python - 如何使用 glXChooseFBConfig 和 ctypes 模块初始化 OpenGL？

Question

我想在我的 tkinter 窗口上制作一些简单的 OpenGL 动画。我不想包含任何不必要的依赖项，因此我使用 ctypes 从头开始​​编写所有内容。到目前为止我有这个:

#!/usr/bin/env python3

import tkinter
import ctypes
from ctypes import cdll

GLX_PIXMAP_BIT = 0x00000002
GLX_WINDOW_BIT = 0x00000001
GLX_PBUFFER_BIT = 0x00000004
GLX_RGBA_BIT = 0x00000001
GLX_COLOR_INDEX_BIT = 0x00000002
GLX_PBUFFER_CLOBBER_MASK = 0x08000000
GLX_FRONT_LEFT_BUFFER_BIT = 0x00000001
GLX_FRONT_RIGHT_BUFFER_BIT = 0x00000002
GLX_BACK_LEFT_BUFFER_BIT = 0x00000004
GLX_BACK_RIGHT_BUFFER_BIT = 0x00000008
GLX_AUX_BUFFERS_BIT = 0x00000010
GLX_DEPTH_BUFFER_BIT = 0x00000020
GLX_STENCIL_BUFFER_BIT = 0x00000040
GLX_ACCUM_BUFFER_BIT = 0x00000080
GLX_CONFIG_CAVEAT = 0x20
GLX_X_VISUAL_TYPE = 0x22
GLX_TRANSPARENT_TYPE = 0x23
GLX_TRANSPARENT_INDEX_VALUE = 0x24
GLX_TRANSPARENT_RED_VALUE = 0x25
GLX_TRANSPARENT_GREEN_VALUE = 0x26
GLX_TRANSPARENT_BLUE_VALUE = 0x27
GLX_TRANSPARENT_ALPHA_VALUE = 0x28
GLX_DONT_CARE = 0xFFFFFFFF
GLX_NONE = 0x8000
GLX_SLOW_CONFIG = 0x8001
GLX_TRUE_COLOR = 0x8002
GLX_DIRECT_COLOR = 0x8003
GLX_PSEUDO_COLOR = 0x8004
GLX_STATIC_COLOR = 0x8005
GLX_GRAY_SCALE = 0x8006
GLX_STATIC_GRAY = 0x8007
GLX_TRANSPARENT_RGB = 0x8008
GLX_TRANSPARENT_INDEX = 0x8009
GLX_VISUAL_ID = 0x800B
GLX_SCREEN = 0x800C
GLX_NON_CONFORMANT_CONFIG = 0x800D
GLX_DRAWABLE_TYPE = 0x8010
GLX_RENDER_TYPE = 0x8011
GLX_X_RENDERABLE = 0x8012
GLX_FBCONFIG_ID = 0x8013
GLX_RGBA_TYPE = 0x8014
GLX_COLOR_INDEX_TYPE = 0x8015
GLX_MAX_PBUFFER_WIDTH = 0x8016
GLX_MAX_PBUFFER_HEIGHT = 0x8017
GLX_MAX_PBUFFER_PIXELS = 0x8018
GLX_PRESERVED_CONTENTS = 0x801B
GLX_LARGEST_PBUFFER = 0x801C
GLX_WIDTH = 0x801D
GLX_HEIGHT = 0x801E
GLX_EVENT_MASK = 0x801F
GLX_DAMAGED = 0x8020
GLX_SAVED = 0x8021
GLX_WINDOW = 0x8022
GLX_PBUFFER = 0x8023
GLX_PBUFFER_HEIGHT = 0x8040
GLX_PBUFFER_WIDTH = 0x8041
GLX_ACCUM_ALPHA_SIZE = 17
GLX_ACCUM_BLUE_SIZE = 16
GLX_ACCUM_GREEN_SIZE = 15
GLX_ACCUM_RED_SIZE = 14
GLX_ALPHA_SIZE = 11
GLX_AUX_BUFFERS = 7
GLX_BAD_ATTRIBUTE = 2
GLX_BAD_CONTEXT = 5
GLX_BAD_ENUM = 7
GLX_BAD_SCREEN = 1
GLX_BAD_VALUE = 6
GLX_BAD_VISUAL = 4
GLX_BLUE_SIZE = 10
GLX_BUFFER_SIZE = 2
GLX_BufferSwapComplete = 1
GLX_DEPTH_SIZE = 12
GLX_DOUBLEBUFFER = 5
GLX_GREEN_SIZE = 9
GLX_LEVEL = 3
GLX_NO_EXTENSION = 3
GLX_PbufferClobber = 0
GLX_RED_SIZE = 8
GLX_RGBA = 4
GLX_STENCIL_SIZE = 13
GLX_STEREO = 6
GLX_USE_GL = 1


class OpenGLView(tkinter.Frame):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self._x_window_id = self.winfo_id()
        self._init_gl()

