turbulence + tuning

assignment-0/src/main.rs

@@ -1,28 +1,43 @@
 use std::{fs::File, path::PathBuf};
 
 use anyhow::Result;
-use clap::Parser;
+use clap::{Parser, ValueEnum};
+use turbulence::generate_turbulence;
 
 use crate::value_noise::generate_noise;
 
 mod ppm;
+mod turbulence;
 mod value_noise;
 mod vec2;
 
 #[derive(Parser)]
 struct Opt {
+  #[clap(long = "algorithm", default_value = "turbulence")]
+  algorithm: Algorithm,
+
+  #[clap(long = "size", default_value = "1024")]
+  size: usize,
+
   #[clap(short = 'o', long = "out", default_value = "out.ppm")]
   output_path: PathBuf,
 }
 
+#[derive(ValueEnum, Clone)]
+enum Algorithm {
+  Noise,
+  Turbulence,
+}
+
 fn main() -> Result<()> {
   let opt = Opt::parse();
 
   let rng = rand::thread_rng();
 
-    let width = 256;
-    let height = 256;
-    let ppm = generate_noise(width, height, rng);
+  let ppm = match opt.algorithm {
+    Algorithm::Noise => generate_noise(opt.size, opt.size, rng),
+    Algorithm::Turbulence => generate_turbulence(opt.size, opt.size, rng),
+  };
 
   {
     let file = File::create(opt.output_path)?;

assignment-0/src/turbulence.rs

@@ -0,0 +1,51 @@
+// https://www.scratchapixel.com/lessons/procedural-generation-virtual-worlds/procedural-patterns-noise-part-1/simple-pattern-examples.html
+
+use rand::RngCore;
+
+use crate::ppm::{Pixel, Ppm};
+use crate::value_noise::ValueNoise;
+use crate::vec2::Vec2;
+
+pub fn generate_turbulence(
+  width: usize,
+  height: usize,
+  rng: impl RngCore,
+) -> Ppm {
+  let mut noise_map = vec![0.0; width * height];
+  let noise = ValueNoise::new(rng);
+
+  let frequency = 0.02;
+  let frequency_mult = 1.8;
+  let amplitude_mult = 0.35;
+  let num_layers = 5;
+  let mut max_noise_val = 0.0f64;
+
+  for j in 0..height {
+    for i in 0..width {
+      let mut noise_point = Vec2::new(i as f64, j as f64) * frequency;
+      let mut amplitude = 1.0;
+
+      for _ in 0..num_layers {
+        noise_map[j * width + i] =
+          (2.0 * noise.eval(noise_point) - 1.0).abs() * amplitude;
+        noise_point = noise_point * frequency_mult;
+        amplitude *= amplitude_mult;
+      }
+
+      max_noise_val = max_noise_val.max(noise_map[j * width + i]);
+    }
+  }
+
+  let data = noise_map
+    .into_iter()
+    .map(|f| {
+      let v = (f / max_noise_val * 192.0 + 32.0).floor() as u8;
+      Pixel(v, v, v)
+    })
+    .collect();
+  Ppm {
+    width,
+    height,
+    data,
+  }
+}

assignment-0/src/value_noise.rs

@@ -1,6 +1,6 @@
 // https://www.scratchapixel.com/lessons/procedural-generation-virtual-worlds/procedural-patterns-noise-part-1/creating-simple-2D-noise.html
 
-use std::mem::{self};
+use std::mem;
 
 use rand::{Rng, RngCore};
 
@@ -42,7 +42,8 @@ pub struct ValueNoise {
 
 impl ValueNoise {
   pub fn new(mut rng: impl RngCore) -> Self {
-        let mut r: [f64; MAX_TABLE_SIZE * MAX_TABLE_SIZE] = unsafe { mem::zeroed() };
+    let mut r: [f64; MAX_TABLE_SIZE * MAX_TABLE_SIZE] =
+      unsafe { mem::zeroed() };
     for k in 0..MAX_TABLE_SIZE * MAX_TABLE_SIZE {
       r[k] = rng.gen_range(0.0..1.0);
     }

assignment-0/src/vec2.rs

@@ -1,5 +1,6 @@
 use std::ops::Mul;
 
+#[derive(Copy, Clone)]
 pub struct Vec2<T = f64> {
   pub x: T,
   pub y: T,

rustfmt.toml

@@ -0,0 +1,2 @@
+max_width = 80
+tab_spaces = 2