pebble/wgpu/
textures.rs

1use crate::{
2    assets::{handle::Handle, storage::Assets, upload::Asset},
3    ecs::system::Res,
4    wgpu::{backend::WGPUBackend, gpu_context::GpuContext, mipmap::MipmapGenerator, texture_format::TextureFormat},
5};
6
7/// Source data for [`GPUTexture`], loaded from a file or supplied as raw
8/// bytes. Fields are private — build one via the
9/// [`from_file`](Self::from_file)/[`from_data`](Self::from_data)/[`empty`](Self::empty)
10/// constructors rather than as a struct literal.
11pub struct Texture {
12    /// File to decode — `width`/`height` are inferred from the image.
13    /// Takes priority over `data` if both are set.
14    file: Option<&'static str>,
15    /// Width in pixels. Ignored when loading from `file`.
16    width: u32,
17    /// Height in pixels. Ignored when loading from `file`.
18    height: u32,
19    /// GPU pixel format to upload as. Defaults to `Rgba8UnormSrgb`.
20    format: TextureFormat,
21    /// Raw pixel bytes, used when `file` is `None`.
22    data: Option<Vec<u8>>,
23    /// Whether to generate a full mip chain (via [`MipmapGenerator`]).
24    generate_mips: bool,
25}
26
27impl Texture {
28    /// Load pixel data from a file. Width/height are inferred from the
29    /// decoded image.
30    pub fn from_file(path: &'static str) -> Self {
31        Self {
32            file: Some(path),
33            width: 0,
34            height: 0,
35            format: TextureFormat::Rgba8UnormSrgb,
36            data: None,
37            generate_mips: false,
38        }
39    }
40
41    /// Supply raw pixel bytes directly, matching `width`/`height`/`format`.
42    pub fn from_data(width: u32, height: u32, format: TextureFormat, data: Vec<u8>) -> Self {
43        Self {
44            file: None,
45            width,
46            height,
47            format,
48            data: Some(data),
49            generate_mips: false,
50        }
51    }
52
53    /// Allocate a texture on the GPU with no initial pixel data. Content is
54    /// undefined until written via [`GPUTexture::write`].
55    pub fn empty(width: u32, height: u32, format: TextureFormat) -> Self {
56        Self {
57            file: None,
58            width,
59            height,
60            format,
61            data: None,
62            generate_mips: false,
63        }
64    }
65
66    pub fn with_format(mut self, format: TextureFormat) -> Self {
67        self.format = format;
68        self
69    }
70
71    pub fn with_mips(mut self) -> Self {
72        self.generate_mips = true;
73        self
74    }
75
76    /// Logs a WARN if [`from_data`](Self::from_data) was given a zero
77    /// width/height — the resulting texture would have no pixels, almost
78    /// certainly an accidental `0` rather than an intentional one.
79    fn validate(&self) {
80        if self.data.is_some() && (self.width == 0 || self.height == 0) {
81            tracing::warn!(
82                "Texture::from_data(): width/height is 0 ({}x{}) — did you swap the argument \
83                 order, or forget to pass the real dimensions?",
84                self.width,
85                self.height,
86            );
87        }
88    }
89
90    /// Consume the builder and return the finished [`Texture`] value.
91    pub fn build(self) -> Self {
92        self.validate();
93        self
94    }
95
96    /// Consume the builder, insert into `assets` under `name`, and return
97    /// the resulting [`Handle<Texture>`].
98    pub fn build_asset(self, name: &str, assets: &mut Assets<Self>) -> Handle<Self> {
99        self.validate();
100        assets.insert(name, self)
101    }
102}
103
104/// A texture uploaded to the GPU, ready to bind (e.g. via
105/// [`BindingInstanceEntry::Texture`](super::instance::BindingInstanceEntry::Texture)).
106/// Opaque — bind it into a bind group via
107/// [`BindGroupBuilder::texture_2d`](super::buffers::BindGroupBuilder::texture_2d),
108/// there's no way to reach the underlying `wgpu::Texture`/`TextureView` from
109/// outside this crate.
110pub struct GPUTexture {
111    texture: wgpu::Texture,
112    view: wgpu::TextureView,
113    width: u32,
114    height: u32,
115    format: TextureFormat,
116    ctx: GpuContext,
117}
118
119impl GPUTexture {
120    /// Overwrites this texture's level-0 pixel data (`pixels` must match the
121    /// dimensions/format this texture was uploaded with). Mip levels beyond
122    /// 0 are *not* regenerated — if this texture was built `with_mips()`,
123    /// they'll go stale relative to the new level-0 data.
