diff --git a/CMakeLists.txt b/CMakeLists.txt

index 8455bb8..c8e0d88 100644

--- a/CMakeLists.txt

+++ b/CMakeLists.txt

@@ -211,6 +211,26 @@ IF ( ASSIMP_NO_EXPORT )

   MESSAGE( STATUS "Build an import-only version of Assimp." )

 ENDIF( ASSIMP_NO_EXPORT )

+# Search for poly2tri

+FIND_LIBRARY(POLY2TRI_LIB poly2tri HINTS ${POLY2TRI_LIB_PATH})

+FIND_FILE(POLY2TRI_H poly2tri.h PATHS ${POLY2TRI_INCLUDE_PATH})

+IF (POLY2TRI_LIB AND POLY2TRI_H)

+  message(status "Found External poly2tri")

+  SET(HAVE_POLY2TRI true)

+ELSE(POLY2TRI_LIB AND POLY2TRI_H)

+  SET(HAVE_POLY2TRI false)

+ENDIF(POLY2TRI_LIB AND POLY2TRI_H)

+

+# Search for clipper

+FIND_LIBRARY(CLIPPER_LIB polyclipping HINTS ${CLIPPER_LIB_PATH})

+FIND_FILE(CLIPPER_H clipper.hpp PATHS ${CLIPPER_INCLUDE_PATH})

+IF (CLIPPER_LIB AND CLIPPER_H)

+  message(status "Found External clipper")

+  SET(HAVE_CLIPPER true)

+ELSE(CLIPPER_LIB AND CLIPPER_H)

+  SET(HAVE_CLIPPER false)

+ENDIF(CLIPPER_LIB AND CLIPPER_H)

+

 SET ( ASSIMP_BUILD_ARCHITECTURE "" CACHE STRING

   "describe the current architecture."

 )

diff --git a/code/BlenderTessellator.h b/code/BlenderTessellator.h

index 530bd2c..a6c9d9e 100644

--- a/code/BlenderTessellator.h

+++ b/code/BlenderTessellator.h

@@ -142,7 +142,7 @@ namespace Assimp

 #if ASSIMP_BLEND_WITH_POLY_2_TRI

-#include "../contrib/poly2tri/poly2tri/poly2tri.h"

+#include "poly2tri/poly2tri.h"

 namespace Assimp

 {

diff --git a/code/CMakeLists.txt b/code/CMakeLists.txt

index 35ecf50..d549c89 100644

--- a/code/CMakeLists.txt

+++ b/code/CMakeLists.txt

@@ -655,12 +655,15 @@ SET( ConvertUTF_SRCS

 )

 SOURCE_GROUP( ConvertUTF FILES ${ConvertUTF_SRCS})

+if (NOT HAVE_CLIPPER)

 SET( Clipper_SRCS

   ../contrib/clipper/clipper.hpp

   ../contrib/clipper/clipper.cpp

 )

 SOURCE_GROUP( Clipper FILES ${Clipper_SRCS})

-

+else (NOT HAVE_CLIPPER)

+SET( Clipper_SRCS "")

+endif(NOT HAVE_CLIPPER)

 SET( Poly2Tri_SRCS

   ../contrib/poly2tri/poly2tri/common/shapes.cc

@@ -743,8 +746,6 @@ SET( assimp_src

   # Third-party libraries

   ${IrrXML_SRCS}

   ${ConvertUTF_SRCS}

-  ${unzip_compile_SRCS}

-  ${Poly2Tri_SRCS}

   ${Clipper_SRCS}

   ${openddl_parser_SRCS}

   # Necessary to show the headers in the project when using the VC++ generator:

@@ -753,6 +754,8 @@ SET( assimp_src

   ${COMPILER_HEADERS}

 )

+

+

 ADD_DEFINITIONS( -DOPENDDLPARSER_BUILD )

 INCLUDE_DIRECTORIES(

@@ -821,6 +824,19 @@ else (UNZIP_FOUND)

   INCLUDE_DIRECTORIES("../")

 endif (UNZIP_FOUND)

+if (HAVE_POLY2TRI)

+  INCLUDE_DIRECTORIES(${POLY2TRI_INCLUDE_PATH})

+  TARGET_LINK_LIBRARIES(assimp ${POLY2TRI_LIB})

+endif(HAVE_POLY2TRI)

+

+if (HAVE_CLIPPER)

+  INCLUDE_DIRECTORIES(${CLIPPER_INCLUDE_PATH})

+  TARGET_LINK_LIBRARIES(assimp ${CLIPPER_LIB})

