sphere.h

#ifndef sphere_h
#define sphere_h

#include "hittable.h"

class sphere : public hittable {
public:
    vec3 center;
    float radius;
    material* mat;
    __device__ sphere() {}
    __device__ sphere(const vec3& a, float b, material* m) {
        center = a;
        radius = b;
        mat = m;
    }
    __device__ bool hit(const ray& r, float min, float max, hit_record& rec) const {
        float a = r.direction.dot(r.direction);//a=dot(direction,direction)
        float b = r.direction.dot(r.origin - center);//2*dot(direction,orgin-center
        float c = (r.origin - center).dot(r.origin - center) - radius * radius; //dot(orgin-center,orgin-center)-radius2
        float discriminant = b * b - a * c;//b2-4ac
        if (discriminant > 0) {//Does not intersect
            float t = (-b - sqrt(discriminant)) / a;
            if (t > min&& t < max) {
                rec.t = t;
                rec.p = r.position(t);
                rec.n = (rec.p - center) / radius;
                rec.mat = mat;
                return true;
            }
            t = (-b + sqrt(discriminant)) / a;
            if (t > min&& t < max) {
                rec.t = t;
                rec.p = r.position(t);
                rec.n = (rec.p - center) / radius;
                rec.mat = mat;
                return true;
            }
        }
        return false;
    }
};


#endif