easy way to switch from bundled libs to system

CMakeLists.txt

@@ -36,13 +36,36 @@ set(STK_INSTALL_BINARY_DIR "bin" CACHE
 set(STK_INSTALL_DATA_DIR "share/supertuxkart" CACHE
     STRING "Install data folder to this directory, absolute or relative to CMAKE_INSTALL_PREFIX")
 
+INCLUDE (FindPkgConfig)
+
 # Build the Bullet physics library
-add_subdirectory("${PROJECT_SOURCE_DIR}/lib/bullet")
-include_directories("${PROJECT_SOURCE_DIR}/lib/bullet/src")
+pkg_search_module(BULLET bullet)
+if(NOT BULLET_FOUND)
+    message("Using bundled bullet libs")
+    add_subdirectory("${PROJECT_SOURCE_DIR}/lib/bullet")
+    include_directories("${PROJECT_SOURCE_DIR}/lib/bullet/src")
+    set(BULLET_LIBRARIES "bulletdynamics;bulletcollision;bulletmath")
+else(NOT BULLET_FOUND)
+    message("Using system bullet libs")
+    include_directories(${BULLET_INCLUDE_DIRS})
+    if(BULLET_VERSION GREATER 2.80)
+        message("We must apply patch for new bullet")
+        execute_process(COMMAND patch -p1 -d ${PROJECT_SOURCE_DIR} -i
+                                      ${PROJECT_SOURCE_DIR}/patches/0001-btKartRaycast.cpp-fix-usage-with-new-bullet.patch)
+    endif(BULLET_VERSION GREATER 2.80)
+endif(NOT BULLET_FOUND)
 
 # Build the ENet UDP network library
-add_subdirectory("${PROJECT_SOURCE_DIR}/lib/enet")
-include_directories("${PROJECT_SOURCE_DIR}/lib/enet/include")
+find_package(ENet)
+if(NOT ENET_FOUND)
+    message("Using bundled enet libs")
+    add_subdirectory("${PROJECT_SOURCE_DIR}/lib/enet")
+    include_directories("${PROJECT_SOURCE_DIR}/lib/enet/include")
+    set(ENet_LIBRARIES "enet")
+else(NOT ENET_FOUND)
+    message("Using system enet libs")
+    include_directories(${ENet_INCLUDE_DIRS})
+endif(NOT ENET_FOUND)
 
 # Build the irrlicht library
 add_subdirectory("${PROJECT_SOURCE_DIR}/lib/irrlicht")
@@ -227,10 +250,8 @@ endif()
 
 # Common library dependencies
 target_link_libraries(supertuxkart
-    bulletdynamics
-    bulletcollision
-    bulletmath
-    enet
+    ${BULLET_LIBRARIES}
+    ${ENet_LIBRARIES}
     stkirrlicht
     ${CURL_LIBRARIES}
     ${OGGVORBIS_LIBRARIES}

cmake/FindENet.cmake

@@ -0,0 +1,48 @@
+# - Try to find enet
+# Once done this will define
+#
+#  ENET_FOUND - system has enet
+#  ENet_INCLUDE_DIRS - the enet include directory
+#  ENet_LIBRARIES - the libraries needed to use enet
+#
+# $ENETDIR is an environment variable used for finding enet.
+#
+#  Borrowed from The Mana World
+#  http://themanaworld.org/
+#
+# Several changes and additions by Fabian 'x3n' Landau
+# Lots of simplifications by Adrian Friedli
+#                 > www.orxonox.net <
+
+FIND_PATH(ENet_INCLUDE_DIRS enet/enet.h
+    PATHS
+    $ENV{ENETDIR}
+    /usr/local
+    /usr
+    PATH_SUFFIXES include
+    )
+
+FIND_LIBRARY(ENet_LIBRARY
+    NAMES enet
+    PATHS
+    $ENV{ENETDIR}
+    /usr/local
+    /usr
+    PATH_SUFFIXES lib
+    )
+
+# handle the QUIETLY and REQUIRED arguments and set ENET_FOUND to TRUE if
+# all listed variables are TRUE
+INCLUDE(FindPackageHandleStandardArgs)
+FIND_PACKAGE_HANDLE_STANDARD_ARGS(ENet DEFAULT_MSG ENet_LIBRARY ENet_INCLUDE_DIRS)
+
+IF (ENET_FOUND)
+    IF(WIN32)
+        SET(WINDOWS_ENET_DEPENDENCIES "ws2_32;winmm")
+        SET(ENet_LIBRARIES ${ENet_LIBRARY} ${WINDOWS_ENET_DEPENDENCIES})
+    ELSE(WIN32)
+        SET(ENet_LIBRARIES ${ENet_LIBRARY})
+    ENDIF(WIN32)
+ENDIF (ENET_FOUND)
+
+MARK_AS_ADVANCED(ENet_LIBRARY ENet_LIBRARIES ENet_INCLUDE_DIRS)

