title: What are shaders in OpenGL and what do we need them for?
body: <p>When I'm trying to get through openGL wiki and tutorials on <a href="http://www.learnopengl.com" rel="nofollow noreferrer">www.learnopengl.com</a>, it never ends up understandable by intuition how whole concept works. Can someone maybe explain me in more abstract way how it works? What are vertex shader and fragment shader and what do we use them for?</p>