Generation of lower resolution textures So I have a game and I am trying to fake glow inside of it by using the hardwares capability to downsize textures causing them to blur.

The texture I wish to do this with is in a render buffer that is the size of the screen (not power of two)

What would be the quickest way to get these lower resolutions created?
Tricking the software to make minimaps?
Another fbo with the texture rendered on it in smaller size?
I would think rendering to a downsampled FBO would be much faster than generating mipmaps.  glGenerateMipmap will generate the complete mipmap pyramid, which seems wasteful:

https://www.khronos.org/opengles/sdk/docs/man/xhtml/glGenerateMipmap.xml

Besides, only OpenGL ES 3.0 lets you manually select mip level when texturing:

https://www.khronos.org/opengles/sdk/docs/man3/html/textureLod.xhtml

Artistically, this might not give you the look you want.  In my experience, simply downsampling gives a grainy look.  I would recommend also doing a pair of one-dimensional blurs, as described in this article from GPU Gems:

http://developer.download.nvidia.com/books/HTML/gpugems/gpugems_ch21.html