Struct BufferSlice

pub struct BufferSlice<'a> {
    pub(crate) buffer: &'a Buffer,
    pub(crate) offset: BufferAddress,
    pub(crate) size: BufferSize,
}

A slice of a Buffer, to be mapped, used for vertex or index data, or the like.

You can create a BufferSlice by calling Buffer::slice:

let slice = buffer.slice(10..20);

This returns a slice referring to the second ten bytes of buffer. To get a slice of the entire Buffer:

let whole_buffer_slice = buffer.slice(..);

You can pass buffer slices to methods like RenderPass::set_vertex_buffer and RenderPass::set_index_buffer to indicate which portion of the buffer a draw call should consult. You can also convert it to a BufferBinding with .into().

To access the slice’s contents on the CPU, you must first map the buffer, and then call BufferSlice::get_mapped_range or BufferSlice::get_mapped_range_mut to obtain a view of the slice’s contents. See the documentation on mapping for more details, including example code.

Unlike a Rust shared slice &[T], whose existence guarantees that nobody else is modifying the T values to which it refers, a BufferSlice doesn’t guarantee that the buffer’s contents aren’t changing. You can still record and submit commands operating on the buffer while holding a BufferSlice. A BufferSlice simply represents a certain range of the buffer’s bytes.

The BufferSlice type is unique to the Rust API of wgpu. In the WebGPU specification, an offset and size are specified as arguments to each call working with the Buffer, instead.

Fields

buffer: &'a Buffer

offset: BufferAddress

size: BufferSize

Implementations

impl<'a> BufferSlice<'a>

pub fn slice<S: RangeBounds<BufferAddress>>(&self, bounds: S) -> BufferSlice<'a>

Return another BufferSlice referring to the portion of self’s contents indicated by bounds.

The range argument can be half or fully unbounded: for example, buffer.slice(..) refers to the entire buffer, and buffer.slice(n..) refers to the portion starting at the nth byte and extending to the end of the buffer.

Panics

• If bounds is outside of the bounds of self.
• If bounds has a length less than 1.

pub fn map_async( &self, mode: MapMode, callback: impl FnOnce(Result<(), BufferAsyncError>) + WasmNotSend + 'static, )

Map the buffer to host (CPU) memory, making it available for reading or writing via get_mapped_range(). The buffer becomes accessible once the callback is invoked with Ok.

Use this when you want to map the buffer immediately. If you need to submit GPU work that uses the buffer before mapping it, use map_buffer_on_submit on CommandEncoder, CommandBuffer, RenderPass, or ComputePass to schedule the mapping after submission. This avoids extra calls to Buffer::map_async() or BufferSlice::map_async() and lets you initiate mapping from a more convenient place.

For the callback to run, either queue.submit(..), instance.poll_all(..), or device.poll(..) must be called elsewhere in the runtime, possibly integrated into an event loop or run on a separate thread.

The callback runs on the thread that first calls one of the above functions after the GPU work completes. There are no restrictions on the code you can run in the callback; however, on native the polling call will not return until the callback finishes, so keep callbacks short (set flags, send messages, etc.).

While a buffer is mapped, it cannot be used by other commands; at any time, either the GPU or the CPU has exclusive access to the buffer’s contents.

This can also be performed using Buffer::map_async().

Panics

• If the buffer is already mapped.
• If the buffer’s BufferUsages do not allow the requested MapMode.
• If the endpoints of this slice are not aligned to MAP_ALIGNMENT within the buffer.

pub fn get_mapped_range(&self) -> BufferView

Gain read-only access to the bytes of a mapped Buffer.

Returns a BufferView referring to the buffer range represented by self. See the documentation for BufferView for details.

Multiple views may be obtained and used simultaneously as long as they are from non-overlapping slices.

This can also be performed using Buffer::get_mapped_range().

Panics

• If the endpoints of this slice are not aligned to MAP_ALIGNMENT within the buffer.
• If the buffer to which self refers is not currently mapped.
• If you try to create a view which overlaps an existing BufferViewMut.

pub fn get_mapped_range_mut(&self) -> BufferViewMut

Gain write access to the bytes of a mapped Buffer.

Returns a BufferViewMut referring to the buffer range represented by self. See the documentation for BufferViewMut for more details.

Multiple views may be obtained and used simultaneously as long as they are from non-overlapping slices.

This can also be performed using Buffer::get_mapped_range_mut().

Panics

• If the endpoints of this slice are not aligned to MAP_ALIGNMENT.
• If the buffer to which self refers is not currently mapped.
• If you try to create a view which overlaps an existing BufferView or BufferViewMut.

pub fn buffer(&self) -> &'a Buffer

Returns the buffer this is a slice of.

You should usually not need to call this, and if you received the buffer from code you do not control, you should refrain from accessing the buffer outside the bounds of the slice. Nevertheless, it’s possible to get this access, so this method makes it simple.

pub fn offset(&self) -> BufferAddress

Returns the offset in Self::buffer() this slice starts at.

pub fn size(&self) -> BufferSize

Returns the size of this slice.

Trait Implementations

impl<'a> Clone for BufferSlice<'a>

fn clone(&self) -> BufferSlice<'a>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<'a> Debug for BufferSlice<'a>

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

Formats the value using the given formatter.

impl<'a> From<BufferSlice<'a>> for BindingResource<'a>

fn from(value: BufferSlice<'a>) -> Self

Convert a BufferSlice to an equivalent BindingResource::Buffer, provided that it will be used without a dynamic offset.

impl<'a> From<BufferSlice<'a>> for BufferBinding<'a>

fn from(value: BufferSlice<'a>) -> Self

Convert a BufferSlice to an equivalent BufferBinding, provided that it will be used without a dynamic offset.

impl<'a> PartialEq for BufferSlice<'a>

fn eq(&self, other: &BufferSlice<'a>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<'a> Copy for BufferSlice<'a>

impl<'a> StructuralPartialEq for BufferSlice<'a>