OpenGL make object face camera

Question

OpenGL ES3, C++ 11, Android, I have an object and a camera implementing third person camera so I want to make the object looks towards the camera when I touch the screen so I have a transformation matrix for the object and the view matrix of the camera, the camera rotates around the object , I want the object rotates towards the camera when I touch the screen so I tried the following:

glm::vec3 up(0, 1, 0);
glm::vec3 camFor(glm::cross(camera.getRight(), up));
GLfloat theta = glm::angle(glm::vec2(camFor.x, camFor.z), glm::vec2(getDirection().x, getDirection().z));
LOGI("game theta %f", theta);
matrix = glm::rotate(matrix, theta, glm::vec3(0.0, 1.0, 0.0));

I get the horizontal angle between the object forward vector and the camera forward one which is glm::vec3(matrix[2][0], matrix[2][1], matrix[2][2]) , first time when the camera is exactly behind the object I get theta equal to pi and that is right then I touch the screen to fire the event the object rotates and looks to the camera as expected and theta become zero, if I rotate the camera around the object and fire the event again it gives unexpected values for theta. the rotation code of the camera is:

void Camera::rotate(GLfloat xoffset, GLfloat yoffset, glm::vec3& c, double& delta, GLboolean constrainpitch) {
    xoffset *= (delta * this->rotSpeed);
    yoffset *= (delta * this->rotSpeed);
    pitch += yoffset;
    yaw += xoffset;
    if (constrainpitch) {
        if (pitch >= maxPitch) {
            pitch = maxPitch;
            yoffset = 0;
        }
        if (pitch <= minPitch) {
            pitch = minPitch;
            yoffset = 0;
        }
    }
    glm::quat Qx(glm::angleAxis(glm::radians(yoffset), glm::vec3(1.0f, 0.0f, 0.0f)));
    glm::quat Qy(glm::angleAxis(glm::radians(xoffset), glm::vec3(0.0f, 1.0f, 0.0f)));
    glm::mat4 rotX = glm::mat4_cast(Qx);
    glm::mat4 rotY = glm::mat4_cast(Qy);
    view = glm::translate(view, c);
    view = rotX * view;
    view = view * rotY;
    view = glm::translate(view, -c);
}

Solution:

the error was in getting the Right vector of the camera matrix this is the correct

glm::vec3& Camera::getRight() {
    right = glm::vec3(view[0][0], view[1][0], view[2][0]);
    return right;
}

Answer 1

the error was in getting the Right vector of the camera matrix this is the correct

glm::vec3& Camera::getRight() {
    right = glm::vec3(view[0][0], view[1][0], view[2][0]);
    return right;
}