mirror of
https://github.com/bevyengine/bevy
synced 2024-11-26 22:50:19 +00:00
01649f13e2
# Objective This is a necessary precursor to #9122 (this was split from that PR to reduce the amount of code to review all at once). Moving `!Send` resource ownership to `App` will make it unambiguously `!Send`. `SubApp` must be `Send`, so it can't wrap `App`. ## Solution Refactor `App` and `SubApp` to not have a recursive relationship. Since `SubApp` no longer wraps `App`, once `!Send` resources are moved out of `World` and into `App`, `SubApp` will become unambiguously `Send`. There could be less code duplication between `App` and `SubApp`, but that would break `App` method chaining. ## Changelog - `SubApp` no longer wraps `App`. - `App` fields are no longer publicly accessible. - `App` can no longer be converted into a `SubApp`. - Various methods now return references to a `SubApp` instead of an `App`. ## Migration Guide - To construct a sub-app, use `SubApp::new()`. `App` can no longer convert into `SubApp`. - If you implemented a trait for `App`, you may want to implement it for `SubApp` as well. - If you're accessing `app.world` directly, you now have to use `app.world()` and `app.world_mut()`. - `App::sub_app` now returns `&SubApp`. - `App::sub_app_mut` now returns `&mut SubApp`. - `App::get_sub_app` now returns `Option<&SubApp>.` - `App::get_sub_app_mut` now returns `Option<&mut SubApp>.`
370 lines
15 KiB
Rust
370 lines
15 KiB
Rust
//! This example shows how to create a custom render pass that runs after the main pass
|
|
//! and reads the texture generated by the main pass.
|
|
//!
|
|
//! The example shader is a very simple implementation of chromatic aberration.
|
|
//! To adapt this example for 2D, replace all instances of 3D structures (such as `Core3D`, etc.) with their corresponding 2D counterparts.
|
|
//!
|
|
//! This is a fairly low level example and assumes some familiarity with rendering concepts and wgpu.
|
|
|
|
use bevy::{
|
|
core_pipeline::{
|
|
core_3d::graph::{Core3d, Node3d},
|
|
fullscreen_vertex_shader::fullscreen_shader_vertex_state,
|
|
},
|
|
ecs::query::QueryItem,
|
|
prelude::*,
|
|
render::{
|
|
extract_component::{
|
|
ComponentUniforms, ExtractComponent, ExtractComponentPlugin, UniformComponentPlugin,
|
|
},
|
|
render_graph::{
|
|
NodeRunError, RenderGraphApp, RenderGraphContext, RenderLabel, ViewNode, ViewNodeRunner,
|
|
},
|
|
render_resource::{
|
|
binding_types::{sampler, texture_2d, uniform_buffer},
|
|
*,
|
|
},
|
|
renderer::{RenderContext, RenderDevice},
|
|
texture::BevyDefault,
|
|
view::ViewTarget,
|
|
RenderApp,
|
|
},
|
|
};
|
|
|
|
fn main() {
|
|
App::new()
|
|
.add_plugins((DefaultPlugins, PostProcessPlugin))
|
|
.add_systems(Startup, setup)
|
|
.add_systems(Update, (rotate, update_settings))
|
|
.run();
|
|
}
|
|
|
|
/// It is generally encouraged to set up post processing effects as a plugin
|
|
struct PostProcessPlugin;
|
|
|
|
impl Plugin for PostProcessPlugin {
|
|
fn build(&self, app: &mut App) {
|
|
app.add_plugins((
|
|
// The settings will be a component that lives in the main world but will
|
|
// be extracted to the render world every frame.
|
|
// This makes it possible to control the effect from the main world.
|
|
// This plugin will take care of extracting it automatically.
|
|
// It's important to derive [`ExtractComponent`] on [`PostProcessingSettings`]
|
|
// for this plugin to work correctly.
|
|
ExtractComponentPlugin::<PostProcessSettings>::default(),
|
|
// The settings will also be the data used in the shader.
|
|
// This plugin will prepare the component for the GPU by creating a uniform buffer
|
|
// and writing the data to that buffer every frame.
|
|
UniformComponentPlugin::<PostProcessSettings>::default(),
|
|
));
|
|
|
|
// We need to get the render app from the main app
|
|
let Some(render_app) = app.get_sub_app_mut(RenderApp) else {
|
|
return;
|
|
};
|
|
|
|
render_app
|
|
// Bevy's renderer uses a render graph which is a collection of nodes in a directed acyclic graph.
