Struct bevy::render::render_resource::CommandEncoder

pub struct CommandEncoder { /* private fields */ }
Expand description

Encodes a series of GPU operations.

A command encoder can record [RenderPass]es, ComputePasses, and transfer operations between driver-managed resources like [Buffer]s and [Texture]s.

When finished recording, call CommandEncoder::finish to obtain a [CommandBuffer] which may be submitted for execution.

Corresponds to WebGPU GPUCommandEncoder.

Implementations§

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impl CommandEncoder

pub fn finish(self) -> CommandBuffer

Finishes recording and returns a [CommandBuffer] that can be submitted for execution.

Examples found in repository?
examples/app/headless_renderer.rs (line 395)
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    fn run(
        &self,
        _graph: &mut RenderGraphContext,
        render_context: &mut RenderContext,
        world: &World,
    ) -> Result<(), NodeRunError> {
        let image_copiers = world.get_resource::<ImageCopiers>().unwrap();
        let gpu_images = world
            .get_resource::<RenderAssets<bevy::render::texture::GpuImage>>()
            .unwrap();

        for image_copier in image_copiers.iter() {
            if !image_copier.enabled() {
                continue;
            }

            let src_image = gpu_images.get(&image_copier.src_image).unwrap();

            let mut encoder = render_context
                .render_device()
                .create_command_encoder(&CommandEncoderDescriptor::default());

            let block_dimensions = src_image.texture_format.block_dimensions();
            let block_size = src_image.texture_format.block_copy_size(None).unwrap();

            // Calculating correct size of image row because
            // copy_texture_to_buffer can copy image only by rows aligned wgpu::COPY_BYTES_PER_ROW_ALIGNMENT
            // That's why image in buffer can be little bit wider
            // This should be taken into account at copy from buffer stage
            let padded_bytes_per_row = RenderDevice::align_copy_bytes_per_row(
                (src_image.size.x as usize / block_dimensions.0 as usize) * block_size as usize,
            );

            let texture_extent = Extent3d {
                width: src_image.size.x,
                height: src_image.size.y,
                depth_or_array_layers: 1,
            };

            encoder.copy_texture_to_buffer(
                src_image.texture.as_image_copy(),
                ImageCopyBuffer {
                    buffer: &image_copier.buffer,
                    layout: ImageDataLayout {
                        offset: 0,
                        bytes_per_row: Some(
                            std::num::NonZeroU32::new(padded_bytes_per_row as u32)
                                .unwrap()
                                .into(),
                        ),
                        rows_per_image: None,
                    },
                },
                texture_extent,
            );

            let render_queue = world.get_resource::<RenderQueue>().unwrap();
            render_queue.submit(std::iter::once(encoder.finish()));
        }

        Ok(())
    }

pub fn begin_render_pass<'pass>( &'pass mut self, desc: &RenderPassDescriptor<'pass, '_> ) -> RenderPass<'pass>

Begins recording of a render pass.

This function returns a [RenderPass] object which records a single render pass.

pub fn begin_compute_pass( &mut self, desc: &ComputePassDescriptor<'_> ) -> ComputePass<'_>

Begins recording of a compute pass.

This function returns a ComputePass object which records a single compute pass.

Examples found in repository?
examples/shader/gpu_readback.rs (lines 275-278)
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    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);
        }

        // Copy the gpu accessible buffer to the cpu accessible buffer
        let buffers = world.resource::<Buffers>();
        render_context.command_encoder().copy_buffer_to_buffer(
            &buffers.gpu_buffer,
            0,
            &buffers.cpu_buffer,
            0,
            (BUFFER_LEN * std::mem::size_of::<u32>()) as u64,
        );

        Ok(())
    }
More examples
Hide additional examples
examples/shader/compute_shader_game_of_life.rs (line 260)
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    fn run(
        &self,
        _graph: &mut render_graph::RenderGraphContext,
        render_context: &mut RenderContext,
        world: &World,
    ) -> Result<(), render_graph::NodeRunError> {
        let bind_groups = &world.resource::<GameOfLifeImageBindGroups>().0;
        let pipeline_cache = world.resource::<PipelineCache>();
        let pipeline = world.resource::<GameOfLifePipeline>();

        let mut pass = render_context
            .command_encoder()
            .begin_compute_pass(&ComputePassDescriptor::default());

        // select the pipeline based on the current state
        match self.state {
            GameOfLifeState::Loading => {}
            GameOfLifeState::Init => {
                let init_pipeline = pipeline_cache
                    .get_compute_pipeline(pipeline.init_pipeline)
                    .unwrap();
                pass.set_bind_group(0, &bind_groups[0], &[]);
                pass.set_pipeline(init_pipeline);
                pass.dispatch_workgroups(SIZE.0 / WORKGROUP_SIZE, SIZE.1 / WORKGROUP_SIZE, 1);
            }
            GameOfLifeState::Update(index) => {
                let update_pipeline = pipeline_cache
                    .get_compute_pipeline(pipeline.update_pipeline)
                    .unwrap();
                pass.set_bind_group(0, &bind_groups[index], &[]);
                pass.set_pipeline(update_pipeline);
                pass.dispatch_workgroups(SIZE.0 / WORKGROUP_SIZE, SIZE.1 / WORKGROUP_SIZE, 1);
            }
        }

        Ok(())
    }

pub fn copy_buffer_to_buffer( &mut self, source: &Buffer, source_offset: u64, destination: &Buffer, destination_offset: u64, copy_size: u64 )

Copy data from one buffer to another.

