First attempt at a GPU runner

Currently failing with an error I don't understand:

```
wgpu error: Validation Error

Caused by:
  In Device::create_shader_module, label = '...\image_binary.spv'

Shader '...\image_binary.spv' parsing error: InvalidTypeWidth(1)
```

.gitea/workflows/ci.yml

@@ -21,7 +21,10 @@ jobs:
     steps:
       - uses: actions/checkout@v6
       - uses: actions-rust-lang/setup-rust-toolchain@v1
+        with:
+          components: clippy
       - run: cargo check --all-targets
+      - run: cargo clippy --all-targets
       - run: cargo test
 
   test-gpu:
@@ -30,5 +33,5 @@ jobs:
     steps:
       - uses: actions/checkout@v6
       - uses: actions-rust-lang/setup-rust-toolchain@v1
-      - run: cargo install --git https://github.com/rust-gpu/rust-gpu cargo-gpu
+      - run: cargo install --git https://github.com/rust-gpu/rust-gpu cargo-gpu --rev 67f1ff2
       - run: cargo gpu check --auto-install-rust-toolchain -p enkou-shaders

Cargo.toml

@@ -1,7 +1,8 @@
 [workspace]
 members = [
     "enkou-shaders",
-    "enkou-shaders-tests",
+    "examples/image-runner",
+    "examples/image-binary",
 ]
 resolver = "3"
 
@@ -13,6 +14,7 @@ license = "MIT"
 repository = ""
 
 [workspace.lints.rust]
+missing_docs = { level = "warn" }
 unexpected_cfgs = { level = "allow", check-cfg = ['cfg(target_arch, values("spirv"))'] }
 
 [workspace.dependencies]
@@ -21,10 +23,14 @@ spirv-std = { git = "https://github.com/Rust-GPU/rust-gpu.git", rev = "67f1ff2"
 
 anyhow = "1.0.102"
 bytemuck = { version = "1.25.0", features = ["derive"] }
+futures = "0.3.32"
 glam = { version = "0.33.1", default-features = false, features = ["bytemuck", "scalar-math"] }
 image = { version = "0.25.10", default-features = false, features = ["default-formats"]}
 libm = "0.2.16"
-rand = {  version = "0.10.1", default-features = false }
+rand = { version = "0.10.1", default-features = false }
 rand_xoshiro = "0.8.1"
 rspirv = "0.13.0"
 tempfile = "3.27.0"
+thiserror = "2.0.19"
+wgpu = { version = "30.0.0", features = ["spirv"] }
+xflags = "0.3.2"

enkou-shaders-tests/src/lib.rs

@@ -1,73 +0,0 @@
-#[cfg(test)]
-mod test {
-    use rspirv::binary::parse_bytes;
-    use rspirv::dr::{Module, Operand};
-    use rspirv::spirv::ExecutionModel;
-    use std::sync::OnceLock;
-
-    static SHADER_MODULE: OnceLock<Module> = OnceLock::new();
-
-    fn shader() -> &'static Module {
-        SHADER_MODULE.get_or_init(|| {
-            let shader_bytes = include_bytes!(env!("SHADER_SPV_PATH"));
-
-            let mut loader = rspirv::dr::Loader::new();
-            parse_bytes(shader_bytes, &mut loader).expect("Unable to parse shader");
-
-            loader.module()
-        })
-    }
-
-    fn has_entry_point(execution_model: ExecutionModel, name: &str) -> bool {
-        for ref entry_point in shader().entry_points.iter() {
-            let operands: Vec<Operand> = entry_point
-                .operands
-                .iter()
-                .filter(|op| match op {
-                    Operand::ExecutionModel(_) | Operand::LiteralString(_) => true,
-                    _ => false,
-                })
-                .map(|op| op.clone())
-                .collect();
-
-            assert_eq!(operands.len(), 2);
-            match &operands[0] {
-                Operand::ExecutionModel(actual) => {
-                    if execution_model != *actual {
-                        continue;
-                    }
-                }
-                op => panic!("Unexpected operand; {}", op),
-            }
-
-            match &operands[1] {
-                Operand::LiteralString(actual) => {
-                    if name != actual {
-                        continue;
-                    }
-                }
-                op => panic!("Unexpected operand; {}", op),
-            }
-
-            return true;
-        }
-
-        false
-    }
-
-    #[test]
-    pub fn has_entry_main_chaos_game() {
-        assert!(has_entry_point(
-            ExecutionModel::GLCompute,
-            "main_chaos_game"
-        ))
-    }
-
-    #[test]
-    pub fn has_entry_main_image_render() {
-        assert!(has_entry_point(
-            ExecutionModel::GLCompute,
-            "main_image_render"
-        ))
-    }
-}

enkou-shaders/Cargo.toml

@@ -16,8 +16,3 @@ libm.workspace = true
 rand.workspace = true
 rand_xoshiro.workspace = true
 spirv-std.workspace = true
-
-[dev-dependencies]
-anyhow.workspace = true
-image.workspace = true
-tempfile.workspace = true

