add inital anti-aliasing

src/camera.h

@@ -4,6 +4,7 @@
 #include "common.h"
 #include "hittable.h"
 
+
 class Camera {
 public:
   double aspect_ratio = 1.0; // Ratio of image width over height

src/canvas.h

@@ -1,6 +1,7 @@
 #ifndef CANVAS_H
 #define CANVAS_H
 
+#include "interval.h"
 #include "vec3.h"
 
 #include <cstdint>
@@ -13,11 +14,10 @@ struct Rgb {
 };
 
 inline Rgb to_rgb(const Color &c) {
-  auto clamp = [](double x) { return x < 0.0 ? 0.0 : (x > 1.0 ? 1.0 : x); };
-
-  return {static_cast<uint8_t>(255.999 * clamp(c.x())),
-          static_cast<uint8_t>(255.999 * clamp(c.y())),
-          static_cast<uint8_t>(255.999 * clamp(c.z()))};
+  static const interval intensity(0.000, 0.999);
+  return {static_cast<uint8_t>(256 * intensity.clamp(c.x())),
+          static_cast<uint8_t>(256 * intensity.clamp(c.y())),
+          static_cast<uint8_t>(256 * intensity.clamp(c.z()))};
 }
 
 struct Canvas {
@@ -32,7 +32,7 @@ struct Canvas {
       pixels[y * width + x] = color;
     }
   }
-  
+
   void set_pixel(int x, int y, Color color) {
     if (x >= 0 && x < width && y >= 0 && y < height) {
       pixels[y * width + x] = to_rgb(color);

src/interval.h

@@ -1,6 +1,8 @@
 #ifndef INTERVAL_H
 #define INTERVAL_H
 
+#include "common.h"
+
 class interval {
 public:
   double min, max;
@@ -14,6 +16,14 @@ public:
   bool contains(double x) const { return min <= x && x <= max; }
 
   bool surrounds(double x) const { return min < x && x < max; }
+
+  double clamp(double x) const {
+    if (x < min)
+      return min;
+    if (x > max)
+      return max;
+    return x;
+  }
 };
 
 static inline const interval empty = interval(+infinity, -infinity);