124    pub fn write(&self, pixels: &[u8]) {
125        write_texture_level0(self.ctx.queue(), &self.texture, 0, self.format.into(), self.width, self.height, pixels);
126    }
127
128    pub fn width(&self) -> u32 {
129        self.width
130    }
131
132    pub fn height(&self) -> u32 {
133        self.height
134    }
135
136    pub(crate) fn view(&self) -> &wgpu::TextureView {
137        &self.view
138    }
139}
140
141/// Overwrites one `origin_z`-indexed layer/face's level-0 pixel data (`0` for
142/// a plain [`GPUTexture`], a layer index for [`GPUTextureArray`](super::texture_array::GPUTextureArray),
143/// a face index for [`GPUCubemap`](super::cubemap::GPUCubemap)) — the one
144/// piece of `write_texture` bookkeeping shared by all three, so a future fix
145/// to it (mip handling, row alignment, ...) doesn't need to land in three
146/// places independently.
147pub(crate) fn write_texture_level0(
148    queue: &wgpu::Queue,
149    texture: &wgpu::Texture,
150    origin_z: u32,
151    format: wgpu::TextureFormat,
152    width: u32,
153    height: u32,
154    pixels: &[u8],
155) {
156    queue.write_texture(
157        wgpu::TexelCopyTextureInfo {
158            texture,
159            mip_level: 0,
160            origin: wgpu::Origin3d { x: 0, y: 0, z: origin_z },
161            aspect: wgpu::TextureAspect::All,
162        },
163        pixels,
164        wgpu::TexelCopyBufferLayout {
165            offset: 0,
166            bytes_per_row: Some(bytes_per_pixel(format) * width),
167            rows_per_image: Some(height),
168        },
169        wgpu::Extent3d { width, height, depth_or_array_layers: 1 },
170    );
171}
172
173/// Bytes-per-pixel for every regular (non-block-compressed, non-multi-planar,
174/// non-depth/stencil) texture format — anything with a well-defined linear
175/// CPU-side byte layout, which covers every format [`decode_file`] can
176/// actually decode into plus everything reasonable to upload via
177/// [`Texture::from_data`]. Block-compressed formats (`Bc*`,
178/// `Etc2*`/`Eac*`, `Astc`) need block-aware row/height math this helper
179/// doesn't do, multi-planar formats (`NV12`/`P010`) need per-plane byte
180/// layouts, and depth/stencil formats aren't meaningful to upload arbitrary
181/// pixel bytes into in the first place — all three panic here.
182pub(crate) fn bytes_per_pixel(format: wgpu::TextureFormat) -> u32 {
183    use wgpu::TextureFormat as F;
184    match format {
185        F::R8Unorm | F::R8Snorm | F::R8Uint | F::R8Sint => 1,
186        F::R16Uint | F::R16Sint | F::R16Unorm | F::R16Snorm | F::R16Float | F::Rg8Unorm | F::Rg8Snorm
187        | F::Rg8Uint | F::Rg8Sint => 2,
188        F::R32Uint | F::R32Sint | F::R32Float | F::Rg16Uint | F::Rg16Sint | F::Rg16Unorm | F::Rg16Snorm
189        | F::Rg16Float | F::Rgba8Unorm | F::Rgba8UnormSrgb | F::Rgba8Snorm | F::Rgba8Uint | F::Rgba8Sint
190        | F::Bgra8Unorm | F::Bgra8UnormSrgb | F::Rgb10a2Uint | F::Rgb10a2Unorm | F::Rg11b10Ufloat
191        | F::Rgb9e5Ufloat => 4,
192        F::R64Uint | F::Rg32Uint | F::Rg32Sint | F::Rg32Float | F::Rgba16Uint | F::Rgba16Sint
193        | F::Rgba16Unorm | F::Rgba16Snorm | F::Rgba16Float => 8,
194        F::Rgba32Uint | F::Rgba32Sint | F::Rgba32Float => 16,
195        other => panic!(
196            "unsupported texture format for GPUTexture: {other:?} — block-compressed, \
197             multi-planar, and depth/stencil formats have no linear CPU-side pixel layout \
198             this helper can compute"
199        ),
200    }
201}
202
203/// Keeps the first `channels` of every 4-channel (RGBA) pixel, dropping the rest.
