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use std::{marker::PhantomData, num::NonZeroU64};
use crate::{
render_resource::Buffer,
renderer::{RenderDevice, RenderQueue},
};
use encase::{
internal::{AlignmentValue, BufferMut, WriteInto},
DynamicUniformBuffer as DynamicUniformBufferWrapper, ShaderType,
UniformBuffer as UniformBufferWrapper,
};
use wgpu::{
util::BufferInitDescriptor, BindingResource, BufferBinding, BufferDescriptor, BufferUsages,
};
use super::IntoBinding;
/// Stores data to be transferred to the GPU and made accessible to shaders as a uniform buffer.
///
/// Uniform buffers are available to shaders on a read-only basis. Uniform buffers are commonly used to make available to shaders
/// parameters that are constant during shader execution, and are best used for data that is relatively small in size as they are
/// only guaranteed to support up to 16kB per binding.
///
/// The contained data is stored in system RAM. [`write_buffer`](UniformBuffer::write_buffer) queues
/// copying of the data from system RAM to VRAM. Data in uniform buffers must follow [std140 alignment/padding requirements],
/// which is automatically enforced by this structure. Per the WGPU spec, uniform buffers cannot store runtime-sized array
/// (vectors), or structures with fields that are vectors.
///
/// Other options for storing GPU-accessible data are:
/// * [`StorageBuffer`](crate::render_resource::StorageBuffer)
/// * [`DynamicStorageBuffer`](crate::render_resource::DynamicStorageBuffer)
/// * [`DynamicUniformBuffer`]
/// * [`GpuArrayBuffer`](crate::render_resource::GpuArrayBuffer)
/// * [`RawBufferVec`](crate::render_resource::RawBufferVec)
/// * [`BufferVec`](crate::render_resource::BufferVec)
/// * [`Texture`](crate::render_resource::Texture)
///
/// [std140 alignment/padding requirements]: https://www.w3.org/TR/WGSL/#address-spaces-uniform
pub struct UniformBuffer<T: ShaderType> {
value: T,
scratch: UniformBufferWrapper<Vec<u8>>,
buffer: Option<Buffer>,
label: Option<String>,
changed: bool,
buffer_usage: BufferUsages,
}
impl<T: ShaderType> From<T> for UniformBuffer<T> {
fn from(value: T) -> Self {
Self {
value,
scratch: UniformBufferWrapper::new(Vec::new()),
buffer: None,
label: None,
changed: false,
buffer_usage: BufferUsages::COPY_DST | BufferUsages::UNIFORM,
}
}
}
impl<T: ShaderType + Default> Default for UniformBuffer<T> {
fn default() -> Self {
Self {
value: T::default(),
scratch: UniformBufferWrapper::new(Vec::new()),
buffer: None,
label: None,
changed: false,
buffer_usage: BufferUsages::COPY_DST | BufferUsages::UNIFORM,
}
}
}
impl<T: ShaderType + WriteInto> UniformBuffer<T> {
#[inline]
pub fn buffer(&self) -> Option<&Buffer> {
self.buffer.as_ref()
}
#[inline]
pub fn binding(&self) -> Option<BindingResource> {
Some(BindingResource::Buffer(
self.buffer()?.as_entire_buffer_binding(),
))
}
/// Set the data the buffer stores.
pub fn set(&mut self, value: T) {
self.value = value;
}
pub fn get(&self) -> &T {
&self.value
}
pub fn get_mut(&mut self) -> &mut T {
&mut self.value
}
pub fn set_label(&mut self, label: Option<&str>) {
let label = label.map(str::to_string);
if label != self.label {
self.changed = true;
}
self.label = label;
}
pub fn get_label(&self) -> Option<&str> {
self.label.as_deref()
}
/// Add more [`BufferUsages`] to the buffer.
///
/// This method only allows addition of flags to the default usage flags.
///
/// The default values for buffer usage are `BufferUsages::COPY_DST` and `BufferUsages::UNIFORM`.
pub fn add_usages(&mut self, usage: BufferUsages) {
self.buffer_usage |= usage;
self.changed = true;
}
/// Queues writing of data from system RAM to VRAM using the [`RenderDevice`]
/// and the provided [`RenderQueue`], if a GPU-side backing buffer already exists.
