Implementation of elbow model for the controller position and rotation.

chrome/browser/android/vr_shell/elbow_model.h

Index: chrome/browser/android/vr_shell/elbow_model.h
diff --git a/chrome/browser/android/vr_shell/elbow_model.h b/chrome/browser/android/vr_shell/elbow_model.h
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+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Adapted from:
+// https://github.com/googlevr/gvr-unity-sdk/blob/master/Samples/DaydreamLabsControllerPlayground/Assets/GoogleVR/Scripts/Controller/GvrArmModel.cs
+
+#ifndef CHROME_BROWSER_ANDROID_VR_SHELL_ELBOW_MODEL_H_
+#define CHROME_BROWSER_ANDROID_VR_SHELL_ELBOW_MODEL_H_
+
+#include "device/vr/vr_types.h"
+#include "third_party/gvr-android-sdk/src/libraries/headers/vr/gvr/capi/include/gvr_types.h"
+
+namespace vr_shell {
+
+class ElbowModel {
+ public:
+  struct UpdateData {
+    bool connected;
+    vr::Quatf orientation;
+    gfx::Vector3dF gyro;
+    gfx::Vector3dF head_direction;
+    float delta_time_seconds;
+  };
+
+  explicit ElbowModel(gvr::ControllerHandedness handedness);
+  ~ElbowModel();
+
+  const gfx::Point3F& GetControllerPosition() const { return wrist_position_; }
+  const vr::Quatf& GetControllerRotation() const { return wrist_rotation_; }
+  float GetAlphaValue() const { return alpha_value_; }
+
+  void Update(const UpdateData& update);
+
+ private:
+  void UpdateHandedness();
+  void UpdateTorsoDirection(const UpdateData& update);
+  void ApplyArmModel(const UpdateData& update);
+  void UpdateTransparency(const UpdateData& update);
+
+  gvr::ControllerHandedness handedness_;
+
+  gfx::Point3F wrist_position_;
+  vr::Quatf wrist_rotation_;
+  float alpha_value_;
+
+  gfx::Point3F elbow_position_;
+  vr::Quatf elbow_rotation_;
+  gfx::Point3F shoulder_position_;
+  vr::Quatf shoulder_rotation_;
+  gfx::Vector3dF torso_direction_;
+  gfx::Vector3dF handed_multiplier_;
+};
+
+}  // namespace vr_shell
+
+#endif  // CHROME_BROWSER_ANDROID_VR_SHELL_ELBOW_MODEL_H_