    def _init_gl(self):
        self._xlib = cdll.LoadLibrary('libX11.so')
        self._gl = cdll.LoadLibrary('libGL.so')
        self._glx = cdll.LoadLibrary('libGLU.so')
        self._x_display = self._xlib.XOpenDisplay()
        elements = [
            GLX_X_RENDERABLE, 1,
            GLX_DRAWABLE_TYPE, GLX_WINDOW_BIT,
            GLX_RENDER_TYPE, GLX_RGBA_BIT,
            GLX_X_VISUAL_TYPE, GLX_TRUE_COLOR,
            GLX_DOUBLEBUFFER, 1,
            GLX_RED_SIZE, 8,
            GLX_GREEN_SIZE, 8,
            GLX_BLUE_SIZE, 8,
            GLX_ALPHA_SIZE, 8,
            GLX_DEPTH_SIZE, 24,
            GLX_STENCIL_SIZE, 8,
            0
        ]
        elements = (ctypes.c_int * len(elements))(*elements)
        gl_configs = self._glx.glXChooseFBConfig(self._x_display, 0, ctypes.byref(elements), ctypes.sizeof(elements))
        context = self._glx.glXCreateNewContext(self._x_display, gl_configs[0], self._glx.GLX_RGBA_TYPE, None, True)
        self._glx.glXMakeContextCurrent(self._x_display, self._x_window_id, self._x_window_id, context)

tk = tkinter.Tk()
v = OpenGLView(tk)
v.pack(fill=tkinter.BOTH, expand=True)
tk.mainloop()

为什么这段代码会产生这个错误？

libGL error: No matching fbConfigs or visuals found
libGL error: failed to load driver: swrast
Segmentation fault (core dumped)

Answer 1

我现在手头没有 Linux 发行版来测试它，但是这个 mcve 怎么样？ ？

from ctypes import c_char_p, c_void_p, cdll
from ctypes import c_bool, c_char_p, c_double, c_float, c_int, c_uint, c_ulong, c_void_p, POINTER
from tkinter import Tk, YES, BOTH

_xlib = cdll.LoadLibrary('libX11.so')
_gl = cdll.LoadLibrary('libGL.so')


# Data types for Linux Platform
XID = c_ulong
GLXDrawable = XID

# Data types for OpenGL
GLbitfield = c_uint
GLubyte = c_char_p
GLclampf = c_float
GLclampd = c_double
GLdouble = c_double
GLenum = c_uint
GLfloat = c_float
GLint = c_int

GL_BLEND = 0x0BE2
GL_COLOR_BUFFER_BIT = 0x00004000
GL_DEPTH_BUFFER_BIT = 0x00000100
GL_DEPTH_TEST = 0x0B71
GL_MODELVIEW = 0x1700
GL_ONE_MINUS_SRC_ALPHA = 0x0303
GL_PROJECTION = 0x1701
GL_QUADS = 0x0007
GL_RENDERER = 0x1F01
GL_SRC_ALPHA = 0x0302
GL_VENDOR = 0x1F00
GL_VERSION = 0x1F02
GL_TRUE = 1

# Constants for Linux Platform
PGLint = GLint * 11

GLX_RGBA = 4
GLX_RED_SIZE = 8
GLX_GREEN_SIZE = 9
GLX_BLUE_SIZE = 10
GLX_DEPTH_SIZE = 12
GLX_DOUBLEBUFFER = 5


# OpenGL Function Definitions
glBegin = _gl.glBegin
glBegin.restype = None
glBegin.argtypes = [GLenum]

glClear = _gl.glClear
glClear.restype = None
glClear.argtypes = [GLbitfield]

glBlendFunc = _gl.glBlendFunc
glBlendFunc.restype = None
glBlendFunc.argtypes = [GLenum, GLenum]

glClearColor = _gl.glClearColor
glClearColor.restype = None
glClearColor.argtypes = [GLclampf, GLclampf, GLclampf, GLclampf]

glClearDepth = _gl.glClearDepth
glClearDepth.restype = None
glClearDepth.argtypes = [GLclampd]

glColor3f = _gl.glColor3f
glColor3f.restype = None
glColor3f.argtypes = [GLfloat, GLfloat, GLfloat]

glEnable = _gl.glEnable
glEnable.restype = None
glEnable.argtypes = [GLenum]

glEnd = _gl.glEnd
glEnd.restype = None
glEnd.argtypes = None

glFlush = _gl.glFlush
glFlush.restype = None
glFlush.argtypes = None

glGetString = _gl.glGetString
glGetString.restype = GLubyte
glGetString.argtypes = [GLenum]

glLoadIdentity = _gl.glLoadIdentity
glLoadIdentity.restype = None
glLoadIdentity.argtypes = None

glMatrixMode = _gl.glMatrixMode
glMatrixMode.restype = None
glMatrixMode.argtypes = None

glOrtho = _gl.glOrtho
glOrtho.restype = None
glOrtho.argtypes = [GLdouble, GLdouble, GLdouble, GLdouble, GLdouble, GLdouble]

glRotatef = _gl.glRotatef
glRotatef.restype = None
glRotatef.argtypes = [GLfloat, GLfloat, GLfloat, GLfloat]

glVertex3f = _gl.glVertex3f
glVertex3f.restype = None
glVertex3f.argtypes = [GLfloat, GLfloat, GLfloat]

