Ghost: Ghost-XR API to abstract away and access OpenXR functionality

Extends Ghost to include an abstraction for OpenXR, which I refer to as
Ghost-XR. Such an API is the base for the following commit, which introduces VR
support to Blender.

Main features:
* Simple and high-level interface for Blender specific code to call.
* Extensible for muliple graphics backends, currently OpenGL and a DirectX
  compatibility layer are supported.
* Carefully designed error handling strategy allowing Blender to handle errors
  gracefully and with useful error messages.
* OpenXR extension and API-layer management.
* OpenXR session management.
* Basic OpenXR event management.
* Debug utilities for Ghost-XR and OpenXR

For more information on this API, check
https://wiki.blender.org/wiki/Source/Interface/XR.

Reviewed by: Brecht Van Lommel

Differential Revision: https://developer.blender.org/D6188

1 files changed, 44 insertions, 0 deletions

diff --git a/intern/ghost/CMakeLists.txt b/intern/ghost/CMakeLists.txt
index c4f1efe1580..07d98475c00 100644
--- a/intern/ghost/CMakeLists.txt
+++ b/intern/ghost/CMakeLists.txt
@@ -357,6 +357,50 @@ elseif(WIN32)
 
 endif()
 
+if(WITH_XR_OPENXR)
+  list(APPEND SRC
+    intern/GHOST_Xr.cpp
+    intern/GHOST_XrContext.cpp
+    intern/GHOST_XrEvent.cpp
+    intern/GHOST_XrGraphicsBinding.cpp
+    intern/GHOST_XrSession.cpp
+    intern/GHOST_XrSwapchain.cpp
+
+    GHOST_IXrContext.h
+    intern/GHOST_IXrGraphicsBinding.h
+    intern/GHOST_Xr_intern.h
+    intern/GHOST_Xr_openxr_includes.h
+    intern/GHOST_XrContext.h
+    intern/GHOST_XrSession.h
+    intern/GHOST_XrSwapchain.h
+  )
+  list(APPEND INC_SYS
+    ${XR_OPENXR_SDK_INCLUDE_DIR}
+  )
+
+  set(XR_PLATFORM_DEFINES -DXR_USE_GRAPHICS_API_OPENGL)
+
+  # Add compiler defines as required by the OpenXR specification.
+  if(WIN32)
+    list(APPEND XR_PLATFORM_DEFINES
+      -DXR_USE_PLATFORM_WIN32
+      -DXR_USE_GRAPHICS_API_D3D11
+    )
+    list(APPEND LIB
+      shlwapi
+    )
+  elseif(UNIX AND NOT APPLE)
+    list(APPEND XR_PLATFORM_DEFINES
+      -DXR_OS_LINUX
+      -DXR_USE_PLATFORM_XLIB
+    )
+  endif()
+
+  add_definitions(-DWITH_XR_OPENXR ${XR_PLATFORM_DEFINES})
+
+  unset(XR_PLATFORM_DEFINES)
+endif()
+
 add_definitions(${GL_DEFINITIONS})
 
 blender_add_lib(bf_intern_ghost "${SRC}" "${INC}" "${INC_SYS}" "${LIB}")