wgpu/util/
mod.rs

1//! Utility structures and functions that are built on top of the main `wgpu` API.
2//!
3//! Nothing in this module is a part of the WebGPU API specification;
4//! they are unique to the `wgpu` library.
5
6mod belt;
7mod device;
8mod encoder;
9mod init;
10mod texture_blitter;
11
12use alloc::{borrow::Cow, format, string::String, vec};
13use core::ptr::copy_nonoverlapping;
14
15pub use belt::StagingBelt;
16pub use device::{BufferInitDescriptor, DeviceExt};
17pub use encoder::RenderEncoder;
18pub use init::*;
19#[cfg(feature = "wgsl")]
20pub use texture_blitter::{TextureBlitter, TextureBlitterBuilder};
21pub use wgt::{
22    math::*, DispatchIndirectArgs, DrawIndexedIndirectArgs, DrawIndirectArgs, TextureDataOrder,
23};
24
25use crate::dispatch;
26
27/// Treat the given byte slice as a SPIR-V module.
28///
29/// # Panic
30///
31/// This function panics if:
32///
33/// - Input length isn't multiple of 4
34/// - Input is longer than [`usize::MAX`]
35/// - Input is empty
36/// - SPIR-V magic number is missing from beginning of stream
37#[cfg(feature = "spirv")]
38pub fn make_spirv(data: &[u8]) -> super::ShaderSource<'_> {
39    super::ShaderSource::SpirV(make_spirv_raw(data))
40}
41
42/// Version of `make_spirv` intended for use with [`Device::create_shader_module_passthrough`].
43/// Returns a raw slice instead of [`ShaderSource`](super::ShaderSource).
44///
45/// [`Device::create_shader_module_passthrough`]: crate::Device::create_shader_module_passthrough
46pub fn make_spirv_raw(data: &[u8]) -> Cow<'_, [u32]> {
47    const MAGIC_NUMBER: u32 = 0x0723_0203;
48    assert_eq!(
49        data.len() % size_of::<u32>(),
50        0,
51        "data size is not a multiple of 4"
52    );
53    assert_ne!(data.len(), 0, "data size must be larger than zero");
54
55    // If the data happens to be aligned, directly use the byte array,
56    // otherwise copy the byte array in an owned vector and use that instead.
57    let mut words = if data.as_ptr().align_offset(align_of::<u32>()) == 0 {
58        let (pre, words, post) = unsafe { data.align_to::<u32>() };
59        debug_assert!(pre.is_empty());
60        debug_assert!(post.is_empty());
61        Cow::from(words)
62    } else {
63        let mut words = vec![0u32; data.len() / size_of::<u32>()];
64        unsafe {
65            copy_nonoverlapping(data.as_ptr(), words.as_mut_ptr() as *mut u8, data.len());
66        }
67        Cow::from(words)
68    };
69
70    // Before checking if the data starts with the magic, check if it starts
71    // with the magic in non-native endianness, own & swap the data if so.
72    if words[0] == MAGIC_NUMBER.swap_bytes() {
73        for word in Cow::to_mut(&mut words) {
74            *word = word.swap_bytes();
75        }
76    }
77
78    assert_eq!(
79        words[0], MAGIC_NUMBER,
80        "wrong magic word {:x}. Make sure you are using a binary SPIRV file.",
81        words[0]
82    );
83
84    words
85}
86
87/// CPU accessible buffer used to download data back from the GPU.
88pub struct DownloadBuffer {
89    _gpu_buffer: super::Buffer,
90    mapped_range: dispatch::DispatchBufferMappedRange,
91}
92
93impl DownloadBuffer {
94    /// Asynchronously read the contents of a buffer.
95    pub fn read_buffer(
96        device: &super::Device,
97        queue: &super::Queue,
98        buffer: &super::BufferSlice<'_>,
99        callback: impl FnOnce(Result<Self, super::BufferAsyncError>) + Send + 'static,
100    ) {
101        let size = match buffer.size {
102            Some(size) => size.into(),
103            None => buffer.buffer.map_context.lock().total_size - buffer.offset,
104        };
105
106        let download = device.create_buffer(&super::BufferDescriptor {
107            size,
108            usage: super::BufferUsages::COPY_DST | super::BufferUsages::MAP_READ,
109            mapped_at_creation: false,
110            label: None,
111        });
112
113        let mut encoder =
114            device.create_command_encoder(&super::CommandEncoderDescriptor { label: None });
115        encoder.copy_buffer_to_buffer(buffer.buffer, buffer.offset, &download, 0, size);
116        let command_buffer: super::CommandBuffer = encoder.finish();
117        queue.submit(Some(command_buffer));
118
119        download
120            .clone()
121            .slice(..)
122            .map_async(super::MapMode::Read, move |result| {
123                if let Err(e) = result {
124                    callback(Err(e));
125                    return;
126                }
127
128                let mapped_range = download.inner.get_mapped_range(0..size);
129                callback(Ok(Self {
130                    _gpu_buffer: download,
131                    mapped_range,
132                }));
133            });
134    }
135}
136
137impl core::ops::Deref for DownloadBuffer {
138    type Target = [u8];
139    fn deref(&self) -> &[u8] {
140        self.mapped_range.slice()
141    }
142}
143
144/// A recommended key for storing [`PipelineCache`]s for the adapter
145/// associated with the given [`AdapterInfo`](wgt::AdapterInfo)
146/// This key will define a class of adapters for which the same cache
147/// might be valid.
