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