Screenshots in OpenGL using python

Question

How do we take a screenshot of the OpenGL windows using python? Using jupyter, opengl and pygame. The code is:

import pygame
from pygame.locals import *
from OpenGL.GL import *
from OpenGL.GLU import *
from math import *


a=[[cos(0.5*pi/180),sin(0.5*pi/180),0],
       [-sin(0.5*pi/180),cos(0.5*pi/180),0],
       [0,0,1]]
def zarb_matris(p,b): 
         c=[b[0][0]*p[0][0]+b[0][1]*p[1][0]+b[0][2]*p[2][0], 
            b[1][0]*p[0][0]+b[1][1]*p[1][0]+b[1][2]*p[2][0], 
            b[2][0]*p[0][0]+b[2][1]*p[1][0]+b[2][2]*p[2][0]] 
         return c 
          
verticies= [ 
         [1, -1, -1], 
         [1, 1, -1], 
         [-1, 1, -1], 
         [-1, -1, -1], 
         [1, -1, 1], 
         [1, 1, 1], 
         [-1, -1, 1], 
         [-1, 1, 1] 
         ] 
      
      
edges = ( 
         (0,1), 
         (0,3), 
         (0,4), 
         (2,1), 
         (2,3), 
         (2,7), 
         (6,3), 
         (6,4), 
         (6,7), 
         (5,1), 
         (5,4), 
         (5,7), 
         ) 
      
surfaces= ( 
         (0,1,2,3), 
         (3,2,7,6), 
         (6,7,5,4), 
         (4,5,1,0), 
         (1,5,7,2), 
         (4,0,3,6) 
         ) 
      
colors = ( 
         (0.9,0,0), 
         (0,1,0), 
         (0.75,0.38,0), 
         (0,0,1), 
         (1,1,0), 
         (1,1,1),    
         (1,0,0), 
         (0,1,0), 
         (0.75,0.38,0), 
         (0,0,1), 
         (1,1,0), 
         (0.9,1,1) 
         ) 
      
      
def Cube(): 
    global verticies 
    glBegin(GL_QUADS) 
    x = 0 
    for surface in surfaces: 
        x+=1 
      
       for vertex in surface: 
            glColor3fv(colors[x]) 
            glVertex3fv(verticies[vertex]) 
    glEnd() 
    glBegin(GL_LINES) 
    glColor3fv((1,1,1)) 
    for edge in edges: 
        for vertex in edge: 
            glVertex3fv(verticies[vertex]) 
    glEnd() 
      
      
def main(): 
    global s 
    pygame.init() 
    display = (800,600) 
    pygame.display.set_mode(display, DOUBLEBUF|OPENGL) 
    glEnable(GL_DEPTH_TEST) 
    gluPerspective(45, (display[0]/display[1]), 0.1, 50.0) 
      
    glTranslatef(1,1, -10) 
      
    while True: 
        for event in pygame.event.get(): 
            if event.type == pygame.QUIT: 
                pygame.quit() 
                quit() 
        glRotatef(1, 12, 0,55115 ) 
        for i in range(8): 
            s=[] 
            for j in verticies[i]: 
                s.append([j]) 
            k=zarb_matris(s,a) 
            verticies[i]=k 
        glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT) 
        Cube() 
        pygame.display.flip() 
        pygame.time.wait(10) 
        
main()

I tried a couple of methods, but none of them seem to work, or require heavy modification of the current code. Is there anything that can be used to change the code minimally, or a library or a documentation that exists so that i can try to implement it?

Answer 1

Read the framebuffer with glReadPixels before the display is updated (before pygame.display.flip() or pygame.display.update()). Use pygame.image.fromstring() to create new Surfaces from the buffer. Finally, save the Surface to a file:

def main(): 
    # [...]
      
    while True: 
        screenshot = False
        for event in pygame.event.get(): 
            if event.type == pygame.QUIT: 
                pygame.quit() 
                quit() 
            if event.type == pygame.KEYDOWN:
                if event.key == pygame.K_s:
                    screenshot = True
        
        glRotatef(1, 12, 0,55115 ) 
        for i in range(8): 
            s=[] 
            for j in verticies[i]: 
                s.append([j]) 
            k=zarb_matris(s,a) 
            verticies[i]=k 

        glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT) 
        Cube() 

        if screenshot:
            screen = pygame.display.get_surface()
            size = screen.get_size()
            buffer = glReadPixels(0, 0, *size, GL_RGBA, GL_UNSIGNED_BYTE)
            screen_surf = pygame.image.fromstring(buffer, size, "RGBA")
            pygame.image.save(screen_surf, "screenshot.jpg")

        pygame.display.flip() 
        pygame.time.wait(10)