2
0
Fork 0
mirror of https://github.com/bevyengine/bevy synced 2024-12-28 14:03:08 +00:00
bevy/examples/shader/gpu_readback.rs
Benjamin Brienen 40640fdf42
Don't reëxport bevy_image from bevy_render ()
# Objective

Fixes 

## Solution

Remove the `pub use` and fix the compile errors.
Make `bevy_image` available as `bevy::image`.

## Testing

Feature Frenzy would be good here! Maybe I'll learn how to use it if I
have some time this weekend, or maybe a reviewer can use it.

## Migration Guide

Use `bevy_image` instead of `bevy_render::texture` items.

---------

Co-authored-by: chompaa <antony.m.3012@gmail.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2024-11-10 06:54:38 +00:00

221 lines
7.9 KiB
Rust

//! Simple example demonstrating the use of the [`Readback`] component to read back data from the GPU
//! using both a storage buffer and texture.
use bevy::{
prelude::*,
render::{
extract_resource::{ExtractResource, ExtractResourcePlugin},
gpu_readback::{Readback, ReadbackComplete},
render_asset::{RenderAssetUsages, RenderAssets},
render_graph::{self, RenderGraph, RenderLabel},
render_resource::{
binding_types::{storage_buffer, texture_storage_2d},
*,
},
renderer::{RenderContext, RenderDevice},
storage::{GpuShaderStorageBuffer, ShaderStorageBuffer},
texture::GpuImage,
Render, RenderApp, RenderSet,
},
};
/// This example uses a shader source file from the assets subdirectory
const SHADER_ASSET_PATH: &str = "shaders/gpu_readback.wgsl";
// The length of the buffer sent to the gpu
const BUFFER_LEN: usize = 16;
fn main() {
App::new()
.add_plugins((
DefaultPlugins,
GpuReadbackPlugin,
ExtractResourcePlugin::<ReadbackBuffer>::default(),
ExtractResourcePlugin::<ReadbackImage>::default(),
))
.insert_resource(ClearColor(Color::BLACK))
.add_systems(Startup, setup)
.run();
}
// We need a plugin to organize all the systems and render node required for this example
struct GpuReadbackPlugin;
impl Plugin for GpuReadbackPlugin {
fn build(&self, _app: &mut App) {}
fn finish(&self, app: &mut App) {
let render_app = app.sub_app_mut(RenderApp);
render_app.init_resource::<ComputePipeline>().add_systems(
Render,
prepare_bind_group
.in_set(RenderSet::PrepareBindGroups)
// We don't need to recreate the bind group every frame
.run_if(not(resource_exists::<GpuBufferBindGroup>)),
);
// Add the compute node as a top level node to the render graph
// This means it will only execute once per frame
render_app
.world_mut()
.resource_mut::<RenderGraph>()
.add_node(ComputeNodeLabel, ComputeNode::default());
}
}
#[derive(Resource, ExtractResource, Clone)]
struct ReadbackBuffer(Handle<ShaderStorageBuffer>);
#[derive(Resource, ExtractResource, Clone)]
struct ReadbackImage(Handle<Image>);
fn setup(
mut commands: Commands,
mut images: ResMut<Assets<Image>>,
mut buffers: ResMut<Assets<ShaderStorageBuffer>>,
) {
// Create a storage buffer with some data
let buffer = vec![0u32; BUFFER_LEN];
let mut buffer = ShaderStorageBuffer::from(buffer);
// We need to enable the COPY_SRC usage so we can copy the buffer to the cpu
buffer.buffer_description.usage |= BufferUsages::COPY_SRC;
let buffer = buffers.add(buffer);
// Create a storage texture with some data
let size = Extent3d {
width: BUFFER_LEN as u32,
height: 1,
..default()
};
let mut image = Image::new_fill(
size,
TextureDimension::D2,
&[0, 0, 0, 0],
TextureFormat::R32Uint,
RenderAssetUsages::RENDER_WORLD,
);
// We also need to enable the COPY_SRC, as well as STORAGE_BINDING so we can use it in the
// compute shader
image.texture_descriptor.usage |= TextureUsages::COPY_SRC | TextureUsages::STORAGE_BINDING;
let image = images.add(image);
// Spawn the readback components. For each frame, the data will be read back from the GPU
