Struct bevy::render::render_resource::CommandEncoder

pub struct CommandEncoder { /* private fields */ }

Encodes a series of GPU operations.

A command encoder can record RenderPasses, ComputePasses, and transfer operations between driver-managed resources like Buffers and Textures.

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

Corresponds to WebGPU GPUCommandEncoder.

Implementations

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)

    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 286-289)

    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
                .buffer()
                .expect("Buffer should have already been uploaded to the gpu"),
            0,
            &buffers.cpu_buffer,
            0,
            (BUFFER_LEN * std::mem::size_of::<u32>()) as u64,
        );

        Ok(())
    }

examples/shader/compute_shader_game_of_life.rs (line 267)

    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 298-307)

    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
                .buffer()
                .expect("Buffer should have already been uploaded to the gpu"),
            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)

    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.

pub unsafe fn as_hal_mut<A, F, R>( &mut self, hal_command_encoder_callback: F, ) -> Option<R>

where A: HalApi, F: FnOnce(Option<&mut <A as Api>::CommandEncoder>) -> R,

Available on wgpu_core only.

Returns the inner hal CommandEncoder using a callback. The hal command encoder will be None if the backend type argument does not match with this wgpu CommandEncoder

This method will start the wgpu_core level command recording.

Safety

• The raw handle obtained from the hal CommandEncoder must not be manually destroyed

impl CommandEncoder

Features::TIMESTAMP_QUERY_INSIDE_ENCODERS 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.

Attention: Since commands within a command recorder may be reordered, there is no strict guarantee that timestamps are taken after all commands recorded so far and all before all commands recorded after. This may depend both on the backend and the driver.

Trait Implementations

impl Debug for CommandEncoder

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

Formats the value using the given formatter.

impl Drop for CommandEncoder

fn drop(&mut self)

Executes the destructor for this type.