Implement a basic Sierpinski Gasket IFS

enkou-shaders/src/lib.rs

@@ -3,12 +3,12 @@
 #![warn(missing_docs)]
 
 pub mod camera;
+pub mod chaos_game;
+pub mod transform;
 
 use bytemuck::{Pod, Zeroable};
 use core::f32::consts::PI;
-use glam::{Affine2, Vec2, Vec3, Vec4, vec2, vec3};
-use rand::distr::StandardUniform;
-use rand::{Rng, RngExt};
+use glam::{Affine2, Vec3, Vec4, vec2, vec3};
 #[cfg(target_arch = "spirv")]
 use spirv_std::num_traits::Float;
 use spirv_std::spirv;
@@ -75,54 +75,6 @@ impl Coefficients2 for Affine2 {
     }
 }
 
-#[derive(Copy, Clone, Pod, Zeroable)]
-#[repr(C)]
-pub struct Transform {
-    pub coefficients: Affine2,
-}
-
-impl Transform {
-    pub fn new(coefficients: Affine2) -> Self {
-        Transform { coefficients }
-    }
-
-    pub fn transform_point(&self, point: Vec2) -> Vec2 {
-        self.coefficients.transform_point2(point)
-    }
-}
-
-/// Iterate one step in the chaos game; choose the next transform, apply it,
-/// and return the resulting point. Also returns the transform index so that
-/// path-dependent weights (the "Xaos" table in Apophysis) can be chosen
-/// for the next iteration step.
-///
-/// # Arguments
-///
-/// * `weights` - Weights are assumed to be normalized; adding all elements together should return the value 1
-pub fn step_chaos_game<R: Rng>(
-    rng: &mut R,
-    point: Vec2,
-    weights: &[f32],
-    transforms: &[Transform],
-) -> (Vec2, u32) {
-    let mut choice_weight = rng.sample::<f32, _>(StandardUniform);
-    let mut transform_index: u32 = 0;
-
-    for weight in weights {
-        choice_weight -= weight;
-        if choice_weight <= 0.0 {
-            break;
-        }
-
-        transform_index += 1;
-    }
-
-    (
-        transforms[transform_index as usize].transform_point(point),
-        transform_index,
-    )
-}
-
 #[derive(Copy, Clone, Pod, Zeroable)]
 #[repr(C)]
 pub struct ShaderConstants {