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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 mixLevel: parameters.get(0).value
    property real targetSize: 250 - (200 * mixLevel) // TODO: fix ...
    property real resS: targetSize
    property real resT: targetSize

    fragmentShaderSrc: "uniform float dividerValue;
                        uniform float mixLevel;
                        uniform float resS;
                        uniform float resT;

                        uniform sampler2D source;
                        uniform lowp float qt_Opacity;
                        varying vec2 qt_TexCoord0;

                        void main()
                        {
                            vec2 uv = qt_TexCoord0.xy;
                            vec4 c = vec4(0.0);
                            if (uv.x < dividerValue) {
                                vec2 st = qt_TexCoord0.st;
                                vec3 irgb = texture2D(source, st).rgb;
                                vec2 stp0 = vec2(1.0 / resS, 0.0);
                                vec2 st0p = vec2(0.0       , 1.0 / resT);
                                vec2 stpp = vec2(1.0 / resS, 1.0 / resT);
                                vec2 stpm = vec2(1.0 / resS, -1.0 / resT);
                                const vec3 W = vec3(0.2125, 0.7154, 0.0721);
                                float i00   = dot(texture2D(source, st).rgb, W);
                                float im1m1 = dot(texture2D(source, st-stpp).rgb, W);
                                float ip1p1 = dot(texture2D(source, st+stpp).rgb, W);
                                float im1p1 = dot(texture2D(source, st-stpm).rgb, W);
                                float ip1m1 = dot(texture2D(source, st+stpm).rgb, W);
                                float im10  = dot(texture2D(source, st-stp0).rgb, W);
                                float ip10  = dot(texture2D(source, st+stp0).rgb, W);
                                float i0m1  = dot(texture2D(source, st-st0p).rgb, W);
                                float i0p1  = dot(texture2D(source, st+st0p).rgb, W);
                                float h = -1.0*im1p1 - 2.0*i0p1 - 1.0*ip1p1 + 1.0*im1m1 + 2.0*i0m1 + 1.0*ip1m1;
                                float v = -1.0*im1m1 - 2.0*im10 - 1.0*im1p1 + 1.0*ip1m1 + 2.0*ip10 + 1.0*ip1p1;
                                float mag = 1.0 - length(vec2(h, v));
                                vec3 target = vec3(mag, mag, mag);
                                c = vec4(target, 1.0);
                            } else {
                                c = texture2D(source, qt_TexCoord0);
                            }
                            gl_FragColor = qt_Opacity * c;
                        }"
}