OpenGL 2D hud in 3D application

Question

I have been trying to create a hud in my OpenGL application. Having looked around, it seems the way to do it is with an ortho projection, but so far I have not been able to

Answer 1

Once you're done rendering the HUD, you need to re-enable the depth writes

glDepthMask(GL_TRUE);

Answer 2

When you clear the buffers when rendering your HUD, all that has been drawn so far (your 3D scene) will also be cleared. So don't clear the buffer twice.