Chapter 6: Antialiasing

code/camera.h

@@ -0,0 +1,27 @@
+#ifndef CAMERA_H
+#define CAMERA_H
+
+#include "ray.h"
+
+class camera
+{
+public:
+    camera()
+    {
+        lower_left_corner = vec3(-2.0, -1.0, -1.0);
+        horizontal = vec3(4.0, 0.0, 0.0);
+        vertical = vec3(0.0, 2.0, 0.0);
+        origin = vec3(0.0, 0.0, 0.0);
+    }
+    ray get_ray(float u, float v)
+    {
+        return ray(origin, lower_left_corner + u * horizontal + v * vertical - origin);
+    }
+
+    vec3 origin;
+    vec3 lower_left_corner;
+    vec3 horizontal;
+    vec3 vertical;
+};
+
+#endif

code/rt_weekend.cpp

@@ -1,48 +1,53 @@
+#include <float.h>
 #include "rt_weekend.h"
-#include "ray.h"
+#include "sphere.h"
+#include "target_list.h"
+#include "camera.h"
 
-bool hit_sphere(const vec3 &center, float radius, const ray &r)
+vec3 color(const ray &r, target *world)
 {
-    vec3 oc = r.origin() - center;
-    float a = dot(r.direction(), r.direction());
-    float b = 2.0 * dot(oc, r.direction());
-    float c = dot(oc, oc) - radius * radius;
-    float discriminant = b * b - 4 * a * c;
-
-    return (discriminant > 0);
+    hit_record rec;
+    if (world->hit(r, 0.0, MAXFLOAT, rec))
+    {
+        return 0.5 * vec3(rec.normal.x() + 1, rec.normal.y() + 1, rec.normal.z() + 1);
     }
-
-vec3 color (const ray &r)
+    else
     {
-    if (hit_sphere(vec3(0, 0, -1), 0.5, r))
-        return vec3(1, 0, 0);
         vec3 unit_direction = unit_vector(r.direction());
         float t = 0.5 * (unit_direction.y() + 1.0);
         return (1.0 - t) * vec3(1.0, 1.0, 1.0) + t * vec3(0.5, 0.7, 1.0);
     }
+}
 
 extern "C"
 void
 PluginUpdateAndRender(plugin_offscreen_buffer *Buffer)
 {
+    int ns = 1;
     int Pitch = Buffer->Pitch;
     uint8_t *Row = (uint8_t *)Buffer->Memory;
 
-    vec3 lower_left_corner(-2.0, -1.0, -1.0);
-    vec3 horizontal(4.0, 0.0, 0.0);
-    vec3 vertical(0.0, 2.0, 0.0);
-    vec3 origin(0.0, 0.0, 0.0);
-
+    target *list[2];
+    list[0] = new sphere(vec3(0, 0, -1), 0.5);
+    list[1] = new sphere(vec3(0, -100.5, -1), 100);
+    target *world = new target_list(list, 2);
+    camera cam;
 
     for(int j = Buffer->Height - 1; j >= 0; j--)
     {
         uint32_t *Pixel = (uint32_t *)Row;
         for(int i = 0; i < Buffer->Width; i++)
         {
-            float u = float(i) / float(Buffer->Width);
-            float v = float(j) / float(Buffer->Height);
-            ray r(origin, lower_left_corner + u * horizontal + v * vertical);
-            vec3 col = color(r);
+            vec3 col(0, 0, 0);
+            for (int s = 0; s < ns; s++)
+            {
+                float u = float(i + drand48()) / float(Buffer->Width);
+                float v = float(j + drand48()) / float(Buffer->Height);
+                ray r = cam.get_ray(u, v);
+                vec3 p = r.point_at_parameter(2.0);
+                col += color(r, world);
+            }
+            col /= float(ns);
             int ir = int(255.99 * col[0]);
             int ig = int(255.99 * col[1]);
             int ib = int(255.99 * col[2]);

code/sdl_platform.cpp

@@ -12,7 +12,7 @@
 
 const char *WindowTitle = "Ray Tracing in a Weekend";
 
-const uint32_t TARGET_FRAME_RATE = 15;
+const uint32_t TARGET_FRAME_RATE = 10;
 const uint32_t TICKS_PER_FRAME = 1000 / TARGET_FRAME_RATE;
 const uint32_t WINDOW_WIDTH = 500;
 const uint32_t WINDOW_HEIGHT = 250;

code/sphere.h

@@ -0,0 +1,46 @@
+#ifndef SPHERE_H
+#define SPHERE_H
+
+#include "target.h"
+
+class sphere: public target
+{
+public:
+    sphere() {};
+    sphere(vec3 cen, float r) : center(cen), radius(r) {};
+    virtual bool hit(const ray &r, float t_min, float t_max, hit_record &rec) const;
+    vec3 center;
+    float radius;
+};
+
+bool sphere::hit(const ray &r, float t_min, float t_max, hit_record &rec) const
+{
+    vec3 oc = r.origin() - center;
+    float a = dot(r.direction(), r.direction());
+    float b = dot(oc, r.direction());
+    float c = dot(oc, oc) - radius * radius;
+    float discriminant = b * b - a * c;
+
+    if (discriminant > 0)
+    {
+        float temp = (-b - sqrt(discriminant)) / a;
+        if (temp < t_max && temp > t_min)
+        {
+            rec.t = temp;
+            rec.p = r.point_at_parameter(rec.t);
+            rec.normal = (rec.p - center) / radius;
+            return true;
+        }
+        temp = (-b + sqrt(discriminant)) / a;
+        if (temp < t_max && temp > t_min)
+        {
+            rec.t = temp;
+            rec.p = r.point_at_parameter(rec.t);
+            rec.normal = (rec.p - center) / radius;
+            return true;
+        }
+    }
+    return false;
+}
+
+#endif

code/target.h

@@ -0,0 +1,19 @@
+#ifndef TARGET_H
+#define TARGET_H
+
+#include "ray.h"
+
+struct hit_record
+{
+    float t;
+    vec3 p;
+    vec3 normal;
+};
+
+class target
+{
+public:
+    virtual bool hit(const ray &r, float t_min, float t_max, hit_record &rec) const = 0;
+};
+
+#endif

code/target_list.h

@@ -0,0 +1,33 @@
+#ifndef TARGETLIST_H
+#define TARGETLIST_H
+
+#include "target.h"
+
+class target_list: public target
+{
+public:
+    target_list() {}
+    target_list(target **l, int n) { list = l; list_size = n; }
+    virtual bool hit(const ray &r, float t_min, float t_max, hit_record &rec) const;
+    target **list;
+    int list_size;
+};
+
+bool target_list::hit(const ray &r, float t_min, float t_max, hit_record &rec) const
+{
+    hit_record temp_rec;
+    bool hit_anything = false;
+    double closest_so_far = t_max;
+    for (int i = 0; i < list_size; i++)
+    {
+        if (list[i]->hit(r, t_min, closest_so_far, temp_rec))
+        {
+            hit_anything = true;
+            closest_so_far = temp_rec.t;
+            rec = temp_rec;
+        }
+    }
+    return hit_anything;
+}
+
+#endif

code/vec3.h

@@ -32,10 +32,12 @@ public:
     {
         return sqrt(e[0] * e[0] + e[1] * e[1] + e[2] * e[2]);
     }
+
     inline float squared_length() const
     {
         return e[0] * e[0] + e[1] * e[1] + e[2] * e[2];
     }
+
     inline void make_unit_vector();
 
     float e[3];