add option WITH_SYSTEM_BULLET to link against the bullet installation found on the system.

Note: this doesn't work yet for everything with latest stable bullet (2.81), need to look into why and likely apply some patches upstream.
However I managed to link blender by disabling some features, likely it can be made to work without too much trouble.

CMakeLists.txt

@@ -129,6 +129,8 @@ option(WITH_IK_ITASC      "Enable ITASC IK solver (only disable for development
 option(WITH_IK_SOLVER     "Enable Legacy IK solver (only disable for development)" ON)
 option(WITH_FFTW3         "Enable FFTW3 support (Used for smoke and audio effects)" ON)
 option(WITH_BULLET        "Enable Bullet (Physics Engine)" ON)
+option(WITH_SYSTEM_BULLET "Use the systems bullet library (currently unsupported due to missing features in upstream!)" )
+mark_as_advanced(WITH_SYSTEM_BULLET)
 option(WITH_GAMEENGINE    "Enable Game Engine" ON)
 option(WITH_PLAYER        "Build Player" OFF)
 option(WITH_OPENCOLORIO   "Enable OpenColorIO color management" ON)
@@ -1842,12 +1844,26 @@ else()
 	set(GLEW_INCLUDE_PATH "${CMAKE_SOURCE_DIR}/extern/glew/include")
 endif()
 
+
+#-----------------------------------------------------------------------------
+# Configure Bullet
+
+if(WITH_BULLET AND WITH_SYSTEM_BULLET)
+	find_package(Bullet)
+	if(NOT BULLET_FOUND)
+		set(WITH_BULLET OFF)
+	endif()
+else()
+	set(BULLET_INCLUDE_DIRS "${CMAKE_SOURCE_DIR}/extern/bullet2/src")
+	# set(BULLET_LIBRARIES "")
+endif()
+
 #-----------------------------------------------------------------------------
 # Configure Python.
 
 if(WITH_PYTHON_MODULE)
 	add_definitions(-DPy_ENABLE_SHARED)
-endif()
+endif().
 
 #-----------------------------------------------------------------------------
 # Extra compile flags

build_files/cmake/macros.cmake

@@ -282,7 +282,9 @@ macro(setup_liblinks
 	if(WITH_SYSTEM_GLEW)
 		target_link_libraries(${target} ${GLEW_LIBRARY})
 	endif()
-
+	if(WITH_BULLET AND WITH_SYSTEM_BULLET)
+		target_link_libraries(${target} ${BULLET_LIBRARIES})
+	endif()
 	if(WITH_OPENAL)
 		target_link_libraries(${target} ${OPENAL_LIBRARY})
 	endif()

extern/CMakeLists.txt

@@ -30,7 +30,9 @@ add_subdirectory(colamd)
 add_subdirectory(rangetree)
 
 if(WITH_BULLET)
-	add_subdirectory(bullet2)
+	if(NOT WITH_SYSTEM_BULLET)
+		add_subdirectory(bullet2)
+	endif()
 endif()
 
 # now only available in a branch

intern/smoke/CMakeLists.txt

@@ -29,7 +29,7 @@ set(INC
 )
 
 set(INC_SYS
-	../../extern/bullet2/src
+	${BULLET_INCLUDE_DIRS}
 	${PNG_INCLUDE_DIR}
 	${ZLIB_INCLUDE_DIRS}
 )

source/blender/blenkernel/CMakeLists.txt

@@ -259,7 +259,7 @@ endif()
 
 if(WITH_BULLET)
 	list(APPEND INC_SYS
-		../../../extern/bullet2/src
+		${BULLET_INCLUDE_DIRS}
 	)
 	add_definitions(-DUSE_BULLET)
 endif()

source/blender/bmesh/CMakeLists.txt

@@ -30,7 +30,6 @@ set(INC
 	../blenlib
 	../makesdna
 	../../../intern/guardedalloc
-	../../../extern/bullet2/src
 	../../../extern/rangetree
 	../../../intern/opennl/extern
 )
@@ -127,6 +126,9 @@ endif()
 
 if(WITH_BULLET)
 	add_definitions(-DWITH_BULLET)
+	list(APPEND INC_SYS
+		${BULLET_INCLUDE_DIRS}
+	)
 endif()
 
 if(WITH_INTERNATIONAL)

source/creator/CMakeLists.txt

@@ -893,7 +893,6 @@ endif()
 		ge_scenegraph
 		ge_logic_network
 		ge_logic_ngnetwork
-		extern_bullet
 		ge_logic_loopbacknetwork
 		bf_intern_moto
 		extern_openjpeg
@@ -972,6 +971,10 @@ endif()
 		list(APPEND BLENDER_SORTED_LIBS bf_intern_locale)
 	endif()
 
+	if(WITH_BULLET AND NOT WITH_BULLET_SYSTEM)
+		list_insert_after(BLENDER_SORTED_LIBS "ge_logic_ngnetwork" "extern_bullet")
+	endif()
+
 	foreach(SORTLIB ${BLENDER_SORTED_LIBS})
 		set(REMLIB ${SORTLIB})
 		foreach(SEARCHLIB ${BLENDER_LINK_LIBS})

source/gameengine/BlenderRoutines/CMakeLists.txt

@@ -30,7 +30,6 @@ set(INC
 )
 
 set(INC_SYS
-	../../../extern/bullet2/src
 	${PTHREADS_INCLUDE_DIRS}
 	${GLEW_INCLUDE_PATH}
 	${BOOST_INCLUDE_DIR}
@@ -70,4 +69,12 @@ if(WITH_CODEC_FFMPEG)
 	add_definitions(-DWITH_FFMPEG)
 endif()
 
+if(WITH_BULLET)
+	list(APPEND INC_SYS
+		${BULLET_INCLUDE_DIRS}
+	)
+	add_definitions(-DUSE_BULLET)
+endif()
+
+
 blender_add_lib(ge_blen_routines "${SRC}" "${INC}" "${INC_SYS}")

source/gameengine/Converter/CMakeLists.txt

@@ -112,7 +112,7 @@ set(SRC
 
 if(WITH_BULLET)
 	list(APPEND INC_SYS
-		../../../extern/bullet2/src
+		${BULLET_INCLUDE_DIRS}
 	)
 	add_definitions(-DUSE_BULLET)
 endif()

source/gameengine/Ketsji/CMakeLists.txt

@@ -252,7 +252,7 @@ if(WITH_BULLET)
 		../Physics/Bullet
 	)
 	list(APPEND INC
-		../../../extern/bullet2/src
+		${BULLET_INCLUDE_DIRS}
 	)
 	add_definitions(-DUSE_BULLET)
 endif()

source/gameengine/Physics/Bullet/CMakeLists.txt

@@ -44,7 +44,6 @@ set(INC
 )
 
 set(INC_SYS
-	../../../../extern/bullet2/src
 	${GLEW_INCLUDE_PATH}
 	${PYTHON_INCLUDE_DIRS}
 )
@@ -60,6 +59,9 @@ set(SRC
 )
 
 if(WITH_BULLET)
+	list(APPEND INC
+		${BULLET_INCLUDE_DIRS}
+	)
 	add_definitions(-DUSE_BULLET)
 endif()