Simple-Raytracer/sphere.cpp at master · dgovil/Simple-Raytracer · GitHub

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#include "stdafx.h"
#include "sphere.h"


bool sphere::hit(const ray& r, float t_min, float t_max, hit_record& rec) const
{
	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) return false;

	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;
	}

	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;
}