Add entry points for GPU

enkou-shaders/src/variation.rs

@@ -1,12 +1,11 @@
 //! # Variation
-
 use crate::Coefficients2;
 use bytemuck::{Pod, Zeroable};
 use core::f32::consts::PI;
 use glam::{Affine2, Vec2, vec2};
 use libm::{atan2f, cosf, powf, sinf, sqrtf, tanf};
-use rand::distr::Bernoulli;
-use rand::{Rng, RngExt};
+use rand::Rng;
+use rand::distributions::Standard;
 
 #[derive(Copy, Clone, Pod, Zeroable)]
 #[repr(C)]
@@ -35,6 +34,20 @@ pub struct Variation {
 }
 
 impl Variation {
+    pub const IDENTITY: Variation = Variation {
+        kind: VariationKind::Linear,
+        weight: 1.0,
+        params: VariationParams([0f32; 4]),
+    };
+
+    pub fn new(kind: VariationKind, weight: f32, params: VariationParams) -> Variation {
+        Variation {
+            kind,
+            weight,
+            params,
+        }
+    }
+
     pub fn transform_point<R: Rng>(
         &self,
         point: Vec2,
@@ -60,8 +73,11 @@ fn transform_point_julia<R: Rng>(point: Vec2, rng: &mut R) -> Vec2 {
     let r = sqrtf(x2 + y2);
 
     let theta = atan2f(point.x, point.y);
-    let omega_choice = rng.sample(Bernoulli::new(0.5).unwrap());
-    let omega = if omega_choice { PI } else { 0.0 };
+    let omega = if rng.sample::<f32, _>(Standard) > 0.5 {
+        PI
+    } else {
+        0.0
+    };
 
     let sqrt_r = sqrtf(r);
     let theta_val = theta / 2.0 + omega;