Ogre3d compositor and glsl shaders for Gaussian blur. It use a combination of horizontal blue and vertical blur.

Blur.compositor

compositor SceneCameraBlend
{
    technique
    {
        texture scene target_width target_height PF_A8R8G8B8
        target scene
        {
            input previous
        }
        target scene
        {
            input none
            pass render_quad
            {
                material VBlurMat
                input 0 scene
            }
        }
        target_output
        {
            input none
            pass render_quad
            {
                material HBlurMat
                input 0 blurred
            }
        }
    }
}

Blur.material

///
/// Vertical e Horizontal blur, combinati assieme danno
/// un blur gaussiano.
///

fragment_program VBlur_frag glsl
{
  source VBlur_frag.glsl
}

fragment_program HBlur_frag glsl
{
  source HBlur_frag.glsl
}

fragment_program Blur_frag glsl
{
  source Blur_frag.glsl
}

material VBlurMat
{
   technique
   {

      pass
      {
         lighting off
         fragment_program_ref VBlur_frag
         {
           param_named tex int 0
           param_named blurSize float 4.0
         }
         texture_unit
         {
            tex_coord_set 0
            tex_address_mode clamp
            filtering linear linear linear
         }
      }
   }
}

material HBlurMat
{
   technique
   {

      pass
      {
         lighting off
         fragment_program_ref HBlur_frag
         {
           param_named tex int 0
           param_named blurSize float 4.0
         }
         texture_unit
         {
            tex_coord_set 0
            tex_address_mode clamp
            filtering linear linear linear
         }
      }
   }
}

HBlur_frag.glsl

#version 120

///
/// Blur gaussiano orizzontale
/// Da utilizzare in catena con quello verticale per un blur completo
///

uniform sampler2D tex;
uniform float blurSize;

vec2 pos[11] = vec2[](
    vec2(-5.0, 0.0),
    vec2(-4.0, 0.0),
    vec2(-3.0, 0.0),
    vec2(-2.0, 0.0),
    vec2(-1.0, 0.0),
    vec2( 0.0, 0.0),
    vec2( 1.0, 0.0),
    vec2( 2.0, 0.0),
    vec2( 3.0, 0.0),
    vec2( 4.0, 0.0),
    vec2( 5.0, 0.0)
);

float samples[11] = float[](
	0.01222447,
	0.02783468,
	0.06559061,
	0.12097757,
	0.17466632,
	0.19741265,
	0.17466632,
	0.12097757,
	0.06559061,
	0.02783468,
	0.01222447
);

void main() {
    vec2 coord = vec2(gl_TexCoord[0]);
    vec4 sum = vec4( 0 );
    float bs = blurSize / 1024.0;
    for(int i = 0; i != 11; ++i) {
        sum += texture2D(tex, coord + (pos[i] * bs)) * samples[i];
    }
    gl_FragColor = sum;
}

VBlur_frag.glsl

#version 120

///
/// Blur gaussiano verticale
/// Da utilizzare in catena con quello orizzontale per un blur completo
///

uniform sampler2D tex;
uniform float blurSize;

vec2 pos[11] = vec2[](
    vec2(0.0, -5.0),
    vec2(0.0, -4.0),
    vec2(0.0, -3.0),
    vec2(0.0, -2.0),
    vec2(0.0, -1.0),
    vec2(0.0,  0.0),
    vec2(0.0,  1.0),
    vec2(0.0,  2.0),
    vec2(0.0,  3.0),
    vec2(0.0,  4.0),
    vec2(0.0,  5.0)
);

float samples[11] = float[](
    0.01222447,
    0.02783468,
    0.06559061,
    0.12097757,
    0.17466632,
    0.19741265,
    0.17466632,
    0.12097757,
    0.06559061,
    0.02783468,
    0.01222447
);

void main() {
    vec2 coord = vec2(gl_TexCoord[0]);
    vec4 sum = vec4( 0 );
    float bs = blurSize / 1024.0;
    int i = 0;
    for(; i != 11; ++i) {
        sum += texture2D(tex, coord + (pos[i] * bs)) * samples[i];
    }
    gl_FragColor = sum;
}