bevy/examples/3d/fog_volumes.rs
Kristoffer Søholm 2d1b4939d2
Synchronize removed components with the render world (#15582)
# Objective

Fixes #15560
Fixes (most of) #15570

Currently a lot of examples (and presumably some user code) depend on
toggling certain render features by adding/removing a single component
to an entity, e.g. `SpotLight` to toggle a light. Because of the
retained render world this no longer works: Extract will add any new
components, but when it is removed the entity persists unchanged in the
render world.

## Solution

Add `SyncComponentPlugin<C: Component>` that registers
`SyncToRenderWorld` as a required component for `C`, and adds a
component hook that will clear all components from the render world
entity when `C` is removed. We add this plugin to
`ExtractComponentPlugin` which fixes most instances of the problem. For
custom extraction logic we can manually add `SyncComponentPlugin` for
that component.

We also rename `WorldSyncPlugin` to `SyncWorldPlugin` so we start a
naming convention like all the `Extract` plugins.

In this PR I also fixed a bunch of breakage related to the retained
render world, stemming from old code that assumed that `Entity` would be
the same in both worlds.

I found that using the `RenderEntity` wrapper instead of `Entity` in
data structures when referring to render world entities makes intent
much clearer, so I propose we make this an official pattern.

## Testing

Run examples like

```
cargo run --features pbr_multi_layer_material_textures --example clearcoat
cargo run --example volumetric_fog
```

and see that they work, and that toggles work correctly. But really we
should test every single example, as we might not even have caught all
the breakage yet.

---

## Migration Guide

The retained render world notes should be updated to explain this edge
case and `SyncComponentPlugin`

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Trashtalk217 <trashtalk217@gmail.com>
2024-10-08 22:23:17 +00:00

85 lines
2.7 KiB
Rust

//! Demonstrates fog volumes with voxel density textures.
//!
//! We render the Stanford bunny as a fog volume. Parts of the bunny become
//! lighter and darker as the camera rotates. This is physically-accurate
//! behavior that results from the scattering and absorption of the directional
//! light.
use bevy::{
math::vec3,
pbr::{FogVolume, VolumetricFog, VolumetricLight},
prelude::*,
};
/// Entry point.
fn main() {
App::new()
.add_plugins(DefaultPlugins.set(WindowPlugin {
primary_window: Some(Window {
title: "Bevy Fog Volumes Example".into(),
..default()
}),
..default()
}))
.insert_resource(AmbientLight::NONE)
.add_systems(Startup, setup)
.add_systems(Update, rotate_camera)
.run();
}
/// Spawns all the objects in the scene.
fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
// Spawn a fog volume with a voxelized version of the Stanford bunny.
commands
.spawn(SpatialBundle {
visibility: Visibility::Visible,
transform: Transform::from_xyz(0.0, 0.5, 0.0),
..default()
})
.insert(FogVolume {
density_texture: Some(asset_server.load("volumes/bunny.ktx2")),
density_factor: 1.0,
// Scatter as much of the light as possible, to brighten the bunny
// up.
scattering: 1.0,
..default()
});
// Spawn a bright directional light that illuminates the fog well.
commands.spawn((
Transform::from_xyz(1.0, 1.0, -0.3).looking_at(vec3(0.0, 0.5, 0.0), Vec3::Y),
DirectionalLight {
shadows_enabled: true,
illuminance: 32000.0,
..default()
},
// Make sure to add this for the light to interact with the fog.
VolumetricLight,
));
// Spawn a camera.
commands.spawn((
Camera3d::default(),
Transform::from_xyz(-0.75, 1.0, 2.0).looking_at(vec3(0.0, 0.0, 0.0), Vec3::Y),
Camera {
hdr: true,
..default()
},
VolumetricFog {
// Make this relatively high in order to increase the fog quality.
step_count: 64,
// Disable ambient light.
ambient_intensity: 0.0,
..default()
},
));
}
/// Rotates the camera a bit every frame.
fn rotate_camera(mut cameras: Query<&mut Transform, With<Camera3d>>) {
for mut camera_transform in cameras.iter_mut() {
*camera_transform =
Transform::from_translation(Quat::from_rotation_y(0.01) * camera_transform.translation)
.looking_at(vec3(0.0, 0.5, 0.0), Vec3::Y);
}
}