In-memory picture

rtiww/CMakeLists.txt

@@ -10,3 +10,8 @@ add_executable(rtiww src/main.cpp
   src/sphere.h
   src/camera.h
   src/rtweekend.h)
+
+find_package(OpenMP)
+if(OpenMP_CXX_FOUND)
+    target_link_libraries(rtiww PUBLIC OpenMP::OpenMP_CXX)
+endif()

rtiww/src/color.h

@@ -5,8 +5,38 @@
 #include "vec3.h"
 
 #include <iostream>
+#include <unordered_map>
 
-void write_color(std::ostream &out, color pixel_color, int samples_per_pixel) {
+class picture {
+public:
+    picture() : buffer{} {}
+
+    void set_pixel(int line, int offset, color pixel_color) {
+        int hash = pairing(line, offset);
+        this->buffer[hash] = pixel_color;
+    }
+
+    void write(std::ostream &out, int image_height, int image_width,
+               int samples_per_pixel) {
+        for (int j = image_height - 1; j >= 0; --j) {
+            for (int i = 0; i < image_width; ++i) {
+                int hash = pairing(j, i);
+                color c = this->buffer[hash];
+                write_color(out, c, samples_per_pixel);
+            }
+        }
+    }
+
+public:
+    std::unordered_map<int, color> buffer;
+
+private:
+    int pairing(int a, int b) {
+        return 0.5 * (a + b) * (a + b + 1) + b;
+    }
+
+    void write_color(std::ostream &out, color pixel_color,
+                     int samples_per_pixel) {
         auto r = pixel_color.x();
         auto g = pixel_color.y();
         auto b = pixel_color.z();
@@ -20,5 +50,6 @@ void write_color(std::ostream &out, color pixel_color, int samples_per_pixel) {
             << static_cast<int>(255.999 * clamp(g, 0.0, 0.999)) << ' '
             << static_cast<int>(255.999 * clamp(b, 0.0, 0.999)) << '\n';
     }
+};
 
 #endif // RTIWW_COLOR_H

rtiww/src/main.cpp

@@ -44,10 +44,12 @@ int main() {
   // Render
   std::cout << "P3\n" << image_width << ' ' << image_height << "\n255\n";
 
+  picture p;
+
   for (int j = image_height - 1; j >= 0; --j) {
-    std::cerr << "\rScanlines remaining: " << j << ' ' << std::flush;
     for (int i = 0; i < image_width; ++i) {
       color pixel_color(0, 0, 0);
+
       for (int s = 0; s < samples_per_pixel; ++s) {
         auto u = (i + random_double()) / (image_width - 1);
         auto v = (j + random_double()) / (image_height - 1);
@@ -55,10 +57,12 @@ int main() {
         ray r = cam.get_ray(u, v);
         pixel_color += ray_color(r, world, max_depth);
       }
-      write_color(std::cout, pixel_color, samples_per_pixel);
+
+      p.set_pixel(j,i,pixel_color);
     }
   }
 
+  p.write(std::cout, image_height, image_width, samples_per_pixel);
   std::cerr << "\nDone.\n";
 
   return 0;