Sphere.h

#ifndef Sphere_h
#define Sphere_h

#include "GLObject.h"


class Sphere : public Object {

    public:

        Vec3f center;
        float radius;
        float radius2;

        Sphere(Vec3f c, 
            float r, 
            Vec3f surfaceColor,
            Vec3f emissionColor = BLACK,
            Material material = Material(0.3, 1.0, 0.9, 50),
            float transparency = 0)
            : center(c), radius(r), radius2(r* r), Object(surfaceColor, emissionColor, material, transparency) {}

        bool intersect(Ray& ray, float& t1, float& t2) const {
            // https://www.scratchapixel.com/lessons/3d-basic-rendering/minimal-ray-tracer-rendering-simple-shapes/ray-sphere-intersection
            // Solução geométrica
           
            Vec3f distance = center - ray.origin;
            float distanceProjection = distance.dot(ray.direction);

            if (distanceProjection < 0) return false; // não se cruzam

            float distanceLength2 = distance.length2();
            float rdistance2 = distanceLength2 - distanceProjection * distanceProjection;

            if (rdistance2 > radius2) return false; // não se cruzam

            float interception = sqrt(radius2 - rdistance2); // Metade da interceptação
            t1 = distanceProjection - interception;
            t2 = distanceProjection + interception;
            return true;
        }

        // Normalizar
        Vec3f nhit(Vec3f& phit) const {
            return (phit - center).normalize();
        }

};


#endif