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Move initializing the ComputePipeline and adding to the render graph to build for gpu_readback example.

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This commit is contained in:
andriyDev 2025-07-13 13:56:06 -07:00
parent 4fc5e440aa
commit ab5a35a677
1 changed files with 46 additions and 40 deletions
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86
examples/shader/gpu_readback.rs
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@ -15,7 +15,7 @@ use bevy::{
renderer::{RenderContext, RenderDevice},
storage::{GpuShaderStorageBuffer, ShaderStorageBuffer},
texture::GpuImage,
Render, RenderApp, RenderSystems,
Render, RenderApp, RenderStartup, RenderSystems,
},
};
@ -41,24 +41,22 @@ fn main() {
// 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(RenderSystems::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
fn build(&self, app: &mut App) {
let Some(render_app) = app.get_sub_app_mut(RenderApp) else {
return;
};
render_app
.world_mut()
.resource_mut::<RenderGraph>()
.add_node(ComputeNodeLabel, ComputeNode::default());
.add_systems(
RenderStartup,
(init_compute_pipeline, add_compute_render_graph_node),
)
.add_systems(
Render,
prepare_bind_group
.in_set(RenderSystems::PrepareBindGroups)
// We don't need to recreate the bind group every frame
.run_if(not(resource_exists::<GpuBufferBindGroup>)),
);
}
}
@ -127,6 +125,13 @@ fn setup(
commands.insert_resource(ReadbackImage(image));
}
fn add_compute_render_graph_node(mut render_graph: ResMut<RenderGraph>) {
// Add the compute node as a top-level node to the render graph. This means it will only execute
// once per frame. Normally, adding a node would use the `RenderGraphApp::add_render_graph_node`
// method, but it does not allow adding as a top-level node.
render_graph.add_node(ComputeNodeLabel, ComputeNode::default());
}
#[derive(Resource)]
struct GpuBufferBindGroup(BindGroup);
@ -158,29 +163,30 @@ struct ComputePipeline {
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),
),
fn init_compute_pipeline(
mut commands: Commands,
render_device: Res<RenderDevice>,
asset_server: Res<AssetServer>,
pipeline_cache: Res<PipelineCache>,
) {
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()],
shader: shader.clone(),
..default()
});
ComputePipeline { layout, pipeline }
}
),
);
let shader = asset_server.load(SHADER_ASSET_PATH);
let pipeline = pipeline_cache.queue_compute_pipeline(ComputePipelineDescriptor {
label: Some("GPU readback compute shader".into()),
layout: vec![layout.clone()],
shader: shader.clone(),
..default()
});
commands.insert_resource(ComputePipeline { layout, pipeline });
}
/// Label to identify the node in the render graph