glViewport = _gl.glViewport
glViewport.restype = None
glViewport.argtypes = [GLint, GLint, GLint, GLint]

glXChooseVisual = _gl.glXChooseVisual
glXChooseVisual.argtypes = [c_void_p, c_int, POINTER(c_int)]
glXChooseVisual.restype = c_void_p

glXCreateContext = _gl.glXCreateContext
glXCreateContext.argtypes = [c_void_p, c_void_p, c_void_p, c_bool]
glXCreateContext.restype = c_void_p

glXMakeCurrent = _gl.glXMakeCurrent
glXMakeCurrent.argtypes = [c_void_p, GLXDrawable, c_void_p]
glXMakeCurrent.restype = c_bool

glXSwapBuffers = _gl.glXSwapBuffers
glXSwapBuffers.argtypes = [c_void_p, GLXDrawable]
glXSwapBuffers.resttype = None

X11_None = 0

x_open_display = _xlib.XOpenDisplay
x_open_display.argtypes = [c_char_p]
x_open_display.restype = c_void_p


class TkOglWin(Frame):

    def __init__(self, parent, *args, **kwargs):
        Frame.__init__(self, parent, *args, **kwargs)
        self.parent = parent
        self.parent.title(kwargs.get('app_title', 'Opengl Test'))
        self.bind('<Configure>', self.on_resize)
        self.parent.after(100, self._cfg_tkogl)

    def _cfg_tkogl(self):
        att = PGLint(
            GLX_RGBA, GLX_DOUBLEBUFFER,
            GLX_RED_SIZE, 4,
            GLX_GREEN_SIZE, 4,
            GLX_BLUE_SIZE, 4,
            GLX_DEPTH_SIZE, 16,
            X11_None
        )

        self.dpy = x_open_display(None)
        vi = glXChooseVisual(self.dpy, 0, att)
        glc = glXCreateContext(self.dpy, vi, None, GL_TRUE)
        glXMakeCurrent(self.dpy, self.winfo_id(), glc)
        self.set_ortho_view()
        self.parent.after(10, self._render_loop)

    def on_resize(self, event, arg=None):
        raise NotImplementedError

    def _render_loop(self):
        self.render_scene()
        glXSwapBuffers(self.dpy, self.winfo_id())
        self.parent.after(5, self._render_loop)

    def render_scene(self):
        raise NotImplementedError

    def set_ortho_view(self):
        raise NotImplementedError


class AppOgl(TkOglWin):
    rot = 0

    def on_resize(self, event, arg=None):
        if event:
            w = event.width
            h = event.height
        else:
            if arg:
                w = arg['w']
                h = arg['h']
            else:
                raise Exception

        dx = w / h
        glViewport(0, 0, w, h)
        glMatrixMode(GL_PROJECTION)
        glLoadIdentity()
        glOrtho(-2 * dx, 2 * dx, -2, 2, -2, 2)

    def set_ortho_view(self):
        glEnable(GL_BLEND)
        glEnable(GL_DEPTH_TEST)
        glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)
        glClearColor(0, 0, 0, 0)
        glClearDepth(1)
        glMatrixMode(GL_PROJECTION)

        self.on_resize(None, arg={
            'w': self.winfo_width(),
            'h': self.winfo_height()
        })

        print('%s - %s - %s' % (
            glGetString(GL_VENDOR),
            glGetString(GL_VERSION),
            glGetString(GL_RENDERER)
        ))

    def render_scene(self):
        self.rot += .5

        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
        glMatrixMode(GL_MODELVIEW)
        glLoadIdentity()
        glRotatef(self.rot, 1, 1, 0.5)

        # Draw a simple cube.
        glBegin(GL_QUADS)
        glColor3f(0, 1, 0)
        glVertex3f(1, 1, -1)
        glVertex3f(-1, 1, -1)
        glVertex3f(-1, 1, 1)
        glVertex3f(1, 1, 1)
        glColor3f(1, 0.5, 0)
        glVertex3f(1, -1, 1)
        glVertex3f(-1, -1, 1)
        glVertex3f(-1, -1, -1)
        glVertex3f(1, -1, -1)
        glColor3f(1, 0, 0)
        glVertex3f(1, 1, 1)
        glVertex3f(-1, 1, 1)
        glVertex3f(-1, -1, 1)
        glVertex3f(1, -1, 1)
        glColor3f(1, 1, 0)
        glVertex3f(1, -1, -1)
        glVertex3f(-1, -1, -1)
        glVertex3f(-1, 1, -1)
        glVertex3f(1, 1, -1)
        glColor3f(0, 0, 1)
        glVertex3f(-1, 1, 1)
        glVertex3f(-1, 1, -1)
        glVertex3f(-1, -1, -1)
        glVertex3f(-1, -1, 1)
        glColor3f(1, 0, 1)
        glVertex3f(1, 1, -1)
        glVertex3f(1, 1, 1)
        glVertex3f(1, -1, 1)
        glVertex3f(1, -1, -1)
        glEnd()
        glFlush()

if __name__ == '__main__':
    root = Tk()
    app = AppOgl(root, width=320, height=200)
    app.pack(fill=BOTH, expand=YES)
    app.mainloop()