migration: add install_bgviewer.sh; make FindBgViewer search ./external/BgViewer and respect BGVIEWER_DIR

cmake/FindBgViewer.cmake

@@ -21,16 +21,29 @@
 
 
 
-INCLUDE(FindPackageHandleStandardArgs)
-INCLUDE(FindLibraryWithDebug)
-
-FIND_LIBRARY_WITH_DEBUG(BGVIEWER_DTENTITY_LIBRARY WIN32_DEBUG_POSTFIX d dtEntity)
-FIND_LIBRARY_WITH_DEBUG(BGVIEWER_DTENTITYOSG_LIBRARY WIN32_DEBUG_POSTFIX d dtEntityOSG)
-FIND_PATH(BGVIEWER_INCLUDE_DIR dtEntity/export.h)
-
-FIND_PACKAGE_HANDLE_STANDARD_ARGS(BgViewer DEFAULT_MSG
-                                  BGVIEWER_DTENTITY_LIBRARY
-                                  BGVIEWER_DTENTITYOSG_LIBRARY
-                                  BGVIEWER_INCLUDE_DIR)
-SET(BGVIEWER_LIBRARIES ${BGVIEWER_DTENTITYOSG_LIBRARY}
+INCLUDE(FindPackageHandleStandardArgs)
+INCLUDE(FindLibraryWithDebug)
+
+# Allow user to supply BGVIEWER_DIR or check ./external/BgViewer by default
+if(NOT DEFINED BGVIEWER_DIR)
+  if(DEFINED ENV{EXTERNAL_DIR})
+    set(_external_hint "$ENV{EXTERNAL_DIR}")
+  else()
+    set(_external_hint "${CMAKE_SOURCE_DIR}/external")
+  endif()
+  set(BGVIEWER_DIR "${_external_hint}/BgViewer" CACHE PATH "BgViewer root directory (optional)")
+endif()
+
+# Search in common system locations and in BGVIEWER_DIR
+set(_hints "${BGVIEWER_DIR}/lib" "${BGVIEWER_DIR}/lib/*" "${BGVIEWER_DIR}/lib/*/*")
+
+FIND_LIBRARY_WITH_DEBUG(BGVIEWER_DTENTITY_LIBRARY WIN32_DEBUG_POSTFIX d dtEntity HINTS ${_hints})
+FIND_LIBRARY_WITH_DEBUG(BGVIEWER_DTENTITYOSG_LIBRARY WIN32_DEBUG_POSTFIX d dtEntityOSG HINTS ${_hints})
+FIND_PATH(BGVIEWER_INCLUDE_DIR dtEntity/export.h HINTS "${BGVIEWER_DIR}/include" "${BGVIEWER_DIR}/include/dtEntity" ${_hints} )
+
+FIND_PACKAGE_HANDLE_STANDARD_ARGS(BgViewer DEFAULT_MSG
+                                  BGVIEWER_DTENTITY_LIBRARY
+                                  BGVIEWER_DTENTITYOSG_LIBRARY
+                                  BGVIEWER_INCLUDE_DIR)
+SET(BGVIEWER_LIBRARIES ${BGVIEWER_DTENTITYOSG_LIBRARY}
                        ${BGVIEWER_DTENTITY_LIBRARY})