From 5958307f133a013549415fc54cfe139116cee651 Mon Sep 17 00:00:00 2001
From: hal8174 <henning.lindemann@pm.me>
Date: Sat, 22 Jun 2024 15:41:40 +0200
Subject: [PATCH] Add factor to adjust brightness of the distribution.

---
 .../Assignment3/application_integrator.cpp    | 31 ++++++++++++++++++-
 .../Assignment3/application_integrator.h      |  4 +++
 2 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/Assignments/Assignment3/application_integrator.cpp b/Assignments/Assignment3/application_integrator.cpp
index 2cce185..fa34d83 100644
--- a/Assignments/Assignment3/application_integrator.cpp
+++ b/Assignments/Assignment3/application_integrator.cpp
@@ -6,6 +6,8 @@
 #include "random_sampler.hpp"
 #include "random_sampler_wrapper.hpp"
 #include "tasking/taskschedulerinternal.h"
+#include <atomic>
+#include <mutex>
 #include <vector>
 
 ApplicationIntegrator::ApplicationIntegrator(int argc, char **argv,
@@ -47,6 +49,11 @@ inline float luminance(Vec3fa v) {
 void ApplicationIntegrator::resetRender() {
   Application::resetRender();
 
+  accepted.store(0, std::memory_order_relaxed);
+  luminance_count.store(0, std::memory_order_relaxed);
+  std::lock_guard<std::mutex> guard(large_step_global_luminance_mutex);
+  large_step_global_luminance = 0.0;
+
   if (bMetropolis) {
     data.film.count = false;
   } else {
@@ -174,15 +181,19 @@ void ApplicationIntegrator::mltRender(int *pixels, int width, int height,
   // d = Distribution1D(float* bis_values, num_bins)
   // float integral = d.funcInt;
   // int index_of_the_sampled_bin = d.SampleDiscrete(rng.get1D());
-
+  
+  
   parallel_for(size_t(0), size_t(num_chains), [&](const range<size_t> &range) {
     const int threadIndex = (int)TaskScheduler::threadIndex();
+    float large_luminance_outer_sum = 0.0;
     for (size_t i = range.begin(); i < range.end(); i++) {
       MLTRandomSampler sampler(small_step_size, large_step_probability);
       sampler.init(data.frame_count * num_chains + i);
 
       float last_l = 0.0;
 
+      float large_luminance_sum = 0.0;
+
       for (size_t j = 0; j < chain_lengths; j++) {
 
         sampler.new_ray(RandomSampler_get1D(sampler.sampler) < large_step_probability);
@@ -196,15 +207,32 @@ void ApplicationIntegrator::mltRender(int *pixels, int width, int height,
         Vec3f f = renderPixel(x, y, camera, g_stats[threadIndex], sampler);
         float l = luminance(f);
 
+        if (sampler.is_large_step()) {
+          large_luminance_sum += l;
+          luminance_count.fetch_add(1, std::memory_order_relaxed);
+        }
+
         if ((last_l == 0.0 && l > 0.0) || (last_l > 0.0 && RandomSampler_get1D(sampler.sampler) < l / last_l)) {
           data.film.addSplat(x_pixel, y_pixel, f / l);
           sampler.accept();
+          accepted.fetch_add(1, std::memory_order_relaxed);
         }
 
       }
+      large_luminance_outer_sum += large_luminance_sum;
     }
+    std::lock_guard<std::mutex> guard(large_step_global_luminance_mutex);
+    large_step_global_luminance += large_luminance_outer_sum;
   });
 
+
+  
+  
+  std::lock_guard<std::mutex> guard(large_step_global_luminance_mutex);
+  data.film.scalar = (float)(width * height) * large_step_global_luminance / (accepted.load(std::memory_order_relaxed) * luminance_count.load(std::memory_order_relaxed));
+  
+
+  printf("%f\n", data.film.scalar);
 }
 
 void ApplicationIntegrator::mcRender(int *pixels, int width, int height,
@@ -218,6 +246,7 @@ void ApplicationIntegrator::mcRender(int *pixels, int width, int height,
                    renderTile((int)i, threadIndex, pixels, width, height, time,
                               camera, numTilesX, numTilesY);
                });
+
 }
 
 /* renders a single screen tile */
diff --git a/Assignments/Assignment3/application_integrator.h b/Assignments/Assignment3/application_integrator.h
index 7b9d997..030ddc9 100644
--- a/Assignments/Assignment3/application_integrator.h
+++ b/Assignments/Assignment3/application_integrator.h
@@ -29,6 +29,10 @@ protected:
 		const unsigned int height, const float time, const ISPCCamera& camera, const int numTilesX,
 		const int numTilesY);
 
+	std::atomic<size_t> accepted = 0;
+	std::atomic<size_t> luminance_count = 0;
+	float large_step_global_luminance = 0.0;
+	std::mutex large_step_global_luminance_mutex;
 	int num_chains = 100;
 	int chain_lengths = 100000;
 	float small_step_size = 0.01;