1

I can't run even the simplest program that is using OpenGL / GLUT.

i.e.

from OpenGL.GL import *
from OpenGL.GLU import *
from OpenGL.GLUT import *


def showScreen():
    # Remove everything from screen (i.e. displays all white)
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)


glutInit()  # Initialize a glut instance which will allow us to customize our window
glutInitDisplayMode(GLUT_RGBA)  # Set the display mode to be colored
glutInitWindowSize(500, 500)   # Set the width and height of your window
# Set the position at which this windows should appear
glutInitWindowPosition(0, 0)
wind = glutCreateWindow("OpenGL Coding Practice")  # Give your window a title
# Tell OpenGL to call the showScreen method continuously
glutDisplayFunc(showScreen)
# Draw any graphics or shapes in the showScreen function at all times
glutIdleFunc(showScreen)
glutMainLoop()

I always receive this error message:

Traceback (most recent call last):
  File "/Users/xyz/jebacglut123.py", line 11, in <module>
    glutInit()  # Initialize a glut instance which will allow us to customize our window
  File "/usr/local/anaconda3/envs/opengl/lib/python3.8/site-packages/OpenGL/GLUT/special.py", line 362, in glutInit
    _base_glutInit(ctypes.byref(count), holder)
  File "/usr/local/anaconda3/envs/opengl/lib/python3.8/site-packages/OpenGL/platform/baseplatform.py", line 423, in __call__
    raise error.NullFunctionError(
OpenGL.error.NullFunctionError: Attempt to call an undefined function glutInit, check for bool(glutInit) before calling

I'm using MacOS Big Sur 20B29, python 3.8.5 and PyOpenGL 3.1.5. I have modified the PyOpenGL file using this tutorial to fix other error.

genpfault
  • 51,148
  • 11
  • 85
  • 139
padar
  • 13
  • 4

1 Answers1

2

The cause of this problem is quite similar to that in the question you mentioned.

To address this problem, just replace the line (in the file OpenGL/platform/ctypesloader.py)

fullName = util.find_library( name )

with

if name == 'OpenGL':
    fullName = '/System/Library/Frameworks/OpenGL.framework/OpenGL'
elif name == 'GLUT':
    fullName = '/System/Library/Frameworks/GLUT.framework/GLUT'
Zhuxian
  • 21
  • 3