added Materials

Lambertian: scatter ray randomly with absorption

Metal: reflect ray with absorption

meson.build

@@ -27,7 +27,6 @@ if get_option('native')
 endif
 
 
-
 rand_proj = subproject('rand', default_options : ['warning_level=0', 'werror=false'])
 rand_dep = rand_proj.get_variable('rand_dep')
 

src/colour.h

@@ -44,6 +44,14 @@ class Colour {
         return *this;
     }
 
+    constexpr Colour& operator*=(const Colour& c) {
+        r_ *= c.r();
+        g_ *= c.g();
+        b_ *= c.b();
+
+        return *this;
+    }
+
     constexpr Colour to_gamma2() const {
         return Colour{std::sqrt(r()), std::sqrt(g()), std::sqrt(b())};
     }
@@ -79,6 +87,14 @@ constexpr Colour operator+(Colour c1, Colour c2) {
     return out;
 }
 
+constexpr Colour operator*(Colour c1, Colour c2) {
+    Colour out{c1};
+
+    out *= c2;
+
+    return out;
+}
+
 inline std::ostream& operator<<(std::ostream& os, Colour c) {
     double r = c.r();
     double g = c.g();

src/main.cc

@@ -1,5 +1,6 @@
 #include <iostream>
 #include <memory>
+#include <utility>
 
 #include "camera.h"
 #include "colour.h"
@@ -16,10 +17,24 @@ int main(int /* argc */, char* /* argv */[]) {
 
     RenderObjectList world;
 
-    auto lamb = std::make_shared<Lambertian>(Colour{0.1, 0.4, 0.8});
+    /* auto lamb = std::make_shared<Lambertian>(Colour{0.7, 0.0, 0.5});
+    auto metal = std::make_shared<Metal>(Colour{0.3, 0.3, 0.3});
 
-    world.Add(std::make_unique<Sphere>(Vec3{0, -100.5, -1}, 100, lamb));
-    world.Add(std::make_unique<Sphere>(-Vec3::e_z, 0.5, lamb));
+    auto ground = std::make_unique<Sphere>(Point3{0, -100.5, -1}, 100, metal);
+    auto sphere = std::make_unique<Sphere>(-Vec3::e_z, 0.5, lamb);
+
+    world.Add(std::move(ground));
+    world.Add(std::move(sphere)); */
+
+    auto material_ground = std::make_shared<Lambertian>(Colour(0.8, 0.8, 0.0));
+    auto material_center = std::make_shared<Lambertian>(Colour(0.7, 0.3, 0.3));
+    auto material_left = std::make_shared<Metal>(Colour(0.8, 0.8, 0.8), 0.05);
+    auto material_right = std::make_shared<Metal>(Colour(0.8, 0.5, 0.4), 0.5);
+
+    world.Add(std::make_unique<Sphere>(Point3(0.0, -100.5, -1.0), 100.0, material_ground));
+    world.Add(std::make_unique<Sphere>(Point3(0.0, 0.0, -1.0), 0.5, material_center));
+    world.Add(std::make_unique<Sphere>(Point3(-1.0, 0.0, -1.0), 0.5, material_left));
+    world.Add(std::make_unique<Sphere>(Point3(1.0, 0.0, -1.0), 0.5, material_right));
 
     // camera
 

src/material.h

@@ -1,11 +1,13 @@
 #pragma once
 
+#include <cassert>
 #include <optional>
 #include <tuple>
 
 #include "colour.h"
 #include "rand.h"
 #include "ray.h"
+#include "raytracer.h"
 #include "renderobject.h"
 
 class Material {
@@ -37,10 +39,9 @@ class Lambertian : public Material {
                                                    const HitRecord& hit_record) const override {
         auto scatter_dir = hit_record.normal + rand().GenOnUnitSphere();
 
-        // TODO: enable
-        /* if (scatter_dir.almost_zero()) {
+        if (scatter_dir.almost_zero()) {
             scatter_dir = hit_record.normal;
-        } */
+        }
 
         Ray scattered{hit_record.p, scatter_dir};
 
