gaussian_blur_vert.glsl

#version 120
uniform sampler2D input;
uniform int n;
varying vec2 x; // texture coordinates
uniform float dx; // delta

void main()
{
    vec3 v = vec3(0,0,0);
    float totWeight = 0;
    for(int j = -n; j<=n; ++j) {
        vec2 tx = x + vec2(0,j*dx);
        float weight = exp(-((tx.y-x.y)*(tx.y-x.y)));
        v+= weight * texture2D(input, tx).xyz;
        totWeight += weight;
    }
    
    // gl_FragData[0] is buffer output
    gl_FragData[0] = vec4(v/totWeight,1);
}