|
|
// It currently runs on each view/camera and executes each node in the specified order.
|
|
// It will make sure that any node that needs a dependency from another node
|
|
// only runs when that dependency is done.
|
|
//
|
|
// Each node can execute arbitrary work, but it generally runs at least one render pass.
|
|
// A node only has access to the render world, so if you need data from the main world
|
|
// you need to extract it manually or with the plugin like above.
|
|
// Add a [`Node`] to the [`RenderGraph`]
|
|
// The Node needs to impl FromWorld
|
|
//
|
|
// The [`ViewNodeRunner`] is a special [`Node`] that will automatically run the node for each view
|
|
// matching the [`ViewQuery`]
|
|
.add_render_graph_node::<ViewNodeRunner<PostProcessNode>>(
|
|
// Specify the label of the graph, in this case we want the graph for 3d
|
|
Core3d,
|
|
// It also needs the label of the node
|
|
PostProcessLabel,
|
|
)
|
|
.add_render_graph_edges(
|
|
Core3d,
|
|
// Specify the node ordering.
|
|
// This will automatically create all required node edges to enforce the given ordering.
|
|
(
|
|
Node3d::Tonemapping,
|
|
PostProcessLabel,
|
|
Node3d::EndMainPassPostProcessing,
|
|
),
|
|
);
|
|
}
|
|
|
|
fn finish(&self, app: &mut App) {
|
|
// We need to get the render app from the main app
|
|
let Some(render_app) = app.get_sub_app_mut(RenderApp) else {
|
|
return;
|
|
};
|
|
|
|
render_app
|
|
// Initialize the pipeline
|
|
.init_resource::<PostProcessPipeline>();
|
|
}
|
|
}
|
|
|
|
#[derive(Debug, Hash, PartialEq, Eq, Clone, RenderLabel)]
|
|
struct PostProcessLabel;
|
|
|
|
// The post process node used for the render graph
|
|
#[derive(Default)]
|
|
struct PostProcessNode;
|
|
|
|
// The ViewNode trait is required by the ViewNodeRunner
|
|
impl ViewNode for PostProcessNode {
|
|
// The node needs a query to gather data from the ECS in order to do its rendering,
|
|
// but it's not a normal system so we need to define it manually.
|
|
//
|
|
// This query will only run on the view entity
|
|
type ViewQuery = (
|
|
&'static ViewTarget,
|
|
// This makes sure the node only runs on cameras with the PostProcessSettings component
|
|
&'static PostProcessSettings,
|
|
);
|
|
|
|
// Runs the node logic
|
|
// This is where you encode draw commands.
|
|
//
|
|
// This will run on every view on which the graph is running.
|
|
// If you don't want your effect to run on every camera,
|
|
// you'll need to make sure you have a marker component as part of [`ViewQuery`]
|
|
// to identify which camera(s) should run the effect.
|
|
fn run(
|
|
&self,
|
|
_graph: &mut RenderGraphContext,
|
|
render_context: &mut RenderContext,
|
|
(view_target, _post_process_settings): QueryItem<Self::ViewQuery>,
|
|
world: &World,
|
|
) -> Result<(), NodeRunError> {
|
|
// Get the pipeline resource that contains the global data we need
|
|
// to create the render pipeline
|
|
let post_process_pipeline = world.resource::<PostProcessPipeline>();
|
|
|
|
// The pipeline cache is a cache of all previously created pipelines.
|
|
// It is required to avoid creating a new pipeline each frame,
|
|
// which is expensive due to shader compilation.
|
|
let pipeline_cache = world.resource::<PipelineCache>();
|
|
|
|
// Get the pipeline from the cache
|
|
let Some(pipeline) = pipeline_cache.get_render_pipeline(post_process_pipeline.pipeline_id)
|
|
else {
|
|
return Ok(());
|
|
};
|
|
|
|
// Get the settings uniform binding
|
|
let settings_uniforms = world.resource::<ComponentUniforms<PostProcessSettings>>();
|
|
let Some(settings_binding) = settings_uniforms.uniforms().binding() else {
|
|
return Ok(());
|
|
};
|
|
|
|
// This will start a new "post process write", obtaining two texture
|
|
// views from the view target - a `source` and a `destination`.
