1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
|
/*
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/reflection_kernel.h"
#include "base/logging.h"
#include "geometrical_acoustics/sampling.h"
namespace vraudio {
using Eigen::Vector3f;
AcousticRay ReflectionKernel::Reflect(const AcousticRay& incident_ray) const {
// This function currently uses |random_number_generator| (which returns
// uniformly distributed numbers) to naively sample 1D and 2D points.
AcousticRay::RayType reflected_ray_type =
(random_number_generator_() >= scattering_coefficient_)
? AcousticRay::RayType::kSpecular
: AcousticRay::RayType::kDiffuse;
// Compute the reflected direction.
Vector3f reflected_direction;
const Vector3f& unit_normal =
Vector3f(incident_ray.intersected_geometry_normal()).normalized();
const Vector3f& incident_direction = Vector3f(incident_ray.direction());
switch (reflected_ray_type) {
case AcousticRay::RayType::kSpecular:
reflected_direction =
incident_direction -
2.0f * incident_direction.dot(unit_normal) * unit_normal;
break;
case AcousticRay::RayType::kDiffuse:
// A Lambertian reflection.
reflected_direction = CosineSampleHemisphere(
random_number_generator_(), random_number_generator_(), unit_normal);
break;
}
const Vector3f reflected_origin = Vector3f(incident_ray.origin()) +
incident_ray.t_far() * incident_direction;
const float reflected_ray_prior_distance =
incident_ray.prior_distance() +
incident_ray.t_far() * incident_direction.norm();
// New energies for each frequency band.
CHECK_EQ(reflection_coefficients_.size(), incident_ray.energies().size());
std::array<float, kNumReverbOctaveBands> new_energies =
incident_ray.energies();
for (size_t i = 0; i < new_energies.size(); ++i) {
new_energies[i] *= reflection_coefficients_[i];
}
return AcousticRay(reflected_origin.data(), reflected_direction.data(),
AcousticRay::kRayEpsilon, AcousticRay::kInfinity,
new_energies, reflected_ray_type,
reflected_ray_prior_distance);
}
void ReflectionKernel::ReflectDiffuseRain(
const AcousticRay& incident_ray, const AcousticRay& reference_reflected_ray,
const Eigen::Vector3f& listener_position, float* direction_pdf,
AcousticRay* diffuse_rain_ray) const {
const Vector3f reflection_point_to_listener =
listener_position - Vector3f(reference_reflected_ray.origin());
const Vector3f reflection_point_to_listener_direction =
reflection_point_to_listener.normalized();
const float diffuse_rain_ray_t_far =
reflection_point_to_listener.norm() + reference_reflected_ray.t_near();
*direction_pdf = CosineSampleHemispherePdf(
Vector3f(incident_ray.intersected_geometry_normal()).normalized(),
reflection_point_to_listener_direction);
diffuse_rain_ray->set_origin(reference_reflected_ray.origin());
diffuse_rain_ray->set_direction(
reflection_point_to_listener_direction.data());
diffuse_rain_ray->set_t_near(reference_reflected_ray.t_near());
diffuse_rain_ray->set_t_far(diffuse_rain_ray_t_far);
diffuse_rain_ray->set_energies(reference_reflected_ray.energies());
diffuse_rain_ray->set_type(reference_reflected_ray.type());
diffuse_rain_ray->set_prior_distance(
reference_reflected_ray.prior_distance());
}
} // namespace vraudio
|
