Merge pull request #75 from DickerDackel/find_library

Find versionless libEGL.so and libGL.so without installed dev package

Author: szabolcsdombi

_zengl.py

@@ -261,6 +261,8 @@ class DefaultLoader:
     def __init__(self):
         import ctypes
 
+        from ctypes.util import find_library
+
         def funcptr(lib, name):
             return ctypes.cast(getattr(lib, name, 0), ctypes.c_void_p).value or 0
 
@@ -275,7 +277,11 @@ def loader(name):
 
         elif sys.platform.startswith('linux'):
             try:
-                lib = ctypes.CDLL('libEGL.so')
+                libegl = find_library('EGL')
+                if libegl is None:
+                    raise RuntimeError("Cannot find OpenGL support library libEGL")
+
+                lib = ctypes.CDLL(libegl)
                 proc = ctypes.cast(lib.eglGetProcAddress, ctypes.CFUNCTYPE(ctypes.c_ulonglong, ctypes.c_char_p))
                 if not lib.eglGetCurrentContext():
                     raise RuntimeError('Cannot detect window with OpenGL support')
@@ -284,7 +290,11 @@ def loader(name):
                     return proc(name.encode())
 
             except:
-                lib = ctypes.CDLL('libGL.so')
+                libgl = find_library('GL')
+                if libgl is None:
+                    raise RuntimeError("Cannot find OpenGL support library libGL")
+
+                lib = ctypes.CDLL(libgl)
                 proc = ctypes.cast(lib.glXGetProcAddress, ctypes.CFUNCTYPE(ctypes.c_ulonglong, ctypes.c_char_p))
                 if not lib.glXGetCurrentContext():
                     raise RuntimeError('Cannot detect window with OpenGL support') from None