflectDeserializer` for deserializing data with known `TypeInfo` * Renamed `ReflectDeserializer` to `UntypedReflectDeserializer` * ~~Replaced usages of `deserialize_any` with `deserialize_map` for non-self-describing formats~~ Reverted this change since there are still some issues that need to be sorted out (in a separate PR). By reverting this, crates like `bincode` can throw an error when attempting to deserialize non-self-describing formats (`bincode` results in `DeserializeAnyNotSupported`) * Structs, tuples, tuple structs, arrays, and enums are now all de/serialized using conventional serde methods ## Migration Guide * This PR reduces the verbosity of the scene format. Scenes will need to be updated accordingly: ```js // Old format { "type": "my_game::item::Item", "struct": { "id": { "type": "alloc::string::String", "value": "bevycraft:stone", }, "tags": { "type": "alloc::vec::Vec<alloc::string::String>", "list": [ { "type": "alloc::string::String", "value": "material" }, ], }, } // New format { "my_game::item::Item": ( id: "bevycraft:stone", tags: ["material"] ) } ``` [^1]: Some derives omitted for brevity.
2022-09-20 19:38:18 +00:00
),
rotation: (
x: 0.0,
y: 0.0,
z: 0.0,
w: 1.0,
),
bevy_scene: Use map for scene `components` (#6345) # Objective Currently scenes define components using a list: ```rust [ ( entity: 0, components: [ { "bevy_transform::components::transform::Transform": ( translation: ( x: 0.0, y: 0.0, z: 0.0 ), rotation: (0.0, 0.0, 0.0, 1.0), scale: ( x: 1.0, y: 1.0, z: 1.0 ), ), }, { "my_crate::Foo": ( text: "Hello World", ), }, { "my_crate::Bar": ( baz: 123, ), }, ], ), ] ``` However, this representation has some drawbacks (as pointed out by @Metadorius in [this](https://github.com/bevyengine/bevy/pull/4561#issuecomment-1202215565) comment): 1. Increased nesting and more characters (minor effect on overall size) 2. More importantly, by definition, entities cannot have more than one instance of any given component. Therefore, such data is best stored as a map— where all values are meant to have unique keys. ## Solution Change `components` to store a map of components rather than a list: ```rust [ ( entity: 0, components: { "bevy_transform::components::transform::Transform": ( translation: ( x: 0.0, y: 0.0, z: 0.0 ), rotation: (0.0, 0.0, 0.0, 1.0), scale: ( x: 1.0, y: 1.0, z: 1.0 ), ), "my_crate::Foo": ( text: "Hello World", ), "my_crate::Bar": ( baz: 123 ), }, ), ] ``` #### Code Representation This change only affects the scene format itself. `DynamicEntity` still stores its components as a list. The reason for this is that storing such data as a map is not really needed since: 1. The "key" of each value is easily found by just calling `Reflect::type_name` on it 2. We should be generating such structs using the `World` itself which upholds the one-component-per-entity rule One could in theory create manually create a `DynamicEntity` with duplicate components, but this isn't something I think we should focus on in this PR. `DynamicEntity` can be broken in other ways (i.e. storing a non-component in the components list), and resolving its issues can be done in a separate PR. --- ## Changelog * The scene format now uses a map to represent the collection of components rather than a list ## Migration Guide The scene format now uses a map to represent the collection of components. Scene files will need to update from the old list format. <details> <summary>Example Code</summary> ```rust // OLD [ ( entity: 0, components: [ { "bevy_transform::components::transform::Transform": ( translation: ( x: 0.0, y: 0.0, z: 0.0 ), rotation: (0.0, 0.0, 0.0, 1.0), scale: ( x: 1.0, y: 1.0, z: 1.0 ), ), }, { "my_crate::Foo": ( text: "Hello World", ), }, { "my_crate::Bar": ( baz: 123, ), }, ], ), ] // NEW [ ( entity: 0, components: { "bevy_transform::components::transform::Transform": ( translation: ( x: 0.0, y: 0.0, z: 0.0 ), rotation: (0.0, 0.0, 0.0, 1.0), scale: ( x: 1.0, y: 1.0, z: 1.0 ), ), "my_crate::Foo": ( text: "Hello World", ), "my_crate::Bar": ( baz: 123 ), }, ), ] ``` </details>
