Blender_bevy_components_workflow/crates/bevy_gltf_blueprints/README.md

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# bevy_gltf_blueprints

Built on [bevy_gltf_components](https://crates.io/crates/bevy_gltf_components) this crate adds the ability to define Blueprints/Prefabs for [Bevy](https://bevyengine.org/) inside gltf files and spawn them in Bevy.

* Allows you to create lightweight levels, where all assets are different gltf files and loaded after the main level is loaded
* Allows you to spawn different entities from gtlf files at runtime in a clean manner, including simplified animation support !

A blueprint is a set of **overrideable** components + a hierarchy: ie 

    * just a Gltf file with Gltf_extras specifying components 
    * a component called BlueprintName

Particularly useful when using [Blender](https://www.blender.org/) as an editor for the [Bevy](https://bevyengine.org/) game engine, combined with the Blender add-ons that do a lot of the work for you 
- [gltf_auto_export](https://github.com/kaosat-dev/Blender_bevy_components_workflow/tree/main/tools/gltf_auto_export)
- [bevy_components](https://github.com/kaosat-dev/Blender_bevy_components_workflow/tree/main/tools/bevy_components) 


## Usage

Here's a minimal usage example:

```toml
# Cargo.toml
[dependencies]
bevy="0.13"
bevy_gltf_blueprints = { version = "0.10"} 

```

```rust no_run
use bevy::prelude::*;
use bevy_gltf_blueprints::*;

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_plugins(BlueprintsPlugin)

        .run();
}

// not shown here: any other setup that is not specific to blueprints

fn spawn_blueprint(
    mut commands: Commands,
    keycode: Res<Input<KeyCode>>,
){
    if keycode.just_pressed(KeyCode::S) {
        let new_entity = commands.spawn((
            BlueprintName("Health_Pickup".to_string()), // mandatory !!
            SpawnHere, // mandatory !!
            TransformBundle::from_transform(Transform::from_xyz(x, 2.0, y)), // VERY important !!
            // any other component you want to insert
        ));
    }
}
```

##  Installation

Add the following to your `[dependencies]` section in `Cargo.toml`:

```toml
bevy_gltf_blueprints = "0.10"
```

Or use `cargo add`:

```toml
cargo add bevy_gltf_blueprints
```

## Setup

```rust no_run
use bevy::prelude::*;
use bevy_gltf_blueprints::*;

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_plugin(BlueprintsPlugin)

        .run();
}

```

you may want to configure your "library"/"blueprints" settings:

```rust no_run
use bevy::prelude::*;
use bevy_gltf_blueprints::*;

fn main() {
    App::new()
        .add_plugins((
             BlueprintsPlugin{
                aabbs: true, // defaults to false, enable this to automatically calculate aabb for the scene/blueprint
                material_library: true,  // defaults to false, enable this to enable automatic injection of materials from material library files
                ..Default::default()
            }
        ))
        .run();
}

```

## Spawning entities from blueprints

You can spawn entities from blueprints like this:
```rust no_run
commands.spawn((
    BlueprintName("Health_Pickup".to_string()), // mandatory !!
    SpawnHere, // mandatory !!
    
    TransformBundle::from_transform(Transform::from_xyz(x, 2.0, y)), // optional
    // any other component you want to insert
))

``` 

Once spawning of the actual entity is done, the spawned Blueprint will be *gone/merged* with the contents of Blueprint !

