feat: add antialiasing

camera.h

@@ -0,0 +1,31 @@
+#ifndef CAMERA_H
+#define CAMERA_H
+
+#include "rtweekend.h"
+
+class camera {
+	public:
+		camera() {
+			auto aspect_ratio = 16.0 / 9.0;
+			auto viewport_height = 2.0;
+			auto viewport_width = aspect_ratio * viewport_height;
+			auto focal_length = 1.0;
+
+			origin = point3(0, 0, 0);
+			horizontal = vec3(viewport_width, 0, 0);
+			vertical = vec3(0, viewport_height, 0);
+			lower_left_corner = origin - horizontal/2 - vertical/2 - vec3(0, 0, focal_length);
+		}
+
+		ray get_ray(double u, double v) const {
+			return ray(origin, lower_left_corner + u*horizontal + v*vertical - origin);
+		}
+
+	private:
+		point3 origin;
+		point3 lower_left_corner;
+		vec3 horizontal;
+		vec3 vertical;
+};
+
+#endif

color.h

@@ -2,14 +2,20 @@
 #define COLOR_H
 
 #include "vec3.h"
+#include "rtweekend.h"
 
 #include <iostream>
 
-void write_color(std::ostream &out, color pixel_color) {
+void write_color(std::ostream &out, color pixel_color, int samples_per_pixel) {
+	auto scale = 1.0 / samples_per_pixel;
+	auto r = pixel_color.x() * scale;
+	auto g = pixel_color.y() * scale;
+	auto b = pixel_color.z() * scale;
+
 	// Write the translated [0,255] value of each color component
-	out << static_cast<int>(255.999 * pixel_color.x()) << " "
-			<< static_cast<int>(255.999 * pixel_color.y()) << " "
-			<< static_cast<int>(255.999 * pixel_color.z()) << "\n";
+	out << static_cast<int>(256 * clamp(r, 0.0, 0.999)) << " "
+			<< static_cast<int>(256 * clamp(g, 0.0, 0.999)) << " "
+			<< static_cast<int>(256 * clamp(b, 0.0, 0.999)) << "\n";
 }
 
 #endif

main.cc

@@ -3,6 +3,7 @@
 #include "color.h"
 #include "hittable_list.h"
 #include "sphere.h"
+#include "camera.h"
 
 #include <iostream>
 
@@ -22,6 +23,7 @@ int main() {
 	const auto aspect_ratio = 16.0 / 9.0;
 	const int image_width = 400;
 	const int image_height = static_cast<int>(image_width / aspect_ratio);
+	const int samples_per_pixel = 10;
 
 	// World
 	hittable_list world;
@@ -29,25 +31,21 @@ int main() {
 	world.add(make_shared<sphere>(point3(0, -100.5, -1), 100));
 
 	// Camera
-	auto viewport_height = 2.0;
-	auto viewport_width = aspect_ratio * viewport_height;
-	auto focal_length = 1.0;
-
-	auto origin = point3(0, 0, 0);
-	auto horizontal = vec3(viewport_width, 0, 0);
-	auto vertical = vec3(0, viewport_height, 0);
-	auto lower_left_corner = origin - horizontal/2 - vertical/2 - vec3(0, 0, focal_length);
+	camera cam;
 
 	// Render
 	std::cout<<"P3\n"<<image_width<<" "<<image_height<<"\n255\n";
 	for (int j = image_height-1; j >= 0; --j) {
 		std::cerr<<"\rScanlines remaining: "<<j<<" "<<std::flush;
 		for (int i = 0; i < image_width; ++i) {
-			auto u = double(i) / (image_width-1);
-			auto v = double(j) / (image_height-1);
-			ray r(origin, lower_left_corner + u*horizontal + v*vertical - origin);
-			color pixel_color = ray_color(r, world);
-			write_color(std::cout, pixel_color);
+			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);
+				ray r = cam.get_ray(u, v);
+				pixel_color += ray_color(r, world);
+			}
+			write_color(std::cout, pixel_color, samples_per_pixel);
 		}
 	}
 	std::cerr<<"\nDone.\n";

rtweekend.h

@@ -4,6 +4,7 @@
 #include <cmath>
 #include <limits>
 #include <memory>
+#include <cstdlib>
 
 // Usings
 using std::shared_ptr;
@@ -19,6 +20,22 @@ inline double degrees_to_radians(double degrees) {
 	return degrees * pi / 180.0;
 }
 
+// Returns a random number between (0,1]
+inline double random_double() {
+	return rand() / (RAND_MAX + 1.0);
+}
+
+inline double clamp(double x, double min, double max) {
+	if (x < min) return min;
+	if (x > max) return max;
+	return x;
+}
+
+// Returns a random number between (min,max]
+inline double random_double(double min, double max) {
+	return min + (max - min) * random_double();
+}
+
 // Common headers
 #include "ray.h"
 #include "vec3.h"