Defocus blur

rtiww/src/camera.h

@@ -5,34 +5,42 @@
 
 class camera {
 public:
-    camera(point3 lookfrom, point3 lookat, vec3 vup, double vfov /*vertical field-of-view in degrees*/,
-           double aspect_ratio) {
+  camera(point3 lookfrom, point3 lookat, vec3 vup,
+         double vfov, // vertical field-of-view in degrees
+         double aspect_ratio, double aperture, double focus_dist) {
 
-        auto theta = degrees_to_radians(vfov);
-        auto h = tan(theta / 2);
-        auto viewport_height = 2.0 * h;
-        auto viewport_width = aspect_ratio * viewport_height;
+    auto theta = degrees_to_radians(vfov);
+    auto h = tan(theta / 2);
+    auto viewport_height = 2.0 * h;
+    auto viewport_width = aspect_ratio * viewport_height;
 
-        auto w = unit_vector(lookfrom - lookat);
-        auto u = unit_vector(cross(vup, w));
-        auto v = cross(w, u);
+    w = unit_vector(lookfrom - lookat);
+    u = unit_vector(cross(vup, w));
+    v = cross(w, u);
 
-        origin = lookfrom;
-        horizontal = viewport_width * u;
-        vertical = viewport_height * v;
-        lower_left_corner = origin - horizontal/2 - vertical/2 - w;
-    }
+    origin = lookfrom;
+    horizontal = focus_dist * viewport_width * u;
+    vertical = focus_dist * viewport_height * v;
+    lower_left_corner = origin - horizontal / 2 - vertical / 2 - focus_dist * w;
 
-    ray get_ray(double s, double t) const {
-        return ray(origin,
-                   lower_left_corner + s*horizontal + t*vertical - origin);
-    }
+    lens_radius = aperture / 2;
+  }
+
+  ray get_ray(double s, double t) const {
+    vec3 rd = lens_radius * random_in_unit_disk();
+    vec3 offset = u * rd.x() + v * rd.y();
+
+    return ray(origin + offset, lower_left_corner + s * horizontal +
+                                    t * vertical - origin - offset);
+  }
 
 private:
-    point3 origin;
-    point3 lower_left_corner;
-    vec3 horizontal;
-    vec3 vertical;
+  point3 origin;
+  point3 lower_left_corner;
+  vec3 horizontal;
+  vec3 vertical;
+  vec3 u, v, w;
+  double lens_radius;
 };
 
 #endif // CAMERA_H_

rtiww/src/main.cpp

@@ -59,7 +59,12 @@ int main() {
 
   // Camera
 
-  camera cam(point3(-2,2,1), point3(0,0,-1), vec3(0,1,0), 90, aspect_ratio);
+  point3 lookfrom(3, 3, 2);
+  point3 lookat(0, 0, -1);
+  vec3 vup(0, 1, 0);
+  auto dist_to_focus = (lookfrom - lookat).length();
+  auto aperture = 2.0;
+  camera cam(lookfrom, lookat, vup, 20, aspect_ratio, aperture, dist_to_focus);
 
   // Render
 

rtiww/src/vec3.h

@@ -131,4 +131,13 @@ vec3 refract(const vec3 &v, const vec3 &n, double etai_over_etat) {
   return r_out_perp + r_out_parallel;
 }
 
+vec3 random_in_unit_disk() {
+  while (true) {
+    auto p = vec3(random_double(-1, 1), random_double(-1, 1), 0);
+    if (p.length_squared() >= 1)
+      continue;
+    return p;
+  }
+}
+
 #endif // RTIWW_VEC3_H