PyOpenGL: move two objects separately?

Question

I am pretty new in using PyOpenGL and I want to load an obj file, move it, then draw a sphere and move it. I want the two objects to move separately when I use different keyboard buttons. Is it possible? (I also need the coordinate of the center of each object). The problem is that they both move even if I use Push and Pop matrix commands

Here is my code:

    rom objloader import *



def main():

    pygame.init()
    display  = (800,600)
    pygame.display.set_mode(display, OPENGL | DOUBLEBUF) 

    glMatrixMode(GL_PROJECTION) 
    gluPerspective(45.0, display[0]/display[1], 0.1, 100.0)

    glLightfv(GL_LIGHT5, GL_POSITION,  (-40, 200, 100, 0.0))
    glLightfv(GL_LIGHT5, GL_AMBIENT, (0.2, 0.2, 0.2, 1.0))
    glLightfv(GL_LIGHT5, GL_DIFFUSE, (0.5, 0.5, 0.5, 1.0))
    glEnable(GL_LIGHT5) 
    glEnable(GL_LIGHTING)
    glEnable(GL_COLOR_MATERIAL)
    glEnable(GL_DEPTH_TEST)
    glShadeModel(GL_SMOOTH) 

    glMatrixMode(GL_MODELVIEW) 



    glTranslatef(0, 0, -5)
    x = 0
    y = 0
    z = - 5
    xx = 0
    yy = 0
    zz = -5

    # LOAD OBJECT 
    obj = OBJ(sys.argv[1], swapyz=True)
    sphere = gluNewQuadric() #Create new sphere
    model = glGetDoublev(GL_MODELVIEW_MATRIX)

    rx, ry = (0,0)
    tx, ty = (0,0)
    zpos = 5
    rotate = move = False

    clock = pygame.time.Clock() 

    while 1:
        clock.tick(30)
        glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT) #Clear the screen


        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                sys.exit()
            if event.type == pygame.KEYDOWN:
                if event.key == pygame.K_ESCAPE or event.key == pygame.K_RETURN:
                    sys.exit()  

        keypress = pygame.key.get_pressed()


        glMatrixMode(GL_MODELVIEW)


        glPushMatrix()
        glLoadIdentity()


        if keypress[pygame.K_w]:
            glTranslatef(0,-0.01,0)
            y = y - 0.01
        if keypress[pygame.K_s]:
            glTranslatef(0,0.01,0)
            y = y + 0.01
        if keypress[pygame.K_d]:
            glTranslatef(0.01,0,0)
            x = x + 0.01
        if keypress[pygame.K_a]:
            glTranslatef(-0.01,0,0)
            x = x - 0.01
        if keypress[pygame.K_z]:
            glTranslatef(0, 0, -0.01)
            z = z - 0.01
        if keypress[pygame.K_x]:
            glTranslatef(0,0,0.01)
            z = z + 0.01
        if keypress[pygame.K_0]:
            start = x, y, z
            print('start is', start)


        #model = glGetDoublev(GL_MODELVIEW_MATRIX)
        glMultMatrixf(model)
        model = glGetDoublev(GL_MODELVIEW_MATRIX)
        glMultMatrixf(model)
        glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT)
        glScalef(0.1, 0.1, 0.1)
        glColor4f(0.5, 0.2, 0.2, 1)
        gluSphere(sphere, 1.0, 32, 16)
        glPopMatrix()



        glPushMatrix()
        glLoadIdentity()

        if keypress[pygame.K_u]:
            glTranslatef(0,-0.01,0)
            yy = yy - 0.01
        if keypress[pygame.K_j]:
            glTranslatef(0,0.01,0)
            yy = yy + 0.01
        if keypress[pygame.K_k]:
            glTranslatef(0.01,0,0)
            xx = xx + 0.01 
        if keypress[pygame.K_h]:
            glTranslatef(-0.01,0,0)
            xx = xx - 0.01
        if keypress[pygame.K_n]:
            glTranslatef(0, 0, -0.01)
            zz = zz - 0.01
        if keypress[pygame.K_m]:
            glTranslatef(0,0,0.01)
            zz = zz + 0.01
        if keypress[pygame.K_l]:
            glRotatef(1, 0, 1, 5)
            xx = xx*math.cos(rad)-y*math.sin(rad)
            yy = xx*math.sin(rad)+yy*math.cos(rad)
        if keypress[pygame.K_g]:
            #glTranslatef(xx, yy, zz)
            glRotatef(1, 0, 1, -5)
            #glTranslatef(-xx, -yy, -zz)
            rad = 1*180/math.pi
            xx = xx*math.cos(rad)-yy*math.sin(rad)
            yy = xx*math.sin(rad)+yy*math.cos(rad)
            print(xx, yy, math.sin( rad))
        if keypress [pygame.K_9]:
            print('obj coord', xx, yy, zz)


        glMultMatrixf(model)
        model = glGetDoublev(GL_MODELVIEW_MATRIX)
        glMultMatrixf(model)
        #glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT) --> se lo metti non vedi l'oggetto prima
        glScalef(0.1, 0.1, 0.1)
        glCallList(obj.gl_list)



        glPopMatrix()


        pygame.display.flip() #Update the screen


main()

Answer 1

The problem is that they both move even if I use Push and Pop matrix commands

The model matrix defines the position orientation and scale of a single object (mesh) in the scene. Thus you need a separate model matrix for each object:

def main():

    # [...]

    glMatrixMode(GL_PROJECTION) 
    glLoadIdentity() 
    gluPerspective(45.0, display[0]/display[1], 0.1, 100.0)

    glMatrixMode(GL_MODELVIEW)
    glLoadIdentity() 

    glTranslatef(0, 0, -5)
    model_1 = glGetDoublev(GL_MODELVIEW_MATRIX)
    model_2 = model_1

    # [...]

    while 1:
        # [...]

        glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT)

        glMatrixMode(GL_MODELVIEW)


        # Model 1

        glPushMatrix()
        glLoadIdentity()

        # rotate and translate model 1
        # [...] 

        glMultMatrixf(model_1)
        model_1 = glGetDoublev(GL_MODELVIEW_MATRIX)

        glScalef(0.1, 0.1, 0.1)

        # draw model 1
        glColor4f(0.5, 0.2, 0.2, 1)
        gluSphere(sphere, 1.0, 32, 16)

        glPopMatrix()


        # Model 2

        glPushMatrix()
        glLoadIdentity()

        # rotate and translate model 2
        # [...] 

        glMultMatrixf(model_2)
        model_2 = glGetDoublev(GL_MODELVIEW_MATRIX)
        glScalef(0.1, 0.1, 0.1)

        # draw model 1
        glCallList(obj.gl_list)

        glPopMatrix()


        pygame.display.flip() #Update the screen