Add image accumulation entry point

I was hoping to implement the image filter/reduction step as well, but that seems to be meaningfully more complex

enkou-shaders-tests/src/lib.rs

@@ -54,6 +54,9 @@ mod test {
 
     #[test]
     fn has_entry_main_camera() {
-        assert!(has_entry_point(ExecutionModel::GLCompute, "main_camera"))
+        assert!(has_entry_point(
+            ExecutionModel::GLCompute,
+            "main_image_accumulate"
+        ))
     }
 }

enkou-shaders/examples/gasket.rs

@@ -2,6 +2,7 @@ use anyhow::{Context, Result};
 use enkou_shaders::Coefficients2;
 use enkou_shaders::camera::Camera;
 use enkou_shaders::chaos_game::ChaosGame;
+use enkou_shaders::image::{BlendMode, ImageSettings};
 use enkou_shaders::transform::Transform;
 use enkou_shaders::variation::Variation;
 use glam::{Affine2, UVec2, Vec2, uvec2, vec2};
@@ -50,6 +51,8 @@ pub fn main() -> Result<()> {
         IMAGE_DIMENSION.as_vec2(),
     );
 
+    let image_settings = ImageSettings::new(BlendMode::Linear, IMAGE_DIMENSION);
+
     let mut image = GrayImage::new(IMAGE_DIMENSION.x, IMAGE_DIMENSION.y);
 
     let chaos_game = ChaosGame::new(&mut rng, &transforms, &weights, &variations);
@@ -57,7 +60,8 @@ pub fn main() -> Result<()> {
     chaos_game
         .skip(ITERATIONS_DISCARD)
         .take(ITERATIONS)
-        .filter_map(|(point_ifs, _)| camera.transform_point_to_image(point_ifs))
+        .map(|(point_ifs, _)| camera.transform_point(point_ifs))
+        .filter_map(|point_pixel| image_settings.transform_point_to_image(point_pixel))
         .for_each(|point_pixel| image.put_pixel(point_pixel.x, point_pixel.y, Luma([255])));
 
     let temp = NamedTempFile::with_suffix(".png").context("Unable to create file for image")?;

enkou-shaders/src/camera.rs

@@ -12,7 +12,6 @@ use libm::powf;
 #[derive(Copy, Clone, Pod, Zeroable)]
 #[repr(C)]
 pub struct Camera {
-    dimensions: UVec2,
     transform: Affine2,
 }
 
@@ -23,7 +22,7 @@ impl Camera {
     /// to express the transform steps individually.
     ///
     /// # Arguments
-    ///
+    /// * `blend_mode` - Color blending mode for the output image
     /// * `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.
@@ -47,10 +46,7 @@ impl Camera {
             * zoom_transform
             * ifs_center_transform;
 
-        Camera {
+        Camera { transform }
-            dimensions,
-            transform,
-        }
     }
 
     /// Map a point from IFS coordinates to pixel coordinates.
@@ -73,40 +69,6 @@ impl Camera {
     pub fn transform_point(&self, point: Vec2) -> IVec2 {
         self.transform.transform_point2(point).as_ivec2()
     }
-
-    /// 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
-        {
-            None
-        } else {
-            Some(pixel_coordinates.as_uvec2())
-        }
-    }
-}
-
-/// Shader entry point for running the camera transformation over a list of IFS coordinates
-pub mod entry {
-    use crate::camera::Camera;
-    use spirv_std::glam::{IVec2, Vec2};
-    use spirv_std::spirv;
-
-    /// 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)] coordinates_ifs: &[Vec2],
-        #[spirv(storage_buffer, descriptor_set = 1, binding = 0)] coordinates_pixel: &mut [IVec2],
-    ) {
-        for i in 0..coordinates_ifs.len() {
-            coordinates_pixel[i] = camera.transform_point(coordinates_ifs[i])
-        }
-    }
 }
 
 #[cfg(test)]
@@ -148,9 +110,10 @@ mod test {
 
         // The camera is implemented by composing affine transforms,
         // which ends up with a slightly different result because of rounding.
-        let error = camera.transform_point(starting_point) - point;
+        let error = (camera.transform_point(starting_point) - point)
-        assert!(error.x.abs() <= 1);
+            .abs()
-        assert!(error.y.abs() <= 1);
+            .as_uvec2();
+        assert!(error.x <= 1 && error.y <= 1);
     }
 
