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<h1 class="title">squircle.cpp Example File</h1>
<span class="subtitle">scenegraph/openglunderqml/squircle.cpp</span>
<!-- $$$scenegraph/openglunderqml/squircle.cpp-description -->
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<pre class="cpp"><span class="comment">/****************************************************************************
**
** Copyright (C) 2015 The Qt Company Ltd.
** Contact: http://www.qt.io/licensing/
**
** This file is part of the demonstration applications of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL21$
** 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 http://www.qt.io/terms-conditions. For further
** information use the contact form at http://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 or version 3 as published by the Free
** Software Foundation and appearing in the file LICENSE.LGPLv21 and
** LICENSE.LGPLv3 included in the packaging of this file. Please review the
** following information to ensure the GNU Lesser General Public License
** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** As a special exception, The Qt Company gives you certain additional
** rights. These rights are described in The Qt Company LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** $QT_END_LICENSE$
**
****************************************************************************/</span>

<span class="preprocessor">#include &quot;squircle.h&quot;</span>

<span class="preprocessor">#include &lt;QtQuick/qquickwindow.h&gt;</span>
<span class="preprocessor">#include &lt;QtGui/QOpenGLShaderProgram&gt;</span>
<span class="preprocessor">#include &lt;QtGui/QOpenGLContext&gt;</span>

Squircle<span class="operator">::</span>Squircle()
    : m_t(<span class="number">0</span>)
    <span class="operator">,</span> m_renderer(<span class="number">0</span>)
{
    connect(<span class="keyword">this</span><span class="operator">,</span> SIGNAL(windowChanged(<span class="type"><a href="qquickwindow.html">QQuickWindow</a></span><span class="operator">*</span>))<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> SLOT(handleWindowChanged(<span class="type"><a href="qquickwindow.html">QQuickWindow</a></span><span class="operator">*</span>)));
}

<span class="type">void</span> Squircle<span class="operator">::</span>setT(<span class="type">qreal</span> t)
{
    <span class="keyword">if</span> (t <span class="operator">=</span><span class="operator">=</span> m_t)
        <span class="keyword">return</span>;
    m_t <span class="operator">=</span> t;
    <span class="keyword">emit</span> tChanged();
    <span class="keyword">if</span> (window())
        window()<span class="operator">-</span><span class="operator">&gt;</span>update();
}

<span class="type">void</span> Squircle<span class="operator">::</span>handleWindowChanged(<span class="type"><a href="qquickwindow.html">QQuickWindow</a></span> <span class="operator">*</span>win)
{
    <span class="keyword">if</span> (win) {
        connect(win<span class="operator">,</span> SIGNAL(beforeSynchronizing())<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> SLOT(sync())<span class="operator">,</span> <span class="type">Qt</span><span class="operator">::</span>DirectConnection);
        connect(win<span class="operator">,</span> SIGNAL(sceneGraphInvalidated())<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> SLOT(cleanup())<span class="operator">,</span> <span class="type">Qt</span><span class="operator">::</span>DirectConnection);
        <span class="comment">// If we allow QML to do the clearing, they would clear what we paint</span>
        <span class="comment">// and nothing would show.</span>
        win<span class="operator">-</span><span class="operator">&gt;</span>setClearBeforeRendering(<span class="keyword">false</span>);
    }
}

<span class="type">void</span> Squircle<span class="operator">::</span>cleanup()
{
    <span class="keyword">if</span> (m_renderer) {
        <span class="keyword">delete</span> m_renderer;
        m_renderer <span class="operator">=</span> <span class="number">0</span>;
    }
}

SquircleRenderer<span class="operator">::</span><span class="operator">~</span>SquircleRenderer()
{
    <span class="keyword">delete</span> m_program;
}

<span class="type">void</span> Squircle<span class="operator">::</span>sync()
{
    <span class="keyword">if</span> (<span class="operator">!</span>m_renderer) {
        m_renderer <span class="operator">=</span> <span class="keyword">new</span> SquircleRenderer();
        connect(window()<span class="operator">,</span> SIGNAL(beforeRendering())<span class="operator">,</span> m_renderer<span class="operator">,</span> SLOT(paint())<span class="operator">,</span> <span class="type">Qt</span><span class="operator">::</span>DirectConnection);
    }
    m_renderer<span class="operator">-</span><span class="operator">&gt;</span>setViewportSize(window()<span class="operator">-</span><span class="operator">&gt;</span>size() <span class="operator">*</span> window()<span class="operator">-</span><span class="operator">&gt;</span>devicePixelRatio());
    m_renderer<span class="operator">-</span><span class="operator">&gt;</span>setT(m_t);
}