///
/// If a GPU-side buffer does not already exist for this data, such a buffer is initialized with currently
/// available data.
pub fn write_buffer(&mut self, device: &RenderDevice, queue: &RenderQueue) {
self.scratch.write(&self.value).unwrap();
if self.changed || self.buffer.is_none() {
self.buffer = Some(device.create_buffer_with_data(&BufferInitDescriptor {
label: self.label.as_deref(),
usage: self.buffer_usage,
contents: self.scratch.as_ref(),
}));
self.changed = false;
} else if let Some(buffer) = &self.buffer {
queue.write_buffer(buffer, 0, self.scratch.as_ref());
}
}
}
impl<'a, T: ShaderType + WriteInto> IntoBinding<'a> for &'a UniformBuffer<T> {
#[inline]
fn into_binding(self) -> BindingResource<'a> {
self.buffer()
.expect("Failed to get buffer")
.as_entire_buffer_binding()
.into_binding()
}
}
/// Stores data to be transferred to the GPU and made accessible to shaders as a dynamic uniform buffer.
///
/// Dynamic uniform buffers are available to shaders on a read-only basis. Dynamic uniform buffers are commonly used to make
/// available to shaders runtime-sized arrays of parameters that are otherwise constant during shader execution, and are best
/// suited to data that is relatively small in size as they are only guaranteed to support up to 16kB per binding.
///
/// The contained data is stored in system RAM. [`write_buffer`](DynamicUniformBuffer::write_buffer) queues
/// copying of the data from system RAM to VRAM. Data in uniform buffers must follow [std140 alignment/padding requirements],
/// which is automatically enforced by this structure. Per the WGPU spec, uniform buffers cannot store runtime-sized array
/// (vectors), or structures with fields that are vectors.
///
/// Other options for storing GPU-accessible data are:
/// * [`StorageBuffer`](crate::render_resource::StorageBuffer)
/// * [`DynamicStorageBuffer`](crate::render_resource::DynamicStorageBuffer)
/// * [`UniformBuffer`]
/// * [`DynamicUniformBuffer`]
/// * [`GpuArrayBuffer`](crate::render_resource::GpuArrayBuffer)
/// * [`RawBufferVec`](crate::render_resource::RawBufferVec)
/// * [`BufferVec`](crate::render_resource::BufferVec)
/// * [`Texture`](crate::render_resource::Texture)
///
/// [std140 alignment/padding requirements]: https://www.w3.org/TR/WGSL/#address-spaces-uniform
pub struct DynamicUniformBuffer<T: ShaderType> {
scratch: DynamicUniformBufferWrapper<Vec<u8>>,
buffer: Option<Buffer>,
label: Option<String>,
changed: bool,
buffer_usage: BufferUsages,
_marker: PhantomData<fn() -> T>,
}
impl<T: ShaderType> Default for DynamicUniformBuffer<T> {
fn default() -> Self {
Self {
scratch: DynamicUniformBufferWrapper::new(Vec::new()),
buffer: None,
label: None,
changed: false,
buffer_usage: BufferUsages::COPY_DST | BufferUsages::UNIFORM,
_marker: PhantomData,
}
}
}
impl<T: ShaderType + WriteInto> DynamicUniformBuffer<T> {
pub fn new_with_alignment(alignment: u64) -> Self {
Self {
scratch: DynamicUniformBufferWrapper::new_with_alignment(Vec::new(), alignment),
buffer: None,
label: None,
changed: false,
buffer_usage: BufferUsages::COPY_DST | BufferUsages::UNIFORM,
_marker: PhantomData,
}
}
#[inline]
pub fn buffer(&self) -> Option<&Buffer> {
self.buffer.as_ref()
}
#[inline]
pub fn binding(&self) -> Option<BindingResource> {
Some(BindingResource::Buffer(BufferBinding {
buffer: self.buffer()?,
offset: 0,
size: Some(T::min_size()),
}))
}
#[inline]
pub fn is_empty(&self) -> bool {
self.scratch.as_ref().is_empty()
}
/// Push data into the `DynamicUniformBuffer`'s internal vector (residing on system RAM).
#[inline]
pub fn push(&mut self, value: &T) -> u32 {
self.scratch.write(value).unwrap() as u32
}
pub fn set_label(&mut self, label: Option<&str>) {
let label = label.map(str::to_string);
if label != self.label {
self.changed = true;
}
self.label = label;
}
pub fn get_label(&self) -> Option<&str> {
self.label.as_deref()
}
/// Add more [`BufferUsages`] to the buffer.
///
/// This method only allows addition of flags to the default usage flags.
///
/// The default values for buffer usage are `BufferUsages::COPY_DST` and `BufferUsages::UNIFORM`.
pub fn add_usages(&mut self, usage: BufferUsages) {
self.buffer_usage |= usage;
self.changed = true;
}
/// Creates a writer that can be used to directly write elements into the target buffer.
///
/// This method uses less memory and performs fewer memory copies using over [`push`] and [`write_buffer`].
///
/// `max_count` *must* be greater than or equal to the number of elements that are to be written to the buffer, or
/// the writer will panic while writing. Dropping the writer will schedule the buffer write into the provided
/// [`RenderQueue`].