enkou-shaders/examples/gasket.rs

@@ -1,105 +0,0 @@
-use anyhow::{Context, Result};
-use enkou_shaders::Coefficients2;
-use enkou_shaders::camera::Camera;
-use enkou_shaders::camera::entry::main_image_render;
-use enkou_shaders::chaos_game::entry::main_chaos_game;
-use enkou_shaders::transform::Transform;
-use enkou_shaders::variation::Variation;
-use glam::{Affine2, UVec2, Vec2, Vec4, uvec2, vec2};
-use image::{Rgba, Rgba32FImage};
-use std::mem;
-use std::process::Command;
-use tempfile::NamedTempFile;
-
-const ITERATIONS_DISCARD: u32 = 20;
-const ITERATIONS: u32 = 50_000;
-const IMAGE_DIMENSION: UVec2 = uvec2(600, 600);
-
-pub fn main() -> Result<()> {
-    let transforms = [
-        // F_0: (x / 2, y / 2)
-        Transform::new(
-            Affine2::from_coefficients(0.5, 0.0, 0.0, 0.0, 0.5, 0.0),
-            uvec2(0, 1),
-            vec2(0.0, 0.0),
-        ),
-        // F_1: ((x + 1) / 2, y / 2)
-        Transform::new(
-            Affine2::from_coefficients(0.5, 0.0, 0.5, 0.0, 0.5, 0.0),
-            uvec2(0, 1),
-            vec2(0.0, 0.0),
-        ),
-        // F_2: (x / 2, (y + 1) / 2)
-        Transform::new(
-            Affine2::from_coefficients(0.5, 0.0, 0.0, 0.0, 0.5, 0.5),
-            uvec2(0, 1),
-            vec2(0.0, 0.0),
-        ),
-    ];
-
-    let weights = [1.0 / 3.0, 1.0 / 3.0, 1.0 / 3.0];
-
-    let variations = [Variation::IDENTITY];
-
-    let mut output_points_ifs = Vec::new();
-    output_points_ifs.resize(ITERATIONS as usize, Vec4::ZERO);
-
-    main_chaos_game(
-        ITERATIONS_DISCARD,
-        &[4u8; 32],
-        &transforms,
-        &weights,
-        &variations,
-        &mut output_points_ifs,
-    );
-
-    // The gasket is defined on the range [0, 1] for both X and Y
-    let camera = Camera::new(
-        IMAGE_DIMENSION,
-        Vec2::ONE * 0.5,
-        0.0,
-        Vec2::ZERO,
-        IMAGE_DIMENSION.as_vec2(),
-    );
-
-    let palette = &[Vec4::ONE; 2];
-
-    let mut output_points_pixel = Vec::new();
-    output_points_pixel.resize(ITERATIONS as usize, Vec4::ZERO);
-
-    main_image_render(
-        &camera,
-        palette,
-        &output_points_ifs,
-        &mut output_points_pixel,
-    );
-
-    let mut image = Rgba32FImage::new(IMAGE_DIMENSION.x, IMAGE_DIMENSION.y);
-    for x in 0..image.dimensions().0 {
-        for y in 0..image.dimensions().1 {
-            let pixel_index = y * IMAGE_DIMENSION.x + x;
-            let pixel = output_points_pixel[pixel_index as usize];
-            image.put_pixel(x, y, Rgba(pixel.into()));
-        }
-    }
-
-    let temp = NamedTempFile::with_suffix(".png").context("Unable to create file for image")?;
-    image.save(temp.path()).context("Unable to save image")?;
-
-    let open_program: &str = cfg_select! {
-        unix => Some("xdg-open"),
-        _ => None,
-    }
-    .expect("No available program to open images");
-
-    Command::new(open_program)
-        .arg(temp.path())
-        .spawn()?
-        .wait()?;
-
-    // In case the image viewer forks and gives control back prior to reading the file,
-    // drop it and don't run the destructor
-    mem::forget(temp);
-
-    Ok(())
-}

enkou-shaders/src/camera.rs

@@ -2,47 +2,8 @@
 //!
 //! Map points from the IFS coordinate system to pixel coordinates. This is a lossy transformation.
 use bytemuck::{Pod, Zeroable};
-use glam::{Affine2, IVec2, UVec2, Vec2, Vec4, Vec4Swizzles, vec2};
-use libm::{floorf, powf};
-
-/// Blending modes for mapping IFS color values (which are on a scale `[0, 1]`)
-/// to RGBA colors.
-#[derive(Copy, Clone)]
-#[repr(u32)]
-pub enum BlendMode {
-    /// Map IFS color values to a linear blend of the nearest two palette colors
-    Linear = 0,
-
-    /// Map IFS color values to the nearest single palette color
-    Step = 1,
-}
-
-impl Default for BlendMode {
-    fn default() -> Self {
-        BlendMode::Linear
-    }
-}
-
-impl BlendMode {
-    /// Map an IFS color value to RGBA color from the provided palette.
-    pub fn ifs_to_rgb(&self, color: f32, palette: &[Vec4]) -> Vec4 {
-        let colors_m_one = palette.len() - 1;
-        let period = 1.0 / colors_m_one as f32;
-        let index_lower = floorf(color / period) as usize;
-        let index_upper = (index_lower + 1).clamp(0, colors_m_one);
-        let rem = color % period / period;
-
-        match self {
-            BlendMode::Linear => palette[index_lower].lerp(palette[index_upper], rem),
-            BlendMode::Step => palette[index_lower],
-        }
-    }
-}
-
-// UNSAFE: Sound because enum has guaranteed layout (u32) and defined zero-value
-unsafe impl bytemuck::Zeroable for BlendMode {}
-// UNSAFE: Sound because enum has guaranteed layout (u32) and defined zero-value
-unsafe impl bytemuck::Pod for BlendMode {}
+use glam::{Affine2, IVec2, UVec2, Vec2, vec2};
+use libm::powf;
 
 /// Settings used to map IFS coordinates to pixel coordinates.
 ///
@@ -53,8 +14,6 @@ unsafe impl bytemuck::Pod for BlendMode {}
 pub struct Camera {
     dimensions: UVec2,
     transform: Affine2,
-    blend_mode: BlendMode,
-    image_gamma: f32,
 }
 
 impl Camera {
@@ -67,14 +26,14 @@ impl Camera {
     ///
     /// * `dimensions` - Width and height of the output image (in pixels).
     /// * `center` - Location of the origin in IFS coordinates. Positive `x` shifts the image
-    ///     left, and positive `y` position shifts the image up.
+    ///   left, and positive `y` position shifts the image up.
     /// * `rotate` - Rotation angle (in radians) of IFS coordinates. Rotation is applied after the
-    ///     `center` translation, so it is about the new origin.
+    ///   `center` translation, so it is about the new origin.
     /// * `zoom` - Zoom factor applied to IFS coordinates. IFS coordinates are scaled by
-    ///     `pow(2, zoom)`, so a zoom factor of 0 is the identity.
+    ///   `pow(2, zoom)`, so a zoom factor of 0 is the identity.
     /// * `scale` - Pixels per unit of IFS coordinates. This parameter is usually chosen such
-    ///     that the largest dimension will cover the range `[-2, 2]`, but values higher or lower
-    ///     can be used as a secondary zoom.
+    ///   that the largest dimension will cover the range `[-2, 2]`, but values higher or lower
+    ///   can be used as a secondary zoom.
     pub fn new(dimensions: UVec2, center: Vec2, rotate: f32, zoom: Vec2, scale: Vec2) -> Camera {
         let ifs_center_transform = Affine2::from_translation(-center);
         let zoom_transform = Affine2::from_scale(vec2(powf(2.0, zoom.x), powf(2.0, zoom.y)));
@@ -91,122 +50,73 @@ impl Camera {
         Camera {
             dimensions,
             transform,
-            blend_mode: BlendMode::Linear,
-            image_gamma: 1.5,
         }
     }
 
-    fn transform_point(&self, point: Vec2) -> IVec2 {
+    /// Map a point from IFS coordinates to pixel coordinates.
+    ///
+    /// ```
+    /// # use glam::{vec2, ivec2, uvec2, Vec2};
+    /// # use crate::enkou_shaders::camera::Camera;
+    /// // Output image is 600x600 pixels, centered at the origin, no rotation, no zoom,
+    /// // and scaled such that it covers the range [-2, 2].
+    /// // Use the origin as the IFS coordinate, so the pixel coordinate is the center of the image
+    /// let camera = Camera::new(
+    ///     uvec2(600, 600),
+    ///     Vec2::ZERO,
+    ///     0.0,
+    ///     Vec2::ZERO,
+    ///     vec2(150.0, 150.0)
+    /// );
+    /// assert_eq!(camera.transform_point(vec2(0.0, 0.0)), ivec2(300, 300));
+    /// ```
+    pub fn transform_point(&self, point: Vec2) -> IVec2 {
         self.transform.transform_point2(point).as_ivec2()
     }
 