     #[test]

enkou-shaders/src/chaos_game.rs

@@ -83,10 +83,7 @@ impl<'a, R: Rng> ChaosGame<'a, R> {
         weights: &'a [f32],
         variations: &'a [Variation],
     ) -> Self {
-        let current_point = vec2(
+        let current_point = vec2(rng.sample(BiUnit), rng.sample(BiUnit));
-            rng.sample(BiUnit),
-            rng.sample(BiUnit),
-        );
         let current_color = rng.sample(StandardUniform);
         ChaosGame {
             current_point,

enkou-shaders/src/entry/image_accumulate.rs

@@ -0,0 +1,63 @@
+//! Image Accumulate
+
+use crate::camera::Camera;
+use crate::chaos_game::ChaosGame;
+use crate::image::ImageSettings;
+use crate::rng::xoshiro256starstar_from_seed;
+use crate::transform::Transform;
+use crate::variation::Variation;
+use glam::{UVec2, Vec4};
+use spirv_std::spirv;
+
+/// Run the chaos game and accumulate points into the output image buffer
+///
+/// # Arguments
+/// * `iterations` - Controls the iteration count; the first `x` iterations are discarded,
+///   the next `y` iterations are accumulated into the output image
+/// * `rng_seed`
+/// * `transforms`
+/// * `weights`
+/// * `variations`
+/// * `camera` - Camera transformation to map IFS coordinates to pixel coordinates
+/// * `image_settings` - Settings to use for image accumulation
+/// * `palette` - List of colors to use for the image palette; assumed to be RGB values scaled to `[0-255]`, with an alpha of 255
+/// * `image` - Output image buffer
+#[spirv(compute(entry_point_name = "main_image_accumulate", threads(1)))]
+pub fn main_image_accumulate(
+    #[spirv(storage_buffer, descriptor_set = 0, binding = 0)] iterations: &UVec2,
+    #[spirv(storage_buffer, descriptor_set = 0, binding = 1)] rng_seed: &[u8],
+    #[spirv(storage_buffer, descriptor_set = 0, binding = 2)] transforms: &[Transform],
+    #[spirv(storage_buffer, descriptor_set = 0, binding = 3)] weights: &[f32],
+    #[spirv(storage_buffer, descriptor_set = 0, binding = 4)] variations: &[Variation],
+    #[spirv(storage_buffer, descriptor_set = 0, binding = 5)] camera: &Camera,
+    #[spirv(storage_buffer, descriptor_set = 0, binding = 6)] image_settings: &ImageSettings,
+    #[spirv(storage_buffer, descriptor_set = 0, binding = 7)] palette: &[Vec4],
+    #[spirv(storage_buffer, descriptor_set = 1, binding = 0)] image: &mut [Vec4],
+) {
+    let mut rng_seed_actual = [0u8; 32];
+    for i in 0..rng_seed_actual.len() {
+        rng_seed_actual[i] = rng_seed[i];
+    }
+
+    let mut rng = xoshiro256starstar_from_seed(rng_seed_actual);
+
+    let chaos_game = ChaosGame::new(&mut rng, transforms, weights, variations);
+    let (iterations_fuse, iterations_accumulate) = (iterations.x, iterations.y);
+
+    let ifs_to_image = |(ifs_point, ifs_color)| {
+        let pixel_coordinates = camera.transform_point(ifs_point);
+        let pixel_color = image_settings.transform_color(ifs_color, palette);
+        image_settings
+            .transform_point_to_index(pixel_coordinates)
+            .map(|pixel_index| (pixel_index, pixel_color))
+    };
+
+    for ifs_point in chaos_game
+        .skip(iterations_fuse as usize)
+        .take(iterations_accumulate as usize)
+    {
+        if let Some((pixel_index, pixel_color)) = ifs_to_image(ifs_point) {
+            image[pixel_index as usize] = pixel_color;
+        }
+    }
+}

enkou-shaders/src/entry/mod.rs

@@ -0,0 +1,4 @@
+//! # Entry
+//!
+//! Entry points for Enkou shaders
+pub mod image_accumulate;

enkou-shaders/src/image.rs

@@ -1,5 +1,7 @@
 //! Image
-use glam::Vec4;
+
+use bytemuck::{Pod, Zeroable};
+use glam::{IVec2, UVec2, Vec4};
 use libm::floorf;
 
 /// Blending modes for mapping IFS color values (which are on a scale `[0, 1]`)
@@ -36,10 +38,53 @@ unsafe impl bytemuck::Zeroable for BlendMode {}
 // UNSAFE: Sound because enum has guaranteed layout (u32) and defined zero-value
 unsafe impl bytemuck::Pod for BlendMode {}
 
