--- CMakeLists.txt.orig	2018-04-23 17:26:25 UTC
+++ CMakeLists.txt
@@ -6,6 +6,7 @@ set(CMAKE_CXX_STANDARD 14)
 
 
 option (REGOTH_BUILD_WITH_INSTALLER_EXTRACTOR "Compile with library to extract some installers of Gothic" OFF) 
+option (REGOTH_BUILD_WITH_SYSTEM_OPENAL "Compile with system OpenAL" OFF) 
 
 
 # Vim - You Complete Me
@@ -174,6 +175,9 @@ include_directories(lib/bullet3/src)
 set(BULLET_LIBRARIES BulletSoftBody BulletDynamics BulletCollision LinearMath)
 set(BULLET_MISC Bullet3Dynamics Bullet2FileLoader Bullet3Collision Bullet3Geometry Bullet3OpenCL_clew BulletFileLoader BulletWorldImporter BulletXmlWorldImporter ConvexDecomposition GIMPACTUtils HACD Test_BulletDynamics Test_BulletInverseDynamics Test_Collision)
 
+# Find OpenGL
+find_package(OpenGL REQUIRED)
+include_directories(${OPENGL_INCLUDE_DIR}) # required by glfw headers
 
 # ------------------ Engine lib ------------------
 file(GLOB ENGINE_SRC
@@ -223,54 +227,64 @@ endif()
 # ------------------ OpenAL ------------------
 
 # Set up OpenAL
+if(REGOTH_BUILD_WITH_SYSTEM_OPENAL AND NOT EMSCRIPTEN)
+    find_package(OpenAL REQUIRED)
+    include_directories(${OPENAL_INCLUDE_DIR})
 
-set(ALSOFT_CONFIG OFF CACHE BOOL "" FORCE)
-set(ALSOFT_EXAMPLES OFF CACHE BOOL "" FORCE)
-set(ALSOFT_INSTALL OFF CACHE BOOL "" FORCE)
-
-if (UNIX)
-    set(LIBTYPE STATIC CACHE STRING "" FORCE)
-    if (${CMAKE_SYSTEM_NAME} STREQUAL "Linux")
-        set(ALSOFT_REQUIRE_ALSA ON CACHE BOOL "" FORCE)
-        set(ALSOFT_BACKEND_OSS OFF CACHE BOOL "" FORCE)
-    elseif(${CMAKE_SYSTEM_NAME} STREQUAL "FreeBSD")
-        set(ALSOFT_REQUIRE_ALSA OFF CACHE BOOL "" FORCE)
-        set(ALSOFT_BACKEND_OSS ON CACHE BOOL "" FORCE)
-        set(ALSOFT_BACKEND_SNDIO OFF CACHE BOOL "" FORCE)
-        set(ALSOFT_BACKEND_SOLARIS OFF CACHE BOOL "" FORCE)
-    elseif(${CMAKE_SYSTEM_NAME} STREQUAL "OpenBSD")
-        set(ALSOFT_REQUIRE_ALSA OFF CACHE BOOL "" FORCE)
-        set(ALSOFT_BACKEND_OSS OFF CACHE BOOL "" FORCE)
-        set(ALSOFT_BACKEND_SNDIO ON CACHE BOOL "" FORCE)
-        set(ALSOFT_BACKEND_SOLARIS OFF CACHE BOOL "" FORCE)
+    if (UNIX)
+        target_link_libraries(engine ${OPENAL_LIBRARY})
+    elseif(WIN32)
+        target_link_libraries(engine common ${OPENAL_LIBRARY})
     endif()
 else()
-    set(LIBTYPE SHARED CACHE STRING "" FORCE)
-endif()
+    set(ALSOFT_CONFIG OFF CACHE BOOL "" FORCE)
+    set(ALSOFT_EXAMPLES OFF CACHE BOOL "" FORCE)
+    set(ALSOFT_INSTALL OFF CACHE BOOL "" FORCE)
 
