- Qt 5.5
- Qt Quick
- Qt Quick Particles Examples - CustomParticle
- fragmentshader.qml Example File
- Qt 5.5.1 Reference Documentation

# fragmentshader.qml Example File

particles/customparticle/content/fragmentshader.qml

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the examples of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:BSD$
    ** You may use this file under the terms of the BSD license as follows:
    **
    ** "Redistribution and use in source and binary forms, with or without
    ** modification, are permitted provided that the following conditions are
    ** met:
    **   * Redistributions of source code must retain the above copyright
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    **     notice, this list of conditions and the following disclaimer in
    **     the documentation and/or other materials provided with the
    **     distribution.
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    **     contributors may be used to endorse or promote products derived
    **     from this software without specific prior written permission.
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    **
    ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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    import QtQuick 2.0
    import QtQuick.Particles 2.0

    ParticleSystem {
        id: root
        width: 320
        height: 480
        Rectangle {
            z: -1
            anchors.fill: parent
            color: "black"
            Text {
                anchors.bottom: parent.bottom
                anchors.horizontalCenter: parent.horizontalCenter
                font.pixelSize: 14
                color: "white"
                text: "It's all in the fragment shader."
            }
        }

        Emitter {
            emitRate: 400
            lifeSpan: 8000
            size: 24
            sizeVariation: 16
            velocity: PointDirection {x: root.width/10; y: root.height/10;}
            acceleration: PointDirection {x: -root.width/40; y: -root.height/40; xVariation: -root.width/20; yVariation: -root.width/20}
        }

        CustomParticle {
            vertexShader:"
                uniform lowp float qt_Opacity;
                varying lowp float fFade;
                varying highp vec2 fPos;

                void main() {
                    qt_TexCoord0 = qt_ParticleTex;
                    highp float size = qt_ParticleData.z;
                    highp float endSize = qt_ParticleData.w;

                    highp float t = (qt_Timestamp - qt_ParticleData.x) / qt_ParticleData.y;

                    highp float currentSize = mix(size, endSize, t * t);

                    if (t < 0. || t > 1.)
                    currentSize = 0.;

                    highp vec2 pos = qt_ParticlePos
                    - currentSize / 2. + currentSize * qt_ParticleTex          // adjust size
                    + qt_ParticleVec.xy * t * qt_ParticleData.y         // apply velocity vector..
                    + 0.5 * qt_ParticleVec.zw * pow(t * qt_ParticleData.y, 2.);

                    gl_Position = qt_Matrix * vec4(pos.x, pos.y, 0, 1);

                    highp float fadeIn = min(t * 20., 1.);
                    highp float fadeOut = 1. - max(0., min((t - 0.75) * 4., 1.));

                    fFade = fadeIn * fadeOut * qt_Opacity;
                    fPos = vec2(pos.x/320., pos.y/480.);
                }
            "
            fragmentShader: "
                varying highp vec2 fPos;
                varying lowp float fFade;
                varying highp vec2 qt_TexCoord0;
                void main() {//*2 because this generates dark colors mostly
                    highp vec2 circlePos = qt_TexCoord0*2.0 - vec2(1.0,1.0);
                    highp float dist = length(circlePos);
                    highp float circleFactor = max(min(1.0 - dist, 1.0), 0.0);
                    gl_FragColor = vec4(fPos.x*2.0 - fPos.y, fPos.y*2.0 - fPos.x, fPos.x*fPos.y*2.0, 0.0) * circleFactor * fFade;
                }"

        }
    }