Struct HostBuffer 

pub struct HostBuffer<B = Buffer> { /* private fields */ }

One growable GPU buffer plus the CPU-side staging vector a frame bump- allocates into.

Generic over the buffer type (B) for the same reason crate::texture::Texture is generic over its texture: the bump pointer, alignment, growth and flush behavior are exercised on a host with a stand-in value. The engine always uses the default HostBuffer<wgpu::Buffer>.

Implementations

impl<B> HostBuffer<B>

pub fn new(caps: &TierCaps) -> Self

An empty arena aligned for caps’ adapter. No GPU buffer exists until the first Self::flush that has bytes to upload.

pub fn with_label(caps: &TierCaps, label: &str) -> Self

Self::new with a caller-chosen debug label on the GPU buffer, for a host that runs more than one arena and wants to tell them apart in a graphics debugger.

pub fn alloc(&mut self, bytes: &[u8], align: u32) -> BufferSlice

Appends bytes to this frame’s data and returns the slice they occupy.

The offset is rounded up to max(align, min_uniform_buffer_offset_alignment), so a caller passes the alignment its own use needs (a vertex stride, 1 for “no opinion”) and never has to know the adapter’s. Padding bytes are zero-filled.

pub fn reset(&mut self)

Rewinds the bump pointer for a new frame, keeping the GPU buffer and its capacity.

Every BufferSlice handed out before this call is stale afterwards — the next frame’s allocations reuse those offsets.

pub fn flush<U>(&mut self, uploader: &U) -> Option<&B>

where U: BufferUploader<Buffer = B>,

Uploads this frame’s bytes in one write_buffer, growing (or creating) the GPU buffer first if the frame outgrew it, and returns the buffer the frame’s BufferSlice offsets refer to.

Answers None only when nothing has ever been allocated, so there is no buffer to name. Call once per frame, after the frame’s last Self::alloc and before submitting commands that read it.

pub fn buffer(&self) -> Option<&B>

The GPU buffer backing the arena, once one exists.

pub fn used(&self) -> u64

Bytes allocated so far this frame, padding included.

pub fn capacity(&self) -> u64

The GPU buffer’s current size in bytes, 0 before the first flush.

pub fn high_water_mark(&self) -> u64

The largest single frame the arena has ever held, in bytes — what a host would size an initial capacity against.

pub fn buffer_allocations(&self) -> u64

How many times a GPU buffer has been created: one for the first non-empty frame, plus one per growth. A steady-state frame loop leaves this constant.

pub fn flush_count(&self) -> u64

How many uploads the arena has issued — one per non-empty flush.

pub fn min_alignment(&self) -> u32

The alignment floor every slice is rounded up to, from the adapter’s min_uniform_buffer_offset_alignment.

Trait Implementations

impl<B: Debug> Debug for HostBuffer<B>

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

Formats the value using the given formatter.