sphere.h

#ifndef SPHERE_H
#define SPHERE_H

#include "hittable.h"


class sphere: public hittable{
public:
	
	sphere(const point3& center, double radius, shared_ptr<material>mat)
		: center(center), radius(fmax(0, radius)), mat(mat){}
	// sphere(const point3& center, double radius): center(center), radius(fmax(0, radius)){}


	bool hit(const ray& r, interval ray_t, hit_record& rec) const override{
		vec3 oc = center - r.origin();
		auto a = r.direction().length_squared();
		auto h = dot(r.direction(), oc);
		auto c = oc.length_squared() - radius*radius;

		auto discriminant = h*h - a*c;
		if(discriminant<0)
			return false;

		auto sqrtd = sqrt(discriminant);

		auto root = (h-sqrtd)/a;
		if(!ray_t.surrounds(root)){
			root = (h+sqrtd)/a;
			if(!ray_t.surrounds(root)){
				return false;
			}
		}

		rec.t = root;
		rec.p = r.at(rec.t);
		vec3 outward_normal = (rec.p-center)/radius;
		rec.set_face_normal(r, outward_normal);
		rec.mat = mat;


		return true;

	}

private:
	point3 center;
	double radius;
	shared_ptr<material>mat;
};

#endif