1 /****************************************************************************
3 ** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
4 ** Contact: http://www.qt-project.org/
6 ** This file is part of the demonstration applications of the Qt Toolkit.
8 ** $QT_BEGIN_LICENSE:LGPL$
9 ** GNU Lesser General Public License Usage
10 ** This file may be used under the terms of the GNU Lesser General Public
11 ** License version 2.1 as published by the Free Software Foundation and
12 ** appearing in the file LICENSE.LGPL included in the packaging of this
13 ** file. Please review the following information to ensure the GNU Lesser
14 ** General Public License version 2.1 requirements will be met:
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17 ** In addition, as a special exception, Nokia gives you certain additional
18 ** rights. These rights are described in the Nokia Qt LGPL Exception
19 ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
21 ** GNU General Public License Usage
22 ** Alternatively, this file may be used under the terms of the GNU General
23 ** Public License version 3.0 as published by the Free Software Foundation
24 ** and appearing in the file LICENSE.GPL included in the packaging of this
25 ** file. Please review the following information to ensure the GNU General
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40 ****************************************************************************/
44 #include <QtQuick/qquickcanvas.h>
45 #include <QOpenGLShaderProgram>
50 setFlag(ItemHasContents);
53 void Squircle::itemChange(ItemChange change, const ItemChangeData &)
55 // The ItemSceneChange event is sent when we are first attached to a canvas.
56 if (change == ItemSceneChange) {
57 QQuickCanvas *c = canvas();
59 // Connect our the beforeRendering signal to our paint function.
60 // Since this call is executed on the rendering thread it must be
61 // a Qt::DirectConnection
62 connect(c, SIGNAL(beforeRendering()), this, SLOT(paint()), Qt::DirectConnection);
64 // If we allow QML to do the clearing, they would clear what we paint
65 // and nothing would show.
66 c->setClearBeforeRendering(false);
70 void Squircle::paint()
73 m_program = new QOpenGLShaderProgram();
74 m_program->addShaderFromSourceCode(QOpenGLShader::Vertex,
75 "attribute highp vec4 vertices;"
76 "varying highp vec2 coords;"
78 " gl_Position = vertices;"
79 " coords = vertices.xy;"
81 m_program->addShaderFromSourceCode(QOpenGLShader::Fragment,
82 "uniform lowp float t;"
83 "varying highp vec2 coords;"
85 " lowp float i = 1. - (pow(coords.x, 4.) + pow(coords.y, 4.));"
86 " i = smoothstep(t - 0.3, t + 0.3, i);"
87 " gl_FragColor = vec4(coords / 2. + .5, i, i);"
90 m_program->bindAttributeLocation("vertices", 0);
96 m_program->enableAttributeArray(0);
104 m_program->setAttributeArray(0, GL_FLOAT, values, 2);
105 m_program->setUniformValue("t", (float) m_t);
107 glViewport(0, 0, canvas()->width(), canvas()->height());
109 glDisable(GL_DEPTH_TEST);
111 glClearColor(0, 0, 0, 1);
112 glClear(GL_COLOR_BUFFER_BIT);
115 glBlendFunc(GL_SRC_ALPHA, GL_ONE);
117 glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
119 m_program->disableAttributeArray(0);
120 m_program->release();