sphere.hpp

#ifndef SPHERE_H
#define SPHERE_H

#include "ray.hpp"
#include "hitable.h"

class sphere: public hitable
{
    public:
        sphere() {}
        sphere(glm::vec3 cen, float r): center(cen), radius(r) {};
        virtual bool hit(const ray& r, float t_min, float t_max, hit_record& rec) const;

        //Data
        glm::vec3 center;
        float radius;
};

bool sphere::hit(const ray& r, float t_min, float t_max, hit_record& rec) const
{
    glm::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)
    {
        //First root
        float temp = (-b - sqrt(b*b - a*c))/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;
        }
        //Other root
        temp = (-b - sqrt(b*b - a*c))/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