Linux OpenGL test

linux_gl.py

from ctypes import CDLL, c_int, byref
import faulthandler
import vtk as _vtk
faulthandler.enable()
renderWindow = _vtk.vtkRenderWindow()
logger = _vtk.vtkLogger
logger.Init()
logger.SetStderrVerbosity(_vtk.vtkLogger.VERBOSITY_MAX)
renderWindow.DebugOn()
renderWindow.SetOffScreenRendering(True)
exited = False


def _obs(obj, event):
    print(obj, event)
    global exited
    exited = True


renderWindow.AddObserver(_vtk.vtkCommand.ExitEvent, _obs)
assert renderWindow.HasObserver(_vtk.vtkCommand.ExitEvent)
# Eventually we should add more special cases here, but let's at least catch
# the linux-with-no-display and linux-with-old-opengl cases
# adapted from https://github.com/Kitware/VTK/blob/master/Rendering/OpenGL2/vtkXOpenGLRenderWindow.cxx
if isinstance(renderWindow, _vtk.vtkXOpenGLRenderWindow):
    # "bad X server connection"
    xlib = CDLL('libX11.so.6')
    assert xlib is not None
    display = xlib.XOpenDisplay()
    if not display:
        raise RuntimeError('Could not initialize display')
    # "Could not find a decent config"
    glx = CDLL('libGL.so')
    assert glx is not None
    attributes = [0] * 50
    attributes[:15] = [
        0x8010,  # GLX_DRAWABLE_TYPE
        0x00000001,  # GLX_WINDOW_BIT
        0x8011,  # GLX_RENDER_TYPE
        0x00000001,  # GLX_RGBA_BIT
        8,  # GLX_RED_SIZE
        1,
        9,  # GLX_GREEN_SIZE
        1,
        10,  # GLX_BLUE_SIZE
        1,
        12,  # GLX_DEPTH_SIZE
        1,
        11,  # GLX_ALPHA_SIZE
        1,
        0,
    ]
    attributes = (c_int * len(attributes))(*attributes)
    tmp = c_int(0)
    fb = glx.glXChooseFBConfig(
        display, xlib.XDefaultScreen(display), attributes, byref(tmp))
    try:
        if not fb or tmp.value <= 0:
            raise RuntimeError('no decent framebuffer')
    finally:
        pass
        if fb:
            xlib.XFree(fb)
        xlib.XCloseDisplay(display)
    # Cannot create GLX context
    renderWindow.Initialize()
    if exited:
        raise RuntimeError('Could not create GLX context')
    print('Usable')