+/// Settings to use for mapping the IFS coordinates to an output image
+#[derive(Copy, Clone, Pod, Zeroable)]
+#[repr(C)]
+pub struct ImageSettings {
+    blend_mode: BlendMode,
+    dimensions: UVec2,
+}
+
+impl ImageSettings {
+    /// Create a new settings object
+    pub fn new(blend_mode: BlendMode, dimensions: UVec2) -> Self {
+        ImageSettings {
+            blend_mode,
+            dimensions,
+        }
+    }
+
+    /// Map a point from camera coordinates to pixel coordinates,
+    /// and check that the result is within the provided image dimensions.
+    pub fn transform_point_to_image(&self, point: IVec2) -> Option<UVec2> {
+        if 0 <= point.x
+            && (point.x as u32) < self.dimensions.x
+            && 0 <= point.y
+            && (point.y as u32) < self.dimensions.y
+        {
+            Some(point.as_uvec2())
+        } else {
+            None
+        }
+    }
+
+    /// Map a point from camera coordinates to a final pixel index
+    pub fn transform_point_to_index(&self, point: IVec2) -> Option<u32> {
+        self.transform_point_to_image(point)
+            .map(|pixel| self.dimensions.with_x(1).dot(pixel))
+    }
+
+    /// Map an IFS color coordinate to the palette RGB value
+    pub fn transform_color(&self, color: f32, palette: &[Vec4]) -> Vec4 {
+        self.blend_mode.ifs_to_rgb(color, palette)
+    }
+}
+
 #[cfg(test)]
 mod test {
-    use glam::Vec4;
+    use crate::image::{BlendMode, ImageSettings};
-    use crate::image::BlendMode;
+    use glam::{Vec4, ivec2, uvec2};
 
     #[test]
     fn blend_linear() {
@@ -55,7 +100,12 @@ mod test {
         assert_eq!(ifs_to_rgb(0.5, palette), Vec4::splat(2.0));
         assert_eq!(ifs_to_rgb(1.0, palette), Vec4::splat(3.0));
 
-        let palette = &[Vec4::splat(1.0), Vec4::splat(2.0), Vec4::splat(3.0), Vec4::splat(4.0)];
+        let palette = &[
+            Vec4::splat(1.0),
+            Vec4::splat(2.0),
+            Vec4::splat(3.0),
+            Vec4::splat(4.0),
+        ];
         assert_eq!(ifs_to_rgb(0.0, palette), Vec4::splat(1.0));
         assert_eq!(ifs_to_rgb(0.5, palette), Vec4::splat(2.5));
         assert_eq!(ifs_to_rgb(1.0, palette), Vec4::splat(4.0));
@@ -76,4 +126,30 @@ mod test {
         assert_eq!(ifs_to_rgb(0.7, palette), palette[1]);
         assert_eq!(ifs_to_rgb(1.0, palette), palette[2]);
     }
+
+    #[test]
+    fn image_bounds() {
+        let image_settings = ImageSettings::new(BlendMode::Linear, uvec2(100, 100));
+
+        assert!(
+            image_settings
+                .transform_point_to_image(ivec2(-1, -1))
+                .is_none()
+        );
+        assert!(
+            image_settings
+                .transform_point_to_image(ivec2(0, 0))
+                .is_some()
+        );
+        assert!(
+            image_settings
+                .transform_point_to_image(ivec2(99, 99))
+                .is_some()
+        );
+        assert!(
+            image_settings
+                .transform_point_to_image(ivec2(100, 100))
+                .is_none()
+        );
+    }
 }

enkou-shaders/src/lib.rs

@@ -1,14 +1,21 @@
 //! # Enkou
 #![no_std]
 #![warn(missing_docs)]
-#![allow(clippy::needless_range_loop)] // SPIR-V backend has issues with iteration over items
+
+// SPIR-V backend has issues with iteration over items:
+#![allow(clippy::needless_range_loop)]
+#![allow(clippy::manual_memcpy)]
+
+// Shader entry points are expected to have a lot of arguments:
+#![allow(clippy::too_many_arguments)]
 
 pub mod camera;
 pub mod chaos_game;
+pub mod entry;
+pub mod image;
 mod rng;
 pub mod transform;
 pub mod variation;
-pub mod image;
 
 use glam::Affine2;
 

enkou-shaders/src/transform.rs

@@ -66,7 +66,7 @@ mod test {
     use crate::rng::xoshiro256starstar_from_seed;
     use crate::transform::Transform;
     use crate::variation::{Variation, VariationKind};
-    use glam::{Affine2, uvec2, vec2, Vec2};
+    use glam::{Affine2, Vec2, uvec2, vec2};
 
     #[test]
     fn transform_scaling() {
@@ -91,7 +91,12 @@ mod test {
     #[test]
     fn transform_scaling_post() {
         let scale_coefficients = vec2(2.0, 0.5);
-        let transform_pdj = Transform::new(Affine2::IDENTITY, Affine2::IDENTITY, uvec2(0, 1), Vec2::ZERO);
+        let transform_pdj = Transform::new(
+            Affine2::IDENTITY,
+            Affine2::IDENTITY,
+            uvec2(0, 1),
+            Vec2::ZERO,
+        );
         let transform_pdj_post = Transform::new(
             Affine2::IDENTITY,
             Affine2::from_scale(scale_coefficients),