#ifndef INTERSECTION_SLANG
#define INTERSECTION_SLANG

namespace rt {

struct hit_data {
	float t;
	float3 n;
};

Optional<hit_data> intersect_sphere(
		in const float3 r_o,
		in const float3 r_d,
		in const float3 s_o,
		in const float s_r) {
	let oc = r_o - s_o;
	let a = dot(r_d, r_d);
	let b = 2.0 * dot(oc, r_d);
	let c = dot(oc, oc) - s_r * s_r;
	let discriminant = b * b - 4.0 * a * c;

	if (discriminant < 0.0) {
		return none;
	}

	let sqrt_d = sqrt(discriminant);
	let t1 = (-b - sqrt_d) / (2.0 * a);
	let t2 = (-b + sqrt_d) / (2.0 * a);

	if (t1 > 0.0) {
		let p = r_o + r_d * t1;
		return hit_data(t1, normalize(p - s_o));
	}

	if (t2 > 0.0) {
		let p = r_o + r_d * t2;
		return hit_data(t2, normalize(p - s_o));
	} 

	return none;
}

}

#endif