///
/// If there is no GPU-side buffer allocated to hold the data currently stored, or if a GPU-side buffer previously
/// allocated does not have enough capacity to hold `max_count` elements, a new GPU-side buffer is created.
///
/// Returns `None` if there is no allocated GPU-side buffer, and `max_count` is 0.
///
/// [`push`]: Self::push
/// [`write_buffer`]: Self::write_buffer
#[inline]
pub fn get_writer<'a>(
&'a mut self,
max_count: usize,
device: &RenderDevice,
queue: &'a RenderQueue,
) -> Option<DynamicUniformBufferWriter<'a, T>> {
let alignment = if cfg!(feature = "ios_simulator") {
// On iOS simulator on silicon macs, metal validation check that the host OS alignment
// is respected, but the device reports the correct value for iOS, which is smaller.
// Use the larger value.
// See https://github.com/bevyengine/bevy/pull/10178 - remove if it's not needed anymore.
AlignmentValue::new(256)
} else {
AlignmentValue::new(device.limits().min_uniform_buffer_offset_alignment as u64)
};
let mut capacity = self.buffer.as_deref().map(wgpu::Buffer::size).unwrap_or(0);
let size = alignment
.round_up(T::min_size().get())
.checked_mul(max_count as u64)
.unwrap();
if capacity < size || (self.changed && size > 0) {
let buffer = device.create_buffer(&BufferDescriptor {
label: self.label.as_deref(),
usage: self.buffer_usage,
size,
mapped_at_creation: false,
});
capacity = buffer.size();
self.buffer = Some(buffer);
self.changed = false;
}
if let Some(buffer) = self.buffer.as_deref() {
let buffer_view = queue
.write_buffer_with(buffer, 0, NonZeroU64::new(buffer.size())?)
.unwrap();
Some(DynamicUniformBufferWriter {
buffer: encase::DynamicUniformBuffer::new_with_alignment(
QueueWriteBufferViewWrapper {
capacity: capacity as usize,
buffer_view,
},
alignment.get(),
),
_marker: PhantomData,
})
} else {
None
}
}
/// Queues writing of data from system RAM to VRAM using the [`RenderDevice`]
/// and the provided [`RenderQueue`].
///
/// If there is no GPU-side buffer allocated to hold the data currently stored, or if a GPU-side buffer previously
/// allocated does not have enough capacity, a new GPU-side buffer is created.
#[inline]
pub fn write_buffer(&mut self, device: &RenderDevice, queue: &RenderQueue) {
let capacity = self.buffer.as_deref().map(wgpu::Buffer::size).unwrap_or(0);
let size = self.scratch.as_ref().len() as u64;
if capacity < size || (self.changed && size > 0) {
self.buffer = Some(device.create_buffer_with_data(&BufferInitDescriptor {
label: self.label.as_deref(),
usage: self.buffer_usage,
contents: self.scratch.as_ref(),
}));
self.changed = false;
} else if let Some(buffer) = &self.buffer {
queue.write_buffer(buffer, 0, self.scratch.as_ref());
}
}
#[inline]
pub fn clear(&mut self) {
self.scratch.as_mut().clear();
self.scratch.set_offset(0);
}
}
/// A writer that can be used to directly write elements into the target buffer.
///
/// For more information, see [`DynamicUniformBuffer::get_writer`].
pub struct DynamicUniformBufferWriter<'a, T> {
buffer: encase::DynamicUniformBuffer<QueueWriteBufferViewWrapper<'a>>,
_marker: PhantomData<fn() -> T>,
}
impl<'a, T: ShaderType + WriteInto> DynamicUniformBufferWriter<'a, T> {
pub fn write(&mut self, value: &T) -> u32 {
self.buffer.write(value).unwrap() as u32
}
}
/// A wrapper to work around the orphan rule so that [`wgpu::QueueWriteBufferView`] can implement
/// [`BufferMut`].
struct QueueWriteBufferViewWrapper<'a> {
buffer_view: wgpu::QueueWriteBufferView<'a>,
// Must be kept separately and cannot be retrieved from buffer_view, as the read-only access will
// invoke a panic.
capacity: usize,
}
impl<'a> BufferMut for QueueWriteBufferViewWrapper<'a> {
#[inline]
fn capacity(&self) -> usize {
self.capacity
}
#[inline]
fn write<const N: usize>(&mut self, offset: usize, val: &[u8; N]) {
self.buffer_view.write(offset, val);
}
#[inline]
fn write_slice(&mut self, offset: usize, val: &[u8]) {
self.buffer_view.write_slice(offset, val);
}
}
impl<'a, T: ShaderType + WriteInto> IntoBinding<'a> for &'a DynamicUniformBuffer<T> {
#[inline]
fn into_binding(self) -> BindingResource<'a> {
self.binding().unwrap()
}
}