qt-everywhere-src-5.15.1/qtquick3d/src/imports/materiallib/shaders/frostedThinGlassBlurX.frag

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#define QSSG_ENABLE_UV0 1
#define QSSG_ENABLE_WORLD_POSITION 1
#define QSSG_ENABLE_TEXTAN 1

vec3 texCoord0;
out vec4 fragColor;

uniform sampler2D BlurBuffer;

void main()
{
    vec2 texSize = vec2( textureSize( BlurBuffer, 0 ) );
    texSize = vec2(1.0) / texSize;
    texCoord0.z = 0.0;
    texCoord0.xy = vec2(gl_FragCoord.xy * texSize);

    float sigma = clamp(blur_size * 0.5, 0.5, 100.0);
    int smpCount = int(ceil( sigma ));
    vec4 value = texture(BlurBuffer, texCoord0.xy);
    float wtsum = 1.0;
    for (int i = 1; i <= smpCount; ++i)
    {
        // Base 2 Gaussian blur
        float wt = float(i) / (sigma * 0.5);
        wt = exp2( -wt*wt );
        vec2 texOfs = vec2(i, 0) * texSize;
        value += wt * texture(BlurBuffer, texCoord0.xy+texOfs);
        value += wt * texture(BlurBuffer, texCoord0.xy-texOfs);
        wtsum += wt * 2.0;
    }

    fragColor = value / wtsum;
    fragColor.a = 1.0;
}