Love2d/glsl blur radial shader

--(c)Kekeke License, all rights not reserved, creating by Tomato for love2d-framework.
--OH MY GOSH! I WRITE A SHADER! WOW!

--It's silly way for creating glow effect, but fast and ok.
--If you want to use it into glsl, replace all 'number' to 'float'.
--This shader

ragialGlow = love.graphics.newShader[[
extern number quality = 2.0;                            //1.0 = ~pi steps  (1-inf)
extern number depth = 5.0;                              //depth of pixels (1-inf)
extern number power = 0.8;                              //power of bloom  (0.0-inf)
number tau = 2*3.1415;                                  //pi*2

float average(vec4 p) { return (p.r + p.g + p.b)*0.33;}

vec4 effect(vec4 color, Image texture, vec2 texture_coords, vec2 pixel_coords)
{
    vec2 screenFactor = vec2(1)/vec2(love_ScreenSize);  //vec2 pixel size, use vec2(1)/vec2(image_size), i use it for post-processing
    number i;                                           //optimisation
    vec4 pixel = Texel(texture, texture_coords);        //current pixel
    float step = 1.0/quality;                           //angle step
    float averageFactor = 1.0/quality/tau;              //also, count of steps
    vec4 bloom = vec4(0);                               //capacitor of color
    if (pixel.a < 0.1 || average(pixel) < 0.1){         //optimisation (do that for low color/alpha)
        for (i = 0.0; i < tau; i += step)               //angles for check-points
            bloom += Texel(texture, texture_coords + vec2(cos(i), sin(i)) * screenFactor * depth);  //store colors of check-points
        return vec4(bloom)*averageFactor*power;         //average color
    }
    return pixel;
}
]]

--Example images:
--low power, low depth:     pp.vk.me/c629520/v629520715/3767b/yJQFxw0AkWU.jpg
--low power, high depth:    pp.vk.me/c629520/v629520715/3768a/DDN6akGcdJc.jpg
--low power, high depth 2:  pp.vk.me/c629520/v629520715/376c5/-esPnKpapMQ.jpg
--high power, high depth:   pp.vk.me/c629520/v629520715/376ce/mGwzlt_iiiE.jpg