§Panics
  • Buffer offsets or copy size not a multiple of COPY_BUFFER_ALIGNMENT.
  • Copy would overrun buffer.
  • Copy within the same buffer.
Examples found in repository?
examples/shader/gpu_readback.rs (lines 287-293)
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    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);
        }

        // Copy the gpu accessible buffer to the cpu accessible buffer
        let buffers = world.resource::<Buffers>();
        render_context.command_encoder().copy_buffer_to_buffer(
            &buffers.gpu_buffer,
            0,
            &buffers.cpu_buffer,
            0,
            (BUFFER_LEN * std::mem::size_of::<u32>()) as u64,
        );

        Ok(())
    }

pub fn copy_buffer_to_texture( &mut self, source: ImageCopyBuffer<&Buffer>, destination: ImageCopyTexture<&Texture>, copy_size: Extent3d )

Copy data from a buffer to a texture.

pub fn copy_texture_to_buffer( &mut self, source: ImageCopyTexture<&Texture>, destination: ImageCopyBuffer<&Buffer>, copy_size: Extent3d )

Copy data from a texture to a buffer.

Examples found in repository?
examples/app/headless_renderer.rs (lines 377-392)
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    fn run(
        &self,
        _graph: &mut RenderGraphContext,
        render_context: &mut RenderContext,
        world: &World,
    ) -> Result<(), NodeRunError> {
        let image_copiers = world.get_resource::<ImageCopiers>().unwrap();
        let gpu_images = world
            .get_resource::<RenderAssets<bevy::render::texture::GpuImage>>()
            .unwrap();

        for image_copier in image_copiers.iter() {
            if !image_copier.enabled() {
                continue;
            }

            let src_image = gpu_images.get(&image_copier.src_image).unwrap();

            let mut encoder = render_context
                .render_device()
                .create_command_encoder(&CommandEncoderDescriptor::default());

            let block_dimensions = src_image.texture_format.block_dimensions();
            let block_size = src_image.texture_format.block_copy_size(None).unwrap();

            // Calculating correct size of image row because
            // copy_texture_to_buffer can copy image only by rows aligned wgpu::COPY_BYTES_PER_ROW_ALIGNMENT
            // That's why image in buffer can be little bit wider
            // This should be taken into account at copy from buffer stage
            let padded_bytes_per_row = RenderDevice::align_copy_bytes_per_row(
                (src_image.size.x as usize / block_dimensions.0 as usize) * block_size as usize,
            );

            let texture_extent = Extent3d {
                width: src_image.size.x,
                height: src_image.size.y,
                depth_or_array_layers: 1,
            };

            encoder.copy_texture_to_buffer(
                src_image.texture.as_image_copy(),
                ImageCopyBuffer {
                    buffer: &image_copier.buffer,
                    layout: ImageDataLayout {
                        offset: 0,
                        bytes_per_row: Some(
                            std::num::NonZeroU32::new(padded_bytes_per_row as u32)
                                .unwrap()
                                .into(),
                        ),
                        rows_per_image: None,
                    },
                },
                texture_extent,
            );

            let render_queue = world.get_resource::<RenderQueue>().unwrap();
            render_queue.submit(std::iter::once(encoder.finish()));
        }

        Ok(())
    }

pub fn copy_texture_to_texture( &mut self, source: ImageCopyTexture<&Texture>, destination: ImageCopyTexture<&Texture>, copy_size: Extent3d )

Copy data from one texture to another.

§Panics
  • Textures are not the same type
  • If a depth texture, or a multisampled texture, the entire texture must be copied
  • Copy would overrun either texture

pub fn clear_texture( &mut self, texture: &Texture, subresource_range: &ImageSubresourceRange )

Clears texture to zero.

Note that unlike with clear_buffer, COPY_DST usage is not required.

§Implementation notes
  • implemented either via buffer copies and render/depth target clear, path depends on texture usages
  • behaves like texture zero init, but is performed immediately (clearing is not delayed via marking it as uninitialized)
§Panics
  • CLEAR_TEXTURE extension not enabled
  • Range is out of bounds

pub fn clear_buffer(&mut self, buffer: &Buffer, offset: u64, size: Option<u64>)

Clears buffer to zero.

§Panics
  • Buffer does not have COPY_DST usage.
  • Range is out of bounds

pub fn insert_debug_marker(&mut self, label: &str)

Inserts debug marker.

pub fn push_debug_group(&mut self, label: &str)

Start record commands and group it into debug marker group.

pub fn pop_debug_group(&mut self)

Stops command recording and creates debug group.

pub fn resolve_query_set( &mut self, query_set: &QuerySet, query_range: Range<u32>, destination: &Buffer, destination_offset: u64 )

Resolves a query set, writing the results into the supplied destination buffer.

Occlusion and timestamp queries are 8 bytes each (see [crate::QUERY_SIZE]). For pipeline statistics queries, see [PipelineStatisticsTypes] for more information.

§

impl CommandEncoder

Features::TIMESTAMP_QUERY must be enabled on the device in order to call these functions.

pub fn write_timestamp(&mut self, query_set: &QuerySet, query_index: u32)

Issue a timestamp command at this point in the queue. The timestamp will be written to the specified query set, at the specified index.

Must be multiplied by [Queue::get_timestamp_period] to get the value in nanoseconds. Absolute values have no meaning, but timestamps can be subtracted to get the time it takes for a string of operations to complete.

Trait Implementations§

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impl Debug for CommandEncoder

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fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter. Read more
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impl Drop for CommandEncoder

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fn drop(&mut self)

Executes the destructor for this type. Read more

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fn as_bind_group_shader_type(&self, _images: &RenderAssets<GpuImage>) -> U

Return the T ShaderType for self. When used in AsBindGroup derives, it is safe to assume that all images in self exist.
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