Add FOV API to OSG viewer

CHANGELOG.md

@@ -1,5 +1,11 @@
 ## DART 6
 
+### DART 6.5.0 (201X-XX-XX)
+
+* GUI
+
+  * Added FOV AI to OSG viewer: [#1048](https://github.com/dartsim/dart/pull/1048)
+
 ### [DART 6.4.0 (2018-03-26)](https://github.com/dartsim/dart/milestone/39?closed=1)
 
 * Common

dart/gui/osg/Viewer.cpp

@@ -843,6 +843,68 @@ const ::osg::ref_ptr<::osg::Group>& Viewer::getRootGroup() const
   return mRootGroup;
 }
 
+//==============================================================================
+void Viewer::setVerticalFieldOfView(const double fov)
+{
+  double fovy;
+  double aspectRatio;
+  double zNear;
+  double zFar;
+
+  auto* camera = getCamera();
+
+  if (!camera)
+  {
+    dtwarn << "[Viewer::setMasterCameraFieldOfView] This viewer doesn't have "
+           << "any cameras. Ignoring this request.\n";
+    return;
+  }
+
+  const bool result = camera->getProjectionMatrixAsPerspective(
+      fovy, aspectRatio, zNear, zFar);
+
+  if (!result)
+  {
+    dtwarn << "[Viewer::setMasterCameraFieldOfView] Attemping to set vertical "
+           << "field of view while the camera isn't perspective view. "
+           << "Ignoring this request.\n";
+    return;
+  }
+
+  camera->setProjectionMatrixAsPerspective(fov, aspectRatio, zNear, zFar);
+}
+
+//==============================================================================
+double Viewer::getVerticalFieldOfView() const
+{
+  double fovy;
+  double aspectRatio;
+  double zNear;
+  double zFar;
+
+  const auto* camera = getCamera();
+
+  if (!camera)
+  {
+    dtwarn << "[Viewer::getMasterCameraFieldOfView] This viewer doesn't have "
+           << "any cameras. Returning 0.0.\n";
+    return 0.0;
+  }
+
+  const bool result = camera->getProjectionMatrixAsPerspective(
+      fovy, aspectRatio, zNear, zFar);
+
+  if (!result)
+  {
+    dtwarn << "[Viewer::getMasterCameraFieldOfView] Vertical field of view is "
+           << "requested while the camera isn't perspective view. "
+           << "Returning 0.0.\n";
+    return 0.0;
+  }
+
+  return fovy;
+}
+
 } // namespace osg
 } // namespace gui
 } // namespace dart

dart/gui/osg/Viewer.hpp

@@ -293,6 +293,15 @@ class Viewer : public osgViewer::Viewer, public dart::common::Subject
   /// Get the root ::osg::Group of this Viewer
   const ::osg::ref_ptr<::osg::Group>& getRootGroup() const;
 
+  /// Sets the vertical field of view of the master camera of the view.
+  /// \param[in] fov Vertical field of view in degrees.
+  void setVerticalFieldOfView(double fov);
+
+  /// Returns the vertical field of view of the master camera of the view.
+  /// \return Vertical field of view in degrees if the camera is perspective
+  /// view, 0.0 otherwise.
+  double getVerticalFieldOfView() const;
+
 protected:
 
   friend class SaveScreen;