SFML Blur Shader shows no effect

Question

I'm trying to implement a SFML Shader following their example and it doesn't show up.

GameObject is a class that inherits and implements sf::Drawable . Inside GameObject I have a sf::Texture and a sf::Sprite objects, responsible for the image of the game object. I'm trying to apply a blur effect on it. Here's the .cpp where I load the image and shader:

x = new GameObject("Images/apple.png", 100, 100, 1, 1);
mshade.loadFromFile("Shaders/blur.frag", sf::Shader::Fragment);
mshade.setParameter("texture", *(x)->objectTexture);
mshade.setParameter("blur_radius", 200);

And this is how I draw it:

gameWindow->draw(*x, &mshade);

And this is the GLSL code to create the blur shader:

uniform sampler2D texture;
uniform float blur_radius;

void main()
{
    vec2 offx = vec2(blur_radius, 0.0);
    vec2 offy = vec2(0.0, blur_radius);

    vec4 pixel = texture2D(texture, gl_TexCoord[0].xy)               * 4.0 +
                 texture2D(texture, gl_TexCoord[0].xy - offx)        * 2.0 +
                 texture2D(texture, gl_TexCoord[0].xy + offx)        * 2.0 +
                 texture2D(texture, gl_TexCoord[0].xy - offy)        * 2.0 +
                 texture2D(texture, gl_TexCoord[0].xy + offy)        * 2.0 +
                 texture2D(texture, gl_TexCoord[0].xy - offx - offy) * 1.0 +
                 texture2D(texture, gl_TexCoord[0].xy - offx + offy) * 1.0 +
                 texture2D(texture, gl_TexCoord[0].xy + offx - offy) * 1.0 +
                 texture2D(texture, gl_TexCoord[0].xy + offx + offy) * 1.0;

    gl_FragColor =  gl_Color * (pixel / 16.0);
}

But for some reason the image is displayed just as normally, without any effect. I also don't get any error. Does anyone know why the blur effect doesn't show up?

Answer 1

I don't know anything about SFML, but i looks like your blur_radius is not well chosen. Your image has the size 100x100 and you Blur-Shader samples the image with distance of 200px (blur_radius). So if your texture has gl_repeat enabled , you hit exactly the same pixel as the original one. -> no blur

Try using a lower blur_radius maybe something around 2-5

Answer 2

Well in my question at: SFML shader not working I got help on this issue aswell I recoomend you go check out tntxtnt's answer that will probably help you. but basicly it dosent blur the outline of the textures it only blurs the colors inside the sprite.