| 1 | /* |
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| 2 | Copyright 2018 Google Inc. All Rights Reserved. |
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| 3 | |
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| 4 | Licensed under the Apache License, Version 2.0 (the "License"); |
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| 5 | you may not use this file except in compliance with the License. |
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| 6 | You may obtain a copy of the License at |
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| 7 | |
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| 8 | http://www.apache.org/licenses/LICENSE-2.0 |
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| 9 | |
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| 10 | Unless required by applicable law or agreed to in writing, software |
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| 11 | distributed under the License is distributed on an "AS-IS" BASIS, |
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| 12 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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| 13 | See the License for the specific language governing permissions and |
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| 14 | limitations under the License. |
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| 15 | */ |
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| 16 | |
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| 17 | #include "dsp/occlusion_calculator.h" |
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| 18 | |
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| 19 | #include <cmath> |
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| 20 | |
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| 21 | #include "base/logging.h" |
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| 22 | #include "base/misc_math.h" |
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| 23 | |
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| 24 | namespace vraudio { |
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| 25 | |
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| 26 | float CalculateDirectivity(float alpha, float order, |
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| 27 | const SphericalAngle& spherical_angle) { |
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| 28 | // Clamp alpha weighting. |
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| 29 | const float alpha_clamped = std::min(a: std::max(a: alpha, b: 0.0f), b: 1.0f); |
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| 30 | |
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| 31 | // Check for zero-valued alpha (omnidirectional). |
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| 32 | if (alpha_clamped < std::numeric_limits<float>::epsilon()) { |
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| 33 | return 1.0f; |
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| 34 | } else { |
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| 35 | const float gain = (1.0f - alpha_clamped) + |
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| 36 | alpha_clamped * (std::cos(x: spherical_angle.azimuth()) * |
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| 37 | std::cos(x: spherical_angle.elevation())); |
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| 38 | |
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| 39 | return std::pow(x: std::abs(x: gain), y: std::max(a: order, b: 1.0f)); |
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| 40 | } |
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| 41 | } |
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| 42 | |
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| 43 | float CalculateOcclusionFilterCoefficient(float directivity, |
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| 44 | float occlusion_intensity) { |
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| 45 | DCHECK_GE(occlusion_intensity, 0.0f); |
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| 46 | |
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| 47 | const float occlusion_factor = |
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| 48 | 1.0f / IntegerPow(base: occlusion_intensity + 1.0f, exp: 4); |
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| 49 | return std::max(a: 0.0f, b: 1.0f - directivity * occlusion_factor); |
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| 50 | } |
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| 51 | |
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| 52 | } // namespace vraudio |
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| 53 | |
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