using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace RaytracerEngine
{
    public class sphere : hitable
    {
        vec3 center;
        float radius;
        public sphere() { }
        public sphere(vec3 cen, float r) { center = cen; radius = r; }

        public override bool hit(ray r, float t_min, float t_max, out hit_record rec)
        {
            vec3 oc = r.origin - center;
            float a = vec3.dot(r.direction, r.direction);
            float b = vec3.dot(oc, r.direction);
            float c = vec3.dot(oc, oc) - radius * radius;
            float discriminant = b * b - a * c;
            if (discriminant > 0)
            {
                float temp = (float)((-b - Math.Sqrt(discriminant)) / a);
                if (temp < t_max && temp > t_min)
                {
                    rec.t = temp;
                    rec.p = r.pap(rec.t);
                    rec.normal = (rec.p - center) / radius;
                    return true;
                }
                temp = (float)((-b + Math.Sqrt(discriminant)) / a);
                if (temp < t_max && temp > t_min)
                {
                    rec.t = temp;
                    rec.p = r.pap(rec.t);
                    rec.normal = (rec.p - center) / radius;
                    return true;
                }
            }

            rec = new hit_record();
            return false;
        }
    }
}