Chapter 6: Antialiasing

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