added very basic multithreading to renderer

CMakeLists.txt

@@ -2,6 +2,7 @@ cmake_minimum_required(VERSION 3.5)
 project(CG1_Tracer LANGUAGES CXX)
 set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_CXX_FLAGS "-O3 -pthread")
 
 if(NOT WIN32)
   find_package(Threads REQUIRED)

common/ray.cpp

@@ -1,3 +1,3 @@
 #include "ray.h"
 
-int Ray::rayCount = 0;
+std::atomic_int Ray::rayCount = 0;

common/ray.h

@@ -42,7 +42,7 @@ private:
   int remainingBounces = ICG_RAY_BOUNCES;
 #endif
 
-  static int rayCount;
+  static std::atomic_int rayCount;
 };
 
 #endif

renderer/simplerenderer.cpp

@@ -4,6 +4,7 @@
 #include <iostream>
 #include <chrono>
 #include <iomanip>
+#include <thread>
 
 Texture SimpleRenderer::renderImage(Scene const &scene, Camera const &camera, int width, int height) {
   Texture image(width, height);
@@ -17,28 +18,35 @@ Texture SimpleRenderer::renderImage(Scene const &scene, Camera const &camera, in
   // Super-hacky progress bar!
   std::cout << "(SimpleRenderer): Begin rendering..." << std::endl;
   std::cout << "| 0%";
-  int const barSize = 50;
-  int const stepSize = (width * height) / barSize;
-  for (int i = 0; i < barSize - 3 - 5; ++i)
-    std::cout << " ";
+  int const barSizeGoal = 100;
+  int const stepSize = width / barSizeGoal;
+  for (int i = 0; i < width / stepSize - 3 - 5; ++i)
+      std::cout << " ";
   std::cout << "100% |" << std::endl << "|";
   int k = 0;
 
   // Start timer
   start = std::chrono::steady_clock::now();
 
-  float const aspectRatio = static_cast<float>(height) / width;
-  for (int x = 0; x < image.width(); ++x) {
-    for (int y = 0; y < image.height(); ++y) {
-      Ray ray = camera.createRay((static_cast<float>(x) / width * 2 - 1), -(static_cast<float>(y) / height * 2 - 1) * aspectRatio);
-      image.setPixelAt(x, y, clamped(scene.traceRay(ray)));
-
-      // Super hacky progress bar!
-      if (++k % stepSize == 0) {
-        std::cout << "=" << std::flush;
-      }
+    float const aspectRatio = static_cast<float>(height) / static_cast<float>(width);
+    std::vector<std::thread> threads;
+    threads.reserve(width);
+    for (int x = 0; x < image.width(); ++x) {
+        threads.emplace_back([&image, aspectRatio](auto camera, auto scene, int x) {
+            for (int y = 0; y < image.height(); ++y) {
+                Ray ray = camera->createRay((static_cast<float>(x) / image.width() * 2.0f - 1),
+                                            -(static_cast<float>(y) / image.height() * 2 - 1) * aspectRatio);
+                image.setPixelAt(x, y, clamped(scene->traceRay(ray)));
+            }
+        }, &camera, &scene, x);
+    }
+    for (auto &thread: threads) {
+        thread.join();
+        // Super hacky progress bar!
+        if (++k % stepSize == 0) {
+            std::cout << "=" << std::flush;
+        }
     }
-  }
 
   // Stop timer
   stop = std::chrono::steady_clock::now();