added Philox random gen

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "subprojects/philox"]
+	path = subprojects/philox
+	url = git@github.com:MorizzG/philox

meson.build

@@ -3,7 +3,7 @@ project('ray-tracer', 'cpp', default_options : [
     'werror=true',
     'cpp_std=c++23',
     'b_lto=true',
-    'b_lto_mode=thin',
+    # 'b_lto_mode=thin',
 ])
 
 add_project_arguments(
@@ -12,9 +12,14 @@ add_project_arguments(
     language : 'cpp'
 )
 
+
+philox_proj = subproject('philox', default_options : ['warning_level=0', 'werror=false'])
+philox_dep = philox_proj.get_variable('philox_dep')
+
+
 sources = []
 subdir('src')
 
 inc = include_directories('src')
 
-executable('ray-tracer', sources, include_directories : inc)
+executable('ray-tracer', sources, include_directories : inc, dependencies : [philox_dep])

src/main.cc

@@ -15,18 +15,18 @@ int main(int /* argc */, char* /* argv */[]) {
 
     RenderObjectList world;
 
-    // world.Add(std::make_shared<Sphere>(Vec3{0, -100.5, -1}, 100));
+    world.Add(std::make_shared<Sphere>(Vec3{0, -100.5, -1}, 100));
     world.Add(std::make_shared<Sphere>(-Vec3::e_z, 0.5));
 
     // camera
 
-    // constexpr f64 aspect_ratio = 16.0 / 9.0;
+    constexpr f64 aspect_ratio = 16.0 / 9.0;
 
-    // constexpr u32 image_width = 800;
-    // constexpr auto image_height = static_cast<u32>(image_width / aspect_ratio);
+    constexpr u32 image_width = 800;
+    constexpr auto image_height = static_cast<u32>(image_width / aspect_ratio);
 
-    constexpr u32 image_width = 1920;
-    constexpr u32 image_height = 1080;
+    // constexpr u32 image_width = 1920;
+    // constexpr u32 image_height = 1080;
 
     static_assert(image_height >= 1);
 

src/rand.h

@@ -1,47 +1,47 @@
 #pragma once
 
-#include <cassert>
+#include <philox.h>
 
 #include "raytracer.h"
-class Random {
+#include "vec3.h"
+
+class RandomGen {
    public:
-    constexpr explicit Random(u64 j) {
-        assert(j != v_);
+    constexpr u64 GenU64() { return philox_.Next(); }
+    // constexpr u32 GenU32() { return static_cast<u32>(GenU64()); }
 
-        u_ = j ^ v_;
-        GenU64();
+    constexpr f64 GenUniform() { return philox_.NextF64(); }
 
-        v_ = u_;
-        GenU64();
+    constexpr f64 GenUniform(f64 min, f64 max) { return min + (max - min) * GenUniform(); }
 
-        w_ = v_;
-        GenU64();
+    constexpr Vec3 GenVec3() { return Vec3{GenUniform(), GenUniform(), GenUniform()}; }
+
+    constexpr Vec3 GenVec3(f64 min, f64 max) {
+        return Vec3{GenUniform(min, max), GenUniform(min, max), GenUniform(min, max)};
     }
 
-    constexpr u64 GenU64() {
-        u_ = u_ * 2862933555777941757ULL + 7046029254386353087ULL;
+    constexpr Vec3 GenInUnitBall() {
+        while (true) {
+            Vec3 v = GenVec3(-1.0, 1.0);
 
-        v_ ^= v_ >> 17;
-        v_ ^= v_ << 31;
-        v_ ^= v_ >> 8;
-
-        w_ = 4294957665ULL * (w_ & 0xffffffffULL) + (w_ >> 32);
-
-        u64 x = u_ ^ (u_ << 21);
-        x ^= x >> 35;
-        x ^= x << 4;
-
-        return (x + v_) ^ w_;
+            if (v.norm() < 1.0) {
+                return v;
+            }
+        }
     }
 
-    constexpr u32 GenU32() { return static_cast<u32>(GenU64()); }
+    constexpr Vec3 GenOnUnitSphere() { return GenInUnitBall().normed(); }
 
-    constexpr f64 GenF64() { return 5.42101086242752217E-20 * static_cast<f64>(GenU64()); }
+    constexpr Vec3 GenOnHemisphere(const Vec3& normal) {
+        Vec3 v = GenOnUnitSphere();
 
-    constexpr f64 GenF64(f64 min, f64 max) { return min + (max - min) * GenF64(); }
+        if (dot(v, normal) < 0) {
+            v = -v;
+        }
+
+        return v;
+    }
 
    private:
-    u64 u_ = 0ULL;
-    u64 v_ = 4101842887655102017ULL;
-    u64 w_ = 1ULL;
+    Philox philox_;
 };

src/renderer.h

@@ -15,7 +15,7 @@
 class Renderer {
    public:
     constexpr explicit Renderer(Camera camera, u32 samples_per_pixel = 10)
-        : camera_{camera}, rand_{0}, samples_per_pixel_{samples_per_pixel} {}
+        : camera_{camera}, samples_per_pixel_{samples_per_pixel} {}
 
     constexpr Image Render(const RenderObject& world) {
         Image img{camera_.image_width(), camera_.image_height()};
@@ -43,8 +43,8 @@ class Renderer {
     constexpr Ray SampleRay(u32 i, u32 j) {
         auto pixel_centre = camera_.PixelToWorld(i, j);
 
-        Vec3 random_shift = rand_.GenF64(-0.5, 0.5) * camera_.d_u_pixel() +
-                            rand_.GenF64(-0.5, 0.5) * camera_.d_v_pixel();
+        Vec3 random_shift = rand_.GenUniform(-0.5, 0.5) * camera_.d_u_pixel() +
+                            rand_.GenUniform(-0.5, 0.5) * camera_.d_v_pixel();
 
         pixel_centre += random_shift;
 
@@ -53,17 +53,22 @@ class Renderer {
         return Ray{camera_.centre(), ray_direction};
     }
 
-    static constexpr Colour Cast(const Ray& ray, const RenderObject& world) {
+    constexpr Colour Cast(const Ray& ray, const RenderObject& world) {
         auto hit_record = world.hit(ray, Interval::kPositive);
 
         if (hit_record.has_value()) {
-            Vec3 n = hit_record->normal;
+            Vec3 normal = hit_record->normal;
 
             if (!hit_record->front_face) {
                 return Colour::kBlack;
             }
 
-            return Colour{0.5 * (n + Vec3{1, 1, 1})};
+            Vec3 new_origin = hit_record->p;
+            Vec3 new_direction = rand_.GenOnHemisphere(normal);
+
+            Ray new_ray{new_origin, new_direction};
+
+            return 0.5 * Cast(new_ray, world);
         }
 
         auto unit_dir = ray.direction().normed();
@@ -75,7 +80,7 @@ class Renderer {
 
     Camera camera_;
 
-    Random rand_;
+    RandomGen rand_{};
 
     u32 samples_per_pixel_;
 };

subprojects/philox

@@ -0,0 +1 @@
+Subproject commit cf69284bd2d82b279c34fb1cf90543fd04b3a038