use cmake ExternalProject for glm in Interface

CMakeLists.txt

@@ -104,6 +104,7 @@ set(HIFI_LIBRARY_DIR "${CMAKE_CURRENT_SOURCE_DIR}/libraries")
 set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_CURRENT_SOURCE_DIR}/cmake/modules/")
 
 set(MACRO_DIR "${CMAKE_CURRENT_SOURCE_DIR}/cmake/macros")
+set(EXTERNAL_PROJECT_DIR "${CMAKE_CURRENT_SOURCE_DIR}/cmake/externals")
 
 file(GLOB HIFI_CUSTOM_MACROS "cmake/macros/*.cmake")
 foreach(CUSTOM_MACRO ${HIFI_CUSTOM_MACROS})

cmake/externals/glm/CMakeLists.txt

@@ -0,0 +1,11 @@
+include(ExternalProject)
+ExternalProject_Add(
+  glm
+  URL https://github.com/g-truc/glm/archive/0.9.5.4.zip
+  CONFIGURE_COMMAND ""
+  BUILD_COMMAND ""
+  INSTALL_COMMAND ""
+  LOG_DOWNLOAD ON
+)
+ExternalProject_Get_Property(glm source_dir)
+set(GLM_INCLUDE_DIRS ${source_dir}/glm)

cmake/macros/AddDependencyExternalProject.cmake

@@ -0,0 +1,15 @@
+# 
+#  SetupExternalProject.cmake
+#  cmake/macros
+# 
+#  Copyright 2015 High Fidelity, Inc.
+#  Created by Stephen Birarda on February 13, 2014
+#
+#  Distributed under the Apache License, Version 2.0.
+#  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
+# 
+
+macro(ADD_DEPENDENCY_EXTERNAL_PROJECT _PROJ_NAME)
+  add_subdirectory(${EXTERNAL_PROJECT_DIR}/${_PROJ_NAME} ${EXTERNAL_PROJECT_DIR}/${_PROJ_NAME}/build)
+  add_dependencies(${TARGET_NAME} ${_PROJ_NAME})
+endmacro()

interface/CMakeLists.txt

@@ -32,8 +32,6 @@ elseif (WIN32)
   set(GL_HEADERS "#include <windowshacks.h>\n#include <GL/glew.h>\n#include <GL/wglew.h>")
 endif ()
 
-# set up the external glm library
-include_glm()
 include_bullet()
 
 # create the InterfaceConfig.h file based on GL_HEADERS above
@@ -109,6 +107,10 @@ endif()
 # create the executable, make it a bundle on OS X
 add_executable(${TARGET_NAME} MACOSX_BUNDLE ${INTERFACE_SRCS} ${QM})
 
+# set up the external glm library
+add_dependency_external_project(glm)
+target_include_directories(${TARGET_NAME} PUBLIC ${GLM_INCLUDE_DIRS})
+
 # link required hifi libraries
 link_hifi_libraries(shared octree environment gpu model fbx metavoxels networking entities avatars 
                     audio audio-client animation script-engine physics