Sphere intersection optimized

RayTracer/shape/Sphere.cpp

@@ -19,21 +19,17 @@ std::optional<cam::Hit> Sphere::intersect(const cam::Ray& r) const {
 	float discrim = b * b - 4 * a * c;
 
 	if (discrim >= 0) {
-		float t1 = (-b - sqrt(b * b - 4 * a * c)) / (2 * a);
+		float t1 = (-b - sqrt(discrim)) / (2 * a);
 
 		if (r.in_range(t1)) {
 			util::Vec3 t1HitPoint = r(t1);
-			float theta = acos(t1HitPoint.y() / radius);
-			float phi = M_PI + atan2(t1HitPoint.x(), t1HitPoint.z());
 			return std::optional<cam::Hit>({t1HitPoint, t1HitPoint,
 			                                texture_coordinates(t1HitPoint), t1,
 			                                material});
 		} else {
-			float t2 = (-b + sqrt(b * b - 4 * a * c)) / (2 * a);
+			float t2 = (-b + sqrt(discrim)) / (2 * a);
 			if (r.in_range(t2)) {
 				util::Vec3 t2HitPoint = r(t2);
-				float theta = acos(t2HitPoint.y() / radius);
-				float phi = M_PI + atan2(t2HitPoint.x(), t2HitPoint.z());
 				return std::optional<cam::Hit>({t2HitPoint, t2HitPoint,
 				                                texture_coordinates(t2HitPoint),
 				                                t2, material});
@@ -74,10 +70,12 @@ util::Vec3 Sphere::calculateLightEmission(const util::SurfacePoint& p,
 	// the light in regard to the angle.
 	// Uniform pdf of shape is 1/area, converting to pdf over solid angle is
 	// pdf/(dot/length^2).
+	// This is wrong. We just need the normal pdf, per area, as we do not sample
+	// with regard to a direction.
 	auto emission = p.emission();
 	auto dot = std::max<float>(util::dot(p.normal(), d.normalize()), 0);
 	auto area = 4 * M_PI * std::pow(radius, 2);
-	auto pdf = std::pow(d.length(), 2) / (dot * area);
+	auto pdf = 1 / area;
 	return emission / pdf;
 }
 }  // namespace shapes