<span class="type">void</span> SquircleRenderer<span class="operator">::</span>paint()
{
    <span class="keyword">if</span> (<span class="operator">!</span>m_program) {
        initializeOpenGLFunctions();

        m_program <span class="operator">=</span> <span class="keyword">new</span> <span class="type">QOpenGLShaderProgram</span>();
        m_program<span class="operator">-</span><span class="operator">&gt;</span>addShaderFromSourceCode(<span class="type">QOpenGLShader</span><span class="operator">::</span>Vertex<span class="operator">,</span>
                                           <span class="string">&quot;attribute highp vec4 vertices;&quot;</span>
                                           <span class="string">&quot;varying highp vec2 coords;&quot;</span>
                                           <span class="string">&quot;void main() {&quot;</span>
                                           <span class="string">&quot;    gl_Position = vertices;&quot;</span>
                                           <span class="string">&quot;    coords = vertices.xy;&quot;</span>
                                           <span class="string">&quot;}&quot;</span>);
        m_program<span class="operator">-</span><span class="operator">&gt;</span>addShaderFromSourceCode(<span class="type">QOpenGLShader</span><span class="operator">::</span>Fragment<span class="operator">,</span>
                                           <span class="string">&quot;uniform lowp float t;&quot;</span>
                                           <span class="string">&quot;varying highp vec2 coords;&quot;</span>
                                           <span class="string">&quot;void main() {&quot;</span>
                                           <span class="string">&quot;    lowp float i = 1. - (pow(abs(coords.x), 4.) + pow(abs(coords.y), 4.));&quot;</span>
                                           <span class="string">&quot;    i = smoothstep(t - 0.8, t + 0.8, i);&quot;</span>
                                           <span class="string">&quot;    i = floor(i * 20.) / 20.;&quot;</span>
                                           <span class="string">&quot;    gl_FragColor = vec4(coords * .5 + .5, i, i);&quot;</span>
                                           <span class="string">&quot;}&quot;</span>);

        m_program<span class="operator">-</span><span class="operator">&gt;</span>bindAttributeLocation(<span class="string">&quot;vertices&quot;</span><span class="operator">,</span> <span class="number">0</span>);
        m_program<span class="operator">-</span><span class="operator">&gt;</span>link();

    }
    m_program<span class="operator">-</span><span class="operator">&gt;</span>bind();

    m_program<span class="operator">-</span><span class="operator">&gt;</span>enableAttributeArray(<span class="number">0</span>);

    <span class="type">float</span> values<span class="operator">[</span><span class="operator">]</span> <span class="operator">=</span> {
        <span class="operator">-</span><span class="number">1</span><span class="operator">,</span> <span class="operator">-</span><span class="number">1</span><span class="operator">,</span>
        <span class="number">1</span><span class="operator">,</span> <span class="operator">-</span><span class="number">1</span><span class="operator">,</span>
        <span class="operator">-</span><span class="number">1</span><span class="operator">,</span> <span class="number">1</span><span class="operator">,</span>
        <span class="number">1</span><span class="operator">,</span> <span class="number">1</span>
    };
    m_program<span class="operator">-</span><span class="operator">&gt;</span>setAttributeArray(<span class="number">0</span><span class="operator">,</span> GL_FLOAT<span class="operator">,</span> values<span class="operator">,</span> <span class="number">2</span>);
    m_program<span class="operator">-</span><span class="operator">&gt;</span>setUniformValue(<span class="string">&quot;t&quot;</span><span class="operator">,</span> (<span class="type">float</span>) m_t);

    glViewport(<span class="number">0</span><span class="operator">,</span> <span class="number">0</span><span class="operator">,</span> m_viewportSize<span class="operator">.</span>width()<span class="operator">,</span> m_viewportSize<span class="operator">.</span>height());

    glDisable(GL_DEPTH_TEST);

    glClearColor(<span class="number">0</span><span class="operator">,</span> <span class="number">0</span><span class="operator">,</span> <span class="number">0</span><span class="operator">,</span> <span class="number">1</span>);
    glClear(GL_COLOR_BUFFER_BIT);

    glEnable(GL_BLEND);
    glBlendFunc(GL_SRC_ALPHA<span class="operator">,</span> GL_ONE);

    glDrawArrays(GL_TRIANGLE_STRIP<span class="operator">,</span> <span class="number">0</span><span class="operator">,</span> <span class="number">4</span>);

    m_program<span class="operator">-</span><span class="operator">&gt;</span>disableAttributeArray(<span class="number">0</span>);
    m_program<span class="operator">-</span><span class="operator">&gt;</span>release();
}</pre>
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<!-- @@@scenegraph/openglunderqml/squircle.cpp -->
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