Color PathTracer::Radiance_internal(const Scene &scene, const Ray &ray, Random &rnd, const int depth, const bool intersected, Scene::IntersectionInformation &intersect, const Vector3 &normal) {
if (!intersected) {
if (scene.GetIBL()) {
//return scene.GetIBL()->Sample(ray); // 正確に背景との衝突位置を計算する
return scene.GetIBL()->Sample(ray.dir); // レイが原点から始まっているとみなして計算する
} else {
return scene.Background();
}
}
Color &textured = intersect.texturedHitpointColor = GetTexturedColor(intersect.object->material, intersect.hit.uv);
Color income;
// この if 文を有効にすると、直接光のみ考慮するようになる
//if (depth >= 1) {
// return intersect.object->material.emission;
//}
double russian_roulette_probability = std::max(textured.x, std::max(textured.y, textured.z)); // 適当
if (depth > MaxDepth) {
russian_roulette_probability *= pow(0.5, depth - MaxDepth);
}
if (depth > MinDepth) {
if (rnd.nextDouble() >= russian_roulette_probability) {
// 各 radiance を計算するときに直接光を計算しているので、
// 「eye から直接 light に hit した場合」のみ、emission を income に加える
if (depth == 0 || !m_performNextEventEstimation) {
if (intersect.object->material.emission.lengthSq() != 0) {
m_hitToLightCount++;
}
return intersect.object->material.emission;
}
return scene.Background();
}
} else {
russian_roulette_probability = 1.0; // no roulette
}
switch (intersect.object->material.reflection_type) {
case Material::REFLECTION_TYPE_LAMBERT:
income = Radiance_Lambert(scene, ray, rnd, depth, intersect, normal, russian_roulette_probability);
break;
case Material::REFLECTION_TYPE_SPECULAR:
income = Radiance_Specular(scene, ray, rnd, depth, intersect, normal, russian_roulette_probability);
break;
case Material::REFLECTION_TYPE_REFRACTION:
income = Radiance_Refraction(scene, ray, rnd, depth, intersect, normal, russian_roulette_probability);
break;
}
// 各 radiance を計算するときに直接光を計算しているので、
// 「eye から直接 light に hit した場合」のみ、emission を income に加える
if (depth == 0 || !m_performNextEventEstimation) {
// --> eye から直接 light に hit し、 light 自身が反射率を持つ場合にここが有効になる
income += intersect.object->material.emission;
if (intersect.object->material.emission.lengthSq() != 0) {
m_hitToLightCount++;
}
}
return income;
}
// 直接光による Radiance の評価
Color PathTracer::DirectRadiance_Lambert(const Scene &scene, const Ray &ray, Random &rnd, const int depth, const bool intersected, Scene::IntersectionInformation &intersect, const Vector3 &normal) {
assert(intersected);
// ライトに当たっていたら無視
if (dynamic_cast<LightBase *>(intersect.object) != nullptr)
{
return Color(0, 0, 0);
}
const vector<LightBase *> &lights = scene.GetLights();
if (lights.size() == 0) return scene.Background();
// pick a random light according to light power
double totalPower = 0.0;
vector<double> eachLightProbability, accumulatedProbability;
for (size_t i = 0; i < lights.size(); i++) {
double power = lights[i]->TotalPower();
eachLightProbability.push_back(power);
accumulatedProbability.push_back(totalPower + power);
totalPower += power;
}
// 確率へ正規化
for (size_t i = 0; i < lights.size(); i++) {
eachLightProbability[i] /= totalPower;
accumulatedProbability[i] /= totalPower;
}
static const int NumberOfLightSamples = 1;
Color income;
for (int lightCount = 0; lightCount < NumberOfLightSamples; lightCount++) {
double next = rnd.nextDouble();
int index = 0;
for (size_t i = 0; i < lights.size(); i++) {
if (next <= accumulatedProbability[i]) {
index = i; break;
}
}
const LightBase *selectedLight = lights[index];
// pick a one point
Vector3 point, light_normal; double pdf = 0.0;
//selectedLight->SampleOnePoint(point, light_normal, pdf, rnd);
if (!selectedLight->SampleOnePointWithTargetPoint(point, light_normal, pdf, intersect.hit.position, rnd)) {
continue;
}
Vector3 dir((point - intersect.hit.position)); dir.normalize();
double cos_shita = dir.dot(normal);
double light_cos_shita = -dir.dot(light_normal);
if (cos_shita < 0 || light_cos_shita < 0) {
// cannot reach to the light
continue;
}
// check visibility
Scene::IntersectionInformation hit;
if (scene.CheckIntersection(Ray(intersect.hit.position, dir), hit)) {
if (dynamic_cast<LightBase *>(hit.object) == selectedLight) {
// visible
// BRDF = color/PI
double G = cos_shita * light_cos_shita / (hit.hit.distance * hit.hit.distance);
Vector3 reflect_rate(intersect.texturedHitpointColor / PI * G / (pdf * eachLightProbability[index]));
income.x += reflect_rate.x * hit.object->material.emission.x;
income.y += reflect_rate.y * hit.object->material.emission.y;
income.z += reflect_rate.z * hit.object->material.emission.z;
// direct_illum = 1/N*ΣL_e*BRDF*G*V/pdf(light)
m_hitToLightCount++;
}
}
m_omittedRayCount++;
}
return income / NumberOfLightSamples;
}