Add iridescent material

.cargo/config.toml

@@ -0,0 +1,3 @@
+
+[build]
+rustflags = ["-C raget-cpu=native"]

.gitignore

@@ -1,2 +1,3 @@
 target
 **.exr
+**.png

flake.nix

@@ -6,22 +6,30 @@
     flake-utils.url = "github:numtide/flake-utils";
   };
 
-  outputs = { self, nixpkgs, flake-utils }:
-    flake-utils.lib.eachDefaultSystem (system:
+  outputs =
+    {
+      self,
+      nixpkgs,
+      flake-utils,
+    }:
+    flake-utils.lib.eachDefaultSystem (
+      system:
       let
         pkgs = nixpkgs.legacyPackages.${system};
         # Read the file relative to the flake's root
         overrides = (builtins.fromTOML (builtins.readFile (self + "/rust-toolchain.toml")));
-        libPath = with pkgs; lib.makeLibraryPath [
-          # load external libraries that you need in your rust project here
-        ];
+        libPath =
+          with pkgs;
+          lib.makeLibraryPath [
+            # load external libraries that you need in your rust project here
+          ];
       in
       {
         devShells.default = pkgs.mkShell rec {
           nativeBuildInputs = [ pkgs.pkg-config ];
 
           packages = with pkgs; [
-            
+
             tev
             shaderc
             vulkan-headers
@@ -31,6 +39,7 @@
             python3
           ];
           buildInputs = with pkgs; [
+            fontconfig
             clang
             llvmPackages.bintools
             rustup
@@ -38,14 +47,14 @@
 
           # VULKAN_SDK = "${vulkan-validation-layers}/share/vulkan/explicit_layer.d";
 
-          LD_LIBRARY_PATH="${pkgs.wayland}/lib:${pkgs.libxkbcommon}/lib:${pkgs.vulkan-loader}/lib:${pkgs.vulkan-validation-layers}/lib";
+          LD_LIBRARY_PATH = "${pkgs.wayland}/lib:${pkgs.libxkbcommon}/lib:${pkgs.vulkan-loader}/lib:${pkgs.vulkan-validation-layers}/lib";
           VK_LAYER_PATH = "${pkgs.vulkan-validation-layers}/share/vulkan/explicit_layer.d";
 
           RUSTC_VERSION = overrides.toolchain.channel;
-          
+
           # https://github.com/rust-lang/rust-bindgen#environment-variables
           LIBCLANG_PATH = pkgs.lib.makeLibraryPath [ pkgs.llvmPackages_latest.libclang.lib ];
-          
+
           shellHook = ''
             export PATH=$PATH:''${CARGO_HOME:-~/.cargo}/bin
             export PATH=$PATH:''${RUSTUP_HOME:-~/.rustup}/toolchains/$RUSTC_VERSION-x86_64-unknown-linux-gnu/bin/
@@ -53,26 +62,27 @@
           '';
 
           # Add precompiled library to rustc search path
-          RUSTFLAGS = (builtins.map (a: ''-L ${a}/lib'') [
-            # add libraries here (e.g. pkgs.libvmi)
-          ]);
-          
+          RUSTFLAGS = (
+            builtins.map (a: ''-L ${a}/lib'') [
+              # add libraries here (e.g. pkgs.libvmi)
+            ]
+          );
+
           # LD_LIBRARY_PATH = pkgs.lib.makeLibraryPath (buildInputs ++ nativeBuildInputs);
 
-          
           # Add glibc, clang, glib, and other headers to bindgen search path
           BINDGEN_EXTRA_CLANG_ARGS =
-          # Includes normal include path
-          (builtins.map (a: ''-I"${a}/include"'') [
-            # add dev libraries here (e.g. pkgs.libvmi.dev)
-            pkgs.glibc.dev
-          ])
-          # Includes with special directory paths
-          ++ [
-            ''-I"${pkgs.llvmPackages_latest.libclang.lib}/lib/clang/${pkgs.llvmPackages_latest.libclang.version}/include"''
-            ''-I"${pkgs.glib.dev}/include/glib-2.0"''
-            ''-I${pkgs.glib.out}/lib/glib-2.0/include/''
-          ];
+            # Includes normal include path
+            (builtins.map (a: ''-I"${a}/include"'') [
+              # add dev libraries here (e.g. pkgs.libvmi.dev)
+              pkgs.glibc.dev
+            ])
+            # Includes with special directory paths
+            ++ [
+              ''-I"${pkgs.llvmPackages_latest.libclang.lib}/lib/clang/${pkgs.llvmPackages_latest.libclang.version}/include"''
+              ''-I"${pkgs.glib.dev}/include/glib-2.0"''
+              ''-I${pkgs.glib.out}/lib/glib-2.0/include/''
+            ];
         };
       }
     );

