How did I just use an OpenGL 3 feature in a 1.1 context?

Question

I just started programming in OpenGL a few weeks ago, and as people suggested to me, I used GLFW as my window handler. I also used GLEW as my extensions handler. So I go through the whole process of making a vertex buffer with three points to draw a triangle and passing it to OpenGL to draw it and I compile and run. No triangle draws, presumably because I didn't have any shaders. So I think to myself "Why don't I lower my OpenGL version through the context creation using GLFW?" and I did that. From OpenGL 3.3 to 1.1 and surely enough, there's a triangle. Success, I thought. Then I remember an article saying that vertex buffers have only been introduce in OpenGL 3, so how have I possibly used an OpenGL 3 feature in a 1.1 context?

Without the code, I am guessing that you have set OpenGL version with glfwWindowHint. Have you checked the actual version afterwards with glfwGetWindowAttrib? — Keugyeol
Correct, I have used glfwWindowHint to set context version major and minor, and no I have not checked. — Nooble

Colonel Thirty Two Colonel Thirty Two · Accepted Answer · 2014-08-27T03:12:33

The graphics driver is free to give you a context which is a different version than what you requested, as long as they are compatible. For example, you may get a v3.0 context even if you ask for a v1.1 context, as OpenGL 3.0 does not change or remove any features from OpenGL 1.1.

Additionally, often times the only difference between OpenGL versions is what extensions that the GPU must support. If you have a v1.1 context but ARB_vertex_buffer_object is supported, then you will still be able to use VBOs (though you may need to append the ARB suffix to the function names).

How did I just use an OpenGL 3 feature in a 1.1 context?

1 Answers