-    /// Map a point from IFS coordinates to a pixel index and RGBA value; if the IFS coordinate
-    /// is outside the viewable range, return [`None`].
-    pub fn transform_point_to_image(&self, point: Vec4, palette: &[Vec4]) -> Option<(usize, Vec4)> {
-        let pixel_coordinates = self.transform_point(point.xy());
+    /// Map a point from IFS coordinates to pixel coordinates (like [`transform_point`](Camera::transform_point)),
+    /// and check that the result is within the provided image dimensions.
+    pub fn transform_point_to_image(&self, point: Vec2) -> Option<UVec2> {
+        let pixel_coordinates = self.transform_point(point);
         if pixel_coordinates.x < 0
             || pixel_coordinates.y < 0
             || (pixel_coordinates.x as u32) >= self.dimensions.x
             || (pixel_coordinates.y as u32) >= self.dimensions.y
         {
-            return None;
+            None
+        } else {
+            Some(pixel_coordinates.as_uvec2())
         }
-
-        let to_pixel_index = self.dimensions.with_y(0);
-        let pixel_index = pixel_coordinates.as_uvec2().dot(to_pixel_index) as usize;
-
-        let rgba = self.blend_mode.ifs_to_rgb(point.w, palette);
-
-        Some((pixel_index, rgba))
     }
 }
 
-#[allow(missing_docs)]
+/// Shader entry point for running the camera transformation over a list of IFS coordinates
 pub mod entry {
     use crate::camera::Camera;
-    use glam::Vec4;
-    use libm::log10f;
+    use spirv_std::glam::{IVec2, Vec2};
     use spirv_std::spirv;
 
-    /// Render an output image from a list of IFS coordinates.
-    ///
-    /// Arguments:
-    /// * `camera` - Camera settings for mapping IFS coordinates to pixel coordinates
-    /// * `palette` - Color palette to use when mapping IFS color to RGB colors. Individual elements
-    ///     are assumed to be RGBA values on the scale of `[0, 1]`
-    /// * `coordinates_ifs` - IFS coordinates to use for the output image
-    /// * `image` - Buffer for the output image
-    #[spirv(compute(entry_point_name = "main_image_render", threads(1)))]
-    pub fn main_image_render(
+    /// Transform IFS coordinates to pixel coordinates
+    #[spirv(compute(entry_point_name = "main_camera", threads(1)))]
+    pub fn main_camera(
         #[spirv(storage_buffer, descriptor_set = 0, binding = 0)] camera: &Camera,
-        #[spirv(storage_buffer, descriptor_set = 0, binding = 1)] palette: &[Vec4],
-        #[spirv(storage_buffer, descriptor_set = 0, binding = 1)] coordinates_ifs: &[Vec4],
-        #[spirv(storage_buffer, descriptor_set = 1, binding = 0)] image: &mut [Vec4],
+        #[spirv(storage_buffer, descriptor_set = 0, binding = 1)] coordinates_ifs: &[Vec2],
+        #[spirv(storage_buffer, descriptor_set = 1, binding = 0)] coordinates_pixel: &mut [IVec2],
     ) {
-        for coordinate_index in 0..coordinates_ifs.len() {
-            camera
-                .transform_point_to_image(coordinates_ifs[coordinate_index], palette)
-                .map(|(pixel_index, rgba)| image[pixel_index] += rgba);
-        }
-
-        for pixel_index in 0..image.len() {
-            // TODO: Fix the bootleg gamma adjustment
-            let pixel_unscaled = image[pixel_index];
-            let pixel =
-                pixel_unscaled * log10f(pixel_unscaled.w) / (pixel_unscaled.w * camera.image_gamma);
-            image[pixel_index] = pixel;
+        for i in 0..coordinates_ifs.len() {
+            coordinates_pixel[i] = camera.transform_point(coordinates_ifs[i])
         }
     }
 }
 
 #[cfg(test)]
 mod test {
-    use crate::camera::{BlendMode, Camera};
-    use glam::{Affine2, Vec2, Vec4, ivec2, uvec2, vec2};
+    use crate::camera::Camera;
+    use glam::{Affine2, Vec2, ivec2, uvec2, vec2};
     use libm::powf;
 
-    fn vec4s(value: f32) -> Vec4 {
-        Vec4::splat(value)
-    }
-
     #[test]
-    fn blend_linear() {
-        let ifs_to_rgb = |color, palette| BlendMode::Linear.ifs_to_rgb(color, palette);
-
-        let palette = &[vec4s(0.0), vec4s(1.0)];
-        assert_eq!(ifs_to_rgb(0.0, palette), vec4s(0.0));
-        assert_eq!(ifs_to_rgb(0.5, palette), vec4s(0.5));
-        assert_eq!(ifs_to_rgb(1.0, palette), vec4s(1.0));
-
-        let palette = &[vec4s(1.0), vec4s(2.0), vec4s(3.0)];
-        assert_eq!(ifs_to_rgb(0.0, palette), vec4s(1.0));
-        assert_eq!(ifs_to_rgb(0.5, palette), vec4s(2.0));
-        assert_eq!(ifs_to_rgb(1.0, palette), vec4s(3.0));
-
-        let palette = &[vec4s(1.0), vec4s(2.0), vec4s(3.0), vec4s(4.0)];
-        assert_eq!(ifs_to_rgb(0.0, palette), vec4s(1.0));
-        assert_eq!(ifs_to_rgb(0.5, palette), vec4s(2.5));
-        assert_eq!(ifs_to_rgb(1.0, palette), vec4s(4.0));
-    }
-
-    #[test]
-    fn blend_step() {
-        let ifs_to_rgb = |color, palette| BlendMode::Step.ifs_to_rgb(color, palette);
-
-        let palette = &[vec4s(0.0), vec4s(1.0)];
-        assert_eq!(ifs_to_rgb(0.5, palette), vec4s(0.0));
-
-        let palette = &[vec4s(1.0), vec4s(2.0), vec4s(3.0)];
-        assert_eq!(ifs_to_rgb(0.0, palette), palette[0]);
-        assert_eq!(ifs_to_rgb(0.25, palette), palette[0]);
-        assert_eq!(ifs_to_rgb(0.4, palette), palette[0]);
-        assert_eq!(ifs_to_rgb(0.5, palette), palette[1]);
-        assert_eq!(ifs_to_rgb(0.7, palette), palette[1]);
-        assert_eq!(ifs_to_rgb(1.0, palette), palette[2]);
-    }
-
-    #[test]
-    fn camera_manual() {
+    pub fn manual_camera() {
         let starting_point = vec2(1.0, 1.0);
 
         // Move the origin; points move right and up by one unit, giving us (2.0, 2.0)
@@ -244,7 +154,7 @@ mod test {
     }
 
