pebble/wgpu/
textures.rs

1use crate::{
2    assets::upload::Asset,
3    ecs::system::Res,
4    wgpu::{backend::WGPUBackend, gpu_context::GpuContext, mipmap::MipmapGenerator},
5};
6
7/// Source data for [`GPUTexture`], loaded from a file or supplied as raw
8/// bytes. Prefer the [`from_file`](Self::from_file)/[`from_data`](Self::from_data)
9/// constructors over setting fields by hand.
10pub struct TextureDescriptor {
11    /// File to decode — `width`/`height` are inferred from the image.
12    /// Takes priority over `data` if both are set.
13    pub file: Option<&'static str>,
14    /// Width in pixels. Ignored when loading from `file`.
15    pub width: u32,
16    /// Height in pixels. Ignored when loading from `file`.
17    pub height: u32,
18    /// GPU pixel format to upload as. Defaults to `Rgba8UnormSrgb`.
19    pub format: wgpu::TextureFormat,
20    /// Raw pixel bytes, used when `file` is `None`.
21    pub data: Option<Vec<u8>>,
22    /// Whether to generate a full mip chain (via [`MipmapGenerator`]).
23    pub generate_mips: bool,
24}
25
26impl TextureDescriptor {
27    /// Load pixel data from a file. Width/height are inferred from the
28    /// decoded image.
29    pub fn from_file(path: &'static str) -> Self {
30        Self {
31            file: Some(path),
32            width: 0,
33            height: 0,
34            format: wgpu::TextureFormat::Rgba8UnormSrgb,
35            data: None,
36            generate_mips: false,
37        }
38    }
39
40    /// Supply raw pixel bytes directly, matching `width`/`height`/`format`.
41    pub fn from_data(width: u32, height: u32, format: wgpu::TextureFormat, data: Vec<u8>) -> Self {
42        Self {
43            file: None,
44            width,
45            height,
46            format,
47            data: Some(data),
48            generate_mips: false,
49        }
50    }
51
52    pub fn with_format(mut self, format: wgpu::TextureFormat) -> Self {
53        self.format = format;
54        self
55    }
56
57    pub fn with_mips(mut self) -> Self {
58        self.generate_mips = true;
59        self
60    }
61}
62
63/// A texture uploaded to the GPU, ready to bind (e.g. via
64/// [`BindingInstanceEntry::Texture`](super::instance::BindingInstanceEntry::Texture)).
65/// Opaque — bind it into a bind group via
66/// [`BindGroupBuilder::texture_2d`](super::buffers::BindGroupBuilder::texture_2d),
67/// there's no way to reach the underlying `wgpu::Texture`/`TextureView` from
68/// outside this crate.
69pub struct GPUTexture {
70    texture: wgpu::Texture,
71    view: wgpu::TextureView,
72    width: u32,
73    height: u32,
74    format: wgpu::TextureFormat,
75    ctx: GpuContext,
76}
77
78impl GPUTexture {
79    /// Overwrites this texture's level-0 pixel data (`pixels` must match the
80    /// dimensions/format this texture was uploaded with). Mip levels beyond
81    /// 0 are *not* regenerated — if this texture was built `with_mips()`,
82    /// they'll go stale relative to the new level-0 data.
83    pub fn write(&self, pixels: &[u8]) {
84        write_texture_level0(self.ctx.queue(), &self.texture, 0, self.format, self.width, self.height, pixels);
85    }
86
87    pub fn width(&self) -> u32 {
88        self.width
89    }
90
91    pub fn height(&self) -> u32 {
92        self.height
93    }
94
95    pub(crate) fn view(&self) -> &wgpu::TextureView {
96        &self.view
97    }
98}
99
100/// Overwrites one `origin_z`-indexed layer/face's level-0 pixel data (`0` for
101/// a plain [`GPUTexture`], a layer index for [`GPUTextureArray`](super::texture_array::GPUTextureArray),
102/// a face index for [`GPUCubemap`](super::cubemap::GPUCubemap)) — the one
103/// piece of `write_texture` bookkeeping shared by all three, so a future fix
104/// to it (mip handling, row alignment, ...) doesn't need to land in three
105/// places independently.
106pub(crate) fn write_texture_level0(
107    queue: &wgpu::Queue,
108    texture: &wgpu::Texture,
109    origin_z: u32,
110    format: wgpu::TextureFormat,
111    width: u32,
112    height: u32,
113    pixels: &[u8],
114) {
115    queue.write_texture(
116        wgpu::TexelCopyTextureInfo {
117            texture,
118            mip_level: 0,
119            origin: wgpu::Origin3d { x: 0, y: 0, z: origin_z },
120            aspect: wgpu::TextureAspect::All,
121        },
122        pixels,
123        wgpu::TexelCopyBufferLayout {
124            offset: 0,
125            bytes_per_row: Some(bytes_per_pixel(format) * width),
126            rows_per_image: Some(height),
127        },
128        wgpu::Extent3d { width, height, depth_or_array_layers: 1 },
129    );
130}
131
132/// Bytes-per-pixel for the pixel formats this loader knows how to produce.
