Struct InstanceBuffer 

pub struct InstanceBuffer {
    desc: InstanceStreamDesc,
    buffer: Option<Buffer>,
    capacity: u32,
    staging: StagingBuffer,
}

A reused vertex buffer holding one frame’s packed instance records.

The buffer grows geometrically and is reused between frames, so a steady scene allocates nothing. Bytes reach it through a StagingBuffer, the same path the camera and frame globals take.

Fields

desc: InstanceStreamDesc

Where the stream binds and how wide one record is.

buffer: Option<Buffer>

The buffer holding the last upload, allocated on the first one.

capacity: u32

How many records the buffer can hold.

staging: StagingBuffer

The staging buffers the uploads pass through.

Implementations

impl InstanceBuffer

pub fn new(desc: InstanceStreamDesc) -> Self

Create an empty stream for desc, allocating no GPU buffer until the first upload.

Panics

If desc names a stride that is not a multiple of [wgpu::VERTEX_ALIGNMENT], which a vertex-buffer layout cannot declare.

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

The buffer holding the last upload, or None before the first one.

pub fn upload( &mut self, device: &Device, encoder: &mut CommandEncoder, records: &[u8], )

Upload records as this frame’s instance stream.

A stream with no stride uploads nothing, and so does an empty one: a family with no visible instances binds no buffer, exactly as one that declares no stream does.

Panics

If records.len() is not a whole number of records.

fn reserve(&mut self, device: &Device, count: u32)

Grow the buffer geometrically so it can hold count records.