0029384: Visualization, TKOpenGl - basic integration with OpenVR

V3d_View::AutoZFit() is now called only before redraw
within methods V3d_View::Redraw() and V3d_View::Update().

Graphic3d_CView now holds Aspect_ExtendedRealitySession object.
Aspect_OpenVRSession implements new interface via optional OpenVR library.
Graphic3d_CView::ProcessInput() - added new interface method
which should be called for processing positional input (head tracking).

Graphic3d_Camera now allows setting custom stereoscopic Projection matrices.

OpenGl_Context::Camera() - context now holds Camera object
in addition to active camera matrices.

genproj.tcl has been extended to handle optional CSF_OpenVR dependency.

src/Aspect/Aspect_XRHapticActionData.hxx

@@ -0,0 +1,38 @@
+// Copyright (c) 2020 OPEN CASCADE SAS
+//
+// This file is part of Open CASCADE Technology software library.
+//
+// This library is free software; you can redistribute it and/or modify it under
+// the terms of the GNU Lesser General Public License version 2.1 as published
+// by the Free Software Foundation, with special exception defined in the file
+// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
+// distribution for complete text of the license and disclaimer of any warranty.
+//
+// Alternatively, this file may be used under the terms of Open CASCADE
+// commercial license or contractual agreement.
+
+#ifndef _Aspect_XRHapticActionData_HeaderFile
+#define _Aspect_XRHapticActionData_HeaderFile
+
+//! Haptic output XR action data.
+struct Aspect_XRHapticActionData
+{
+  float Delay;     //!< delay in seconds before start
+  float Duration;  //!< duration in seconds
+  float Frequency; //!< vibration frequency
+  float Amplitude; //!< vibration amplitude
+
+  //! Return TRUE if data is not empty.
+  bool IsValid() const
+  {
+    return Duration > 0.0f
+        && Amplitude > 0.0f
+        && Frequency > 0.0f
+        && Delay >= 0.0f;
+  }
+
+  //! Empty constructor.
+  Aspect_XRHapticActionData() : Delay (0.0f), Duration (0.0f), Frequency (0.0f), Amplitude (0.0f) {}
+};
+
+#endif // _Aspect_XRHapticActionData_HeaderFile