To render heli-gym, OpenGL is used. OpenGL written in C++ and connect with Python with shared libraries DLL (for Windows) and so (for Linux) as a part of API. By using Python's ctypes module, API can be used by loading shared libraries.
OpenGL structure based on this Tutorial. The tutorial is very effective and suggested for who interested to learn OpenGL.
If any C++ files changed somehow (adding new methods etc.) API should be re-compiled. To build and compile the API, CMake is used.
In Windows, MSVC is suggested compiler to build DLL file. To use MSVC for building API in Windows, there is two way.
First way is using CMake GUI. In GUI firstly set source code folder which is ...path_to_heli-gym_folder.../heli-gym/heligym/envs/renderer. After that set build folder as ...path_to_heli-gym_folder.../heli-gym/heligym/envs/renderer/build. If there is no build folder, GUI pop up an dialog box to warn you and accept it. After setting the folder, click the Configure button. Select the MSVC version and press Finish. If there is no error (which written in RED color (warnings are also in RED))which means Configuring done message appear at the end of gui, click the Generate button. Click the Open Project button to open MSVC solution. Lastly, compile the MSVC solution and make sure that config in MSVC is Release.
Second way is using cmd. Firstly call the
cd ...path_to_heli-gym_folder.../heli-gym/heligym/envs/renderercommand. Create the build folder and change the directory to folder, call the
mkdir build && cd buildcommand. Then, to build (like Configure and Generate in GUI), call the
cmake ..command. To compile in Release config, call the
cmake --build . --config Releasecommand.
These two way creates the Heligym.dll file which is shared libraries for Python and C++ linkage. The file should be in ...path_to_heli-gym_folder.../heli-gym/heligym/envs/renderer/python folder. Even it setted to output to the ../python folder, make sure that your last compiled DLL file should be in the folder.
In Linux, GCC is suggested compiler to build so file. To use GCC for building API in Linux, there is two way.
First way is using CMake GUI. In GUI firstly set source code folder which is ...path_to_heli-gym_folder.../heli-gym/heligym/envs/renderer. After that set build folder as ...path_to_heli-gym_folder.../heli-gym/heligym/envs/renderer/build. If there is no build folder, GUI pop up an dialog box to warn you and accept it. After setting the folder, click the Configure button. Select the Unix Makefiles as generator and click the Finish. If there is no error (which written in RED color (warnings are also in RED)) which means Configuring done message appear at the end of gui, click the Generate button. Open the terminal, call the
cd ...path_to_heli-gym_folder.../heli-gym/heligym/envs/renderer/buildcommand to be in the build folder. Then to compile, call the
makecommand. Build type is assigned as Release. Therefore just make commant will work.
Second way is using terminal. Firstly call the
cd ...path_to_heli-gym_folder.../heli-gym/heligym/envs/renderercommand. Create the build folder and change the directory to folder, call the
mkdir build && cd buildcommand. Then, to build (like Configure and Generate in GUI), call the
cmake .. or
cmake -G "Unix Makefiles" #for the Unix Makefiles generatorcommand. Build type is assigned as Release. Yet, if you want to make sure, call the
cmake -G "Unix Makefiles" -DCMAKE_BUILD_TYPE=Releasecommand. To compile, call the
makecommand.
These two way creates the libHeligym.so file which is shared libraries for Python and C++ linkage. The file should be in ...path_to_heli-gym_folder.../heli-gym/heligym/envs/renderer/python folder. Even it setted to output to the ../python folder, make sure that your last compiled so file should be in the folder.
There is several libraries for OpenGL application. Some of them should be in shared libraries. Therefore, in some OS, these libraries should be re-compiled. These libraries are Assimp for asset importing and GLFW for creating windows, contexts and surfaces, receiving input and events.
In Windows OS, these libraries are not need to re-compile. The conflict occurs in Linux distros. To re-compile these libraries, CMake can be used.
Heli-gym uses assimp 5.0.1. From Assimp Download, download the zip file (if you want you can use tar file also). Extract the file and open the terminal. Then call the,
cd ...path_to_assimp_5.0.1_/command. Then, to create build folder and change directory in the folder call the
mkdir build && cd buildcommand. To build, call the
cmake ..command. To compile the assimp, call the
makecommand. make command creates libassimp.so, libassimp.so.5 and libassimp.so.5.0.1 in ...path_to_assimp_5.0.1_/build/bin folder. These files should be copied to ...path_to_heli-gym_folder.../heli-gym/heligym/envs/renderer/libs folder. It can be also done in terminal. First change directory to bin folder with
cd ...path_to_assimp_5.0.1_/build/bincommand. Then copy the files to ...path_to_heli-gym_folder.../heli-gym/heligym/envs/renderer/libs with
cp libassimp.so libassimp.so.5 libassimp.so.5.0.1 ...path_to_heli-gym_folder.../heli-gym/heligym/envs/renderer/libscommand.
Heli-gym uses GLFW 3.3.4. From GLFW, download the zip file. Extract the file and open the terminal. Then call the,
cd ...path_to_glfw_3.3.4/command. Then, to create build folder and change directory in the folder call the
mkdir build && cd buildcommand. To build for shared librares (for details look Docs ), call the
cmake -DBUILD_SHARED_LIBS=ON ..command. To compile the glfw, call the
makecommand. make command creates libglfw.so, libglfw.so.3 and libglfw.so.3.3 in ...path_to_glfw_3.3.4/build/src folder. These files should be copied to ...path_to_heli-gym_folder.../heli-gym/heligym/envs/renderer/libs folder. It can be also done in terminal. First change directory to bin folder with
cd ...path_to_glfw_3.3.4/build/srccommand. Then copy the files to ...path_to_heli-gym_folder.../heli-gym/heligym/envs/renderer/libs with
cp libglfw.so libglfw.so.3 libglfw.so.3.3 ...path_to_heli-gym_folder.../heli-gym/heligym/envs/renderer/libscommand.