Eigen and OpenGL finder (#772)

This also finds manual installs, e.g. in /usr/local.
Based on https://eigen.tuxfamily.org/dox/TopicCMakeGuide.html .
Needs CMake>=3.0

CMakeLists.txt

@@ -31,7 +31,8 @@ elseif (${CMAKE_VERSION} VERSION_GREATER 3.0.0)
 else (${CMAKE_VERSION} VERSION_GREATER 3.9.0)
   project(OpenPose)
 endif (${CMAKE_VERSION} VERSION_GREATER 3.9.0)
-cmake_minimum_required(VERSION 2.8.7 FATAL_ERROR) # min. cmake version recommended by Caffe
+cmake_minimum_required(VERSION 3.0 FATAL_ERROR) # required by cmake eigen finder to find locally installed versions (e.g., CUDA 9.2 support was added in eigen 3.3.5)
+# cmake_minimum_required(VERSION 2.8.7 FATAL_ERROR) # min. cmake version recommended by Caffe
 
 
 ### Extra functionality
@@ -275,11 +276,11 @@ option(WITH_OPENCV_WITH_OPENGL "Much faster GUI display, but you must also enabl
 
 # Set the acceleration library
 if (WIN32 OR APPLE)
-  set(WITH_EIGEN NONE CACHE STRING "Select the Eigen mode (NONE if not required or DOWNLOAD to let OpenPose download it).")
-  set_property(CACHE WITH_EIGEN PROPERTY STRINGS NONE BUILD)
+  set(WITH_EIGEN NONE CACHE STRING "Select the Eigen mode: NONE if not required, BUILD to let OpenPose download it, or FIND to let CMake find it (e.g., if you installed it manually).")
+  set_property(CACHE WITH_EIGEN PROPERTY STRINGS NONE BUILD FIND)
 elseif (UNIX AND NOT APPLE)
-  set(WITH_EIGEN NONE CACHE STRING "Select the Eigen mode (NONE if not required, APT_GET if you used `sudo apt-get install libeigen3-dev`, BUILD to let OpenPose download it).")
-  set_property(CACHE WITH_EIGEN PROPERTY STRINGS NONE APT_GET BUILD)
+  set(WITH_EIGEN NONE CACHE STRING "Select the Eigen mode: NONE if not required, BUILD to let OpenPose download it, or FIND to let CMake find it (e.g., if you installed it manually or used `sudo apt-get install libeigen3-dev`).")
+  set_property(CACHE WITH_EIGEN PROPERTY STRINGS NONE BUILD FIND)
 endif (WIN32 OR APPLE)
 
 # # Suboptions for OpenPose tracking
@@ -388,11 +389,18 @@ else (${WITH_EIGEN} MATCHES "NONE")
     download_zip("eigen_2018_05_23.zip" ${OP_URL} ${FIND_LIB_PREFIX} 29B9B2FD4679D587BB67467F09EE8365)
     # Set path
     set(EIGEN3_INCLUDE_DIRS "3rdparty/eigen/include/")
-  # Alread installed with apt-get
-  elseif (${WITH_EIGEN} MATCHES "APT_GET")
+  # Leave to CMake to find it
+  elseif (${WITH_EIGEN} MATCHES "FIND")
     # Eigen
-    find_package(PkgConfig)
-    pkg_check_modules(EIGEN3 REQUIRED eigen3)
+    # # Option a) apt-get
+    # find_package(PkgConfig)
+    # pkg_check_modules(EIGEN3 REQUIRED eigen3)
+    # # Option b) Find it (including apt-get)
+    if (CUDA_VERSION_STRING STRGREATER "9.0")
+      find_package(Eigen3 3.3.5 REQUIRED NO_MODULE)
+    else (CUDA_VERSION_STRING STRGREATER "9.0")
+      find_package(Eigen3 3 REQUIRED NO_MODULE)
+    endif (CUDA_VERSION_STRING STRGREATER "9.0")
   endif (${WITH_EIGEN} MATCHES "BUILD")
 endif (${WITH_EIGEN} MATCHES "NONE")
 
@@ -419,6 +427,8 @@ if (UNIX OR APPLE)
 
   # 3D
   if (WITH_3D_RENDERER)
+    # OpenGL
+    find_package(OpenGL REQUIRED)
     # GLUT
     find_package(GLUT REQUIRED)
     # OpenGL
@@ -440,8 +450,16 @@ if (UNIX OR APPLE)
     if (NOT WITH_3D_RENDERER)
       message(FATAL_ERROR "WITH_3D_RENDERER is required if WITH_3D_ADAM_MODEL is enabled.")
     endif (NOT WITH_3D_RENDERER)
-    find_package(PkgConfig)
-    pkg_check_modules(EIGEN3 REQUIRED eigen3)
+    # Eigen
+    # # Option a) apt-get
+    # find_package(PkgConfig)
+    # pkg_check_modules(EIGEN3 REQUIRED eigen3)
+    # # Option b) Find it (including apt-get)
+    if (CUDA_VERSION_STRING STRGREATER "9.0")
+      find_package(Eigen3 3.3.5 REQUIRED NO_MODULE)
+    else (CUDA_VERSION_STRING STRGREATER "9.0")
+      find_package(Eigen3 3 REQUIRED NO_MODULE)
+    endif (CUDA_VERSION_STRING STRGREATER "9.0")
     # Others: sudo apt-get install libglm-dev
     # http://ceres-solver.org
     find_package(Ceres REQUIRED COMPONENTS SuiteSparse)
@@ -821,6 +839,7 @@ endif (USE_ASIO)
 if (NOT ${WITH_EIGEN} MATCHES "NONE")
   include_directories(
       ${EIGEN3_INCLUDE_DIRS})
+  set(OpenPose_3rdparty_libraries ${OpenPose_3rdparty_libraries} Eigen3::Eigen)
 endif (NOT ${WITH_EIGEN} MATCHES "NONE")
 
 if (APPLE)
@@ -859,9 +878,10 @@ if (WITH_3D_ADAM_MODEL)
                                     include_directories(include/adam) # TODO: TEMPORARY - TO BE REMOVED IN THE FUTURE
   include_directories(${CERES_INCLUDE_DIRS})
   include_directories(${EIGEN3_INCLUDE_DIRS})
+  set(OpenPose_3rdparty_libraries ${OpenPose_3rdparty_libraries} Eigen3::Eigen)
   include_directories(${IGL_INCLUDE_DIRS})
   include_directories(${LIBIGL_INCLUDE_DIRS})
-  include_directories(${GLUT_INCLUDE_DIRS} ${GLEW_INCLUDE_DIRS} ${OPENGL_INCLUDE_DIR})
+  include_directories(${OPENGL_INCLUDE_DIR} ${GLUT_INCLUDE_DIRS} ${GLEW_INCLUDE_DIRS})
 endif (WITH_3D_ADAM_MODEL)
 # Windows includes
 if (WIN32)