PyOpenGL how do I import an obj file?

Set the keyword argument collect_faces = True, when you read the Wavefront .obj file. That causes that triangle face data are collected for every mesh.:
(See PyWavefront)

scene = pywavefront.Wavefront('Handgun_obj.obj', collect_faces=True)

Compute the scene box. The vertices are contained in scene.vertices. Each vertex is tuple with 3 components (x, y, z coordinate):

scene_box = (scene.vertices[0], scene.vertices[0])
for vertex in scene.vertices:
    min_v = [min(scene_box[0][i], vertex[i]) for i in range(3)]
    max_v = [max(scene_box[1][i], vertex[i]) for i in range(3)]
    scene_box = (min_v, max_v)

Compute a translation, that moves the center of the object to the origin and a scale, that scales the object to a defined size (scaled_size):

scene_trans    = [-(scene_box[1][i]+scene_box[0][i])/2 for i in range(3)]

scaled_size    = 5
scene_size     = [scene_box[1][i]-scene_box[0][i] for i in range(3)]
max_scene_size = max(scene_size)
scene_scale    = [scaled_size/max_scene_size for i in range(3)]

Each scene consists of meshes (scene.mesh_list) and each mesh has triangle faces (mesh.faces). Each fac is an array of 3 indies which refer to the array of vertices [scene.vertices]. Crate a function which sets the scale and translation and draw the model in nested loops:

def Model():
    glPushMatrix()
    glScalef(*scene_scale)
    glTranslatef(*scene_trans)

    for mesh in scene.mesh_list:
        glBegin(GL_TRIANGLES)
        for face in mesh.faces:
            for vertex_i in face:
                glVertex3f(*scene.vertices[vertex_i])
        glEnd()

    glPopMatrix()

See also PyGame and OpenGL immediate mode (Legacy OpenGL)


Minimal example (Stanford bunny):

repl.it/@Rabbid76/pygame-opengl-wavefront-obj

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

scene = pywavefront.Wavefront('bunny.obj', collect_faces=True)

scene_box = (scene.vertices[0], scene.vertices[0])
for vertex in scene.vertices:
    min_v = [min(scene_box[0][i], vertex[i]) for i in range(3)]
    max_v = [max(scene_box[1][i], vertex[i]) for i in range(3)]
    scene_box = (min_v, max_v)

scene_size     = [scene_box[1][i]-scene_box[0][i] for i in range(3)]
max_scene_size = max(scene_size)
scaled_size    = 5
scene_scale    = [scaled_size/max_scene_size for i in range(3)]
scene_trans    = [-(scene_box[1][i]+scene_box[0][i])/2 for i in range(3)]

def Model():
    glPushMatrix()
    glScalef(*scene_scale)
    glTranslatef(*scene_trans)

    for mesh in scene.mesh_list:
        glBegin(GL_TRIANGLES)
        for face in mesh.faces:
            for vertex_i in face:
                glVertex3f(*scene.vertices[vertex_i])
        glEnd()

    glPopMatrix()

def main():
        pygame.init()
        display = (800, 600)
        pygame.display.set_mode(display, DOUBLEBUF | OPENGL)
        gluPerspective(45, (display[0] / display[1]), 1, 500.0)
        glTranslatef(0.0, 0.0, -10)

        while True:
            for event in pygame.event.get():
                if event.type == pygame.QUIT:
                    pygame.quit()
                    quit()

                if event.type == pygame.KEYDOWN:
                    if event.key == pygame.K_LEFT:
                        glTranslatef(-0.5,0,0)
                    if event.key == pygame.K_RIGHT:
                        glTranslatef(0.5,0,0)
                    if event.key == pygame.K_UP:
                        glTranslatef(0,1,0)
                    if event.key == pygame.K_DOWN:
                        glTranslatef(0,-1,0)

            glRotatef(1, 5, 1, 1)
            glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT)

            glPolygonMode(GL_FRONT_AND_BACK, GL_LINE)
            Model()
            glPolygonMode(GL_FRONT_AND_BACK, GL_FILL)

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

main()

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