|
|
// `source` is the "current" main texture and you _must_ write into
|
|
// `destination` because calling `post_process_write()` on the
|
|
// [`ViewTarget`] will internally flip the [`ViewTarget`]'s main
|
|
// texture to the `destination` texture. Failing to do so will cause
|
|
// the current main texture information to be lost.
|
|
let post_process = view_target.post_process_write();
|
|
|
|
// The bind_group gets created each frame.
|
|
//
|
|
// Normally, you would create a bind_group in the Queue set,
|
|
// but this doesn't work with the post_process_write().
|
|
// The reason it doesn't work is because each post_process_write will alternate the source/destination.
|
|
// The only way to have the correct source/destination for the bind_group
|
|
// is to make sure you get it during the node execution.
|
|
let bind_group = render_context.render_device().create_bind_group(
|
|
"post_process_bind_group",
|
|
&post_process_pipeline.layout,
|
|
// It's important for this to match the BindGroupLayout defined in the PostProcessPipeline
|
|
&BindGroupEntries::sequential((
|
|
// Make sure to use the source view
|
|
post_process.source,
|
|
// Use the sampler created for the pipeline
|
|
&post_process_pipeline.sampler,
|
|
// Set the settings binding
|
|
settings_binding.clone(),
|
|
)),
|
|
);
|
|
|
|
// Begin the render pass
|
|
let mut render_pass = render_context.begin_tracked_render_pass(RenderPassDescriptor {
|
|
label: Some("post_process_pass"),
|
|
color_attachments: &[Some(RenderPassColorAttachment {
|
|
// We need to specify the post process destination view here
|
|
// to make sure we write to the appropriate texture.
|
|
view: post_process.destination,
|
|
resolve_target: None,
|
|
ops: Operations::default(),
|
|
})],
|
|
depth_stencil_attachment: None,
|
|
timestamp_writes: None,
|
|
occlusion_query_set: None,
|
|
});
|
|
|
|
// This is mostly just wgpu boilerplate for drawing a fullscreen triangle,
|
|
// using the pipeline/bind_group created above
|
|
render_pass.set_render_pipeline(pipeline);
|
|
render_pass.set_bind_group(0, &bind_group, &[]);
|
|
render_pass.draw(0..3, 0..1);
|
|
|
|
Ok(())
|
|
}
|
|
}
|
|
|
|
// This contains global data used by the render pipeline. This will be created once on startup.
|
|
#[derive(Resource)]
|
|
struct PostProcessPipeline {
|
|
layout: BindGroupLayout,
|
|
sampler: Sampler,
|
|
pipeline_id: CachedRenderPipelineId,
|
|
}
|
|
|
|
impl FromWorld for PostProcessPipeline {
|
|
fn from_world(world: &mut World) -> Self {
|
|
let render_device = world.resource::<RenderDevice>();
|
|
|
|
// We need to define the bind group layout used for our pipeline
|
|
let layout = render_device.create_bind_group_layout(
|
|
"post_process_bind_group_layout",
|
|
&BindGroupLayoutEntries::sequential(
|
|
// The layout entries will only be visible in the fragment stage
|
|
ShaderStages::FRAGMENT,
|
|
(
|
|
// The screen texture
|
|
texture_2d(TextureSampleType::Float { filterable: true }),
|
|
// The sampler that will be used to sample the screen texture
|
|
sampler(SamplerBindingType::Filtering),
|
|
// The settings uniform that will control the effect
|
|
uniform_buffer::<PostProcessSettings>(false),
|
|
),
|
|
),
|
|
);
|
|
|
|
// We can create the sampler here since it won't change at runtime and doesn't depend on the view
|
|
let sampler = render_device.create_sampler(&SamplerDescriptor::default());
|
|
|
|
// Get the shader handle
|
|
let shader = world.load_asset("shaders/post_processing.wgsl");
|
|
|
|
let pipeline_id = world
|
|
.resource_mut::<PipelineCache>()
|
|
// This will add the pipeline to the cache and queue it's creation
|
|
.queue_render_pipeline(RenderPipelineDescriptor {
|
|
label: Some("post_process_pipeline".into()),
|
|
layout: vec![layout.clone()],
|
|
// This will setup a fullscreen triangle for the vertex state
|
|
vertex: fullscreen_shader_vertex_state(),
|
|
fragment: Some(FragmentState {
|
|
shader,
|
|
shader_defs: vec![],
|
|
// Make sure this matches the entry point of your shader.
