Implement basic variation support

enkou-shaders/src/transform.rs

@@ -3,24 +3,43 @@
 //! Transforms are the "functions" in an iterated function system. They take in a point,
 //! and generate a new point. For fractal flames, transforms are always affine,
 //! but produce more interesting images once we add variations.
+use crate::variation::Variation;
 use bytemuck::{Pod, Zeroable};
 use glam::{Affine2, Vec2};
+use rand::Rng;
 
 /// Affine transform for use in the [`chaos_game`](crate::chaos_game).
 #[derive(Copy, Clone, Pod, Zeroable)]
 #[repr(C)]
 pub struct Transform {
     coefficients: Affine2,
+    variation_range: [u16; 2],
 }
 
 impl Transform {
     /// Create a new transform from an affine transformation matrix
-    pub fn new(coefficients: Affine2) -> Self {
-        Transform { coefficients }
+    pub fn new(coefficients: Affine2, variation_range: [u16; 2]) -> Self {
+        Transform {
+            coefficients,
+            variation_range,
+        }
     }
 
     /// Apply this transform to a point in IFS coordinates, producing a new point
-    pub fn transform_point(&self, point: Vec2) -> Vec2 {
-        self.coefficients.transform_point2(point)
+    pub fn transform_point<R: Rng>(
+        &self,
+        rng: &mut R,
+        variations: &[Variation],
+        point: Vec2,
+    ) -> Vec2 {
+        let point = self.coefficients.transform_point2(point);
+
+        let mut point_output = Vec2::ZERO;
+        let variation_range = self.variation_range[0] as usize..self.variation_range[1] as usize;
+        for variation in variations[variation_range].iter() {
+            point_output += variation.transform_point(point, rng, &self.coefficients)
+        }
+
+        point_output
     }
 }