Added infrastructure to generate Python bindings

- Added a flag GENERATE_PYTHON_BINDINGS to CMake which enables the use of pybind11
- `create-python-bindings` generates bindings for PcaModel
- pybind11 is added as a submodule; needs to be cloned with `git submodule update --init`
- Increased cmake_minimum_required to 2.8.12 for pybind11

CMakeLists.txt

 project(eos)
-cmake_minimum_required(VERSION 2.8.10)
+cmake_minimum_required(VERSION 2.8.12)
 set(eos_VERSION_MAJOR 0)
 set(eos_VERSION_MINOR 7)
 set(eos_VERSION_PATCH 1)
@@ -58,6 +58,8 @@ option(BUILD_UTILS "Build utility applications." OFF)
 message(STATUS "BUILD_UTILS: ${BUILD_UTILS}")
 option(BUILD_DOCUMENTATION "Build the library documentation." OFF)
 message(STATUS "BUILD_DOCUMENTATION: ${BUILD_DOCUMENTATION}")
+option(GENERATE_PYTHON_BINDINGS "Build python bindings. Needs BUILD_UTILS enabled too." OFF)
+message(STATUS "GENERATE_PYTHON_BINDINGS: ${GENERATE_PYTHON_BINDINGS}")
 
 # Build a CPack driven installer package:
 include(InstallRequiredSystemLibraries) # This module will include any runtime libraries that are needed by the project for the current platform
@@ -140,6 +142,13 @@ source_group(fitting\\detail include/eos/fitting/detail/*)
 source_group(render include/eos/render/*)
 source_group(render\\detail include/eos/render/detail/*)
 
+# Generate python bindings using pybind11:
+if(GENERATE_PYTHON_BINDINGS)
+	set(PYBIND11_PATH "${CMAKE_CURRENT_SOURCE_DIR}/3rdparty/pybind11")
+	add_subdirectory(${PYBIND11_PATH})
+	# If this fails, the repo has probably not been cloned with submodules. Run: git submodule update --init
+endif()
+
 # The install target:
 install(DIRECTORY ${CMAKE_SOURCE_DIR}/include/ DESTINATION include) # our library headers
 install(DIRECTORY ${CMAKE_SOURCE_DIR}/share/ DESTINATION share) # the model and metadata

initial_cache.cmake.template

@@ -25,3 +25,4 @@
 set(BUILD_EXAMPLES ON CACHE BOOL "Build the example applications." FORCE)
 set(BUILD_UTILS OFF CACHE BOOL "Build utility applications." FORCE)
 set(BUILD_DOCUMENTATION OFF CACHE BOOL "Build the library documentation." FORCE)
+set(GENERATE_PYTHON_BINDINGS OFF CACHE BOOL "Build python bindings. Needs BUILD_UTILS enabled too." FORCE)

utils/CMakeLists.txt

 project(utils)
-cmake_minimum_required(VERSION 2.8.10)
+cmake_minimum_required(VERSION 2.8.12)
 
 # The utils need a few additional dependencies (e.g. boost filesystem and OpenCV highgui):
 
@@ -41,6 +41,13 @@ target_link_libraries(scm-to-cereal ${OpenCV_LIBS} ${Boost_LIBRARIES})
 # Store a json file as cereal .bin:
 add_executable(json-to-cereal-binary json-to-cereal-binary.cpp)
 target_link_libraries(json-to-cereal-binary ${OpenCV_LIBS} ${Boost_LIBRARIES})
+# Generate python bindings using pybind11:
+if(GENERATE_PYTHON_BINDINGS)
+	pybind11_add_module(eos_py create-python-bindings.cpp)
+	target_link_libraries(eos_py PRIVATE ${OpenCV_LIBS} ${Boost_LIBRARIES})
+	install(TARGETS eos_py DESTINATION bin)
+endif()
+
 # install target:
 install(TARGETS scm-to-cereal DESTINATION bin)
 install(TARGETS json-to-cereal-binary DESTINATION bin)

utils/create-python-bindings.cpp

+/*
+ * eos - A 3D Morphable Model fitting library written in modern C++11/14.
+ *
+ * File: utils/create-python-bindings.cpp
+ *
+ * Copyright 2016 Patrik Huber
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include "eos/morphablemodel/PcaModel.hpp"
+
+#include "pybind11/pybind11.h"
+
+namespace py = pybind11;
+
+/**
+ * Create python bindings for the eos library using pybind11.
+ */
+PYBIND11_PLUGIN(eos_py) {
+    py::module m("eos_py", "Python bindings to the 3D Morphable Face Model fitting library");
+
+	py::class_<eos::morphablemodel::PcaModel>(m, "PcaModel")
+		.def(py::init<>())
+		.def("get_mean_at_point", &eos::morphablemodel::PcaModel::get_mean_at_point);
+
+    return m.ptr();
+};