204fn take_channels_u8(rgba: &[u8], channels: usize) -> Vec<u8> {
205    rgba.chunks_exact(4).flat_map(|p| p[..channels].to_vec()).collect()
206}
207
208/// Swaps the R and B bytes of every RGBA8 pixel — `image` only decodes to
209/// RGB byte order, so this is how `Bgra8*` gets its channels in the order
210/// wgpu expects.
211fn bgra_swap(rgba: &[u8]) -> Vec<u8> {
212    rgba.chunks_exact(4).flat_map(|p| [p[2], p[1], p[0], p[3]]).collect()
213}
214
215/// Keeps the first `channels` of every 4-channel `f32` pixel, packed down to
216/// half-precision floats.
217fn take_channels_f16(rgba32f: &[f32], channels: usize) -> Vec<u8> {
218    rgba32f
219        .chunks_exact(4)
220        .flat_map(|p| p[..channels].iter().flat_map(|c| half::f16::from_f32(*c).to_le_bytes()))
221        .collect()
222}
223
224/// Keeps the first `channels` of every 4-channel `f32` pixel, as raw `f32` bytes.
225fn take_channels_f32(rgba32f: &[f32], channels: usize) -> Vec<u8> {
226    rgba32f.chunks_exact(4).flat_map(|p| bytemuck::cast_slice(&p[..channels]).to_vec()).collect()
227}
228
229/// Quantizes every 4-channel `f32` pixel (expected in `[0, 1]`) down to
230/// 16-bit unsigned normalized integers.
231fn rgba32f_to_unorm16(rgba32f: &[f32]) -> Vec<u8> {
232    rgba32f
233        .iter()
234        .flat_map(|c| ((c.clamp(0.0, 1.0) * 65535.0).round() as u16).to_le_bytes())
235        .collect()
236}
237
238/// Decodes an image file into raw pixel bytes matching `format`.
239///
240/// LDR 8-bit formats (`Rgba8*`, `Bgra8*`, `R8Unorm`, `Rg8Unorm`) decode
241/// straight through `to_rgba8()`, keeping/reordering channels as needed.
242/// `Rgba16Unorm` decodes through `to_rgba32f()` and quantizes down.
243/// Float formats (`R32Float`/`Rg32Float`/`Rgba32Float`, and the 16-bit float
244/// variants) decode through `to_rgba32f()` so HDR/EXR sources outside
245/// `[0, 1]` survive, then get packed down to the requested channel count and
246/// float width.
247pub(crate) fn decode_file(path: &str, format: wgpu::TextureFormat) -> Option<(u32, u32, Vec<u8>)> {
248    use wgpu::TextureFormat as F;
249
250    let img = match image::open(path) {
251        Ok(img) => img,
252        Err(e) => {
253            tracing::error!("failed to load texture '{path}': {e}");
254            return None;
255        }
256    };
257
258    Some(match format {
259        F::Rgba8Unorm | F::Rgba8UnormSrgb => {
260            let img = img.to_rgba8();
261            let (w, h) = img.dimensions();
262            (w, h, img.into_raw())
263        }
264        F::Bgra8Unorm | F::Bgra8UnormSrgb => {
265            let img = img.to_rgba8();
266            let (w, h) = img.dimensions();
267            (w, h, bgra_swap(&img.into_raw()))
268        }
269        F::R8Unorm => {
270            let img = img.to_rgba8();
271            let (w, h) = img.dimensions();
272            (w, h, take_channels_u8(&img.into_raw(), 1))
273        }
274        F::Rg8Unorm => {
275            let img = img.to_rgba8();
276            let (w, h) = img.dimensions();
277            (w, h, take_channels_u8(&img.into_raw(), 2))
278        }
279        F::Rgba16Unorm => {
280            let img = img.to_rgba32f();
281            let (w, h) = img.dimensions();
282            (w, h, rgba32f_to_unorm16(img.into_raw().as_slice()))
283        }
284        F::Rgba32Float => {
285            let img = img.to_rgba32f();
286            let (w, h) = img.dimensions();
287            let bytes = bytemuck::cast_slice(img.into_raw().as_slice()).to_vec();
288            (w, h, bytes)
289        }
290        F::Rg32Float => {
291            let img = img.to_rgba32f();
292            let (w, h) = img.dimensions();
293            (w, h, take_channels_f32(img.into_raw().as_slice(), 2))
294        }
295        F::R32Float => {
296            let img = img.to_rgba32f();
297            let (w, h) = img.dimensions();
298            (w, h, take_channels_f32(img.into_raw().as_slice(), 1))
299        }
300        F::Rgba16Float => {
301            let img = img.to_rgba32f();
302            let (w, h) = img.dimensions();
303            (w, h, take_channels_f16(img.into_raw().as_slice(), 4))
304        }
305        F::Rg16Float => {
306            let img = img.to_rgba32f();