patches/0001-btKartRaycast.cpp-fix-usage-with-new-bullet.patch

@@ -0,0 +1,61 @@
+From 44c1ff53faf31f4550ee26af4107802773c6f625 Mon Sep 17 00:00:00 2001
+From: Igor Gnatenko <i.gnatenko.brain@gmail.com>
+Date: Fri, 17 Jan 2014 13:11:54 +0400
+Subject: [PATCH] btKartRaycast.cpp: fix usage with new bullet
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+btKartRaycast.cpp:66:78: error: invalid conversion from ‘const btRigidBody*’ to ‘btRigidBody*’ [-fpermissive]
+         btRigidBody* body = btRigidBody::upcast(rayCallback.m_collisionObject);
+                                                                              ^
+make[2]: *** [CMakeFiles/supertuxkart.dir/src/physics/btKartRaycast.cpp.o] Error 1
+
+Signed-off-by: Igor Gnatenko <i.gnatenko.brain@gmail.com>
+---
+ src/physics/btKartRaycast.cpp | 4 ++--
+ src/physics/physics.cpp       | 6 ++----
+ 2 files changed, 4 insertions(+), 6 deletions(-)
+
+diff --git a/src/physics/btKartRaycast.cpp b/src/physics/btKartRaycast.cpp
+index 13b310f..7c00d42 100644
+--- a/src/physics/btKartRaycast.cpp
++++ b/src/physics/btKartRaycast.cpp
+@@ -63,7 +63,7 @@ void* btKartRaycaster::castRay(const btVector3& from, const btVector3& to,
+
+     if (rayCallback.hasHit())
+     {
+-        btRigidBody* body = btRigidBody::upcast(rayCallback.m_collisionObject);
++        const btRigidBody* body = btRigidBody::upcast(rayCallback.m_collisionObject);
+         if (body && body->hasContactResponse())
+         {
+             result.m_hitPointInWorld = rayCallback.m_hitPointWorld;
+@@ -88,7 +88,7 @@ void* btKartRaycaster::castRay(const btVector3& from, const btVector3& to,
+                     result.m_hitNormalInWorld.getZ());
+ #endif
+             }
+-            return body;
++            return (void *) body;
+         }
+     }
+     return 0;
+diff --git a/src/physics/physics.cpp b/src/physics/physics.cpp
+index 927ad6f..d2d00f9 100644
+--- a/src/physics/physics.cpp
++++ b/src/physics/physics.cpp
+@@ -449,10 +449,8 @@ btScalar Physics::solveGroup(btCollisionObject** bodies, int numBodies,
+         btPersistentManifold* contact_manifold =
+             m_dynamics_world->getDispatcher()->getManifoldByIndexInternal(i);
+
+-        btCollisionObject* objA =
+-            static_cast<btCollisionObject*>(contact_manifold->getBody0());
+-        btCollisionObject* objB =
+-            static_cast<btCollisionObject*>(contact_manifold->getBody1());
++        const btCollisionObject* objA = contact_manifold->getBody0();
++        const btCollisionObject* objB = contact_manifold->getBody1();
+
+         unsigned int num_contacts = contact_manifold->getNumContacts();
+         if(!num_contacts) continue;   // no real collision
+-- 
+1.8.4.2
+