关于Vertex Array Objects(VAOs), Vertex
Buffer Objects(VBOs), Vertex and Fragment Shaders的概念还是看官方说明理解的好！
The OpenGL 3.2 core specification removes the majority of the fixed function pipeline previously used, and replaces it with a completely programmable architecture using shaders. Our tutorial will make use of VAOs and VBOs to provide our shaders with data.
A Vertex Array Object (VAO) is an object which contains one or more Vertex Buffer Objects（VBOs） and is designed to store the information for a complete rendered object.
A Vertex Buffer Object (VBO) is a memory buffer in the high speed memory of your video card
designed to hold information about vertices. VBOs can also store information such as normals, texcoords, indicies, etc.
A Vertex Shader in OpenGL is a piece of C like code written to the GLSL specification which influences the attributes
of a vertex. Vertex shaders can be used to modify properties of the vertex such as position, color, and texture coordinates.
A Fragment Shader is similar to a Vertex Shader, but is used for calculating individual fragment colors. This
is where lighting and bump-mapping effects are performed.
There is another shader type called Geometry Shaders which we will be using in a later tutorial. They are used to create additional vertices.
The shader pipeline behaves as follows: Vertex Shaders -> Geometry Shaders -> (Rasterizing Engine) -> Fragment Shaders.
The shaders are compilied and then chained together into a Shader Program.
The shaders receive input data from our VAO through a process of attribute binding, allowing us to perform the needed computations to provide us with the desired results.