<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html>
<html lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>xorblender.cpp Example File | Qt Quick 5.9</title>
<link rel="stylesheet" type="text/css" href="style/offline-simple.css" />
<script type="text/javascript">
document.getElementsByTagName("link").item(0).setAttribute("href", "style/offline.css");
// loading style sheet breaks anchors that were jumped to before
// so force jumping to anchor again
setTimeout(function() {
var anchor = location.hash;
// need to jump to different anchor first (e.g. none)
location.hash = "#";
setTimeout(function() {
location.hash = anchor;
}, 0);
}, 0);
</script>
</head>
<body>
<div class="header" id="qtdocheader">
<div class="main">
<div class="main-rounded">
<div class="navigationbar">
<table><tr>
<td >Qt 5.9</td><td ><a href="qtquick-index.html">Qt Quick</a></td><td ><a href="qtquick-scenegraph-twotextureproviders-example.html">Scene Graph - Two Texture Providers</a></td><td >xorblender.cpp Example File</td></tr></table><table class="buildversion"><tr>
<td id="buildversion" width="100%" align="right">Qt 5.9.4 Reference Documentation</td>
</tr></table>
</div>
</div>
<div class="content">
<div class="line">
<div class="content mainContent">
<div class="sidebar"><div class="sidebar-content" id="sidebar-content"></div></div>
<h1 class="title">xorblender.cpp Example File</h1>
<span class="subtitle">scenegraph/twotextureproviders/xorblender.cpp</span>
<!-- $$$scenegraph/twotextureproviders/xorblender.cpp-description -->
<div class="descr"> <a name="details"></a>
<pre class="cpp">
<span class="comment">/****************************************************************************
**
** Copyright (C) 2014 Gunnar Sletta <gunnar@sletta.org>
** 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."
**
** $QT_END_LICENSE$
**
****************************************************************************/</span>
<span class="preprocessor">#include "xorblender.h"</span>
<span class="preprocessor">#include <QtCore/QPointer></span>
<span class="preprocessor">#include <QtGui/QOpenGLContext></span>
<span class="preprocessor">#include <QtGui/QOpenGLFunctions></span>
<span class="preprocessor">#include <QtQuick/QSGSimpleMaterial></span>
<span class="preprocessor">#include <QtQuick/QSGTexture></span>
<span class="preprocessor">#include <QtQuick/QSGGeometryNode></span>
<span class="preprocessor">#include <QtQuick/QSGTextureProvider></span>
<span class="comment">/* This example could just as well have been implemented all in QML using
* a ShaderEffect, and for 90% of all usecases, using a ShaderEffect will
* be sufficient. This example exists to illustrate how to consume
* texture providers from C++ and how to use multiple texture sources in
* a custom material.
*/</span>
<span class="keyword">struct</span> XorBlendState {
<span class="type"><a href="qsgtexture.html">QSGTexture</a></span> <span class="operator">*</span>texture1;
<span class="type"><a href="qsgtexture.html">QSGTexture</a></span> <span class="operator">*</span>texture2;
};
<span class="keyword">class</span> XorBlendShader : <span class="keyword">public</span> <span class="type"><a href="qsgsimplematerialshader.html">QSGSimpleMaterialShader</a></span><span class="operator"><</span>XorBlendState<span class="operator">></span>
{
QSG_DECLARE_SIMPLE_SHADER(XorBlendShader<span class="operator">,</span> XorBlendState)
<span class="keyword">public</span>:
<span class="keyword">const</span> <span class="type">char</span> <span class="operator">*</span>vertexShader() <span class="keyword">const</span> {
<span class="keyword">return</span>
<span class="string">"attribute highp vec4 aVertex; \n"</span>
<span class="string">"attribute highp vec2 aTexCoord; \n"</span>
<span class="string">"uniform highp mat4 qt_Matrix; \n"</span>
<span class="string">"varying highp vec2 vTexCoord; \n"</span>
<span class="string">"void main() { \n"</span>
<span class="string">" gl_Position = qt_Matrix * aVertex; \n"</span>
<span class="string">" vTexCoord = aTexCoord; \n"</span>
<span class="string">"}"</span>;
}
<span class="keyword">const</span> <span class="type">char</span> <span class="operator">*</span>fragmentShader() <span class="keyword">const</span> {
<span class="keyword">return</span>
<span class="string">"uniform lowp float qt_Opacity; \n"</span>
<span class="string">"uniform lowp sampler2D uSource1; \n"</span>
<span class="string">"uniform lowp sampler2D uSource2; \n"</span>
<span class="string">"varying highp vec2 vTexCoord; \n"</span>
<span class="string">"void main() { \n"</span>
<span class="string">" lowp vec4 p1 = texture2D(uSource1, vTexCoord); \n"</span>
<span class="string">" lowp vec4 p2 = texture2D(uSource2, vTexCoord); \n"</span>
<span class="string">" gl_FragColor = (p1 * (1.0 - p2.a) + p2 * (1.0 - p1.a)) * qt_Opacity; \n"</span>
<span class="string">"}"</span>;
}
<span class="type">QList</span><span class="operator"><</span><span class="type">QByteArray</span><span class="operator">></span> attributes() <span class="keyword">const</span> {
<span class="keyword">return</span> <span class="type">QList</span><span class="operator"><</span><span class="type">QByteArray</span><span class="operator">></span>() <span class="operator"><</span><span class="operator"><</span> <span class="string">"aVertex"</span> <span class="operator"><</span><span class="operator"><</span> <span class="string">"aTexCoord"</span>;
}
<span class="type">void</span> updateState(<span class="keyword">const</span> XorBlendState <span class="operator">*</span>state<span class="operator">,</span> <span class="keyword">const</span> XorBlendState <span class="operator">*</span>) {
