1 files changed, 82 insertions, 0 deletions
diff --git a/src/3rdparty/resonance-audio/resonance_audio/dsp/distance_attenuation.h b/src/3rdparty/resonance-audio/resonance_audio/dsp/distance_attenuation.h
new file mode 100644
index 000000000..2b98ac63c
--- /dev/null
+++ b/src/3rdparty/resonance-audio/resonance_audio/dsp/distance_attenuation.h
@@ -0,0 +1,82 @@
+/*
+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.
+*/
+
+#ifndef RESONANCE_AUDIO_DSP_DISTANCE_ATTENUATION_H_
+#define RESONANCE_AUDIO_DSP_DISTANCE_ATTENUATION_H_
+
+#include "base/misc_math.h"
+#include "base/source_parameters.h"
+
+namespace vraudio {
+
+// Returns the distance attenuation for |source_position| with respect to
+// |listener_position|. The amplitude will decrease by approximately 6 dB every
+// time the distance is doubled, i.e., the sound pressure "p" (amplitude)
+// approximately falls inversely proportional to the distance "1/r".
+//
+// @param listener_position World position of the listener.
+// @param source_position World position of the source.
+// @param min_distance The minimum distance at which distance attenuation is
+//     applied.
+// @param max_distance The maximum distance at which the direct sound has a gain
+//     of 0.0.
+// @return Attenuation (gain) value in range [0.0f, 1.0f].
+float ComputeLogarithmicDistanceAttenuation(
+    const WorldPosition& listener_position,
+    const WorldPosition& source_position, float min_distance,
+    float max_distance);
+
+// Returns the distance attenuation for |source_position| with respect to
+// |listener_position|. The amplitude will decrease linearly between
+// |min_distance| and |max_distance| from 1.0 to 0.0.
+//
+// @param listener_position World position of the listener.
+// @param source_position World position of the source.
+// @param min_distance The minimum distance at which distance attenuation is
+//     applied.
+// @param max_distance The maximum distance at which the direct sound has a gain
+//     of 0.0.
+// @return Attenuation (gain) value in range [0.0f, 1.0f].
+float ComputeLinearDistanceAttenuation(const WorldPosition& listener_position,
+                                       const WorldPosition& source_position,
+                                       float min_distance, float max_distance);
+
+// Calculates the gain to be applied to the near field compensating stereo mix.
+// This function will return 0.0f for all sources further away than one meter
+// and will return a value between 0.0 and 9.0 for sources as they approach
+// the listener's head location.
+//
+// @param listener_position World position of the listener.
+// @param source_position World position of the source.
+// @return Gain value in range [0.0f, 9.0f].
+float ComputeNearFieldEffectGain(const WorldPosition& listener_position,
+                                 const WorldPosition& source_position);
+
+// Calculates and updates gain attenuations of the given source |parameters|.
+//
+// @param master_gain Global gain adjustment in amplitude.
+// @param reflections_gain Reflections gain in amplitude.
+// @param reverb_gain Reverb gain in amplitude.
+// @param listener_position World position of the listener.
+// @param parameters Source parameters to apply the gain attenuations into.
+void UpdateAttenuationParameters(float master_gain, float reflections_gain,
+                                 float reverb_gain,
+                                 const WorldPosition& listener_position,
+                                 SourceParameters* parameters);
+
+}  // namespace vraudio
+
+#endif  // RESONANCE_AUDIO_DSP_DISTANCE_ATTENUATION_H_