Btukfyl

I am trying to render a cube over a detect marker in openGL. I am doing it like this.

    rmtx = cv2.Rodrigues(rvec)[0]

    m1 = np.array([[rmtx[0][0],rmtx[0][1],rmtx[0][2],tvec[0][0][0]],

                    [rmtx[1][0],rmtx[1][1],rmtx[1][2],tvec[0][0][1]],

                    [rmtx[2][0],rmtx[2][1],rmtx[2][2],tvec[0][0][2]],

                    [0.0       ,0.0       ,0.0       ,1.0    ]])

    Inverse_mat = np.array([[ 1.0, 1.0, 1.0, 1.0],

                       [-1.0,-1.0,-1.0,-1.0],

                       [-1.0,-1.0,-1.0,-1.0],

                       [ 1.0, 1.0, 1.0, 1.0]])

    m1 = m1 * Inverse_mat

    m1 = np.transpose(m1)

After loading the matrix m1 there is glutSolidCube() statement. The problem is that the cube is not in the viewable screen of openGL. I even scaled and shifted the tvec parameters of m1.

X = np.array([[1,0,0,x shift],

                        [0,1,0,y shift],

                        [0,0,1,z shift],

                        [0,0,0,1]])

    Y = np.array([[tvec[0][0][0]],

                         [tvec[0][0][1]],

                         [tvec[0][0][2]],

                         [1]])

    tvec = np.array([[sum(a*b for a,b in zip(X_row,Y_col)) for Y_col in zip(*Y)] for X_row in X])

    m1 = np.array([[rmtx[0][0],rmtx[0][1],rmtx[0][2],tvec[0]/scale x],

                    [rmtx[1][0],rmtx[1][1],rmtx[1][2],tvec[1]/scale y],

                    [rmtx[2][0],rmtx[2][1],rmtx[2][2],tvec[2]/scale z],

                    [0.0       ,0.0       ,0.0       ,1.0    ]])

This brings the cube over the marker but it is not aligned properly.

Moreover the values used for scaling and shifting is as per view on my screen and I want a general solution. What should I do?