> Important :
you can **add** or **override** components present inside your Blueprint when spawning the BluePrint itself: ie

### Adding components not specified inside the blueprint

you can just add any additional components you need when spawning :

```rust no_run
commands.spawn((
    BlueprintName("Health_Pickup".to_string()),
    SpawnHere,
    TransformBundle::from_transform(Transform::from_xyz(x, 2.0, y)),
    // from Rapier/bevy_xpbd: this means the entity will also have a velocity component when inserted into the world
    Velocity {
        linvel: Vec3::new(vel_x, vel_y, vel_z),
        angvel: Vec3::new(0.0, 0.0, 0.0),
      },
))

``` 
### Overriding components specified inside the blueprint

any component you specify when spawning the Blueprint that is also specified **within** the Blueprint will **override** that component in the final spawned entity

for example 
```rust no_run
commands.spawn((
    BlueprintName("Health_Pickup".to_string()),
    SpawnHere,
    TransformBundle::from_transform(Transform::from_xyz(x, 2.0, y)),
    HealthPowerUp(20)// if this is component is also present inside the "Health_Pickup" blueprint, that one will be replaced with this component during spawning
))

``` 

### BluePrintBundle

There is also a ```BluePrintBundle``` for convenience , which just has 
 * a ```BlueprintName``` component
 * a ```SpawnHere``` component

## Additional information

- When a blueprint is spawned, all its children entities (and nested children etc) also have an ```InBlueprint``` component that gets insert
- In cases where that is undesirable, you can add a ```NoInBlueprint``` component on the entity you spawn the blueprint with, and the components above will not be add
- if you want to overwrite the **path** where this crate looks for blueprints (gltf files) , you can add a ```Library``` component , and that will be used instead of the default path
ie :

```rust no_run
commands
    .spawn((
        Name::from("test"),
        BluePrintBundle {
            blueprint: BlueprintName("TestBlueprint".to_string()),
            ..Default::default()
        },
        Library("models".into()) // now the path to the blueprint above will be /assets/models/TestBlueprint.glb
    ))
```
- this crate also provides a special optional ```GameWorldTag``` component: this is useful when you want to keep all your spawned entities inside a root entity

You can use it in your queries to add your entities as children of this "world"
This way all your levels, your dynamic entities etc, are kept seperated from UI nodes & other entities that are not relevant to the game world

> Note: you should only have a SINGLE entity tagged with that component !

```rust no_run
    commands.spawn((
        SceneBundle {
            scene: models
                .get(game_assets.world.id())
                .expect("main level should have been loaded")
                .scenes[0]
                .clone(),
            ..default()
        },
        bevy::prelude::Name::from("world"),
        GameWorldTag, // here it is
    ));
```


## SystemSet

the ordering of systems is very important ! 

For example to replace your proxy components (stand-in components when you cannot/ do not want to use real components in the gltf file) with actual ones, which should happen **AFTER** the Blueprint based spawning, 

so ```bevy_gltf_blueprints``` provides a **SystemSet** for that purpose: ```GltfBlueprintsSet```

Typically , the order of systems should be

***bevy_gltf_components (GltfComponentsSet::Injection)*** => ***bevy_gltf_blueprints (GltfBlueprintsSet::Spawn, GltfBlueprintsSet::AfterSpawn)*** => ***replace_proxies***

see https://github.com/kaosat-dev/Blender_bevy_components_workflow/tree/main/examples/bevy_gltf_blueprints/basic for how to set it up correctly



## Animation

```bevy_gltf_blueprints``` provides some lightweight helpers to deal with animations stored in gltf files

 * an ```Animations``` component that gets inserted into spawned (root) entities that contains a hashmap of all animations contained inside that entity/gltf file .
 (this is a copy of the ```named_animations``` inside Bevy's gltf structures )
 * an ```AnimationPlayerLink``` component that gets inserted into spawned (root) entities, to make it easier to trigger/ control animations than it usually is inside Bevy + Gltf files

The workflow for animations is as follows:
* create a gltf file with animations (using Blender & co) as you would normally do
* inside Bevy, use the ```bevy_gltf_blueprints``` boilerplate (see sections above), no specific setup beyond that is required
* to control the animation of an entity, you need to query for entities that have both ```AnimationPlayerLink``` and ```Animations``` components (added by ```bevy_gltf_blueprints```) AND entities with the ```AnimationPlayer``` component
 
For example:

