draw sphere using python3 in GTK+ window using GLUT

Question

My intention is to draw some 3d object in a GTK+ window. I found OpenGL is best for my purpose. So, I am using GTK+ and pyopenGL for the purpose.

This is my current status, and merely able to draw a GtkGlArea:

import gi
import sys
gi.require_version('Gtk', '3.0')
from gi.repository import Gtk, Gio, Gdk
from OpenGL.GL import *
from OpenGL.GLU import *
from OpenGL.GLUT import *


class GridWindow(Gtk.ApplicationWindow):
  def __init__(self, app):
    Gtk.Window.__init__(self, application = app,
                        default_width=1000,
                        default_height=200,
                        border_width=2,
                        name = "MyWindow")

    # Main drawing area
    self.area = DrawArea()
    self.area.set_size_request(1000,800)
    # To attach everything
    grid = Gtk.Grid()

    grid.attach(self.area,1,0,1,1)
    self.add(grid)

class DrawArea(Gtk.GLArea):
    def __init__(self):
        Gtk.GLArea.__init__(self)
        self.connect("realize", self.on_realize)
        self.connect("render", self.render)
        glutInit(sys.argv)
        glutDisplayFunc(self.render)
        return

    def on_realize(self, area):
        ctx = self.get_context()
        ctx.make_current()
        err = self.get_error()
        if err:
            print("The error is {}".format(err))

    def render(self, area, ctx):
        glClearColor(.7,.70,.70,1)
        glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT)
        color = [1.0,0.,0.,1.]
        glutSolidSphere(2,20,20)
        return True

class draw(Gtk.Application):
  def __init__(self):
    Gtk.Application.__init__(self)
  def do_activate(self):
    win = GridWindow(self)
    win.show_all()


app = draw()
exit_status = app.run(sys.argv)
sys.exit(exit_status)

Without the Glut's call, this is showing the GlArea. But as soon as I am trying to draw a sphere using Glut, its throwing error:

python3 devel.py 
Traceback (most recent call last):
  File "devel.py", line 54, in do_activate
    win = GridWindow(self)
  File "devel.py", line 19, in __init__
    self.area = DrawArea()
  File "devel.py", line 33, in __init__
    glutDisplayFunc(self.render)
  File "/usr/lib/python3.6/site-packages/OpenGL/GLUT/special.py", line 147, in __call__
    contextdata.setValue( self.CONTEXT_DATA_KEY, cCallback )
  File "/usr/lib/python3.6/site-packages/OpenGL/contextdata.py", line 58, in setValue
    context = getContext( context )
  File "/usr/lib/python3.6/site-packages/OpenGL/contextdata.py", line 41, in getContext
    """Attempt to retrieve context when no valid context"""
OpenGL.error.Error: Attempt to retrieve context when no valid context

Since there is not much resource in python3+opengl+gtk3, I am in a bit trouble.

Updated Code After First Reply By Rabbid76:

import gi
import sys
gi.require_version('Gtk', '3.0')
from gi.repository import Gtk, Gio, Gdk
from OpenGL.GL import *
from OpenGL.GLU import *
from OpenGL.GLUT import *


class GridWindow(Gtk.ApplicationWindow):
  def __init__(self, app):
    Gtk.Window.__init__(self, application = app,
                        default_width=1000,
                        default_height=200,
                        border_width=2,
                        name = "MyWindow")

    # Main drawing area
    self.area = DrawArea()
    self.area.set_size_request(1000,800)
    # To attach everything
    grid = Gtk.Grid()

    grid.attach(self.area,1,0,1,1)
    self.add(grid)

class DrawArea(Gtk.GLArea):
    def __init__(self):
        Gtk.GLArea.__init__(self)
        self.connect("realize", self.on_realize)
        self.connect("render", self.render)
        glutInit(sys.argv)
        glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH)
        glutInitWindowSize(600, 800)
        glutCreateWindow(b'my OpenGL window')
        glutDisplayFunc(self.render)
        glutMainLoop()

    def on_realize(self, area):
        ctx = self.get_context()
        ctx.make_current()
        err = self.get_error()
        if err:
            print("The error is {}".format(err))

    def render(self):
        glClearColor(.7,.70,.70,1)
        glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT)
        color = [1.0,0.,0.,1.]
        glutSolidSphere(20,20,20)
        glutSwapBuffers()
        glutPostRedisplay()
        return True

class draw(Gtk.Application):
  def __init__(self):
    Gtk.Application.__init__(self)
  def do_activate(self):
    win = GridWindow(self)
    win.show_all()


app = draw()
exit_status = app.run(sys.argv)
sys.exit(exit_status)

That is generic and applied for C language. I need help in this code because pyopengl+gtk documentation is too sparse. But, one info is interesting **Gtk+GLUT does not make sense**. Is it correct? In that case what is the way to draw sphere in openGl? — BaRud, Jan 13 '18 at 13:14

Rabbid76 · Answer 1 · 2018-01-13T16:29:07.360

You cannot use GTK and GLUT together. See How do I use GTK and glut together? .

If you want to draw a glutSolidSphere sphere in a "glut" window, then you have to create a OpenGL window with a current OpenGL context. See glutCreateWindow, glutMainLoop, glutSwapBuffers, glutPostRedisplay :

class DrawArea:
    def __init__(self):
        glutInit(sys.argv)
        glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH)
        glutInitWindowSize(600, 800)
        glutCreateWindow(b'my OpenGL window')
        glutDisplayFunc(self.render)
        glutMainLoop()


   def render(self, area, ctx):

        .....

        glutSwapBuffers()
        glutPostRedisplay()

See also Texture wrapping an entire sphere in PyOpenGL

Hi, thanks for your reply. But this is neither drawing the sphere in glut window,nor glutwindow is openning on GlArea. May you kindly check it a bit more? The updated code is attached — BaRud, Jan 13 '18 at 13:03

draw sphere using python3 in GTK+ window using GLUT

1 Answers1