Configure pyglfw

Question

I am trying to create an OpenGL context using Python. I am attempting to use the python bindings for GLFW but I am having trouble getting them working. I found the bindings at https://github.com/rougier/pyglfw from the GLFW main page.

I am getting the following error when I run my test program:

python HelloOpenGL.py
Traceback (most recent call last):
  File "HelloOpenGL.py", line 2, in <module>
    import glfw             #Windowing Toolkit - GLFW
  File "C:\<...>\glfw.py", line 60, in <module>
    raise OSError('GLFW library not found')
OSError: GLFW library not found

I suspect that I need a glfw dll (I could be wrong). I have tried copying over the dll I use for C++ GLFW but I get the same error. I have tried both the 32 and 64 bit dlls for GLFW 3.1 compiled with the GNU compiler. I am using a Windows 10 64 bit OS and Python 3.4.

I also came across this question: Configuring glfw for Python in Eclipse. The answer is particularly unhelpful as the problem is not to do with installing pyglfw but setting up other dependencies. I did use pip to install pyglfw initially but it did not work correctly and python couldn't find the module; I have installed pyglfw manually and it is working.

Question: can someone provide instructions for setting up pyglfw? I have been unable to find anything relevant. I need to know what dependencies are needed to make it work as well.

Here is the test program:

import OpenGL.GL as gl  #OpenGL
import glfw             #Windowing Toolkit - GLFW

glfw.init()

if (glfw.OpenWindow(800, 600, 5, 6, 5, 0, 8, 0, glfw.FULLSCREEN) != True):
    glfw.Terminate(); # calls glfwTerminate() and exits
glfw.SetWindowTitle("The GLFW Window");

Answer 1

I just figured this out a few seconds ago, and it turns out that on 64-bit systems with 32 bit python, you need to put the DLL in C:\Windows\SysWOW64, then python can find it.

Answer 2

I opened up the pyglfw module. This is a problem that will occur on Windows systems because of the way the module searches for the GLFW DLL. The module searches for the library path using ctypes.util.find_library(), which searches directories in the PATH environment variable, and not the working directory.

The solution for me was to hard-code the DLL in pyglfw. This can be done with the following code:

_glfw = ctypes.WinDLL('glfw3')

This will now load the glfw3.dll so long as it is placed in the same directory. (For older versions of GLFW the DLL is glfw.dll)

This code should replace lines 45-53 in the original code:

# First if there is an environment variable pointing to the library
if 'GLFW_LIBRARY' in os.environ:
    if os.path.exists(os.environ['GLFW_LIBRARY']):
        _glfw_file = os.path.realpath(os.environ['GLFW_LIBRARY'])

# Else, try to find it
if _glfw_file is None:
    order = ['glfw', 'glfw3']
    for check in order:
        _glfw_file = ctypes.util.find_library(check)
        if _glfw_file is not None:
            break

# Else, we failed and exit
if _glfw_file is None:
    raise OSError('GLFW library not found')

# Load it
_glfw = ctypes.CDLL(_glfw_file)

This question: find_library() in ctypes details the solutions to loading libraries on windows.

This outlines another solution, which would be to set the search path at runtime:

You can add the DLL directory to PATH dynamically at runtime (in contrast to the Linux loader's caching of LD_LIBRARY_PATH at startup). For example, say your DLL dependencies are in the "dlls" subdirectory of your package. You can prepend this directory as follows:

import os

basepath = os.path.dirname(os.path.abspath(__file__))
dllspath = os.path.join(basepath, 'dlls')
os.environ['PATH'] = dllspath + os.pathsep + os.environ['PATH']