completed perlin textures

src/main.rs

@@ -23,11 +23,11 @@ use demos::Demo;
 
 use std::time::Instant;
 
-const NUM_SAMPLES: u8 = 25;
+const NUM_SAMPLES: u8 = 255;
 const VERTICAL_PARTITION: usize = 12;
 const HORIZONTAL_PARTITION: usize = 12;
-const WIDTH: usize = 1920;
-const HEIGHT: usize = 1080;
+const WIDTH: usize = 2560;
+const HEIGHT: usize = 1440;
 
 fn main() -> Result<(), String> {
     run(WIDTH, HEIGHT)
@@ -134,9 +134,9 @@ fn run(mut width: usize, mut height: usize) -> Result<(), String> {
 
 #[cfg(not(feature = "gui"))]
 fn run(width: usize, height: usize) -> Result<(), String> {
-    //    run_and_save_demo(demos::CheckeredMotionBlur {}, width, height);
+    run_and_save_demo(demos::CheckeredMotionBlur {}, width, height);
 
-    //run_and_save_demo(demos::TwoSpheres {}, width, height);
+    run_and_save_demo(demos::TwoSpheres {}, width, height);
 
     run_and_save_demo(demos::PerlinNoiseBall {}, width, height);
 

src/texture/perlin.rs

@@ -1,10 +1,10 @@
 use crate::types::Vec3;
-use rand::{distributions::Uniform, Rng};
+use rand::Rng;
 
 const POINT_COUNT: usize = 256;
 
 pub struct Perlin {
-    points: Vec<f64>,
+    points: Vec<Vec3>,
 
     permute_x: Vec<usize>,
     permute_y: Vec<usize>,
@@ -13,10 +13,9 @@ pub struct Perlin {
 
 impl Perlin {
     pub fn new<R: Rng + ?Sized>(rng: &mut R) -> Self {
-        let points = rng
-            .sample_iter(Uniform::from(0.0..=1.0))
-            .take(POINT_COUNT)
-            .collect::<Vec<f64>>();
+        let points = (0..POINT_COUNT)
+            .map(|_| Vec3::random(rng).unit_vector())
+            .collect::<Vec<Vec3>>();
 
         let permute_x = Self::perlin_generate_permutation(rng);
         let permute_y = Self::perlin_generate_permutation(rng);
@@ -37,41 +36,57 @@ impl Perlin {
     }
 
     pub fn noise(&self, p: Vec3) -> f64 {
+        let mut smooth_grid = [[[Vec3::new(0.0, 0.0, 0.0); 2]; 2]; 2];
+
+        {
             let i = p.x().floor() as i32;
             let j = p.y().floor() as i32;
             let k = p.z().floor() as i32;
-
-        let mut smooth_grid = [[[0.0; 2]; 2]; 2];
-
             for (di, a) in smooth_grid.iter_mut().enumerate() {
                 let di = di as i32;
                 for (dj, b) in a.iter_mut().enumerate() {
                     let dj = dj as i32;
                     for (dk, c) in b.iter_mut().enumerate() {
                         let dk = dk as i32;
+
                         *c = self.points[self.permute_x[((i + di) & 255) as usize]
                             ^ self.permute_y[((j + dj) & 255) as usize]
                             ^ self.permute_z[((k + dk) & 255) as usize]]
                     }
                 }
             }
+        }
 
-        let mut u = p.x() - p.x().floor();
-        let mut v = p.y() - p.y().floor();
-        let mut w = p.z() - p.z().floor();
+        let u = p.x() - p.x().floor();
+        let v = p.y() - p.y().floor();
+        let w = p.z() - p.z().floor();
 
-        // Hermitian smoothing so we don't see obvious grid features in the picture
-        // Those features show up when we interpolate colors. Those features are
-        // also called mach bands
-        u = u * u * (3.0 - 2.0 * u);
-        v = v * v * (3.0 - 2.0 * v);
-        w = w * w * (3.0 - 2.0 * w);
+        perlin_interpolate(smooth_grid, u, v, w)
+    }
 
-        return trilinear_interpolate(smooth_grid, u, v, w);
+    pub fn turbulence(&self, p: Vec3, depth: u32) -> f64 {
+        let mut acc = 0.0f64;
+        let mut weight = 1.0;
+        let mut temp_p = p;
+
+        for _i in 0..depth {
+            acc += weight * self.noise(temp_p);
+            weight *= 0.5;
+            temp_p *= 2.0;
+        }
+
+        acc.abs()
     }
 }
 
-fn trilinear_interpolate(smooth_grid: [[[f64; 2]; 2]; 2], u: f64, v: f64, w: f64) -> f64 {
+fn perlin_interpolate(smooth_grid: [[[Vec3; 2]; 2]; 2], u: f64, v: f64, w: f64) -> f64 {
+    // Hermitian smoothing so we don't see obvious grid features in the picture
+    // Those features show up when we interpolate colors. Those features are
+    // also called mach bands
+    let uu = u * u * (3.0 - 2.0 * u);
+    let vv = v * v * (3.0 - 2.0 * v);
+    let ww = w * w * (3.0 - 2.0 * w);
+
     let mut acc = 0.0;
 
     for (di, a) in smooth_grid.iter().enumerate() {
@@ -80,10 +95,13 @@ fn trilinear_interpolate(smooth_grid: [[[f64; 2]; 2]; 2], u: f64, v: f64, w: f64
             let dj = dj as f64;
             for (dk, c) in b.iter().enumerate() {
                 let dk = dk as f64;
-                acc += (di * u + (1.0 - di) * (1.0 - u))
-                    * (dj * v + (1.0 - dj) * (1.0 - v))
-                    * (dk * w + (1.0 - dk) * (1.0 - w))
-                    * c;
+
+                let wt = Vec3::new(u - di, v - dj, w - dk);
+
+                acc += (di * uu + (1.0 - di) * (1.0 - uu))
+                    * (dj * vv + (1.0 - dj) * (1.0 - vv))
+                    * (dk * ww + (1.0 - dk) * (1.0 - ww))
+                    * c.dot(&wt);
             }
         }
     }

src/texture/perlin_noise.rs

@@ -26,6 +26,8 @@ impl PerlinNoise {
 
 impl Texture for PerlinNoise {
     fn value(&self, _u: f64, _v: f64, p: Vec3) -> Vec3 {
-        Vec3::new(1.0, 1.0, 1.0) * self.noise.noise(p * self.scale)
+        Vec3::new(1.0, 1.0, 1.0)
+            * 0.5
+            * (1.0 + (self.scale * p.z() + 10.0 * self.noise.turbulence(p, 7)).sin())
     }
 }

src/types/vec3.rs

@@ -3,6 +3,8 @@ use std::{
     ops::{Add, AddAssign, Div, DivAssign, Index, IndexMut, Mul, MulAssign, Neg, Sub, SubAssign},
 };
 
+use rand::Rng;
+
 #[derive(Debug, Copy, Clone)]
 pub struct Vec3([f64; 3]);
 
@@ -73,6 +75,11 @@ impl Vec3 {
         let length = self.length();
         Vec3([self[0] / length, self[1] / length, self[2] / length])
     }
+
+    #[inline]
+    pub fn random<R: Rng + ?Sized>(rng: &mut R) -> Vec3 {
+        Vec3([rng.gen(), rng.gen(), rng.gen()])
+    }
 }
 
 impl Add for Vec3 {