fragmentshader.qml Example File

/****************************************************************************
**
** Copyright (C) 2017 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** BSD License Usage
** Alternatively, 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
**     notice, this list of conditions and the following disclaimer.
**   * Redistributions in binary form must reproduce the above copyright
**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
**     distribution.
**   * Neither the name of The Qt Company Ltd nor the names of its
**     contributors may be used to endorse or promote products derived
**     from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/
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;
            }"
    }
}