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import QtQuick 2.0

Effect {
    parameters: ListModel {
        ListElement {
            name: "threshold"
            value: 0.5
        }
    }

    // Transform slider values, and bind result to shader uniforms
    property real weight: parameters.get(0).value

    fragmentShaderSrc: "#version 130
                        uniform sampler2D source;
                        uniform float dividerValue;
                        uniform float weight;
                        mat3 G[2] = mat3[](
                            mat3( 1.0, 2.0, 1.0, 0.0, 0.0, 0.0, -1.0, -2.0, -1.0 ),
                            mat3( 1.0, 0.0, -1.0, 2.0, 0.0, -2.0, 1.0, 0.0, -1.0 )
                        );
                        uniform lowp float qt_Opacity;
                        in vec2 qt_TexCoord0;
                        out vec4 FragmentColor;
                        void main() {
                            vec2 uv = qt_TexCoord0.xy;
                            vec4 c = vec4(0.0);
                            if (uv.x < dividerValue) {
                                mat3 intensity;
                                float conv[2];
                                vec3 sample;
                                for (int i=0; i<3; ++i) {
                                    for (int j=0; j<3; ++j) {
                                        sample = texelFetch(source, ivec2(gl_FragCoord) + ivec2(i-1, j-1), 0).rgb;
                                        intensity[i][j] = length(sample) * weight;
                                    }
                                }
                                for (int i=0; i<2; ++i) {
                                    float dp3 = dot(G[i][0], intensity[0]) + dot(G[i][1], intensity[1]) + dot(G[i][2], intensity[2]);
                                    conv[i] = dp3 * dp3;
                                }
                                c = vec4(0.5 * sqrt(conv[0]*conv[0] + conv[1]*conv[1]));
                            } else {
                                c = texture2D(source, qt_TexCoord0);
                            }
                            FragmentColor = qt_Opacity * c;
                        }"
}