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/*
Copyright 2018 Google Inc. All Rights Reserved.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS-IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
#include "geometrical_acoustics/path_tracer.h"
#include <memory>
#include <random>
#include <unordered_set>
#include <vector>
#include "third_party/googletest/googletest/include/gtest/gtest.h"
#include "geometrical_acoustics/mesh.h"
#include "geometrical_acoustics/test_util.h"
namespace vraudio {
namespace {
using Eigen::Vector3f;
class PathTracerTest : public testing::Test {
public:
PathTracerTest() : random_engine_(), distribution_(0.0f, 1.0f) {
random_number_generator_ = [this] { return distribution_(random_engine_); };
}
void BuildEmptyScene() {
scene_manager_.reset(new SceneManager);
scene_manager_->BuildScene(std::vector<Vertex>(), std::vector<Triangle>());
all_triangle_indices_.clear();
}
void BuildGroundScene() {
scene_manager_.reset(new SceneManager);
std::vector<Vertex> ground_vertices{{0.0f, 0.0f, 0.0f},
{0.0f, 1.0f, 0.0f},
{1.0f, 0.0f, 0.0f},
{1.0f, 1.0f, 0.0f}};
std::vector<Triangle> ground_triangles{{0, 3, 1}, {0, 2, 3}};
scene_manager_->BuildScene(ground_vertices, ground_triangles);
all_triangle_indices_ = {0, 1};
}
void BuildBoxScene() {
scene_manager_.reset(new SceneManager);
std::vector<Vertex> box_vertices;
std::vector<Triangle> box_triangles;
BuildTestBoxScene({0.0f, 0.0f, 0.0f}, {1.0f, 1.0f, 1.0f}, &box_vertices,
&box_triangles, nullptr);
scene_manager_->BuildScene(box_vertices, box_triangles);
all_triangle_indices_.clear();
for (unsigned int i = 0; i < 12; ++i) {
all_triangle_indices_.insert(i);
}
}
protected:
const std::array<float, kNumReverbOctaveBands> kZeroAbsorptionCoefficients = {
{0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f}};
std::unique_ptr<SceneManager> scene_manager_;
std::unordered_set<unsigned int> all_triangle_indices_;
std::default_random_engine random_engine_;
std::uniform_real_distribution<float> distribution_;
std::function<float()> random_number_generator_;
};
TEST_F(PathTracerTest, AllPathsHaveLengthOneInEmptySceneTest) {
BuildEmptyScene();
PathTracer path_tracer(*scene_manager_);
AcousticSource source({0.0f, 0.0f, 0.0f}, kUnitEnergies,
random_number_generator_);
const size_t min_num_rays = 100;
const size_t max_depth = 10;
const float energy_thresold = 1e-6f;
std::vector<Path> paths =
path_tracer.TracePaths(source, min_num_rays, max_depth, energy_thresold);
EXPECT_LE(paths.size(), min_num_rays);
for (size_t i = 0; i < paths.size(); ++i) {
EXPECT_EQ(static_cast<int>(paths[i].rays.size()), 1);
}
}
TEST_F(PathTracerTest, GroundSceneTest) {
BuildGroundScene();
// Associate a perfect reflection to all triangles.
ReflectionKernel reflection_kernel(kZeroAbsorptionCoefficients, 0.0f,
random_number_generator_);
scene_manager_->AssociateReflectionKernelToTriangles(reflection_kernel,
all_triangle_indices_);
PathTracer path_tracer(*scene_manager_);
AcousticSource source({0.5f, 0.5f, 0.1f}, kUnitEnergies,
random_number_generator_);
const size_t min_num_rays = 100;
const size_t max_depth = 10;
const float energy_thresold = 1e-6f;
std::vector<Path> paths =
path_tracer.TracePaths(source, min_num_rays, max_depth, energy_thresold);
// All paths have at least one ray (for those that did not hit the ground)
// and at most two rays (for those hitting the ground).
for (size_t i = 0; i < paths.size(); ++i) {
EXPECT_GE(static_cast<int>(paths[i].rays.size()), 1);
EXPECT_LE(static_cast<int>(paths[i].rays.size()), 2);
// For those with length = 2, validate that the first ray ends on the
// ground plane.
if (paths[i].rays.size() == 2) {
const AcousticRay& first_ray = paths[i].rays.front();
const Vector3f& end_point =
Vector3f(first_ray.origin()) +
first_ray.t_far() * Vector3f(first_ray.direction());
EXPECT_NEAR(end_point.z(), 0.0f, 1e-7f);
}
}
}
TEST_F(PathTracerTest, TerminateAtMaxDepthTest) {
// A box scene within which rays never escape.
BuildBoxScene();
// Associate a perfect reflection to all triangles. Theoretically there should
// be infinite reflections, but the path tracer stops once each path reaches
// length |max_depth|.
ReflectionKernel reflection_kernel(kZeroAbsorptionCoefficients, 0.0f,
random_number_generator_);
scene_manager_->AssociateReflectionKernelToTriangles(reflection_kernel,
all_triangle_indices_);
PathTracer path_tracer(*scene_manager_);
AcousticSource source({0.5f, 0.5f, 0.5f}, kUnitEnergies,
random_number_generator_);
const size_t min_num_rays = 100;
const size_t max_depth = 10;
const float energy_thresold = 1e-6f;
std::vector<Path> paths =
path_tracer.TracePaths(source, min_num_rays, max_depth, energy_thresold);
for (size_t i = 0; i < paths.size(); ++i) {
EXPECT_EQ(paths[i].rays.size(), max_depth);
}
}
TEST_F(PathTracerTest, TerminateWhenEnergyBelowThresholdTest) {
// A box scene within which rays never escape.
BuildBoxScene();
// Associate an absorptive reflection with an absorption coefficient slightly
// over 90% to all triangles.
std::array<float, kNumReverbOctaveBands> absorption_coefficients;
absorption_coefficients.fill(0.9001f);
ReflectionKernel reflection_kernel(absorption_coefficients, 0.0f,
random_number_generator_);
scene_manager_->AssociateReflectionKernelToTriangles(reflection_kernel,
all_triangle_indices_);
PathTracer path_tracer(*scene_manager_);
// Since the reflected energy is slightly below 1e-1 after each reflection,
// we expect the path tracer to stop after X reflections for an
// energy threshold of 1e-X, and that each path is of length X.
AcousticSource source({0.5f, 0.5f, 0.5f}, kUnitEnergies,
random_number_generator_);
const size_t min_num_rays = 100;
const size_t max_depth = 10;
const float energy_thresold = 1e-6f;
std::vector<Path> paths =
path_tracer.TracePaths(source, min_num_rays, max_depth, energy_thresold);
for (size_t i = 0; i < paths.size(); ++i) {
EXPECT_EQ(static_cast<int>(paths[i].rays.size()), 6);
}
}
} // namespace
} // namespace vraudio
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