Not everything that you ask OpenGL to render will actually render. OpenGL makes the decision of what to render and not to render depending on what can be seen in a viewing volume. Learn how Clipping occurs in OpenGL.
Have you ever wondered how does the OpenGL Graphics Pipeline receives data? Learn about the mechanism that OpenGL uses to declare data that will be used as input and what stages are responsible for providing this data to the vertex shader.
The OpenGL API is vast. It has so many function calls that remembering them is an uphill battle. OpenGL is also a state machine. There are so many steps that you need to remember. Remembering in OpenGL is quite simple, but...
Class Templates, just like Function Templates, can help you avoid code duplication in your app. They are simple to set up and yet very powerful. Learn more about them.