// asynchronously and trigger the `ReadbackComplete` event on this entity. Despawn the entity
// to stop reading back the data.
commands.spawn(Readback::buffer(buffer.clone())).observe(
|trigger: Trigger<ReadbackComplete>| {
// This matches the type which was used to create the `ShaderStorageBuffer` above,
// and is a convenient way to interpret the data.
let data: Vec<u32> = trigger.event().to_shader_type();
info!("Buffer {:?}", data);
},
);
// This is just a simple way to pass the buffer handle to the render app for our compute node
commands.insert_resource(ReadbackBuffer(buffer));
// Textures can also be read back from the GPU. Pay careful attention to the format of the
// texture, as it will affect how the data is interpreted.
commands.spawn(Readback::texture(image.clone())).observe(
|trigger: Trigger<ReadbackComplete>| {
// You probably want to interpret the data as a color rather than a `ShaderType`,
// but in this case we know the data is a single channel storage texture, so we can
// interpret it as a `Vec<u32>`
let data: Vec<u32> = trigger.event().to_shader_type();
info!("Image {:?}", data);
},
);
commands.insert_resource(ReadbackImage(image));
}
#[derive(Resource)]
struct GpuBufferBindGroup(BindGroup);
fn prepare_bind_group(
mut commands: Commands,
pipeline: Res<ComputePipeline>,
render_device: Res<RenderDevice>,
buffer: Res<ReadbackBuffer>,
image: Res<ReadbackImage>,
buffers: Res<RenderAssets<GpuShaderStorageBuffer>>,
images: Res<RenderAssets<GpuImage>>,
) {
let buffer = buffers.get(&buffer.0).unwrap();
let image = images.get(&image.0).unwrap();
let bind_group = render_device.create_bind_group(
None,
&pipeline.layout,
&BindGroupEntries::sequential((
buffer.buffer.as_entire_buffer_binding(),
image.texture_view.into_binding(),
)),
);
commands.insert_resource(GpuBufferBindGroup(bind_group));
}
#[derive(Resource)]
struct ComputePipeline {
layout: BindGroupLayout,
pipeline: CachedComputePipelineId,
}
impl FromWorld for ComputePipeline {
fn from_world(world: &mut World) -> Self {
let render_device = world.resource::<RenderDevice>();
let layout = render_device.create_bind_group_layout(
None,
&BindGroupLayoutEntries::sequential(
ShaderStages::COMPUTE,
(
storage_buffer::<Vec<u32>>(false),
texture_storage_2d(TextureFormat::R32Uint, StorageTextureAccess::WriteOnly),
),
),
);
let shader = world.load_asset(SHADER_ASSET_PATH);
let pipeline_cache = world.resource::<PipelineCache>();
let pipeline = pipeline_cache.queue_compute_pipeline(ComputePipelineDescriptor {
label: Some("GPU readback compute shader".into()),
layout: vec![layout.clone()],
push_constant_ranges: Vec::new(),
shader: shader.clone(),
shader_defs: Vec::new(),
entry_point: "main".into(),
zero_initialize_workgroup_memory: false,
});
ComputePipeline { layout, pipeline }
}
}
/// Label to identify the node in the render graph
#[derive(Debug, Hash, PartialEq, Eq, Clone, RenderLabel)]
struct ComputeNodeLabel;
/// The node that will execute the compute shader
#[derive(Default)]
struct ComputeNode {}
impl render_graph::Node for ComputeNode {
fn run(
&self,
_graph: &mut render_graph::RenderGraphContext,
render_context: &mut RenderContext,
world: &World,
) -> Result<(), render_graph::NodeRunError> {
let pipeline_cache = world.resource::<PipelineCache>();
let pipeline = world.resource::<ComputePipeline>();
let bind_group = world.resource::<GpuBufferBindGroup>();
if let Some(init_pipeline) = pipeline_cache.get_compute_pipeline(pipeline.pipeline) {
let mut pass =
render_context
.command_encoder()
.begin_compute_pass(&ComputePassDescriptor {
label: Some("GPU readback compute pass"),
..default()
});
pass.set_bind_group(0, &bind_group.0, &[]);
pass.set_pipeline(init_pipeline);
pass.dispatch_workgroups(BUFFER_LEN as u32, 1, 1);
}
Ok(())
}
}