     #[test]
-    fn camera_point_outside_image() {
+    pub fn point_outside_camera() {
         // Scale 250 for an image 1000 x 1000 gives an effective range of [-2, 2]
         let camera = Camera::new(
             uvec2(1000, 1000),
@@ -259,7 +169,7 @@ mod test {
     }
 
     #[test]
-    fn camera_point_outside_image_negative() {
+    pub fn point_outside_camera_negative() {
         // Scale 250 for an image 1000 x 1000 gives an effective range of [-2, 2]
         let camera = Camera::new(
             uvec2(1000, 1000),
@@ -274,7 +184,7 @@ mod test {
     }
 
     #[test]
-    fn camera_aspect_ratio() {
+    pub fn aspect_ratio() {
         // Scale 100 for an image 1600 x 900 gives an effective X range of [-8, 8],
         // and effective Y range of [-4.5, 4.5]
         let camera = Camera::new(

enkou-shaders/src/chaos_game.rs

@@ -12,6 +12,7 @@
 //!
 //! This algorithm is also known as the ["chaos game"](https://en.wikipedia.org/wiki/Chaos_game),
 //! and it forms the basic system for producing images.
+
 use crate::transform::Transform;
 use crate::variation::Variation;
 use rand::distr::{Distribution, StandardUniform};
@@ -35,14 +36,13 @@ impl Distribution<f32> for BiUnit {
 /// * `weights` - Weights are assumed to be normalized; adding all elements together should return the value 1
 pub fn step_chaos_game<R: Rng>(
     point: Vec2,
-    color: f32,
     rng: &mut R,
     transforms: &[Transform],
     weights: &[f32],
     variations: &[Variation],
-) -> (Vec2, f32, usize) {
+) -> (Vec2, u32) {
     let mut choice_weight = rng.sample::<f32, _>(StandardUniform);
-    let mut transform_index: usize = 0;
+    let mut transform_index: u32 = 0;
 
     for i in 0..weights.len() {
         choice_weight -= weights[i];
@@ -53,10 +53,8 @@ pub fn step_chaos_game<R: Rng>(
         transform_index += 1;
     }
 
-    let ref transform = transforms[transform_index];
     (
-        transform.transform_point(rng, variations, point),
-        transform.transform_color(color),
+        transforms[transform_index as usize].transform_point(rng, variations, point),
         transform_index,
     )
 }
@@ -67,7 +65,6 @@ pub fn step_chaos_game<R: Rng>(
 /// New points in the chaos game are produced by iterating on the chaos game.
 pub struct ChaosGame<'a, R: Rng> {
     current_point: Vec2,
-    current_color: f32,
     rng: &'a mut R,
     transforms: &'a [Transform],
     weights: &'a [f32],
@@ -82,9 +79,9 @@ impl<'a, R: Rng> ChaosGame<'a, R> {
         weights: &'a [f32],
         variations: &'a [Variation],
     ) -> Self {
+        let current_point = vec2(rng.sample(BiUnit), rng.sample(BiUnit));
         ChaosGame {
-            current_point: vec2(rng.sample(BiUnit), rng.sample(BiUnit)),
-            current_color: rng.sample(StandardUniform),
+            current_point,
             rng,
             transforms,
             weights,
@@ -94,65 +91,18 @@ impl<'a, R: Rng> ChaosGame<'a, R> {
 }
 
 impl<'a, R: Rng> Iterator for ChaosGame<'a, R> {
-    type Item = (Vec2, f32);
+    type Item = Vec2;
 
     fn next(&mut self) -> Option<Self::Item> {
-        let (next_point, next_color, _) = step_chaos_game(
+        let (next_point, _) = step_chaos_game(
             self.current_point,
-            self.current_color,
             self.rng,
             self.transforms,
             self.weights,
             self.variations,
         );
         self.current_point = next_point;
-        self.current_color = next_color;
 
-        Some((next_point, next_color))
-    }
-}
-
-/// Shader entry point for running the chaos game to produce new IFS coordinates
-pub mod entry {
-    use crate::chaos_game::ChaosGame;
-    use crate::rng::xoshiro256starstar_from_seed;
-    use crate::transform::Transform;
-    use crate::variation::Variation;
-    use glam::Vec4;
-    use spirv_std::spirv;
-
-    /// Given a set of fractal flame parameters, generate new IFS coordinates
-    /// and store them in the output array.
-    ///
-    /// Arguments:
-    /// * `iteration_discard` - Choas game steps to discard prior to recording into the output buffer
-    /// * `output` - Output buffer to record chaos game steps into. Because of alignment issues,
-    ///     the output is recorded as a [`Vec4`]; the IFS (x, y) coordinate is in `x` and `y`,
-    ///     and color is in `w`
-    #[spirv(compute(entry_point_name = "main_chaos_game", threads(1)))]
-    pub fn main_chaos_game(
-        #[spirv(spec_constant(id = 1, default = 20))] iteration_discard: u32,
-        #[spirv(storage_buffer, descriptor_set = 0, binding = 0)] rng_seed: &[u8],
-        #[spirv(storage_buffer, descriptor_set = 0, binding = 1)] transforms: &[Transform],
-        #[spirv(storage_buffer, descriptor_set = 0, binding = 2)] weights: &[f32],
-        #[spirv(storage_buffer, descriptor_set = 0, binding = 3)] variations: &[Variation],
-        #[spirv(storage_buffer, descriptor_set = 1, binding = 0)] output: &mut [Vec4],
-    ) {
-        let mut rng_seed_actual = [0u8; 32];
-        (0..32).for_each(|i| rng_seed_actual[i] = rng_seed[i]);
-
-        let mut rng = xoshiro256starstar_from_seed(rng_seed_actual);
-        let mut chaos_game = ChaosGame::new(&mut rng, transforms, weights, variations);
-
-        for _ in 0..iteration_discard {
-            chaos_game.next().unwrap();
-        }
-
-        for i in 0..output.len() {
-            output[i] = chaos_game
-                .next()
-                .map(|output| (output.0, 0.0, output.1).into())
-                .unwrap();
-        }
+        Some(next_point)
     }
 }

enkou-shaders/src/lib.rs

@@ -1,10 +1,12 @@
 //! # Enkou
-#![no_std]
-#![warn(missing_docs)]
+#![cfg_attr(target_arch = "spirv", no_std)]
+
+// SPIR-V backend is unable to compile iteration over items
+#![allow(clippy::needless_range_loop)]
 
 pub mod camera;
 pub mod chaos_game;
-mod rng;
+pub mod rng;
 pub mod transform;
 pub mod variation;
 

enkou-shaders/src/rng.rs

@@ -1,3 +1,6 @@
+//! # RNG
+//!
+//! Random number generation utilities for shaders
 use rand::SeedableRng;
 use rand_xoshiro::Xoshiro256StarStar;
 
