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|
use std::marker::PhantomData;
use std::ops::RangeBounds;
pub const MAX_WRITE_SIZE: usize = 1024 * 100;
#[derive(Debug)]
pub struct Buffer<T> {
label: &'static str,
size: u64,
usage: wgpu::BufferUsages,
pub(crate) raw: wgpu::Buffer,
offsets: Vec<wgpu::BufferAddress>,
type_: PhantomData<T>,
}
impl<T: bytemuck::Pod> Buffer<T> {
pub fn new(
device: &wgpu::Device,
label: &'static str,
amount: usize,
usage: wgpu::BufferUsages,
) -> Self {
let size = next_copy_size::<T>(amount);
let raw = device.create_buffer(&wgpu::BufferDescriptor {
label: Some(label),
size,
usage,
mapped_at_creation: false,
});
Self {
label,
size,
usage,
raw,
offsets: Vec::new(),
type_: PhantomData,
}
}
pub fn resize(&mut self, device: &wgpu::Device, new_count: usize) -> bool {
let new_size = (std::mem::size_of::<T>() * new_count) as u64;
if self.size < new_size {
self.offsets.clear();
self.raw = device.create_buffer(&wgpu::BufferDescriptor {
label: Some(self.label),
size: new_size,
usage: self.usage,
mapped_at_creation: false,
});
self.size = new_size;
true
} else {
false
}
}
/// Returns the size of the written bytes.
pub fn write(
&mut self,
device: &wgpu::Device,
encoder: &mut wgpu::CommandEncoder,
belt: &mut wgpu::util::StagingBelt,
offset: usize,
contents: &[T],
) -> usize {
let bytes: &[u8] = bytemuck::cast_slice(contents);
if bytes.len() <= MAX_WRITE_SIZE {
belt.write_buffer(
encoder,
&self.raw,
offset as u64,
(bytes.len() as u64).try_into().expect("Non-empty write"),
device,
)
.copy_from_slice(bytes);
} else {
let mut bytes_written = 0;
let bytes_per_chunk = (bytes.len().min(MAX_WRITE_SIZE) as u64)
.try_into()
.expect("Non-empty write");
while bytes_written < bytes.len() {
belt.write_buffer(
encoder,
&self.raw,
(offset + bytes_written) as u64,
bytes_per_chunk,
device,
)
.copy_from_slice(
&bytes[bytes_written
..bytes_written + bytes_per_chunk.get() as usize],
);
bytes_written += bytes_per_chunk.get() as usize;
}
}
self.offsets.push(offset as u64);
bytes.len()
}
pub fn slice(
&self,
bounds: impl RangeBounds<wgpu::BufferAddress>,
) -> wgpu::BufferSlice<'_> {
self.raw.slice(bounds)
}
/// Returns the slice calculated from the offset stored at the given index.
pub fn slice_from_index(&self, index: usize) -> wgpu::BufferSlice<'_> {
self.raw.slice(self.offset_at(index)..)
}
/// Clears any temporary data (i.e. offsets) from the buffer.
pub fn clear(&mut self) {
self.offsets.clear();
}
/// Returns the offset at `index`, if it exists.
fn offset_at(&self, index: usize) -> &wgpu::BufferAddress {
self.offsets.get(index).expect("No offset at index.")
}
}
fn next_copy_size<T>(amount: usize) -> u64 {
let align_mask = wgpu::COPY_BUFFER_ALIGNMENT - 1;
(((std::mem::size_of::<T>() * amount).next_power_of_two() as u64
+ align_mask)
& !align_mask)
.max(wgpu::COPY_BUFFER_ALIGNMENT)
}
|
