Please document OpenVR's requirements & recommendation of texture

[anatawa12]

It looks there's no documentation to describe the requirements of texture to pass OpenVR. However, in OpenGL, some texture formats such as 'GL_RGBA' is not accepted. Please document them.

In my environment, any formats except GL_RED, GL_RG, GL_RGB are accepted.

test: https://gist.github.com/anatawa12/6fd75182296019b01dd5da0fbaefa26c

document I've seen: https://github.com/ValveSoftware/openvr/wiki/IVROverlay::SetOverlayTexture

[aleiby]

I've gone ahead and updated the wiki page above to list supported OpenGL formats for Windows. I would expect GL_RGBA to work. On Linux, I believe we are currently limited to 8-bit SRGB formats for OpenGL textures.