1 files changed, 96 insertions, 0 deletions
diff --git a/src/3rdparty/resonance-audio/resonance_audio/geometrical_acoustics/path_tracer.cc b/src/3rdparty/resonance-audio/resonance_audio/geometrical_acoustics/path_tracer.cc
new file mode 100644
index 000000000..6f4c6652a
--- /dev/null
+++ b/src/3rdparty/resonance-audio/resonance_audio/geometrical_acoustics/path_tracer.cc
@@ -0,0 +1,96 @@
+/*
+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 <cmath>
+
+#include "base/logging.h"
+#include "geometrical_acoustics/parallel_for.h"
+#include "geometrical_acoustics/reflection_kernel.h"
+
+namespace vraudio {
+
+std::vector<Path> PathTracer::TracePaths(const AcousticSource& source,
+                                         size_t min_num_rays, size_t max_depth,
+                                         float energy_threshold) {
+  // The tracing would not work if the scene is not committed.
+  CHECK(scene_manager_.is_scene_committed());
+
+  // Find the actual number of rays to trace as the next square number greater
+  // or equal to |min_num_rays|.
+  const size_t sqrt_num_rays = static_cast<size_t>(
+      std::ceil(std::sqrt(static_cast<float>(min_num_rays))));
+  const size_t num_rays = sqrt_num_rays * sqrt_num_rays;
+
+  // In the current implementation, one ray does not spawn more than one child
+  // ray, hence the number of paths is the same as the number of rays from the
+  // source.
+  std::vector<Path> paths(num_rays);
+  std::vector<AcousticRay> rays_from_source =
+      source.GenerateStratifiedRays(num_rays, sqrt_num_rays);
+  const unsigned int num_threads = GetNumberOfHardwareThreads();
+  ParallelFor(
+      num_threads, num_rays,
+      [&rays_from_source, &paths, this, max_depth,
+       energy_threshold](size_t ray_index) {
+        if (max_depth == 0) return;
+        Path& path = paths.at(ray_index);
+
+        // Pre-allocate memory space for better performance.
+        path.rays.reserve(max_depth);
+
+        path.rays.push_back(rays_from_source[ray_index]);
+        size_t depth = 0;
+        while (true) {
+          AcousticRay& current_ray = path.rays.back();
+
+          // Stop generating new rays if the current ray escapes.
+          if (!current_ray.Intersect(scene_manager_.scene())) {
+            break;
+          }
+
+          // Stop generating new rays if |depth| reaches |max_depth|.
+          ++depth;
+          if (depth >= max_depth) {
+            break;
+          }
+
+          // Handle interactions with scene geometries.
+          const ReflectionKernel& reflection =
+              scene_manager_.GetAssociatedReflectionKernel(
+                  current_ray.intersected_primitive_id());
+          AcousticRay new_ray = reflection.Reflect(current_ray);
+
+          // Stop tracing if all energies in all frequency bands of the new ray
+          // are too low in energy.
+          bool is_energy_high_enough = false;
+          for (const float energy : new_ray.energies()) {
+            if (energy >= energy_threshold) {
+              is_energy_high_enough = true;
+              break;
+            }
+          }
+          if (!is_energy_high_enough) {
+            break;
+          }
+          path.rays.push_back(new_ray);
+        }
+      });
+  return paths;
+}
+
+}  // namespace vraudio