ray-tracing-material-visualizer/src/main.rs

@@ -10,6 +10,7 @@ use rand::{rngs::SmallRng, SeedableRng};
 use ray_tracing_core::prelude::*;
 use ray_tracing_material::{
     diffuse::DiffuseMaterial,
+    iridescent::Iridescent,
     microfacet::{BeckmannDistribution, Microfacet},
     mirror::Mirror,
     oren_nayar::OrenNayar,
@@ -35,6 +36,9 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     let m = OrenNayar::new(0.5, color);
     generate_chart("oren-nayar.png", &m, 100, w_in)?;
 
+    let m = Iridescent::new(300.0, 300.0, 1.0, 1.5, 10);
+    generate_chart("iridescent.png", &m, 2, w_in)?;
+
     Ok(())
 }
 

ray-tracing-material/src/iridescent.rs

@@ -0,0 +1,207 @@
+use core::f32;
+
+use ray_tracing_core::prelude::*;
+
+#[derive(Debug)]
+pub struct Iridescent {
+    d1: f32,
+    d2: f32,
+    n1: f32,
+    n2: f32,
+    n: f32,
+}
+
+impl Iridescent {
+    pub fn new(d1: f32, d2: f32, n1: f32, n2: f32, n: u32) -> Self {
+        Self {
+            d1,
+            d2,
+            n1,
+            n2,
+            n: n as f32,
+        }
+    }
+
+    fn fresnel_reflection(&self, theta1: f32, theta2: f32, s_polaized: bool) -> f32 {
+        if s_polaized {
+            (self.n1 * theta1.cos() - self.n2 * theta2.cos())
+                / (self.n1 * theta1.cos() + self.n2 * theta2.cos())
+        } else {
+            (self.n2 * theta1.cos() - self.n1 * theta2.cos())
+                / (self.n2 * theta1.cos() + self.n1 * theta2.cos())
+        }
+    }
+
+    fn abs_r_1_squared(&self, l: f32, theta1: f32, theta2: f32, s_polaized: bool) -> f32 {
+        let r12 = self.fresnel_reflection(theta1, theta2, s_polaized);
+
+        let phi = 2.0 * f32::consts::PI * self.n2 * self.d2 * theta2.cos() / l;
+
+        let num_real = r12 * (1.0 - f32::cos(-2.0 * phi));
+        let num_imag = r12 * (1.0 - f32::sin(-2.0 * phi));
+
+        let denom_real = 1.0 - r12 * r12 * f32::cos(-2.0 * phi);
+        let denom_imag = 1.0 - r12 * r12 * f32::sin(-2.0 * phi);
+
+        let real = (num_real * denom_real + num_imag * denom_imag)
+            / (denom_real * denom_real + denom_imag * denom_imag);
+
+        let imag = (num_imag * denom_real - num_real * denom_imag)
+            / (denom_real * denom_real + denom_imag * denom_imag);
+
+        real * real + imag * imag
+    }
+
+    fn abs_C_squared(&self, l: f32, theta1: f32, theta2: f32, s_polaized: bool) -> f32 {
+        let local_abs_r_1_squared = self.abs_r_1_squared(l, theta1, theta2, s_polaized);
+
+        local_abs_r_1_squared / (local_abs_r_1_squared + 1.0)
+    }
+
+    fn cos_K_Delta(&self, l: f32, theta1: f32, theta2: f32, s_polaized: bool) -> f32 {
+        let k1z = 2.0 * f32::consts::PI * self.n1 * theta1.cos() / l;
+        let k2z = 2.0 * f32::consts::PI * self.n2 * theta2.cos() / l;
+
+        let omega = if s_polaized {
+            k2z / k1z + k1z / k2z
+        } else {
+            (self.n1 * self.n1 * k2z) / (self.n2 * self.n2 * k1z)
+                + (self.n2 * self.n2 * k1z) / (self.n1 * self.n1 * k2z)
+        };
+
+        f32::cos(k1z * self.d1) * f32::cos(k2z * self.d2)
+            - 0.5 * omega * f32::sin(k1z * self.d1) * f32::sin(k2z * self.d2)
+    }
+
+    fn reflectance(&self, l: f32, theta1: f32, s_polaized: bool) -> f32 {
+        let theta2 = f32::asin(f32::sin(theta1) * self.n1 / self.n2);
+
+        let local_cos_k_delta = self.cos_K_Delta(l, theta1, theta2, s_polaized);
+
+        let local_c_squred = self.abs_C_squared(l, theta1, theta2, s_polaized);
+
+        if !local_c_squred.is_normal() || !local_cos_k_delta.is_normal() {
+            dbg!((
+                l,
+                theta1,
+                theta2,
+                local_cos_k_delta,