2022-10-27 01:46:33 +00:00
scale: (
bevy_reflect: Improve serialization format even more (#5723) > Note: This is rebased off #4561 and can be viewed as a competitor to that PR. See `Comparison with #4561` section for details. # Objective The current serialization format used by `bevy_reflect` is both verbose and error-prone. Taking the following structs[^1] for example: ```rust // -- src/inventory.rs #[derive(Reflect)] struct Inventory { id: String, max_storage: usize, items: Vec<Item> } #[derive(Reflect)] struct Item { name: String } ``` Given an inventory of a single item, this would serialize to something like: ```rust // -- assets/inventory.ron { "type": "my_game::inventory::Inventory", "struct": { "id": { "type": "alloc::string::String", "value": "inv001", }, "max_storage": { "type": "usize", "value": 10 }, "items": { "type": "alloc::vec::Vec<alloc::string::String>", "list": [ { "type": "my_game::inventory::Item", "struct": { "name": { "type": "alloc::string::String", "value": "Pickaxe" }, }, }, ], }, }, } ``` Aside from being really long and difficult to read, it also has a few "gotchas" that users need to be aware of if they want to edit the file manually. A major one is the requirement that you use the proper keys for a given type. For structs, you need `"struct"`. For lists, `"list"`. For tuple structs, `"tuple_struct"`. And so on. It also ***requires*** that the `"type"` entry come before the actual data. Despite being a map— which in programming is almost always orderless by default— the entries need to be in a particular order. Failure to follow the ordering convention results in a failure to deserialize the data. This makes it very prone to errors and annoyances. ## Solution Using #4042, we can remove a lot of the boilerplate and metadata needed by this older system. Since we now have static access to type information, we can simplify our serialized data to look like: ```rust // -- assets/inventory.ron { "my_game::inventory::Inventory": ( id: "inv001", max_storage: 10, items: [ ( name: "Pickaxe" ), ], ), } ``` This is much more digestible and a lot less error-prone (no more key requirements and no more extra type names). Additionally, it is a lot more familiar to users as it follows conventional serde mechanics. For example, the struct is represented with `(...)` when serialized to RON. #### Custom Serialization Additionally, this PR adds the opt-in ability to specify a custom serde implementation to be used rather than the one created via reflection. For example[^1]: ```rust // -- src/inventory.rs #[derive(Reflect, Serialize)] #[reflect(Serialize)] struct Item { #[serde(alias = "id")] name: String } ``` ```rust // -- assets/inventory.ron { "my_game::inventory::Inventory": ( id: "inv001", max_storage: 10, items: [ ( id: "Pickaxe" ), ], ), }, ``` By allowing users to define their own serialization methods, we do two things: 1. We give more control over how data is serialized/deserialized to the end user 2. We avoid having to re-define serde's attributes and forcing users to apply both (e.g. we don't need a `#[reflect(alias)]` attribute). ### Improved Formats One of the improvements this PR provides is the ability to represent data in ways that are more conventional and/or familiar to users. Many users are familiar with RON so here are some of the ways we can now represent data in RON: ###### Structs ```js { "my_crate::Foo": ( bar: 123 ) } // OR { "my_crate::Foo": Foo( bar: 123 ) } ``` <details> <summary>Old Format</summary> ```js { "type": "my_crate::Foo", "struct": { "bar": { "type": "usize", "value": 123 } } } ``` </details> ###### Tuples ```js { "(f32, f32)": (1.0, 2.0) } ``` <details> <summary>Old Format</summary> ```js { "type": "(f32, f32)", "tuple": [ { "type": "f32", "value": 1.0 }, { "type": "f32", "value": 2.0 } ] } ``` </details> ###### Tuple Structs ```js { "my_crate::Bar": ("Hello World!") } // OR { "my_crate::Bar": Bar("Hello World!") } ``` <details> <summary>Old Format</summary> ```js { "type": "my_crate::Bar", "tuple_struct": [ { "type": "alloc::string::String", "value": "Hello World!" } ] } ``` </details> ###### Arrays It may be a bit surprising to some, but arrays now also use the tuple format. This is because they essentially _are_ tuples (a sequence of values with a fixed size), but only allow for homogenous types. Additionally, this is how RON handles them and is probably a result of the 32-capacity limit imposed on them (both by [serde](https://docs.rs/serde/latest/serde/trait.Serialize.html#impl-Serialize-for-%5BT%3B%2032%5D) and by [bevy_reflect](https://docs.rs/bevy/latest/bevy/reflect/trait.GetTypeRegistration.html#impl-GetTypeRegistration-for-%5BT%3B%2032%5D)). ```js { "[i32; 3]": (1, 2, 3) } ``` <details> <summary>Old Format</summary> ```js { "type": "[i32; 3]", "array": [ { "type": "i32", "value": 1 }, { "type": "i32", "value": 2 }, { "type": "i32", "value": 3 } ] } ``` </details> ###### Enums To make things simple, I'll just put a struct variant here, but the style applies to all variant types: ```js { "my_crate::ItemType": Consumable( name: "Healing potion" ) } ``` <details> <summary>Old Format</summary> ```js { "type": "my_crate::ItemType", "enum": { "variant": "Consumable", "struct": { "name": { "type": "alloc::string::String", "value": "Healing potion" } } } } ``` </details> ### Comparison with #4561 This PR is a rebased version of #4561. The reason for the split between the two is because this PR creates a _very_ different scene format. You may notice that the PR descriptions for either PR are pretty similar. This was done to better convey the changes depending on which (if any) gets merged first. If #4561 makes it in first, I will update this PR description accordingly. --- ## Changelog * Re-worked serialization/deserialization for reflected types * Added `TypedReflectDeserializer` for deserializing data with known `TypeInfo` * Renamed `ReflectDeserializer` to `UntypedReflectDeserializer` * ~~Replaced usages of `deserialize_any` with `deserialize_map` for non-self-describing formats~~ Reverted this change since there are still some issues that need to be sorted out (in a separate PR). By reverting this, crates like `bincode` can throw an error when attempting to deserialize non-self-describing formats (`bincode` results in `DeserializeAnyNotSupported`) * Structs, tuples, tuple structs, arrays, and enums are now all de/serialized using conventional serde methods ## Migration Guide * This PR reduces the verbosity of the scene format. Scenes will need to be updated accordingly: ```js // Old format { "type": "my_game::item::Item", "struct": { "id": { "type": "alloc::string::String", "value": "bevycraft:stone", }, "tags": { "type": "alloc::vec::Vec<alloc::string::String>", "list": [ { "type": "alloc::string::String", "value": "material" }, ], }, } // New format { "my_game::item::Item": ( id: "bevycraft:stone", tags: ["material"] ) } ``` [^1]: Some derives omitted for brevity.
2022-09-20 19:38:18 +00:00
x: 1.0,
bevy_scene: Use map for scene `components` (#6345) # Objective Currently scenes define components using a list: ```rust [ ( entity: 0, components: [ { "bevy_transform::components::transform::Transform": ( translation: ( x: 0.0, y: 0.0, z: 0.0 ), rotation: (0.0, 0.0, 0.0, 1.0), scale: ( x: 1.0, y: 1.0, z: 1.0 ), ), }, { "my_crate::Foo": ( text: "Hello World", ), }, { "my_crate::Bar": ( baz: 123, ), }, ], ), ] ``` However, this representation has some drawbacks (as pointed out by @Metadorius in [this](https://github.com/bevyengine/bevy/pull/4561#issuecomment-1202215565) comment): 1. Increased nesting and more characters (minor effect on overall size) 2. More importantly, by definition, entities cannot have more than one instance of any given component. Therefore, such data is best stored as a map— where all values are meant to have unique keys. ## Solution Change `components` to store a map of components rather than a list: ```rust [ ( entity: 0, components: { "bevy_transform::components::transform::Transform": ( translation: ( x: 0.0, y: 0.0, z: 0.0 ), rotation: (0.0, 0.0, 0.0, 1.0), scale: ( x: 1.0, y: 1.0, z: 1.0 ), ), "my_crate::Foo": ( text: "Hello World", ), "my_crate::Bar": ( baz: 123 ), }, ), ] ``` #### Code Representation This change only affects the scene format itself. `DynamicEntity` still stores its components as a list. The reason for this is that storing such data as a map is not really needed since: 1. The "key" of each value is easily found by just calling `Reflect::type_name` on it 2. We should be generating such structs using the `World` itself which upholds the one-component-per-entity rule One could in theory create manually create a `DynamicEntity` with duplicate components, but this isn't something I think we should focus on in this PR. `DynamicEntity` can be broken in other ways (i.e. storing a non-component in the components list), and resolving its issues can be done in a separate PR. --- ## Changelog * The scene format now uses a map to represent the collection of components rather than a list ## Migration Guide The scene format now uses a map to represent the collection of components. Scene files will need to update from the old list format. <details> <summary>Example Code</summary> ```rust // OLD [ ( entity: 0, components: [ { "bevy_transform::components::transform::Transform": ( translation: ( x: 0.0, y: 0.0, z: 0.0 ), rotation: (0.0, 0.0, 0.0, 1.0), scale: ( x: 1.0, y: 1.0, z: 1.0 ), ), }, { "my_crate::Foo": ( text: "Hello World", ), }, { "my_crate::Bar": ( baz: 123, ), }, ], ), ] // NEW [ ( entity: 0, components: { "bevy_transform::components::transform::Transform": ( translation: ( x: 0.0, y: 0.0, z: 0.0 ), rotation: (0.0, 0.0, 0.0, 1.0), scale: ( x: 1.0, y: 1.0, z: 1.0 ), ), "my_crate::Foo": ( text: "Hello World", ), "my_crate::Bar": ( baz: 123 ), }, ), ] ``` </details>
2022-10-27 01:46:33 +00:00
y: 1.0,
z: 1.0
),
bevy_scene: Use map for scene `components` (#6345) # Objective Currently scenes define components using a list: ```rust [ ( entity: 0, components: [ { "bevy_transform::components::transform::Transform": ( translation: ( x: 0.0, y: 0.0, z: 0.0 ), rotation: (0.0, 0.0, 0.0, 1.0), scale: ( x: 1.0, y: 1.0, z: 1.0 ), ), }, { "my_crate::Foo": ( text: "Hello World", ), }, { "my_crate::Bar": ( baz: 123, ), }, ], ), ] ``` However, this representation has some drawbacks (as pointed out by @Metadorius in [this](https://github.com/bevyengine/bevy/pull/4561#issuecomment-1202215565) comment): 1. Increased nesting and more characters (minor effect on overall size) 2. More importantly, by definition, entities cannot have more than one instance of any given component. Therefore, such data is best stored as a map— where all values are meant to have unique keys. ## Solution Change `components` to store a map of components rather than a list: ```rust [ ( entity: 0, components: { "bevy_transform::components::transform::Transform": ( translation: ( x: 0.0, y: 0.0, z: 0.0 ), rotation: (0.0, 0.0, 0.0, 1.0), scale: ( x: 1.0, y: 1.0, z: 1.0 ), ), "my_crate::Foo": ( text: "Hello World", ), "my_crate::Bar": ( baz: 123 ), }, ), ] ``` #### Code Representation This change only affects the scene format itself. `DynamicEntity` still stores its components as a list. The reason for this is that storing such data as a map is not really needed since: 1. The "key" of each value is easily found by just calling `Reflect::type_name` on it 2. We should be generating such structs using the `World` itself which upholds the one-component-per-entity rule One could in theory create manually create a `DynamicEntity` with duplicate components, but this isn't something I think we should focus on in this PR. `DynamicEntity` can be broken in other ways (i.e. storing a non-component in the components list), and resolving its issues can be done in a separate PR. --- ## Changelog * The scene format now uses a map to represent the collection of components rather than a list ## Migration Guide The scene format now uses a map to represent the collection of components. Scene files will need to update from the old list format. <details> <summary>Example Code</summary> ```rust // OLD [ ( entity: 0, components: [ { "bevy_transform::components::transform::Transform": ( translation: ( x: 0.0, y: 0.0, z: 0.0 ), rotation: (0.0, 0.0, 0.0, 1.0), scale: ( x: 1.0, y: 1.0, z: 1.0 ), ), }, { "my_crate::Foo": ( text: "Hello World", ), }, { "my_crate::Bar": ( baz: 123, ), }, ], ), ] // NEW [ ( entity: 0, components: { "bevy_transform::components::transform::Transform": ( translation: ( x: 0.0, y: 0.0, z: 0.0 ), rotation: (0.0, 0.0, 0.0, 1.0), scale: ( x: 1.0, y: 1.0, z: 1.0 ), ), "my_crate::Foo": ( text: "Hello World", ), "my_crate::Bar": ( baz: 123 ), }, ), ] ``` </details>
2022-10-27 01:46:33 +00:00
),
"scene::ComponentB": (
value: "hello",
),
"scene::ComponentA": (
x: 1.0,
y: 2.0,
),
},
),
1: (
bevy_scene: Use map for scene `components` (#6345) # Objective Currently scenes define components using a list: ```rust [ ( entity: 0, components: [ { "bevy_transform::components::transform::Transform": ( translation: ( x: 0.0, y: 0.0, z: 0.0 ), rotation: (0.0, 0.0, 0.0, 1.0), scale: ( x: 1.0, y: 1.0, z: 1.0 ), ), }, { "my_crate::Foo": ( text: "Hello World", ), }, { "my_crate::Bar": ( baz: 123, ), }, ], ), ] ``` However, this representation has some drawbacks (as pointed out by @Metadorius in [this](https://github.com/bevyengine/bevy/pull/4561#issuecomment-1202215565) comment): 1. Increased nesting and more characters (minor effect on overall size) 2. More importantly, by definition, entities cannot have more than one instance of any given component. Therefore, such data is best stored as a map— where all values are meant to have unique keys. ## Solution Change `components` to store a map of components rather than a list: ```rust [ ( entity: 0, components: { "bevy_transform::components::transform::Transform": ( translation: ( x: 0.0, y: 0.0, z: 0.0 ), rotation: (0.0, 0.0, 0.0, 1.0), scale: ( x: 1.0, y: 1.0, z: 1.0 ), ), "my_crate::Foo": ( text: "Hello World", ), "my_crate::Bar": ( baz: 123 ), }, ), ] ``` #### Code Representation This change only affects the scene format itself. `DynamicEntity` still stores its components as a list. The reason for this is that storing such data as a map is not really needed since: 1. The "key" of each value is easily found by just calling `Reflect::type_name` on it 2. We should be generating such structs using the `World` itself which upholds the one-component-per-entity rule One could in theory create manually create a `DynamicEntity` with duplicate components, but this isn't something I think we should focus on in this PR. `DynamicEntity` can be broken in other ways (i.e. storing a non-component in the components list), and resolving its issues can be done in a separate PR. --- ## Changelog * The scene format now uses a map to represent the collection of components rather than a list ## Migration Guide The scene format now uses a map to represent the collection of components. Scene files will need to update from the old list format. <details> <summary>Example Code</summary> ```rust // OLD [ ( entity: 0, components: [ { "bevy_transform::components::transform::Transform": ( translation: ( x: 0.0, y: 0.0, z: 0.0 ), rotation: (0.0, 0.0, 0.0, 1.0), scale: ( x: 1.0, y: 1.0, z: 1.0 ), ), }, { "my_crate::Foo": ( text: "Hello World", ), }, { "my_crate::Bar": ( baz: 123, ), }, ], ), ] // NEW [ ( entity: 0, components: { "bevy_transform::components::transform::Transform": ( translation: ( x: 0.0, y: 0.0, z: 0.0 ), rotation: (0.0, 0.0, 0.0, 1.0), scale: ( x: 1.0, y: 1.0, z: 1.0 ), ), "my_crate::Foo": ( text: "Hello World", ), "my_crate::Bar": ( baz: 123 ), }, ), ] ``` </details>
2022-10-27 01:46:33 +00:00
components: {
"scene::ComponentA": (
x: 3.0,
y: 4.0,
),
},
),
}
)