307            let (w, h) = img.dimensions();
308            (w, h, take_channels_f16(img.into_raw().as_slice(), 2))
309        }
310        F::R16Float => {
311            let img = img.to_rgba32f();
312            let (w, h) = img.dimensions();
313            (w, h, take_channels_f16(img.into_raw().as_slice(), 1))
314        }
315        other => panic!(
316            "unsupported texture format for GPUTexture: {other:?} — file decoding covers the \
317             regular 8/16/32-bit unorm and float formats; block-compressed and multi-planar \
318             formats aren't decodable from an ordinary image file this way"
319        ),
320    })
321}
322
323impl Asset<WGPUBackend> for GPUTexture {
324    type Source = Texture;
325    type Deps<'a> = Res<'a, MipmapGenerator>;
326
327    fn upload<'a>(
328        source: &Texture,
329        backend: &WGPUBackend,
330        mipmap_generator: &Res<'a, MipmapGenerator>,
331    ) -> Option<Self> {
332        // resolve actual pixel data + real dimensions, whether from a file or already-supplied bytes
333        let (width, height, data) = if let Some(path) = source.file {
334            let (w, h, d) = decode_file(path, source.format.into())?;
335            (w, h, Some(d))
336        } else if let Some(data) = &source.data {
337            (source.width, source.height, Some(data.clone()))
338        } else {
339            // empty texture — no initial data, content is undefined until written
340            (source.width, source.height, None)
341        };
342
343        let mip_count = super::mipmap::mip_count(width.max(height), source.generate_mips);
344
345        let texture = backend.device.create_texture(&wgpu::TextureDescriptor {
346            label: None,
347            size: wgpu::Extent3d {
348                width,
349                height,
350                depth_or_array_layers: 1,
351            },
352            mip_level_count: mip_count, // room allocated for all levels now
353            sample_count: 1,
354            dimension: wgpu::TextureDimension::D2,
355            format: source.format.into(),
356            usage: super::mipmap::texture_usage(mip_count),
357            view_formats: &[],
358        });
359
360        if let Some(data) = &data {
361            // upload level 0 only — fast, synchronous, matches the deferred-mip decision
362            backend.queue.write_texture(
363                wgpu::TexelCopyTextureInfo {
364                    texture: &texture,
365                    mip_level: 0,
366                    origin: wgpu::Origin3d::default(),
367                    aspect: wgpu::TextureAspect::All,
368                },
369                data,
370                wgpu::TexelCopyBufferLayout {
371                    offset: 0,
372                    bytes_per_row: Some(bytes_per_pixel(source.format.into()) * width),
373                    rows_per_image: Some(height),
374                },
375                wgpu::Extent3d {
376                    width,
377                    height,
378                    depth_or_array_layers: 1,
379                },
380            );
381        }
382
383        if mip_count > 1 {
384            mipmap_generator.generate_mips(
385                &backend.device,
386                &backend.queue,
387                &texture,
388                source.format.into(),
389                mip_count,
390                1,
391            );
392        }
393
394        let view = texture.create_view(&wgpu::TextureViewDescriptor::default());
395        Some(Self {
396            texture,
397            view,
398            width,
399            height,
400            format: source.format,
401            ctx: GpuContext::from_backend(backend),
402        })
403    }
404}
405
406crate::wgpu::plugin_macros::mipmap_asset_plugin! {
407    /// Registers the [`GPUTexture`] asset pipeline (`Assets<Texture>`
408    /// → `ProcessedAssets<GPUTexture>`), plus the [`MipmapGenerator`] it depends
409    /// on for `generate_mips`. Included by
410    /// [`WGPUPlugin`](super::backend::WGPUPlugin); add directly only if you're
411    /// assembling the `wgpu` module's plugins by hand.
412    TexturePlugin, GPUTexture
413}
pebble/wgpu/textures.rs

pebble/wgpu/
textures.rs