@@ -50,3 +51,23 @@ class Lambertian : public Material {
    private:
     Colour albedo_;
 };
+
+class Metal : public Material {
+   public:
+    constexpr Metal(Colour albedo, f64 fuzz) : albedo_{albedo}, fuzz_{fuzz} { assert(fuzz <= 1); }
+
+    std::optional<std::tuple<Colour, Ray>> Scatter(const Ray& in,
+                                                   const HitRecord& hit_record) const override {
+        auto reflect_dir = in.direction().reflect(hit_record.normal).normed();
+
+        reflect_dir += fuzz_ * rand().GenOnUnitSphere();
+
+        Ray scattered{hit_record.p, reflect_dir};
+
+        return std::make_tuple(albedo_, scattered);
+    }
+
+   private:
+    Colour albedo_;
+    f64 fuzz_;
+};

src/rand.h

@@ -1,6 +1,6 @@
 #pragma once
 
-#include <philox.h>
+#include <philox.hh>
 
 #include "raytracer.h"
 #include "vec3.h"

src/renderer.h

@@ -76,7 +76,7 @@ class Renderer {
 
         pixel_centre += random_shift;
 
-        auto ray_direction = pixel_centre - camera_.centre();
+        auto ray_direction = (pixel_centre - camera_.centre()).normed();
 
         return Ray{camera_.centre(), ray_direction};
     }
@@ -84,33 +84,32 @@ class Renderer {
     constexpr Colour Cast(const Ray& ray, const RenderObject& world, u32 bounces) {
         auto hit_record = world.hit(ray, Interval{0.001, kInf});
 
-        if (hit_record.has_value()) {
-            if (!hit_record->front_face || bounces == 0) {
-                return Colour::kBlack;
-            }
+        // background
+        if (!hit_record.has_value()) {
+            auto unit_dir = ray.direction().normed();
 
-            /* Vec3 normal = hit_record->normal;
+            f64 a = 0.5 * (unit_dir.y() + 1.0);
 
-            Vec3 new_origin = hit_record->p;
-
-            // Vec3 new_direction = rand_.GenOnHemisphere(normal);
-            Vec3 new_direction = normal + rand_.GenOnUnitSphere();
-
-            Ray new_ray{new_origin, new_direction}; */
-
-            auto res = hit_record->mat->Scatter(ray, hit_record.value());
-
-            auto [albedo, out_ray] = res.value();
-
-            assert(bounces > 0);
-            return 0.5 * Cast(out_ray, world, bounces - 1);
+            return (1.0 - a) * Colour{1.0, 1.0, 1.0} + a * Colour{0.5, 0.7, 1.0};
         }
 
-        auto unit_dir = ray.direction().normed();
+        // hit
 
-        f64 a = 0.5 * (unit_dir.y() + 1.0);
+        if (!hit_record->front_face || bounces == 0) {
+            return Colour::kBlack;
+        }
 
-        return (1.0 - a) * Colour{1.0, 1.0, 1.0} + a * Colour{0.5, 0.7, 1.0};
+        auto res = hit_record->mat->Scatter(ray, hit_record.value());
+
+        if (!res.has_value()) {
+            // absorped
+            return Colour::kBlack;
+        }
+
+        auto [albedo, out_ray] = res.value();
+
+        assert(bounces > 0);
+        return albedo * Cast(out_ray, world, bounces - 1);
     }
 
     Camera camera_;

src/vec3.h

@@ -65,15 +65,13 @@ class Vec3 {
         return std::fabs(x()) < eps && std::fabs(y()) < eps && std::fabs(z()) < eps;
     }
 
-    constexpr f64 squared() const { return x() * x() + y() * y() + z() * z(); }
+    constexpr f64 squared() const;
 
-    constexpr f64 norm() const { return std::sqrt(squared()); }
+    constexpr f64 norm() const;
 
-    constexpr Vec3 normed() const {
-        auto r = *this;
-        r /= norm();
-        return r;
-    }
+    constexpr Vec3 normed() const;
+
+    constexpr Vec3 reflect(Vec3 normal) const;
 
    private:
     std::array<f64, 3> xyz_;
@@ -119,4 +117,10 @@ constexpr Vec3 cross(const Vec3& u, const Vec3& v) {
             u.x() * v.y() - u.y() - v.x()};
 }
 
-constexpr Vec3 normed(const Vec3& v) { return v.normed(); }
+constexpr f64 Vec3::squared() const { return dot(*this, *this); }
+
+constexpr f64 Vec3::norm() const { return std::sqrt(squared()); }
+
+constexpr Vec3 Vec3::normed() const { return *this / norm(); }
+
+constexpr Vec3 Vec3::reflect(Vec3 normal) const { return *this - 2 * dot(*this, normal) * normal; }