+                local_c_squred,
+                s_polaized
+            ));
+        }
+
+        if local_cos_k_delta.abs() <= 1.0 {
+            let k_delta = f32::acos(local_cos_k_delta);
+
+            if !k_delta.is_normal() {
+                dbg!((
+                    l,
+                    theta1,
+                    theta2,
+                    local_cos_k_delta,
+                    local_c_squred,
+                    s_polaized,
+                    k_delta,
+                ));
+            }
+            let u = f32::sin(k_delta) / f32::sin(self.n * k_delta);
+
+            local_c_squred / (local_c_squred + u * u)
+        } else {
+            let imk_delta = -f32::ln(f32::abs(
+                local_cos_k_delta - f32::sqrt(local_cos_k_delta * local_cos_k_delta - 1.0),
+            ));
+
+            if !imk_delta.is_normal() {
+                dbg!((
+                    l,
+                    theta1,
+                    theta2,
+                    local_cos_k_delta,
+                    local_c_squred,
+                    s_polaized,
+                    imk_delta,
+                ));
+            }
+            let u = f32::sinh(imk_delta) / f32::sinh(self.n * imk_delta);
+
+            local_c_squred / (local_c_squred + u * u)
+        }
+    }
+
+    fn averaged_reflectance(&self, l: f32, theta1: f32) -> f32 {
+        0.5 * (self.reflectance(l, theta1, true) + self.reflectance(l, theta1, false))
+    }
+
+    fn piecewise_gaussian(l: f32, mu: f32, tau1: f32, tau2: f32) -> f32 {
+        if l < mu {
+            let s = tau1 * (l - mu);
+            f32::exp(-0.5 * s * s)
+        } else {
+            let s = tau2 * (l - mu);
+            f32::exp(-0.5 * s * s)
+        }
+    }
+
+    fn color_matching_function(l: f32) -> Color {
+        Color::new(
+            1.056 * Self::piecewise_gaussian(l, 599.8, 0.0264, 0.0323)
+                + 0.362 * Self::piecewise_gaussian(l, 442.0, 0.0624, 0.0374)
+                - 0.065 * Self::piecewise_gaussian(l, 501.1, 0.0490, 0.0382),
+            0.821 * Self::piecewise_gaussian(l, 568.8, 0.0213, 0.0247)
+                + 0.286 * Self::piecewise_gaussian(l, 530.9, 0.0613, 0.0322),
+            1.217 * Self::piecewise_gaussian(l, 437.0, 0.0845, 0.0278)
+                + 0.681 * Self::piecewise_gaussian(l, 459.0, 0.0385, 0.0725),
+        )
+    }
+
+    fn monte_carlo_reflectance<R: Rng>(&self, theta1: f32, rng: &mut R) -> Color {
+        let range = 400.0..800.0;
+        let size = range.end - range.start;
+
+        let l = rng.gen_range(range);
+
+        let r = self.averaged_reflectance(l, theta1);
+
+        if !r.is_normal() {
+            dbg!((theta1, l, r));
+        }
+
+        let color = Self::color_matching_function(l);
+
+        if !color.r().is_normal() || !color.g().is_normal() || !color.b().is_normal() {
+            dbg!(color);
+        }
+
+        color * r
+    }
+}
+
+impl<R: Rng> Material<R> for Iridescent {
+    fn eval(
+        &self,
+        w_in: ray_tracing_core::prelude::Dir3,
+        w_out: ray_tracing_core::prelude::Dir3,
+        rng: &mut R,
+    ) -> ray_tracing_core::prelude::Color {
+        let _ = w_in;
+        let _ = w_out;
+        let _ = rng;
+        Color::black()
+    }
+
+    fn sample(&self, w_in: Dir3, rng: &mut R) -> ray_tracing_core::material::SampleResult {
+        let w_out = (2.0 * Dir3::up() * w_in.y()) - w_in;
+
+        let color = self.monte_carlo_reflectance(f32::acos(w_out.z()), rng);
+
+        ray_tracing_core::material::SampleResult::new(w_out, color, true)
+    }
+
+    fn pdf(&self, w_in: Dir3, w_out: Dir3) -> Float {
+        let _ = w_out;
+        let _ = w_in;
+        0.0
+    }
+}