@@ -14,17 +17,17 @@ use rand_xoshiro::Xoshiro256StarStar;
 /// This function assumes a properly-initialized state array;
 /// output may silently degenerate if the initial state is all zeros,
 /// so this module is private to the crate.
-pub(crate) fn xoshiro256starstar_from_seed(
+pub fn xoshiro256starstar_from_seed(
     rng_state: <Xoshiro256StarStar as SeedableRng>::Seed,
 ) -> Xoshiro256StarStar {
     let mut rng_state_actual = [0u64; 4];
 
-    // NOTE: Bit shifting is tedious, but we don't have great alternatives:
+    // NOTE: Bit shifting is bad, but we don't have great alternatives:
     //  - `chunks_exact` has issues with pointer casting
     //  - `u64::from_le_bytes` has issues with `OpBitcast` in SPIR-V validation
     for i in 0..rng_state_actual.len() {
         for j in 0..size_of::<u64>() {
-            rng_state_actual[i] |= (rng_state[i * size_of::<u64>() + j] as u64) << j * 8;
+            rng_state_actual[i] |= (rng_state[i * size_of::<u64>() + j] as u64) << (j * 8);
         }
     }
 

enkou-shaders/src/transform.rs

@@ -5,7 +5,7 @@
 //! but produce more interesting images once we add variations.
 use crate::variation::Variation;
 use bytemuck::{Pod, Zeroable};
-use glam::{Affine2, FloatExt, UVec2, Vec2};
+use glam::{Affine2, UVec2, Vec2};
 use rand::Rng;
 
 /// Affine transform for use in the [`chaos_game`](crate::chaos_game).
@@ -13,22 +13,17 @@ use rand::Rng;
 #[repr(C)]
 pub struct Transform {
     coefficients: Affine2,
+    coefficients_post: Affine2,
     variation_range: UVec2,
-    color: Vec2,
 }
 
 impl Transform {
     /// Create a new transform from an affine transformation matrix
-    ///
-    /// Arguments:
-    /// * `coefficients` - Affine transform coefficients for this transformation. Applied prior to variations
-    /// * `variation_range` - (half-open) range of variations to apply during [`Self::transform_point`]
-    /// * `color` - Color value and speed to apply during [`Self::transform_color`]
-    pub fn new(coefficients: Affine2, variation_range: UVec2, color: Vec2) -> Self {
+    pub fn new(coefficients: Affine2, coefficients_post: Affine2, variation_range: UVec2) -> Self {
         Transform {
             coefficients,
+            coefficients_post,
             variation_range,
-            color,
         }
     }
 
@@ -46,111 +41,57 @@ impl Transform {
         let variation_start = self.variation_range.x;
         let variation_end = self.variation_range.y;
         for variation_index in variation_start..variation_end {
-            let ref variation = variations[variation_index as usize];
+            let variation = &variations[variation_index as usize];
             point_output += variation.transform_point(point, rng, &self.coefficients)
         }
 
-        point_output
-    }
-
-    /// Mix an existing color with this transform's color
-    pub fn transform_color(&self, color: f32) -> f32 {
-        color.lerp(self.color.x, self.color.y)
+        self.coefficients_post.transform_point2(point)
     }
 }
 
 #[cfg(test)]
 mod test {
-    use crate::Coefficients2;
+    use crate::rng::xoshiro256starstar_from_seed;
     use crate::transform::Transform;
     use crate::variation::{Variation, VariationKind};
-    use core::convert::Infallible;
-    use glam::{Affine2, Vec2, uvec2, vec2};
-    use rand::TryRng;
-
-    struct NullRng;
-
-    impl NullRng {
-        pub fn new() -> Self {
-            NullRng
-        }
-    }
-
-    impl TryRng for NullRng {
-        type Error = Infallible;
-
-        fn try_next_u32(&mut self) -> Result<u32, Self::Error> {
-            Ok(0)
-        }
-
-        fn try_next_u64(&mut self) -> Result<u64, Self::Error> {
-            Ok(0)
-        }
-
-        fn try_fill_bytes(&mut self, dst: &mut [u8]) -> Result<(), Self::Error> {
-            dst.iter_mut().for_each(|b| *b = 0);
-            Ok(())
-        }
-    }
+    use glam::{Affine2, uvec2, vec2};
 
     #[test]
-    fn test_transform_point_identity() {
-        let transform = Transform::new(Affine2::IDENTITY, uvec2(0, 1), vec2(0.0, 0.0));
-        let variations = [Variation::IDENTITY];
-
-        let transform_point =
-            |point: Vec2| transform.transform_point(&mut NullRng::new(), &variations, point);
-        for (input, expected) in [
-            (vec2(0.0, 1.0), vec2(0.0, 1.0)),
-            (vec2(1.0, 0.0), vec2(1.0, 0.0)),
-            (vec2(1.0, 1.0), vec2(1.0, 1.0)),
-        ] {
-            assert_eq!(transform_point(input), expected);
-        }
-    }
-
-    #[test]
-    fn test_transform_point_scaling() {
+    fn transform_scaling() {
+        let scale_coefficients = vec2(2.0, 0.5);
         let transform = Transform::new(
-            Affine2::from_coefficients(0.5, 0.0, 0.0, 0.0, 0.5, 0.0),
+            Affine2::from_scale(scale_coefficients),
+            Affine2::IDENTITY,
             uvec2(0, 1),
-            vec2(0.0, 0.0),
         );
+
+        let mut rng = xoshiro256starstar_from_seed([0; 32]);
         let variations = [Variation::IDENTITY];
+        let point = vec2(1.0, 1.0);
 
-        let transform_point =
-            |point: Vec2| transform.transform_point(&mut NullRng::new(), &variations, point);
-        for (input, expected) in [
-            (vec2(0.0, 1.0), vec2(0.0, 0.5)),
-            (vec2(1.0, 0.0), vec2(0.5, 0.0)),
-            (vec2(1.0, 1.0), vec2(0.5, 0.5)),
-        ] {
-            assert_eq!(transform_point(input), expected);
-        }
+        assert_eq!(
+            transform.transform_point(&mut rng, &variations, point),
+            scale_coefficients
+        );
     }
 
     #[test]
-    fn test_transform_point_scaling_variation() {
-        let transform = Transform::new(Affine2::IDENTITY, uvec2(0, 1), vec2(0.0, 0.0));
-        let variations = [Variation::new(VariationKind::Linear, 2.0, [0.0; 4].into())];
+    fn transform_scaling_post() {
+        let scale_coefficients = vec2(2.0, 0.5);
+        let transform_pdj = Transform::new(Affine2::IDENTITY, Affine2::IDENTITY, uvec2(0, 1));
+        let transform_pdj_post = Transform::new(
+            Affine2::IDENTITY,
+            Affine2::from_scale(scale_coefficients),
+            uvec2(0, 1),
+        );
 
