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"""Headless GPU-accelerated OpenGL context creation on Google Colaboratory.
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Typical usage:
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# Optional PyOpenGL configuratiopn can be done here.
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# import OpenGL
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# OpenGL.ERROR_CHECKING = True
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# 'glcontext' must be imported before any OpenGL.* API.
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from lucid.misc.gl.glcontext import create_opengl_context
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# Now it's safe to import OpenGL and EGL functions
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import OpenGL.GL as gl
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# create_opengl_context() creates a GL context that is attached to an
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# offscreen surface of the specified size. Note that rendering to buffers
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# of other sizes and formats is still possible with OpenGL Framebuffers.
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#
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# Users are expected to directly use the EGL API in case more advanced
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# context management is required.
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width, height = 640, 480
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create_opengl_context((width, height))
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# OpenGL context is available here.
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"""
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from __future__ import print_function
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try:
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import OpenGL
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except:
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print('This module depends on PyOpenGL.')
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print('Please run "\033[1m!pip install -q pyopengl\033[0m" '
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'prior importing this module.')
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raise
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import ctypes
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from ctypes import pointer, util
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import os
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os.environ['PYOPENGL_PLATFORM'] = 'egl'
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_find_library_old = ctypes.util.find_library
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try:
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def _find_library_new(name):
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return {
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'GL': 'libOpenGL.so',
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'EGL': 'libEGL.so',
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}.get(name, _find_library_old(name))
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util.find_library = _find_library_new
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import OpenGL.GL as gl
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import OpenGL.EGL as egl
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except:
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print('Unable to load OpenGL libraries. '
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'Make sure you use GPU-enabled backend.')
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print('Press "Runtime->Change runtime type" and set '
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'"Hardware accelerator" to GPU.')
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raise
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finally:
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util.find_library = _find_library_old
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def create_opengl_context(surface_size=(640, 480)):
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"""Create offscreen OpenGL context and make it current.
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Users are expected to directly use EGL API in case more advanced
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context management is required.
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Args:
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surface_size: (width, height), size of the offscreen rendering surface.
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"""
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egl_display = egl.eglGetDisplay(egl.EGL_DEFAULT_DISPLAY)
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major, minor = egl.EGLint(), egl.EGLint()
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egl.eglInitialize(egl_display, pointer(major), pointer(minor))
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config_attribs = [
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egl.EGL_SURFACE_TYPE, egl.EGL_PBUFFER_BIT, egl.EGL_BLUE_SIZE, 8,
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egl.EGL_GREEN_SIZE, 8, egl.EGL_RED_SIZE, 8, egl.EGL_DEPTH_SIZE, 24,
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egl.EGL_RENDERABLE_TYPE, egl.EGL_OPENGL_BIT, egl.EGL_NONE
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]
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config_attribs = (egl.EGLint * len(config_attribs))(*config_attribs)
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num_configs = egl.EGLint()
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egl_cfg = egl.EGLConfig()
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egl.eglChooseConfig(egl_display, config_attribs, pointer(egl_cfg), 1,
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pointer(num_configs))
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width, height = surface_size
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pbuffer_attribs = [
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egl.EGL_WIDTH,
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width,
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egl.EGL_HEIGHT,
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height,
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egl.EGL_NONE,
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]
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pbuffer_attribs = (egl.EGLint * len(pbuffer_attribs))(*pbuffer_attribs)
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egl_surf = egl.eglCreatePbufferSurface(egl_display, egl_cfg,
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pbuffer_attribs)
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egl.eglBindAPI(egl.EGL_OPENGL_API)
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context_attribs = None
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egl_context = egl.eglCreateContext(egl_display, egl_cfg,
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egl.EGL_NO_CONTEXT, context_attribs)
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egl.eglMakeCurrent(egl_display, egl_surf, egl_surf, egl_context)
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buffer_type = egl.EGLint()
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out = egl.eglQueryContext(egl_display, egl_context,
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egl.EGL_CONTEXT_CLIENT_VERSION, buffer_type)
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