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I'm starting to learn modern OpenGL, and as the title says, I just wanted to be sure of the purpose of VAO's in the rendering pipeline.

When rendering we use VBO to store datas, and then we use OpenGL functions like: glAttribe to say to the GPU that we are going to use this datas "in That way", like: the first 3 floats in the vertices that we passes through vbo are in fact positions, and the next 3 floats are colors etc... So then I readed that we need some VAO that stores the descriptions of the vertices but what's the goal there ?

Thanks in advance.

panicq
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  • There's a number of very similar questions with good answers: http://stackoverflow.com/questions/23314787/use-of-vertex-array-objects-and-vertex-buffer-objects, http://stackoverflow.com/questions/11821336/what-are-vertex-array-objects. – Reto Koradi Aug 09 '14 at 17:37

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Vertex array objects store a set of buffer names (usually vertex and index buffers) to get vertex data from, as well as how the vertices are layed out in the vertex buffers.

Their main purpose is so that when you want to render a different model from a different set of buffers, instead of binding each buffer and then setting the vertex attribute formats each time, you just bind a different VAO, and all the buffers and attributes are set up for you.

Not only is this more convenient for the programmer, it reduces the number of OpenGL calls required and thus CPU usage, which can clear up a CPU bottleneck.

Colonel Thirty Two
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