-        let transform_point =
-            |point: Vec2| transform.transform_point(&mut NullRng::new(), &variations, point);
-        for (input, expected) in [
-            (vec2(0.0, 1.0), vec2(0.0, 2.0)),
-            (vec2(1.0, 0.0), vec2(2.0, 0.0)),
-            (vec2(1.0, 1.0), vec2(2.0, 2.0)),
-        ] {
-            assert_eq!(transform_point(input), expected);
-        }
-    }
+        let mut rng = xoshiro256starstar_from_seed([0; 32]);
+        let variations = [Variation::new(VariationKind::Pdj, 1.0, [0.0f32; 4].into())];
+        let point = vec2(1.0, 1.0);
 
-    #[test]
-    fn test_color_mixing() {
-        let transform = Transform::new(Affine2::IDENTITY, uvec2(0, 1), vec2(0.0, 0.5));
+        let point_pdj = transform_pdj.transform_point(&mut rng, &variations, point);
+        let point_pdj_post = transform_pdj_post.transform_point(&mut rng, &variations, point);
 
-        assert_eq!(transform.transform_color(0.0), 0.0);
-        assert_eq!(transform.transform_color(1.0), 0.5);
-        assert_eq!(transform.transform_color(0.5), 0.25);
+        assert_eq!(point_pdj * scale_coefficients, point_pdj_post);
     }
 }

enkou-shaders/src/variation.rs

@@ -21,8 +21,8 @@ use rand::{Rng, RngExt};
 pub struct VariationParams([f32; 4]);
 
 impl From<[f32; 4]> for VariationParams {
-    fn from(value: [f32; 4]) -> Self {
-        VariationParams(value)
+    fn from(v: [f32; 4]) -> Self {
+        VariationParams(v)
     }
 }
 
@@ -68,7 +68,7 @@ impl Variation {
     };
 
     /// Create a new variation by providing the variation kind, weight, and parameters.
-    pub fn new(kind: VariationKind, weight: f32, params: VariationParams) -> Variation {
+    pub const fn new(kind: VariationKind, weight: f32, params: VariationParams) -> Variation {
         Variation {
             kind,
             weight,

examples/image-binary/Cargo.toml

@@ -1,18 +1,16 @@
 [package]
-name = "enkou-shaders-tests"
-publish = false
+name = "image-binary"
 version.workspace = true
 authors.workspace = true
 edition.workspace = true
 license.workspace = true
 repository.workspace = true
 
+[dependencies]
+enkou-shaders = { path = "../../enkou-shaders" }
+glam.workspace = true
+spirv-std.workspace = true
+wgpu = { workspace = true, optional = true }
+
 [lints]
 workspace = true
-
-[dependencies]
-rspirv.workspace = true
-
-[build-dependencies]
-anyhow.workspace = true
-cargo-gpu-install.workspace = true

examples/image-binary/src/lib.rs

@@ -0,0 +1,82 @@
+//! # Binary image
+#![cfg_attr(target_arch = "spirv", no_std)]
+use enkou_shaders::camera::Camera;
+use enkou_shaders::chaos_game::ChaosGame;
+use enkou_shaders::rng::xoshiro256starstar_from_seed;
+use enkou_shaders::transform::Transform;
+use enkou_shaders::variation::Variation;
+use glam::{UVec2, UVec4};
+use spirv_std::spirv;
+
+#[cfg(feature = "wgpu")]
+pub use wgpu::*;
+
+const IMAGE_QUALITY: f32 = 1.0;
+const ITERATIONS_FUSE: u32 = 20;
+
+/// Sierpinski Gasket
+#[spirv(compute(entry_point_name = "main_image_binary", threads(1)))]
+pub fn main_image_binary(
+    #[spirv(storage_buffer, descriptor_set = 0, binding = 0)] image_dimensions: &UVec2,
+    #[spirv(storage_buffer, descriptor_set = 0, binding = 1)] transforms: &[Transform],
+    #[spirv(storage_buffer, descriptor_set = 0, binding = 2)] weights: &[f32],
+    #[spirv(storage_buffer, descriptor_set = 0, binding = 3)] variations: &[Variation],
+    #[spirv(storage_buffer, descriptor_set = 0, binding = 4)] camera: &Camera,
+    #[spirv(storage_buffer, descriptor_set = 0, binding = 5)] image_buffer: &mut [UVec4],
+) {
+    // Initialize RNG and run the chaos game
+    let mut rng = xoshiro256starstar_from_seed([4; 32]);
+    let mut chaos_game = ChaosGame::new(&mut rng, transforms, weights, variations);
+
+    // Discard the first few iterations
+    for _ in 0..ITERATIONS_FUSE {
+        chaos_game.next().unwrap();
+    }
+
+    // Plot the remaining points generated by the chaos game
+    let iterations = (image_dimensions.as_vec2().element_product() * IMAGE_QUALITY) as u32;
+    for _ in 0..iterations {
+        let ifs_point = chaos_game.next().unwrap();
+        let pixel_point = camera.transform_point_to_image(ifs_point);
+
+        if let Some(pixel_point) = pixel_point {
+            let pixel_index = pixel_point.y * image_dimensions.x + pixel_point.x;
+            image_buffer[pixel_index as usize] = UVec4::splat(255);
+        }
+    }
+}
+
+#[cfg(feature = "wgpu")]
+pub mod wgpu {
+    const fn bgle(binding: u32, read_only: bool) -> wgpu::BindGroupLayoutEntry {
+        wgpu::BindGroupLayoutEntry {
+            binding,
+            visibility: wgpu::ShaderStages::COMPUTE,
+            ty: wgpu::BindingType::Buffer {
+                ty: wgpu::BufferBindingType::Storage { read_only },
+                has_dynamic_offset: false,
+                min_binding_size: None,
+            },
+            count: None,
+        }
+    }
+
+    pub const BGLE_IMAGE_DIMENSIONS: wgpu::BindGroupLayoutEntry = bgle(0, true);
+    pub const BGLE_TRANSFORMS: wgpu::BindGroupLayoutEntry = bgle(1, true);
+    pub const BGLE_WEIGHTS: wgpu::BindGroupLayoutEntry = bgle(2, true);
+    pub const BGLE_VARIATIONS: wgpu::BindGroupLayoutEntry = bgle(3, true);
+    pub const BGLE_CAMERA: wgpu::BindGroupLayoutEntry = bgle(4, true);
+    pub const BGLE_IMAGE_BUFFER: wgpu::BindGroupLayoutEntry = bgle(5, false);
+
+    pub const BIND_GROUP_IMAGE_BINARY: wgpu::BindGroupLayoutDescriptor = wgpu::BindGroupLayoutDescriptor {
+        label: Some("main_image_binary"),
+        entries: &[
+            BGLE_IMAGE_DIMENSIONS,
+            BGLE_TRANSFORMS,
+            BGLE_WEIGHTS,
+            BGLE_VARIATIONS,
+            BGLE_CAMERA,
+            BGLE_IMAGE_BUFFER,
+        ],
+    };
+}