```rust no_run
// example of changing animation of entities based on proximity to the player, for "fox" entities (Tag component)
pub fn animation_change_on_proximity_foxes(
    players: Query<&GlobalTransform, With<Player>>,
    animated_foxes: Query<(&GlobalTransform, &AnimationPlayerLink, &Animations ), With<Fox>>,

    mut animation_players: Query<&mut AnimationPlayer>,

){
    for player_transforms in players.iter() {
        for (fox_tranforms, link, animations) in animated_foxes.iter() {
            let distance = player_transforms
                .translation()
                .distance(fox_tranforms.translation());
            let mut anim_name = "Walk"; 
            if distance < 8.5 {
                anim_name = "Run"; 
            }
            else if distance >= 8.5 && distance < 10.0{
                anim_name = "Walk";
            }
            else if distance >= 10.0 && distance < 15.0{
                anim_name = "Survey";
            }
            // now play the animation based on the chosen animation name
            let mut animation_player = animation_players.get_mut(link.0).unwrap();
            animation_player.play_with_transition(
                animations.named_animations.get(anim_name).expect("animation name should be in the list").clone(), 
                Duration::from_secs(3)
            ).repeat();
        }
    }
}
```

see https://github.com/kaosat-dev/Blender_bevy_components_workflow/tree/main/examples/bevy_gltf_blueprints/animation for how to set it up correctly

particularly from https://github.com/kaosat-dev/Blender_bevy_components_workflow/tree/main/examples/bevy_gltf_blueprints/animation/game/in_game.rs


## Materials

You have the option of using "material libraries" to share common textures/materials between blueprints, in order to avoid asset & memory bloat:

Ie for example without this option, 56 different blueprints using the same material with a large texture would lead to the material/texture being embeded
56 times !!


you can configure this with the settings:
```rust
material_library: true  // defaults to false, enable this to enable automatic injection of materials from material library files
```

> Important! you must take care of preloading your material librairy gltf files in advance, using for example ```bevy_asset_loader```since 
```bevy_gltf_blueprints``` currently does NOT take care of loading those at runtime


see https://github.com/kaosat-dev/Blender_bevy_components_workflow/tree/main/examples/bevy_gltf_blueprints/materials for how to set it up correctly

Generating optimised blueprints and material libraries can be automated using the latests version of the [Blender plugin](https://github.com/kaosat-dev/Blender_bevy_components_workflow/tree/main/tools/gltf_auto_export)


## Examples

https://github.com/kaosat-dev/Blender_bevy_components_workflow/tree/main/examples/bevy_gltf_blueprints/basic

https://github.com/kaosat-dev/Blender_bevy_components_workflow/tree/main/examples/bevy_gltf_blueprints/basic_xpbd_physics

https://github.com/kaosat-dev/Blender_bevy_components_workflow/tree/main/examples/bevy_gltf_blueprints/animation

https://github.com/kaosat-dev/Blender_bevy_components_workflow/tree/main/examples/bevy_gltf_blueprints/materials

https://github.com/kaosat-dev/Blender_bevy_components_workflow/tree/main/examples/bevy_gltf_blueprints/multiple_levels_multiple_blendfiles


## Compatible Bevy versions

The main branch is compatible with the latest Bevy release, while the branch `bevy_main` tries to track the `main` branch of Bevy (PRs updating the tracked commit are welcome).

Compatibility of `bevy_gltf_blueprints` versions:
| `bevy_gltf_blueprints` | `bevy` |
| :--                 | :--    |
| `0.9 - 0.10`        | `0.13` |
| `0.3 - 0.8`         | `0.12` |
| `0.1 - 0.2`         | `0.11` |
| branch `main`       | `0.13` |
| branch `bevy_main`  | `main` |


## License

This crate, all its code, contents & assets is Dual-licensed under either of

- Apache License, Version 2.0, ([LICENSE-APACHE](./LICENSE_APACHE.md) or https://www.apache.org/licenses/LICENSE-2.0)
- MIT license ([LICENSE-MIT](./LICENSE_MIT.md) or https://opensource.org/licenses/MIT)