OpenGL functions missing in SFML environment

Question

Following this tutorial I was trying to manage my OpenGL buffers for an OpenGL context I created using SFML, under a visual studio environment. I installed SFML and Glew in their latest versions, did correct linking, and I am able to work with primitives like OpenGL glClear, glBegin and glVertext3d.

However there is plenty of other OpenGL functions that I can t seem to be able to call like glEnableVertexAttribArray or glBindBuffer and I would like to understand why. I noticed that the default OpenGL version set by SFML context is 4.6 but I can t find proper documentation for these functions on khronos website for this version. Moreover my visual studio doesn t even recognize theses functions as part of any library but I might have missed some includes given that I rely on SFML/OpenGL.hpp. Documentation on SFML side is very ligth on this subject...

Thanks !

... and call glewInit() to initialize its function pointers. — Quentin
– Quentin, Commented Jan 21, 2019 at 16:30
Both perfect ! Thanks a lot. Post it as answer if you want some more points ;) — Victor Drouin
– Victor Drouin, Commented Jan 21, 2019 at 17:15

tkausl · Accepted Answer · 2019-01-21 17:40:20Z

2

I am able to work with primitives like OpenGL glClear, glBegin and glVertext3d. However there is plenty of other OpenGL functions that I can t seem to be able to call like glEnableVertexAttribArray or glBindBuffer and I would like to understand why.

The reason for this is that the opengl32 library on windows only provides OpenGL 1.1 functionality, everything else is brought in by your graphics card driver. To actually access these functions, windows provides a function to load them. However, writing all the declarations and loading all functions is a lot of work (See Load OpenGL Functions in the OpenGL Wiki) so libraries exist which do this for you, one such library is glew, "The OpenGL Extension Wrangler Library". After you created your OpenGL context (which SFML does), you must call glewInit() which then loads all the other functions. The declarations for those functions are also provided by glew, so make sure to include the glew header instead of your systems or SFMLs opengl header.

answered Jan 21, 2019 at 17:40

tkausl

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1 Comment

Victor Drouin Over a year ago

I was indeed missing the glew header ;) thanks for your time !

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