148///
149/// If this returns `None`, the adapter doesn't support [`PipelineCache`].
150/// This may be because the API doesn't support application managed caches
151/// (such as browser WebGPU), or that `wgpu` hasn't implemented it for
152/// that API yet.
153///
154/// This key could be used as a filename, as seen in the example below.
155///
156/// # Examples
157///
158/// ```no_run
159/// # use std::path::PathBuf;
160/// use wgpu::PipelineCacheDescriptor;
161/// # let adapter_info = todo!();
162/// # let device: wgpu::Device = todo!();
163/// let cache_dir: PathBuf = unimplemented!("Some reasonable platform-specific cache directory for your app.");
164/// let filename = wgpu::util::pipeline_cache_key(&adapter_info);
165/// let (pipeline_cache, cache_file) = if let Some(filename) = filename {
166///     let cache_path = cache_dir.join(&filename);
167///     // If we failed to read the cache, for whatever reason, treat the data as lost.
168///     // In a real app, we'd probably avoid caching entirely unless the error was "file not found".
169///     let cache_data = std::fs::read(&cache_path).ok();
170///     let pipeline_cache = unsafe {
171///         device.create_pipeline_cache(&PipelineCacheDescriptor {
172///             data: cache_data.as_deref(),
173///             label: None,
174///             fallback: true
175///         })
176///     };
177///     (Some(pipeline_cache), Some(cache_path))
178/// } else {
179///     (None, None)
180/// };
181///
182/// // Run pipeline initialisation, making sure to set the `cache`
183/// // fields of your `*PipelineDescriptor` to `pipeline_cache`
184///
185/// // And then save the resulting cache (probably off the main thread).
186/// if let (Some(pipeline_cache), Some(cache_file)) = (pipeline_cache, cache_file) {
187///     let data = pipeline_cache.get_data();
188///     if let Some(data) = data {
189///         let temp_file = cache_file.with_extension("temp");
190///         std::fs::write(&temp_file, &data)?;
191///         std::fs::rename(&temp_file, &cache_file)?;
192///     }
193/// }
194/// # Ok::<_, std::io::Error>(())
195/// ```
196///
197/// [`PipelineCache`]: super::PipelineCache
198pub fn pipeline_cache_key(adapter_info: &wgt::AdapterInfo) -> Option<String> {
199    match adapter_info.backend {
200        wgt::Backend::Vulkan => Some(format!(
201            // The vendor/device should uniquely define a driver
202            // We/the driver will also later validate that the vendor/device and driver
203            // version match, which may lead to clearing an outdated
204            // cache for the same device.
205            "wgpu_pipeline_cache_vulkan_{}_{}",
206            adapter_info.vendor, adapter_info.device
207        )),
208        _ => None,
209    }
210}
211
212/// Adds extra conversion functions to `TextureFormat`.
213pub trait TextureFormatExt {
214    /// Finds the [`TextureFormat`](wgt::TextureFormat) corresponding to the given
215    /// [`StorageFormat`](wgc::naga::StorageFormat).
216    ///
217    /// # Examples
218    /// ```
219    /// use wgpu::util::TextureFormatExt;
220    /// assert_eq!(wgpu::TextureFormat::from_storage_format(wgpu::naga::StorageFormat::Bgra8Unorm), wgpu::TextureFormat::Bgra8Unorm);
221    /// ```
222    #[cfg(wgpu_core)]
223    fn from_storage_format(storage_format: crate::naga::StorageFormat) -> Self;
224
225    /// Finds the [`StorageFormat`](wgc::naga::StorageFormat) corresponding to the given [`TextureFormat`](wgt::TextureFormat).
226    /// Returns `None` if there is no matching storage format,
227    /// which typically indicates this format is not supported
228    /// for storage textures.
229    ///
230    /// # Examples
231    /// ```
232    /// use wgpu::util::TextureFormatExt;
233    /// assert_eq!(wgpu::TextureFormat::Bgra8Unorm.to_storage_format(), Some(wgpu::naga::StorageFormat::Bgra8Unorm));
234    /// ```
235    #[cfg(wgpu_core)]
236    fn to_storage_format(&self) -> Option<crate::naga::StorageFormat>;
237}
238
239impl TextureFormatExt for wgt::TextureFormat {
240    #[cfg(wgpu_core)]
241    fn from_storage_format(storage_format: crate::naga::StorageFormat) -> Self {
242        wgc::map_storage_format_from_naga(storage_format)
243    }
244
245    #[cfg(wgpu_core)]
246    fn to_storage_format(&self) -> Option<crate::naga::StorageFormat> {
247        wgc::map_storage_format_to_naga(*self)
248    }
249}
wgpu/util/mod.rs

wgpu/util/
mod.rs