examples/image-runner/Cargo.toml

@@ -0,0 +1,27 @@
+[package]
+name = "image-runner"
+version.workspace = true
+authors.workspace = true
+edition.workspace = true
+license.workspace = true
+repository.workspace = true
+
+[dependencies]
+enkou-shaders = { path = "../../enkou-shaders" }
+image-binary = { path = "../image-binary", features = ["wgpu"] }
+
+anyhow.workspace = true
+bytemuck.workspace = true
+futures.workspace = true
+glam = { workspace = true, features = ["u8"] }
+image.workspace = true
+tempfile.workspace = true
+wgpu.workspace = true
+xflags.workspace = true
+
+[build-dependencies]
+anyhow.workspace = true
+cargo-gpu-install.workspace = true
+
+[lints]
+workspace = true

examples/image-runner/build.rs

@@ -4,7 +4,7 @@ use std::path::PathBuf;
 
 pub fn main() -> anyhow::Result<()> {
     let manifest_dir = env!("CARGO_MANIFEST_DIR");
-    let crate_path = [manifest_dir, "..", "enkou-shaders"]
+    let crate_path = [manifest_dir, "..", "image-binary"]
         .iter()
         .copied()
         .collect::<PathBuf>();
@@ -16,15 +16,13 @@ pub fn main() -> anyhow::Result<()> {
     builder.build_script.defaults = true;
     builder.shader_panic_strategy = ShaderPanicStrategy::SilentExit;
     builder.spirv_metadata = SpirvMetadata::Full;
-    builder.capabilities = vec![
-        Capability::Int8,
-        Capability::Int16,
-        Capability::Int64,
-        Capability::Float64,
-    ];
+    builder.capabilities = vec![Capability::Int8, Capability::Int16, Capability::Int64];
 
     let compile_result = builder.build()?;
     let spv_path = compile_result.module.unwrap_single();
-    println!("cargo::rustc-env=SHADER_SPV_PATH={}", spv_path.display());
+    println!(
+        "cargo::rustc-env=SHADER_SPV_PATH_IMAGE_BINARY={}",
+        spv_path.display()
+    );
     Ok(())
 }

examples/image-runner/src/image_binary.rs

@@ -0,0 +1,210 @@
+use enkou_shaders::Coefficients2;
+use enkou_shaders::transform::Transform;
+use enkou_shaders::variation::Variation;
+use futures::channel::oneshot;
+use futures::executor::block_on;
+use glam::{uvec2, Affine2, UVec2, UVec4, Vec2};
+use image::{Rgba, RgbaImage};
+use image_binary::{main_image_binary, BIND_GROUP_IMAGE_BINARY, BGLE_IMAGE_DIMENSIONS, BGLE_TRANSFORMS, BGLE_WEIGHTS, BGLE_CAMERA, BGLE_IMAGE_BUFFER, BGLE_VARIATIONS};
+use std::path::Path;
+use wgpu::util::DeviceExt;
+use enkou_shaders::camera::Camera;
+
+fn transforms() -> [Transform; 3] {
+    [
+        {
+            // F_0: (x / 2, y / 2)
+            let coefficients = Affine2::from_coefficients(0.5, 0.0, 0.0, 0.0, 0.5, 0.0);
+            Transform::new(coefficients, Affine2::IDENTITY, uvec2(0, 1))
+        },
+        {
+            // F_1: ((x + 1) / 2, y / 2)
+            let coefficients = Affine2::from_coefficients(0.5, 0.0, 0.5, 0.0, 0.5, 0.0);
+            Transform::new(coefficients, Affine2::IDENTITY, uvec2(0, 1))
+        },
+        {
+            // F_2: (x / 2, (y + 1) / 2)
+            let coefficients = Affine2::from_coefficients(0.5, 0.0, 0.0, 0.0, 0.5, 0.5);
+            Transform::new(coefficients, Affine2::IDENTITY, uvec2(0, 1))
+        },
+    ]
+}
+
+fn weights() -> [f32; 3] {
+    [1.0 / 3.0; 3]
+}
+
+fn variations() -> [Variation; 1] {
+    [Variation::IDENTITY]
+}
+
+fn camera(image_dimensions: UVec2) -> Camera {
+    Camera::new(
+        image_dimensions,
+        Vec2::ONE * 0.5,
+        0.0,
+        Vec2::ZERO,
+        Vec2::splat(image_dimensions.min_element() as f32),
+    )
+}
+
+pub(crate) fn main_cpu(image_dimensions: UVec2, output_path: &Path) -> Result<(), anyhow::Error> {
+    let mut image_buffer = Vec::<UVec4>::new();
+    image_buffer.resize(image_dimensions.element_product() as usize, UVec4::ZERO);
+
+    main_image_binary(
+        &image_dimensions,
+        &transforms(),
+        &weights(),
+        &variations(),
+        &camera(image_dimensions),
+        &mut image_buffer,
+    );
+
+    let mut image = RgbaImage::new(image_dimensions.x, image_dimensions.y);
+    for (i, color) in image_buffer.into_iter().enumerate() {
+        let image_x = i as u32 % image_dimensions.x;
+        let image_y = i as u32 / image_dimensions.x;
+
+        image.put_pixel(image_x, image_y, color.as_u8vec4().to_array().into());
+    }
+
+    image.save(output_path)?;
+    Ok(())
+}
+
+const SHADER_MODULE: wgpu::ShaderModuleDescriptor = wgpu::include_spirv!(env!("SHADER_SPV_PATH_IMAGE_BINARY"));
+
+fn bge<'a>(entry: &'a wgpu::BindGroupLayoutEntry, buffer: &'a wgpu::Buffer) -> wgpu::BindGroupEntry<'a> {
+    wgpu::BindGroupEntry {
+        binding: entry.binding,
+        resource: buffer.as_entire_binding(),
+    }
+}
+
+pub(crate) fn main_gpu(device: &wgpu::Device, queue: &wgpu::Queue, image_dimensions: UVec2, output_path: &Path) -> Result<(), anyhow::Error> {
+
+    let bind_group_layout = device.create_bind_group_layout(&BIND_GROUP_IMAGE_BINARY);
+
+    let image_dimensions_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
+        label: Some("image_dimensions"),
+        contents: bytemuck::bytes_of(&image_dimensions),
+        usage: wgpu::BufferUsages::COPY_DST | wgpu::BufferUsages::STORAGE,
+    });
+
+    let transforms_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
+        label: Some("transforms"),
+        contents: bytemuck::cast_slice(&transforms()),
+        usage: wgpu::BufferUsages::COPY_DST | wgpu::BufferUsages::STORAGE,
+    });
+
+    let weights_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
+        label: Some("weights"),
+        contents: bytemuck::cast_slice(&weights()),
+        usage: wgpu::BufferUsages::COPY_DST | wgpu::BufferUsages::STORAGE,
+    });
+
+    let variations_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
+        label: Some("variations"),
+        contents: bytemuck::cast_slice(&variations()),
+        usage: wgpu::BufferUsages::COPY_DST | wgpu::BufferUsages::STORAGE,
+    });
+
+    let camera_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
+        label: Some("camera"),
+        contents: bytemuck::bytes_of(&camera(image_dimensions)),
+        usage: wgpu::BufferUsages::COPY_DST | wgpu::BufferUsages::STORAGE,
+    });
+
+    let image_buffer_elements = image_dimensions.element_product() as u64;
+    let image_buffer_size = image_buffer_elements * size_of::<UVec4>() as u64;
+    let image_buffer = device.create_buffer(&wgpu::BufferDescriptor {
+        label: Some("image_buffer"),
+        size: image_buffer_size,
+        usage: wgpu::BufferUsages::COPY_SRC | wgpu::BufferUsages::STORAGE,
+        mapped_at_creation: false,
+    });
+
+    let image_staging = device.create_buffer(&wgpu::BufferDescriptor {
+        label: Some("image_buffer_staging"),
+        size: image_buffer_size,
+        usage: wgpu::BufferUsages::MAP_READ | wgpu::BufferUsages::COPY_DST,
+        mapped_at_creation: false,
+    });
+
+    let bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
+        label: Some("main_image_binary"),
+        layout: &bind_group_layout,
+        entries: &[
+            bge(&BGLE_IMAGE_DIMENSIONS, &image_dimensions_buffer),
+            bge(&BGLE_TRANSFORMS, &transforms_buffer),
+            bge(&BGLE_WEIGHTS, &weights_buffer),
+            bge(&BGLE_VARIATIONS, &variations_buffer),
+            bge(&BGLE_CAMERA, &camera_buffer),
+            bge(&BGLE_IMAGE_BUFFER, &image_buffer),
+        ],
+    });
+
+    let layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
+        label: Some("main_image_binary"),
+        bind_group_layouts: &[Some(&bind_group_layout)],
+        immediate_size: 0,
+    });
+
+    let module = device.create_shader_module(SHADER_MODULE);
+
+    let compute_pipeline = device.create_compute_pipeline(&wgpu::ComputePipelineDescriptor {
+        label: Some("main_image_binary"),
+        layout: Some(&layout),
+        module: &module,
+        entry_point: Some("main_image_binary"),
+        compilation_options: Default::default(),
+        cache: None,
+    });
+
+    let mut encoder = device.create_command_encoder(&wgpu::CommandEncoderDescriptor {
+        label: Some("main_image_binary"),
+    });
+
+    {
+        let mut compute_pass = encoder.begin_compute_pass(&wgpu::ComputePassDescriptor {
+            label: Some("main_image_binary"),
+            timestamp_writes: None,
+        });
+
+        compute_pass.set_pipeline(&compute_pipeline);
+        compute_pass.set_bind_group(0, &bind_group, &[]);
+    }
+
+    encoder.copy_buffer_to_buffer(&image_buffer, 0, &image_staging, 0, Some(image_buffer_size));
+
+    let (sender, receiver) = oneshot::channel();
+    let image_staging_capturable = image_staging.clone();
+    encoder.map_buffer_on_submit(&image_buffer, wgpu::MapMode::Read, .., move |result| {
+        result.expect("unable to map buffer");
+
+        let staging_buffer_view = image_staging_capturable.get_mapped_range(..).expect("Unable to map staging buffer");
+
+        let mut image = RgbaImage::new(image_dimensions.x, image_dimensions.y);
+        let image_buffer_elements = bytemuck::cast_slice::<u8, UVec4>(staging_buffer_view.as_ref());
+        for (i, element) in image_buffer_elements.iter().enumerate() {
+            let image_x = i as u32 % image_dimensions.x;
+            let image_y = i as u32 / image_dimensions.x;
+
+            let pixel_colors = element.as_u8vec4();
+            image.put_pixel(image_x, image_y, Rgba(*pixel_colors.as_ref()))
+        }
+
+        sender.send(image).expect("Unable to send image");
+    });
+
+    queue.submit(Some(encoder.finish()));
+    device.poll(wgpu::PollType::wait_indefinitely())?;
+    let image = block_on(receiver)?;
+
+    image_staging.unmap();
+
+    image.save(output_path)?;
+
+    Ok(())
+}

