From 742ef283e413f1546f96513904623165e4a72e97 Mon Sep 17 00:00:00 2001
From: David <Phireh@hotmail.com>
Date: Sun, 29 Aug 2021 16:17:13 +0200
Subject: [PATCH] Faster random implementation

---
 .gitignore        |  3 +++
 Makefile          |  2 ++
 hittable_list.hpp |  4 ++--
 main.cpp          | 18 ++++++++++++------
 random.h          | 15 +++++++++++++++
 rtweekend.hpp     |  9 ++++++++-
 timer.hpp         |  8 +++++++-
 7 files changed, 49 insertions(+), 10 deletions(-)
 create mode 100644 random.h

diff --git a/.gitignore b/.gitignore
index 7f42aa0..80c9739 100644
--- a/.gitignore
+++ b/.gitignore
@@ -8,3 +8,6 @@ raytracer
 
 # Actual output image
 image.ppm
+
+# Profiler data
+perf.*
diff --git a/Makefile b/Makefile
index 5f5fdf7..6ff5af9 100644
--- a/Makefile
+++ b/Makefile
@@ -5,6 +5,8 @@ FLAGS=-Ofast -march=native -g -Wall -Wextra -Wpedantic
 raytracer: camera.hpp color.hpp hittable.hpp hittable_list.hpp main.cpp material.hpp ray.hpp rtweekend.hpp sphere.hpp vec3.hpp $(INCLUDE)/Remotery.c $(INCLUDE)/Remotery.h
 	g++ $(FLAGS) -I$(INCLUDE) $(LIBS) main.cpp -o raytracer
 
+make debug:
+
 image: raytracer
 	@./raytracer > image.ppm
 	@if [ $$TERM = "xterm-kitty" ]; then\
diff --git a/hittable_list.hpp b/hittable_list.hpp
index a9c2dcd..9c3366e 100644
--- a/hittable_list.hpp
+++ b/hittable_list.hpp
@@ -34,8 +34,8 @@ bool hittable_list<T>::hit(const ray& r, float t_min, float t_max, hit_record& r
     bool hit_anything = false;
     float closest_so_far = t_max;
 
-    
-    for (uint32_t i = 0; i < objects.size(); ++i)
+    uint32_t s = objects.size();
+    for (uint32_t i = 0; i < s; ++i)
     {
         T *object = &objects[i];
         if (object->hit(r, t_min, closest_so_far, temp_rec))
diff --git a/main.cpp b/main.cpp
index 8d5c035..4bb6f64 100644
--- a/main.cpp
+++ b/main.cpp
@@ -2,9 +2,7 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-
-// Disable profiling
-#define RMT_ENABLED 1
+#define RMT_ENABLED 0
 
 // Lib includes
 #pragma GCC diagnostic push
@@ -21,9 +19,15 @@
 #include "sphere.hpp"
 #include "camera.hpp"
 
+#ifdef DEBUG
+#define print_timers() print_timers_()
+#else
+#define print_timers()
+#endif
+
 color ray_color(const ray& r, const hittable& world, int32_t depth);
 float hit_sphere(const point3& center, float radius, const ray& r);
-void print_timers();
+
 hittable_list<sphere> random_scene();
 
 hittable_list<sphere> random_scene() {
@@ -188,10 +192,10 @@ int32_t main()
     rmt_DestroyGlobalInstance(rmt);
 }
 
+#ifdef DEBUG
 debug_record debug_record_array[__COUNTER__];
 
-
-void print_timers()
+void print_timers_()
 {
     for (uint32_t i = 0;
          i < sizeof(debug_record_array) / sizeof(debug_record_array[0]);
@@ -211,3 +215,5 @@ void print_timers()
                 (double)record->cycles / CLOCKS_PER_SEC);
     }
 }
+
+#endif
diff --git a/random.h b/random.h
new file mode 100644
index 0000000..b5f66e7
--- /dev/null
+++ b/random.h
@@ -0,0 +1,15 @@
+// *Really* minimal PCG32 code / (c) 2014 M.E. O'Neill / pcg-random.org
+// Licensed under Apache License 2.0 (NO WARRANTY, etc. see website)
+
+typedef struct { uint64_t state;  uint64_t inc; } pcg32_random_t;
+
+uint32_t pcg32_random_r(pcg32_random_t* rng)
+{
+    uint64_t oldstate = rng->state;
+    // Advance internal state
+    rng->state = oldstate * 6364136223846793005ULL + (rng->inc|1);
+    // Calculate output function (XSH RR), uses old state for max ILP
+    uint32_t xorshifted = ((oldstate >> 18u) ^ oldstate) >> 27u;
+    uint32_t rot = oldstate >> 59u;
+    return (xorshifted >> rot) | (xorshifted << ((-rot) & 31));
+}
diff --git a/rtweekend.hpp b/rtweekend.hpp
index 410329b..13a9781 100644
--- a/rtweekend.hpp
+++ b/rtweekend.hpp
@@ -4,9 +4,16 @@
 #include <math.h>
 #include <memory>
 #include "timer.hpp"
+#include "random.h"
+
+#define FAST_RANDOM 1
+#ifdef FAST_RANDOM
+pcg32_random_t pcg = { 0x853c49e6748fea9bULL, 0xda3e39cb94b95bdbULL };
+#define rand() pcg32_random_r(&pcg)
+#endif
 
 /* Utility functions */
-float degrees_to_radians(float d)
+inline float degrees_to_radians(float d)
 {
     return d * M_PI / 180;
 }
diff --git a/timer.hpp b/timer.hpp
index ed537cb..6a2c689 100644
--- a/timer.hpp
+++ b/timer.hpp
@@ -1,11 +1,15 @@
 #include <x86intrin.h>
 #include "rtweekend.hpp"
 
-
+#ifdef DEBUG
 #define TIMED_BLOCK__(number, ...) timed_block timed_block_##Number(__COUNTER__, __FILE__, __LINE__, __FUNCTION__, ##__VA_ARGS__)
 #define TIMED_BLOCK_(number, ...) TIMED_BLOCK__(number, ##__VA_ARGS__)
 #define TIMED_BLOCK(...) TIMED_BLOCK_(__LINE__, ##__VA_ARGS__)
+#else
+#define TIMED_BLOCK(...)
+#endif
 
+#ifdef DEBUG
 struct debug_record
 {
     uint64_t cycles;
@@ -17,6 +21,7 @@ struct debug_record
     
 };
 
+
 extern debug_record debug_record_array[];
 
 struct timed_block {
@@ -37,3 +42,4 @@ struct timed_block {
         record->cycles += __rdtsc();
     }
 };
+#endif