+else (HAVE_CLIPPER)

+  INCLUDE_DIRECTORIES(../contrib/clipper)

+endif(HAVE_CLIPPER)

+

+

 INSTALL( TARGETS assimp

   LIBRARY DESTINATION ${ASSIMP_LIB_INSTALL_DIR}

   ARCHIVE DESTINATION ${ASSIMP_LIB_INSTALL_DIR}

diff --git a/code/D3MFImporter.cpp b/code/D3MFImporter.cpp

index 1a97168..7377eb4 100644

--- a/code/D3MFImporter.cpp

+++ b/code/D3MFImporter.cpp

@@ -44,7 +44,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 #include <assimp/IOStream.hpp>

 #include <assimp/IOSystem.hpp>

 #include <assimp/DefaultLogger.hpp>

-#include <contrib/unzip/unzip.h>

+#include <minizip/unzip.h>

 #include "irrXMLWrapper.h"

 #include "StringComparison.h"

 #include "StringUtils.h"

diff --git a/code/D3MFOpcPackage.cpp b/code/D3MFOpcPackage.cpp

index 7cc1dd5..2b007db 100644

--- a/code/D3MFOpcPackage.cpp

+++ b/code/D3MFOpcPackage.cpp

@@ -42,7 +42,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 #include "D3MFOpcPackage.h"

 #include "Exceptional.h"

-#include <contrib/unzip/unzip.h>

+#include <minizip/unzip.h>

 #include <assimp/IOStream.hpp>

 #include <assimp/IOSystem.hpp>

 #include <assimp/DefaultLogger.hpp>

diff --git a/code/IFCGeometry.cpp b/code/IFCGeometry.cpp

index 5a2e4a0..0926498 100644

--- a/code/IFCGeometry.cpp

+++ b/code/IFCGeometry.cpp

@@ -49,8 +49,8 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 #include "PolyTools.h"

 #include "ProcessHelper.h"

-#include "../contrib/poly2tri/poly2tri/poly2tri.h"

-#include "../contrib/clipper/clipper.hpp"

+#include "poly2tri/poly2tri.h"

+#include "clipper.hpp"

 #include <memory>

 #include <iterator>

diff --git a/code/IFCLoader.cpp b/code/IFCLoader.cpp

index 34977f5..bc655c0 100644

--- a/code/IFCLoader.cpp

+++ b/code/IFCLoader.cpp

@@ -50,7 +50,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 #include <tuple>

 #ifndef ASSIMP_BUILD_NO_COMPRESSED_IFC

-#   include <contrib/unzip/unzip.h>

+#   include <minizip/unzip.h>

 #endif

 #include "IFCLoader.h"

diff --git a/code/IFCOpenings.cpp b/code/IFCOpenings.cpp

index 51ea143..f0915fb 100644

--- a/code/IFCOpenings.cpp

+++ b/code/IFCOpenings.cpp

@@ -49,8 +49,8 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 #include "PolyTools.h"

 #include "ProcessHelper.h"

-#include "../contrib/poly2tri/poly2tri/poly2tri.h"

-#include "../contrib/clipper/clipper.hpp"

+#include "poly2tri/poly2tri.h"

+#include "clipper.hpp"

 #include <iterator>

diff --git a/code/Q3BSPZipArchive.h b/code/Q3BSPZipArchive.h

index e46a11b..da93e5c 100644

--- a/code/Q3BSPZipArchive.h

+++ b/code/Q3BSPZipArchive.h

@@ -40,7 +40,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 #ifndef AI_Q3BSP_ZIPARCHIVE_H_INC

 #define AI_Q3BSP_ZIPARCHIVE_H_INC

-#include <contrib/unzip/unzip.h>

+#include <minizip/unzip.h>

 #include <assimp/IOStream.hpp>

 #include <assimp/IOSystem.hpp>

 #include <string>

diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt

index df0139d..8b26f22 100644

--- a/test/CMakeLists.txt

+++ b/test/CMakeLists.txt

@@ -37,7 +37,8 @@

 #----------------------------------------------------------------------

 cmake_minimum_required( VERSION 2.6 )

-INCLUDE( AddGTest )

+# Search for Google Test

+FIND_PACKAGE(GTest)

 INCLUDE_DIRECTORIES(

   ${Assimp_SOURCE_DIR}/include

diff --git a/tools/assimp_cmd/CMakeLists.txt b/tools/assimp_cmd/CMakeLists.txt

index f8af93a..3f9a902 100644