I've observed that from Catalyst 10.10a the OpenGL driver includes the extension GL_EXT_shader_image_load_store which is great news.
However, the extension mentions atomic counters that would be available via the extension GL_EXT_shader_atomic_counters, but the extension is not present (even though there is an ARB version of the extension in the extensions list).
Anyway, there is no any documentation about GL_ARB_shader_atomic_counters or GL_EXT_shader_atomic_counters and this way we are unable to use them.
I know that GL_EXT_shader_image_load_store enables atomic R/W operations to buffer objects but I suspect that atomic counters are a much faster way in hardware so it would be a great benefit to be able to use it.
The reason why I opened this topic is that I would like to implement Order Independent Transparency (OIT) in OpenGL and even though it would be possible to do it using only GL_EXT_shader_image_load_store, I suppose performance would benefit from dedicated atomic counters.
Can you give us any (even "non-official") specification of the atomic counters extensions?