It is possible to implement fragment shader to do one-pass gaussian blur? I have found lot of implementation of two-pass blur (gaussian and box blur):

• http://callumhay.blogspot.com/2010/09/gaussian-blur-shader-glsl.html
• http://www.gamerendering.com/2008/10/11/gaussian-blur-filter-shader/
• http://www.geeks3d.com/20100909/shader-library-gaussian-blur-post-processing-filter-in-glsl/

and so on.

I have been thinking of implementing gaussian blur as convolution (in fact, it is the convolution, the examples above are just aproximations):

http://en.wikipedia.org/wiki/Gaussian_blur