|
|
// It can be anything as long as it matches here and in the shader.
|
|
entry_point: "fragment".into(),
|
|
targets: vec![Some(ColorTargetState {
|
|
format: TextureFormat::bevy_default(),
|
|
blend: None,
|
|
write_mask: ColorWrites::ALL,
|
|
})],
|
|
}),
|
|
// All of the following properties are not important for this effect so just use the default values.
|
|
// This struct doesn't have the Default trait implemented because not all field can have a default value.
|
|
primitive: PrimitiveState::default(),
|
|
depth_stencil: None,
|
|
multisample: MultisampleState::default(),
|
|
push_constant_ranges: vec![],
|
|
});
|
|
|
|
Self {
|
|
layout,
|
|
sampler,
|
|
pipeline_id,
|
|
}
|
|
}
|
|
}
|
|
|
|
// This is the component that will get passed to the shader
|
|
#[derive(Component, Default, Clone, Copy, ExtractComponent, ShaderType)]
|
|
struct PostProcessSettings {
|
|
intensity: f32,
|
|
// WebGL2 structs must be 16 byte aligned.
|
|
#[cfg(feature = "webgl2")]
|
|
_webgl2_padding: Vec3,
|
|
}
|
|
|
|
/// Set up a simple 3D scene
|
|
fn setup(
|
|
mut commands: Commands,
|
|
mut meshes: ResMut<Assets<Mesh>>,
|
|
mut materials: ResMut<Assets<StandardMaterial>>,
|
|
) {
|
|
// camera
|
|
commands.spawn((
|
|
Camera3dBundle {
|
|
transform: Transform::from_translation(Vec3::new(0.0, 0.0, 5.0))
|
|
.looking_at(Vec3::default(), Vec3::Y),
|
|
camera: Camera {
|
|
clear_color: Color::WHITE.into(),
|
|
..default()
|
|
},
|
|
..default()
|
|
},
|
|
// Add the setting to the camera.
|
|
// This component is also used to determine on which camera to run the post processing effect.
|
|
PostProcessSettings {
|
|
intensity: 0.02,
|
|
..default()
|
|
},
|
|
));
|
|
|
|
// cube
|
|
commands.spawn((
|
|
PbrBundle {
|
|
mesh: meshes.add(Cuboid::default()),
|
|
material: materials.add(Color::srgb(0.8, 0.7, 0.6)),
|
|
transform: Transform::from_xyz(0.0, 0.5, 0.0),
|
|
..default()
|
|
},
|
|
Rotates,
|
|
));
|
|
// light
|
|
commands.spawn(DirectionalLightBundle {
|
|
directional_light: DirectionalLight {
|
|
illuminance: 1_000.,
|
|
..default()
|
|
},
|
|
..default()
|
|
});
|
|
}
|
|
|
|
#[derive(Component)]
|
|
struct Rotates;
|
|
|
|
/// Rotates any entity around the x and y axis
|
|
fn rotate(time: Res<Time>, mut query: Query<&mut Transform, With<Rotates>>) {
|
|
for mut transform in &mut query {
|
|
transform.rotate_x(0.55 * time.delta_seconds());
|
|
transform.rotate_z(0.15 * time.delta_seconds());
|
|
}
|
|
}
|
|
|
|
// Change the intensity over time to show that the effect is controlled from the main world
|
|
fn update_settings(mut settings: Query<&mut PostProcessSettings>, time: Res<Time>) {
|
|
for mut setting in &mut settings {
|
|
let mut intensity = time.elapsed_seconds().sin();
|
|
// Make it loop periodically
|
|
intensity = intensity.sin();
|
|
// Remap it to 0..1 because the intensity can't be negative
|
|
intensity = intensity * 0.5 + 0.5;
|
|
// Scale it to a more reasonable level
|
|
intensity *= 0.015;
|
|
|
|
// Set the intensity.
|
|
// This will then be extracted to the render world and uploaded to the gpu automatically by the [`UniformComponentPlugin`]
|
|
setting.intensity = intensity;
|
|
}
|
|
}
|