ray-tracing-material/src/lib.rs

@@ -1,5 +1,6 @@
 pub mod default;
 pub mod diffuse;
+pub mod iridescent;
 pub mod microfacet;
 pub mod mirror;
 pub mod oren_nayar;

ray-tracing-scene/src/examples/mod.rs

@@ -1,4 +1,7 @@
 use ray_tracing_core::{prelude::*, scene::Scene};
+use ray_tracing_material::iridescent::Iridescent;
+use ray_tracing_material::microfacet::{BeckmannDistribution, Microfacet};
+use ray_tracing_material::mirror::Mirror;
 use std::collections::HashMap;
 use std::fmt::Debug;
 
@@ -19,9 +22,21 @@ pub fn example_scenes<R: Rng + Debug + 'static>() -> HashMap<&'static str, Box<d
     let mut map: HashMap<&str, Box<dyn ExampleScene<R>>> = HashMap::new();
     map.insert("basic_cornel", Box::new(basic_cornell::BasicCornell::new()));
     map.insert("cornel2", Box::new(cornell2::Cornell2::new()));
+    let color = Color::new(0.2, 0.2, 0.9);
+    let material = Microfacet::new(BeckmannDistribution::new(0.01), color);
     map.insert(
-        "stanford_dragon",
-        Box::new(stanford_dragon::StanfordDragon::new()),
+        "stanford_dragon_microfacet",
+        Box::new(stanford_dragon::StanfordDragon::new(material)),
+    );
+    let material = Iridescent::new(300.0, 300.0, 1.0, 1.5, 10);
+    map.insert(
+        "stanford_dragon_iridescent",
+        Box::new(stanford_dragon::StanfordDragon::new(material)),
+    );
+    let material = Mirror::new(Color::white());
+    map.insert(
+        "stanford_dragon_mirror",
+        Box::new(stanford_dragon::StanfordDragon::new(material)),
     );
     map.insert(
         "stanford_dragon_as",

ray-tracing-scene/src/examples/stanford_dragon.rs

@@ -4,7 +4,7 @@ use ray_tracing_material::{
     microfacet::{BeckmannDistribution, Microfacet},
     oren_nayar::OrenNayar,
 };
-use std::cell::OnceCell;
+use std::cell::{Cell, OnceCell};
 
 use crate::{
     parse_obj::ObjData,
@@ -13,19 +13,21 @@ use crate::{
 
 use super::ExampleScene;
 
-pub struct StanfordDragon<R: Rng> {
+pub struct StanfordDragon<R: Rng, M: Material<R>> {
     scene: OnceCell<TriangleBVH<R>>,
+    material: Cell<Option<M>>,
 }
 
-impl<R: Rng> StanfordDragon<R> {
-    pub fn new() -> Self {
+impl<R: Rng, M: Material<R>> StanfordDragon<R, M> {
+    pub fn new(material: M) -> Self {
         Self {
             scene: OnceCell::new(),
+            material: Cell::new(Some(material)),
         }
     }
 }
 
-impl<R: Rng + 'static> ExampleScene<R> for StanfordDragon<R> {
+impl<R: Rng + 'static, M: Material<R> + 'static> ExampleScene<R> for StanfordDragon<R, M> {
     fn get_scene(&self) -> Box<dyn Scene<R> + Sync> {
         let s = self.scene.get_or_init(|| {
             let obj = ObjData::new("ray-tracing-scene/obj/stanford_dragon.obj").unwrap();
@@ -35,9 +37,8 @@ impl<R: Rng + 'static> ExampleScene<R> for StanfordDragon<R> {
                 .map(|t| Triangle::new(t.v, 0))
                 .collect::<Vec<_>>();
 
-            let color = Color::new(0.2, 0.2, 0.9);
             let materials = vec![
-                BVHMaterial::new_material(Microfacet::new(BeckmannDistribution::new(0.01), color)),
+                BVHMaterial::new_material(self.material.take().unwrap()),
                 BVHMaterial::new_material(OrenNayar::new(0.5, Color::new(0.8, 0.8, 0.8))),
                 BVHMaterial::new_material(OrenNayar::new(0.5, Color::new(0.9, 0.0, 0.0))),
                 BVHMaterial::new_material(OrenNayar::new(0.5, Color::new(0.0, 0.9, 0.0))),