Initial commit

sphere.h

@@ -0,0 +1,51 @@
+#ifndef SPHERE_H
+#define SPHERE_H
+
+#include "hittable.h"
+#include "rayTracer.h"
+
+class sphere : public hittable {
+    private:
+        point3 centre;
+        double radius;
+        shared_ptr<material> mat;
+
+    public: 
+        sphere(const point3& centre, double radius, shared_ptr<material> mat)
+        : centre(centre), radius(fmax(0,radius)), mat(mat) {}
+
+        bool hit(const ray& r, interval rayT, hitRecord& rec) const override {
+            vec3 oc = centre - r.origin();
+            auto a = r.direction().lengthSquared();
+            auto h = dot(r.direction(), oc);
+            auto c = oc.lengthSquared() - radius * radius;
+
+            auto discriminant = h * h - a * c;
+            if (discriminant < 0) {
+                return false;
+            }
+
+            auto sqtd = sqrt(discriminant);
+
+            // Find the nearest root that lies in the acceptable range. 
+            auto root = (h - sqtd) / a;
+            if (!rayT.surrounds(root)) {
+                root = (h + sqtd) / a;
+
+                if (!rayT.surrounds(root)) {
+                    return false;
+                }
+            }
+
+            rec.t = root;
+            rec.p = r.at(rec.t);
+            vec3 outwardNormal = (rec.p - centre) / radius;
+            rec.setFaceNormal(r, outwardNormal);
+            rec.mat = mat;
+
+            return true;
+        }
+
+};
+
+#endif