#include "object.h"

namespace Donut
{
    Ray::Ray(glm::vec3 o, glm::vec3 d) 
        : m_origin(o), 
          m_direction(glm::normalize(d)) { }

    Material::Material(glm::vec3 c, float s, float e)
        : m_color(c), 
          m_specular(s), 
          m_emission(e) { }

    Object::Object(glm::vec3 c, float r, Material m) 
        : m_centre(c), 
          m_radius(r), 
          m_material(m) { }

    bool Object::intersect(Ray &ray, float &t)
    {
        glm::vec3 oc = ray.m_origin - m_centre;
        float a = glm::dot(ray.m_direction, ray.m_direction); 
        float b = 2.0f * glm::dot(oc, ray.m_direction);
        float c = glm::dot(oc, oc) - m_radius * m_radius;
        double discriminant = b*b - 4*a*c;

        if(discriminant < 0)
            return false;

        float intercept = (-b - sqrt(discriminant)) / (2.0f*a);
        if(intercept < 0)
        {
            intercept = (-b + sqrt(discriminant)) / (2.0f*a);
            if(intercept<0)
                return false;
        }

        t = intercept;
        return true;
    }

    glm::vec3 Object::get_normal(glm::vec3 &point) const
    {
        return glm::normalize(point - m_centre);
    }
}