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)
```

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

@@ -1,95 +0,0 @@
-use anyhow::{Context, Result};
-use enkou_shaders::Coefficients2;
-use enkou_shaders::camera::Camera;
-use enkou_shaders::camera::entry::main_camera;
-use enkou_shaders::chaos_game::entry::main_chaos_game;
-use enkou_shaders::transform::Transform;
-use enkou_shaders::variation::Variation;
-use glam::{Affine2, IVec2, UVec2, Vec2, uvec2};
-use image::{GrayImage, Luma};
-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)
-            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))
-        },
-    ];
-
-    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, Vec2::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 mut output_points_pixel = Vec::new();
-    output_points_pixel.resize(ITERATIONS as usize, IVec2::ZERO);
-
-    main_camera(&camera, &output_points_ifs, &mut output_points_pixel);
-
-    let mut image = GrayImage::new(IMAGE_DIMENSION.x, IMAGE_DIMENSION.y);
-    let dimensions = image.dimensions();
-    output_points_pixel
-        .iter()
-        .skip_while(|p| {
-            p.x < 0 || (p.x as u32) > dimensions.0 || p.y < 0 || (p.y as u32) > dimensions.1
-        })
-        .map(|p| (p.x as u32, p.y as u32))
-        .for_each(|(x, y)| image.put_pixel(x, y, Luma([255u8])));
-
-    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 => "xdg-open",
-        _ => panic!("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/chaos_game.rs

@@ -106,39 +106,3 @@ impl<'a, R: Rng> Iterator for ChaosGame<'a, R> {
         Some(next_point)
     }
 }
-
-/// 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::Vec2;
-    use spirv_std::spirv;
-
-    /// Given a set of fractal flame parameters, generate new IFS coordinates
-    /// and store them in the output array.
-    #[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 [Vec2],
-    ) {
-        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().unwrap();
-        }
-    }
-}

enkou-shaders/src/lib.rs

@@ -1,11 +1,12 @@
 //! # Enkou
-#![no_std]
-#![deny(missing_docs)]
-#![allow(clippy::needless_range_loop)] // SPIR-V backend has issues with iteration over items
+#![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;
 
@@ -14,7 +17,7 @@ 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];

enkou-shaders/src/variation.rs

@@ -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,