examples/image-runner/src/main.rs

@@ -0,0 +1,77 @@
+use glam::{uvec2};
+use std::mem;
+use std::process::Command;
+use std::path::PathBuf;
+use futures::executor::block_on;
+use tempfile::NamedTempFile;
+
+mod image_binary;
+
+fn main() -> Result<(), anyhow::Error> {
+    let instance_future = wgpu::util::new_instance_with_webgpu_detection(wgpu::InstanceDescriptor {
+        backends: Default::default(),
+        flags: Default::default(),
+        memory_budget_thresholds: Default::default(),
+        backend_options: Default::default(),
+        display: None,
+    });
+    let instance = block_on(instance_future);
+
+    let adapter_future = instance.request_adapter(&wgpu::RequestAdapterOptions {
+        power_preference: Default::default(),
+        force_fallback_adapter: false,
+        compatible_surface: None,
+        apply_limit_buckets: false,
+    });
+    let adapter = block_on(adapter_future)?;
+
+    let device_future = adapter.request_device(&wgpu::DeviceDescriptor {
+        label: Some("image-runner"),
+        required_features: Default::default(),
+        required_limits: Default::default(),
+        experimental_features: Default::default(),
+        memory_hints: Default::default(),
+        trace: Default::default(),
+    });
+    let (device, queue) = block_on(device_future)?;
+
+    let flags = xflags::parse_or_exit! {
+        /// Image dimensions to output, as `width,height`
+        optional -d, --dimensions dimensions: String
+
+        /// Output pathname to use
+        optional -o, --output output: PathBuf
+
+        /// Image type to generate
+        required image: String
+    };
+
+    let dimensions = if let Some(dimensions) = flags.dimensions {
+        let (width_str, height_str) = dimensions.split_once(",").ok_or(anyhow::anyhow!("Invalid format for image dimensions"))?;
+        uvec2(width_str.parse()?, height_str.parse()?)
+    } else {
+        uvec2(1600, 900)
+    };
+
+    let output = if let Some(output) = flags.output { output } else {
+        let path = NamedTempFile::with_suffix(".png")?;
+        let pathbuf: PathBuf = path.path().into();
+        mem::forget(path);
+        pathbuf
+    };
+
+    match flags.image.as_ref() {
+        "binary_cpu" => image_binary::main_cpu(dimensions, output.as_ref()),
+        "binary_gpu" => image_binary::main_gpu(&device, &queue, dimensions, output.as_ref()),
+        _ => Err(anyhow::anyhow!("Unrecognized image type"))
+    }?;
+
+    let mut command = cfg_select! {
+        unix => Command::new("xdg-open").arg(temp.path()).spawn(),
+        windows => Command::new("PowerShell").arg("-Command").arg(format!("start {}", output.display())).spawn(),
+        _ => Err(anyhow::anyhow!("No available program to open images"))?
+    }?;
+    command.wait()?;
+
+    Ok(())
+}