133pub(crate) fn bytes_per_pixel(format: wgpu::TextureFormat) -> u32 {
134    match format {
135        wgpu::TextureFormat::Rgba8Unorm | wgpu::TextureFormat::Rgba8UnormSrgb => 4,
136        wgpu::TextureFormat::Rgba16Float => 8,
137        wgpu::TextureFormat::Rgba32Float => 16,
138        other => panic!("unsupported texture format for GPUTexture: {other:?}"),
139    }
140}
141
142/// Decodes an image file into raw pixel bytes matching `format`.
143///
144/// LDR formats (Rgba8*) decode straight to 8-bit RGBA. HDR/EXR sources (and
145/// any request for a float format) decode through `to_rgba32f()` so that
146/// values outside `[0, 1]` survive, then get packed down to the requested
147/// float width.
148pub(crate) fn decode_file(path: &str, format: wgpu::TextureFormat) -> Option<(u32, u32, Vec<u8>)> {
149    let img = match image::open(path) {
150        Ok(img) => img,
151        Err(e) => {
152            tracing::error!("failed to load texture '{path}': {e}");
153            return None;
154        }
155    };
156
157    Some(match format {
158        wgpu::TextureFormat::Rgba8Unorm | wgpu::TextureFormat::Rgba8UnormSrgb => {
159            let img = img.to_rgba8();
160            let (w, h) = img.dimensions();
161            (w, h, img.into_raw())
162        }
163        wgpu::TextureFormat::Rgba32Float => {
164            let img = img.to_rgba32f();
165            let (w, h) = img.dimensions();
166            let bytes = bytemuck::cast_slice(img.into_raw().as_slice()).to_vec();
167            (w, h, bytes)
168        }
169        wgpu::TextureFormat::Rgba16Float => {
170            let img = img.to_rgba32f();
171            let (w, h) = img.dimensions();
172            let bytes = img
173                .into_raw()
174                .into_iter()
175                .flat_map(|c| half::f16::from_f32(c).to_le_bytes())
176                .collect();
177            (w, h, bytes)
178        }
179        other => panic!("unsupported texture format for GPUTexture: {other:?}"),
180    })
181}
182
183impl Asset<WGPUBackend> for GPUTexture {
184    type Source = TextureDescriptor;
185    type Deps<'a> = Res<'a, MipmapGenerator>;
186
187    fn upload<'a>(
188        source: &TextureDescriptor,
189        backend: &WGPUBackend,
190        mipmap_generator: &Res<'a, MipmapGenerator>,
191    ) -> Option<Self> {
192        // resolve actual pixel data + real dimensions, whether from a file or already-supplied bytes
193        let (width, height, data) = if let Some(path) = source.file {
194            decode_file(path, source.format)?
195        } else if let Some(data) = &source.data {
196            (source.width, source.height, data.clone())
197        } else {
198            tracing::error!("TextureSpec has neither `file` nor `data` set");
199            return None;
200        };
201
202        let mip_count = super::mipmap::mip_count(width.max(height), source.generate_mips);
203
204        let texture = backend.device.create_texture(&wgpu::TextureDescriptor {
205            label: None,
206            size: wgpu::Extent3d {
207                width,
208                height,
209                depth_or_array_layers: 1,
210            },
211            mip_level_count: mip_count, // room allocated for all levels now
212            sample_count: 1,
213            dimension: wgpu::TextureDimension::D2,
214            format: source.format,
215            usage: super::mipmap::texture_usage(mip_count),
216            view_formats: &[],
217        });
218
219        // upload level 0 only — fast, synchronous, matches the deferred-mip decision
220        backend.queue.write_texture(
221            wgpu::TexelCopyTextureInfo {
222                texture: &texture,
223                mip_level: 0,
224                origin: wgpu::Origin3d::default(),
225                aspect: wgpu::TextureAspect::All,
226            },
227            &data,
228            wgpu::TexelCopyBufferLayout {
229                offset: 0,
230                bytes_per_row: Some(bytes_per_pixel(source.format) * width),
231                rows_per_image: Some(height),
232            },
233            wgpu::Extent3d {
234                width,
235                height,
236                depth_or_array_layers: 1,
237            },
238        );
239
240        if mip_count > 1 {
241            mipmap_generator.generate_mips(
242                &backend.device,
243                &backend.queue,
244                &texture,
245                source.format,
246                mip_count,
247                1,
248            );
249        }
250
251        let view = texture.create_view(&wgpu::TextureViewDescriptor::default());
252        Some(Self {
253            texture,
254            view,
255            width,
256            height,
257            format: source.format,
258            ctx: GpuContext::from_backend(backend),
259        })
260    }
261}
262
263crate::wgpu::plugin_macros::mipmap_asset_plugin! {
264    /// Registers the [`GPUTexture`] asset pipeline (`Assets<TextureDescriptor>`
265    /// → `ProcessedAssets<GPUTexture>`), plus the [`MipmapGenerator`] it depends
266    /// on for `generate_mips`. Included by
267    /// [`WGPUPlugin`](super::backend::WGPUPlugin); add directly only if you're
268    /// assembling the `wgpu` module's plugins by hand.
269    TexturePlugin, GPUTexture
270}
pebble/wgpu/textures.rs

pebble/wgpu/
textures.rs
