From ce6b7852b7de11d485c017e16a9b990b94a66322 Mon Sep 17 00:00:00 2001
From: "Dmitry V. Sokolov" <ha@haqr.eu>
Date: Fri, 18 Mar 2022 17:33:28 +0100
Subject: [PATCH] fstream is a proper RAII object

---
 tinyraytracer.cpp | 40 ++++++++++++++++++----------------------
 1 file changed, 18 insertions(+), 22 deletions(-)

diff --git a/tinyraytracer.cpp b/tinyraytracer.cpp
index 96c89d9..2567af8 100644
--- a/tinyraytracer.cpp
+++ b/tinyraytracer.cpp
@@ -34,19 +34,19 @@ struct Sphere {
     Material material;
 };
 
-static const Material      ivory = {1.0, {0.9,  0.5, 0.1, 0.0}, {0.4, 0.4, 0.3},   50.};
-static const Material      glass = {1.5, {0.0,  0.9, 0.1, 0.8}, {0.6, 0.7, 0.8},  125.};
-static const Material red_rubber = {1.0, {1.4,  0.3, 0.0, 0.0}, {0.3, 0.1, 0.1},   10.};
-static const Material     mirror = {1.0, {0.0, 16.0, 0.8, 0.0}, {1.0, 1.0, 1.0}, 1425.};
+constexpr Material      ivory = {1.0, {0.9,  0.5, 0.1, 0.0}, {0.4, 0.4, 0.3},   50.};
+constexpr Material      glass = {1.5, {0.0,  0.9, 0.1, 0.8}, {0.6, 0.7, 0.8},  125.};
+constexpr Material red_rubber = {1.0, {1.4,  0.3, 0.0, 0.0}, {0.3, 0.1, 0.1},   10.};
+constexpr Material     mirror = {1.0, {0.0, 16.0, 0.8, 0.0}, {1.0, 1.0, 1.0}, 1425.};
 
-static const Sphere spheres[] = {
+constexpr Sphere spheres[] = {
     {{-3,    0,   -16}, 2,      ivory},
     {{-1.0, -1.5, -12}, 2,      glass},
     {{ 1.5, -0.5, -18}, 3, red_rubber},
     {{ 7,    5,   -18}, 4,     mirror}
 };
 
-static const vec3 lights[] = {
+constexpr vec3 lights[] = {
     {-20, 20,  20},
     { 30, 50, -25},
     { 30, 20,  30}
@@ -100,10 +100,10 @@ std::tuple<bool,vec3,vec3,Material> scene_intersect(const vec3 &orig, const vec3
         N = (pt - s.center).normalized();
         material = s.material;
     }
-    return {nearest_dist<1000, pt, N, material};
+    return { nearest_dist<1000, pt, N, material };
 }
 
-vec3 cast_ray(const vec3 &orig, const vec3 &dir, int depth=0) {
+vec3 cast_ray(const vec3 &orig, const vec3 &dir, const int depth=0) {
     auto [hit, point, N, material] = scene_intersect(orig, dir);
     if (depth>4 || !hit)
         return {0.2, 0.7, 0.8}; // background color
@@ -114,7 +114,7 @@ vec3 cast_ray(const vec3 &orig, const vec3 &dir, int depth=0) {
     vec3 refract_color = cast_ray(point, refract_dir, depth + 1);
 
     float diffuse_light_intensity = 0, specular_light_intensity = 0;
-    for (const vec3 light : lights) { // checking if the point lies in the shadow of the light
+    for (const vec3 &light : lights) { // checking if the point lies in the shadow of the light
         vec3 light_dir = (light - point).normalized();
         auto [hit, shadow_pt, trashnrm, trashmat] = scene_intersect(point, light_dir);
         if (hit && (shadow_pt-point).norm() < (light-point).norm()) continue;
@@ -125,29 +125,25 @@ vec3 cast_ray(const vec3 &orig, const vec3 &dir, int depth=0) {
 }
 
 int main() {
-    const int   width  = 1024;
-    const int   height = 768;
-    const float fov    = 1.05; // 60 degrees field of view in radians
+    constexpr int   width  = 1024;
+    constexpr int   height = 768;
+    constexpr float fov    = 1.05; // 60 degrees field of view in radians
     std::vector<vec3> framebuffer(width*height);
 #pragma omp parallel for
-    for (int j = 0; j<height; j++) { // actual rendering loop
-        for (int i = 0; i<width; i++) {
-            float dir_x =  (i + 0.5) -  width/2.;
-            float dir_y = -(j + 0.5) + height/2.;    // this flips the image at the same time
-            float dir_z = -height/(2.*tan(fov/2.));
-            framebuffer[i+j*width] = cast_ray(vec3{0,0,0}, vec3{dir_x, dir_y, dir_z}.normalized());
-        }
+    for (int pix = 0; pix<width*height; pix++) { // actual rendering loop
+        float dir_x =  (pix%width + 0.5) -  width/2.;
+        float dir_y = -(pix/width + 0.5) + height/2.; // this flips the image at the same time
+        float dir_z = -height/(2.*tan(fov/2.));
+        framebuffer[pix] = cast_ray(vec3{0,0,0}, vec3{dir_x, dir_y, dir_z}.normalized());
     }
 
-    std::ofstream ofs; // save the framebuffer to file
-    ofs.open("./out.ppm", std::ios::binary);
+    std::ofstream ofs("./out.ppm", std::ios::binary);
     ofs << "P6\n" << width << " " << height << "\n255\n";
     for (vec3 &color : framebuffer) {
         float max = std::max(1.f, std::max(color[0], std::max(color[1], color[2])));
         for (int chan : {0,1,2})
             ofs << (char)(255 *  color[chan]/max);
     }
-    ofs.close();
     return 0;
 }