-if(NOT EMSCRIPTEN)
-    add_subdirectory(${CMAKE_SOURCE_DIR}/lib/openal-soft)
-    include_directories(${CMAKE_SOURCE_DIR}/lib/openal-soft/include)
-
     if (UNIX)
+        set(LIBTYPE STATIC CACHE STRING "" FORCE)
         if (${CMAKE_SYSTEM_NAME} STREQUAL "Linux")
-          set(ALSOFT_REQUIRE_ALSA ON CACHE BOOL "" FORCE)
-          set(ALSOFT_BACKEND_OSS OFF CACHE BOOL "" FORCE)
+            set(ALSOFT_REQUIRE_ALSA ON CACHE BOOL "" FORCE)
+            set(ALSOFT_BACKEND_OSS OFF CACHE BOOL "" FORCE)
         elseif(${CMAKE_SYSTEM_NAME} STREQUAL "FreeBSD")
-          set(ALSOFT_REQUIRE_ALSA OFF CACHE BOOL "" FORCE)
-          set(ALSOFT_BACKEND_OSS ON CACHE BOOL "" FORCE)
-          set(ALSOFT_BACKEND_SNDIO OFF CACHE BOOL "" FORCE)
-          set(ALSOFT_BACKEND_SOLARIS OFF CACHE BOOL "" FORCE)
+            set(ALSOFT_REQUIRE_ALSA OFF CACHE BOOL "" FORCE)
+            set(ALSOFT_BACKEND_OSS ON CACHE BOOL "" FORCE)
+            set(ALSOFT_BACKEND_SNDIO OFF CACHE BOOL "" FORCE)
+            set(ALSOFT_BACKEND_SOLARIS OFF CACHE BOOL "" FORCE)
         elseif(${CMAKE_SYSTEM_NAME} STREQUAL "OpenBSD")
-          set(ALSOFT_REQUIRE_ALSA OFF CACHE BOOL "" FORCE)
-          set(ALSOFT_BACKEND_OSS OFF CACHE BOOL "" FORCE)
-          set(ALSOFT_BACKEND_SNDIO ON CACHE BOOL "" FORCE)
-          set(ALSOFT_BACKEND_SOLARIS OFF CACHE BOOL "" FORCE)
+            set(ALSOFT_REQUIRE_ALSA OFF CACHE BOOL "" FORCE)
+            set(ALSOFT_BACKEND_OSS OFF CACHE BOOL "" FORCE)
+            set(ALSOFT_BACKEND_SNDIO ON CACHE BOOL "" FORCE)
+            set(ALSOFT_BACKEND_SOLARIS OFF CACHE BOOL "" FORCE)
         endif()
-        target_link_libraries(engine OpenAL)
-    elseif(WIN32)
-        target_link_libraries(engine common OpenAL)
+    else()
+        set(LIBTYPE SHARED CACHE STRING "" FORCE)
     endif()
+
+    if(NOT EMSCRIPTEN)
+        add_subdirectory(${CMAKE_SOURCE_DIR}/lib/openal-soft)
+        include_directories(${CMAKE_SOURCE_DIR}/lib/openal-soft/include)
+
+        if (UNIX)
+            if (${CMAKE_SYSTEM_NAME} STREQUAL "Linux")
+              set(ALSOFT_REQUIRE_ALSA ON CACHE BOOL "" FORCE)
+              set(ALSOFT_BACKEND_OSS OFF CACHE BOOL "" FORCE)
+            elseif(${CMAKE_SYSTEM_NAME} STREQUAL "FreeBSD")
+              set(ALSOFT_REQUIRE_ALSA OFF CACHE BOOL "" FORCE)
+              set(ALSOFT_BACKEND_OSS ON CACHE BOOL "" FORCE)
+              set(ALSOFT_BACKEND_SNDIO OFF CACHE BOOL "" FORCE)
+              set(ALSOFT_BACKEND_SOLARIS OFF CACHE BOOL "" FORCE)
+            elseif(${CMAKE_SYSTEM_NAME} STREQUAL "OpenBSD")
+              set(ALSOFT_REQUIRE_ALSA OFF CACHE BOOL "" FORCE)
+              set(ALSOFT_BACKEND_OSS OFF CACHE BOOL "" FORCE)
+              set(ALSOFT_BACKEND_SNDIO ON CACHE BOOL "" FORCE)
+              set(ALSOFT_BACKEND_SOLARIS OFF CACHE BOOL "" FORCE)
+            endif()
+            target_link_libraries(engine OpenAL)
+        elseif(WIN32)
+            target_link_libraries(engine common OpenAL)
+        endif()
+    endif()
 endif()
 
 # ---------------- libdmusic ----------------
@@ -310,6 +324,10 @@ if(NOT ANDROID)
 else()
     add_definitions(-DRE_USE_SOUND)
     target_link_libraries(engine android_glue)
+endif()
+
+if(${CMAKE_SYSTEM_NAME} STREQUAL "FreeBSD")
+    include_directories("lib/bgfx-cmake/bx/include/compat/freebsd")
 endif()
 
 add_subdirectory(lib/adpcm)