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// Based on http://www.geeks3d.com/20100909/shader-library-gaussian-blur-post-processing-filter-in-glsl/

import QtQuick 2.0

Item {
    id: root
    property bool divider: true
    property real dividerValue: 1
    property ListModel parameters: ListModel {
        ListElement {
            name: "radius"
            value: 0.5
        }
    }

    property alias targetWidth: verticalShader.targetWidth
    property alias targetHeight: verticalShader.targetHeight
    property alias source: verticalShader.source

    Effect {
        id: verticalShader
        anchors.fill:  parent
        dividerValue: parent.dividerValue
        property real blurSize: 4.0 * parent.parameters.get(0).value / targetHeight
        fragmentShaderSrc: "uniform float dividerValue;
                            uniform float blurSize;

                            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) {
                                    c += texture2D(source, uv - vec2(0.0, 4.0*blurSize)) * 0.05;
                                    c += texture2D(source, uv - vec2(0.0, 3.0*blurSize)) * 0.09;
                                    c += texture2D(source, uv - vec2(0.0, 2.0*blurSize)) * 0.12;
                                    c += texture2D(source, uv - vec2(0.0, 1.0*blurSize)) * 0.15;
                                    c += texture2D(source, uv) * 0.18;
                                    c += texture2D(source, uv + vec2(0.0, 1.0*blurSize)) * 0.15;
                                    c += texture2D(source, uv + vec2(0.0, 2.0*blurSize)) * 0.12;
                                    c += texture2D(source, uv + vec2(0.0, 3.0*blurSize)) * 0.09;
                                    c += texture2D(source, uv + vec2(0.0, 4.0*blurSize)) * 0.05;
                                } else {
                                    c = texture2D(source, qt_TexCoord0);
                                }
                                // First pass we don't apply opacity
                                gl_FragColor = c;
                            }"
    }

    Effect {
        id: horizontalShader
        anchors.fill: parent
        dividerValue: parent.dividerValue
        property real blurSize: 4.0 * parent.parameters.get(0).value / parent.targetWidth
        fragmentShaderSrc: "uniform float dividerValue;
                            uniform float blurSize;

                            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) {
                                    c += texture2D(source, uv - vec2(4.0*blurSize, 0.0)) * 0.05;
                                    c += texture2D(source, uv - vec2(3.0*blurSize, 0.0)) * 0.09;
                                    c += texture2D(source, uv - vec2(2.0*blurSize, 0.0)) * 0.12;
                                    c += texture2D(source, uv - vec2(1.0*blurSize, 0.0)) * 0.15;
                                    c += texture2D(source, uv) * 0.18;
                                    c += texture2D(source, uv + vec2(1.0*blurSize, 0.0)) * 0.15;
                                    c += texture2D(source, uv + vec2(2.0*blurSize, 0.0)) * 0.12;
                                    c += texture2D(source, uv + vec2(3.0*blurSize, 0.0)) * 0.09;
                                    c += texture2D(source, uv + vec2(4.0*blurSize, 0.0)) * 0.05;
                                } else {
                                    c = texture2D(source, qt_TexCoord0);
                                }
                                gl_FragColor = qt_Opacity * c;
                            }"
        source: horizontalShaderSource

        ShaderEffectSource {
            id: horizontalShaderSource
            sourceItem: verticalShader
            smooth: true
            hideSource: true
        }
    }
}