<span class="type">QOpenGLFunctions</span> <span class="operator">*</span>f <span class="operator">=</span> <span class="type">QOpenGLContext</span><span class="operator">::</span>currentContext()<span class="operator">-</span><span class="operator">></span>functions();
<span class="comment">// We bind the textures in inverse order so that we leave the updateState</span>
<span class="comment">// function with GL_TEXTURE0 as the active texture unit. This is maintain</span>
<span class="comment">// the "contract" that updateState should not mess up the GL state beyond</span>
<span class="comment">// what is needed for this material.</span>
f<span class="operator">-</span><span class="operator">></span>glActiveTexture(GL_TEXTURE1);
state<span class="operator">-</span><span class="operator">></span>texture2<span class="operator">-</span><span class="operator">></span>bind();
f<span class="operator">-</span><span class="operator">></span>glActiveTexture(GL_TEXTURE0);
state<span class="operator">-</span><span class="operator">></span>texture1<span class="operator">-</span><span class="operator">></span>bind();
}
<span class="type">void</span> resolveUniforms() {
<span class="comment">// The texture units never change, only the texturess we bind to them so</span>
<span class="comment">// we set these once and for all here.</span>
program()<span class="operator">-</span><span class="operator">></span>setUniformValue(<span class="string">"uSource1"</span><span class="operator">,</span> <span class="number">0</span>); <span class="comment">// GL_TEXTURE0</span>
program()<span class="operator">-</span><span class="operator">></span>setUniformValue(<span class="string">"uSource2"</span><span class="operator">,</span> <span class="number">1</span>); <span class="comment">// GL_TEXTURE1</span>
}
};
<span class="comment">/* The rendering is split into two nodes. The top-most node is not actually
* rendering anything, but is responsible for managing the texture providers.
* The XorNode also has a geometry node internally which it uses to render
* the texture providers using the XorBlendShader when all providers and
* textures are all present.
*
* The texture providers are updated solely on the render thread (when rendering
* is happening on a separate thread). This is why we are using preprocess
* and direct signals between the the texture providers and the node rather
* than updating state in updatePaintNode.
*/</span>
<span class="keyword">class</span> XorNode : <span class="keyword">public</span> <span class="type">QObject</span><span class="operator">,</span> <span class="keyword">public</span> <span class="type"><a href="qsgnode.html">QSGNode</a></span>
{
Q_OBJECT
<span class="keyword">public</span>:
XorNode(<span class="type"><a href="qsgtextureprovider.html">QSGTextureProvider</a></span> <span class="operator">*</span>p1<span class="operator">,</span> <span class="type"><a href="qsgtextureprovider.html">QSGTextureProvider</a></span> <span class="operator">*</span>p2)
: m_provider1(p1)
<span class="operator">,</span> m_provider2(p2)
{
setFlag(<span class="type"><a href="qsgnode.html">QSGNode</a></span><span class="operator">::</span>UsePreprocess<span class="operator">,</span> <span class="keyword">true</span>);
<span class="comment">// Set up material so it is all set for later..</span>
m_material <span class="operator">=</span> XorBlendShader<span class="operator">::</span>createMaterial();
m_material<span class="operator">-</span><span class="operator">></span>state()<span class="operator">-</span><span class="operator">></span>texture1 <span class="operator">=</span> <span class="number">0</span>;
m_material<span class="operator">-</span><span class="operator">></span>state()<span class="operator">-</span><span class="operator">></span>texture2 <span class="operator">=</span> <span class="number">0</span>;
m_material<span class="operator">-</span><span class="operator">></span>setFlag(<span class="type"><a href="qsgmaterial.html">QSGMaterial</a></span><span class="operator">::</span>Blending);
m_node<span class="operator">.</span>setMaterial(m_material);
m_node<span class="operator">.</span>setFlag(<span class="type"><a href="qsgnode.html">QSGNode</a></span><span class="operator">::</span>OwnsMaterial);
<span class="comment">// Set up geometry, actual vertices will be initialized in updatePaintNode</span>
m_node<span class="operator">.</span>setGeometry(<span class="keyword">new</span> <span class="type"><a href="qsggeometry.html">QSGGeometry</a></span>(<span class="type"><a href="qsggeometry.html">QSGGeometry</a></span><span class="operator">::</span>defaultAttributes_TexturedPoint2D()<span class="operator">,</span> <span class="number">4</span>));
m_node<span class="operator">.</span>setFlag(<span class="type"><a href="qsgnode.html">QSGNode</a></span><span class="operator">::</span>OwnsGeometry);
<span class="comment">// If this node is used as in a shader effect source, we need to propegate</span>
<span class="comment">// changes that will occur in this node outwards.</span>
connect(m_provider1<span class="operator">.</span>data()<span class="operator">,</span> <span class="operator">&</span><span class="type"><a href="qsgtextureprovider.html">QSGTextureProvider</a></span><span class="operator">::</span>textureChanged<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> <span class="operator">&</span>XorNode<span class="operator">::</span>textureChange<span class="operator">,</span> <span class="type">Qt</span><span class="operator">::</span>DirectConnection);
connect(m_provider2<span class="operator">.</span>data()<span class="operator">,</span> <span class="operator">&</span><span class="type"><a href="qsgtextureprovider.html">QSGTextureProvider</a></span><span class="operator">::</span>textureChanged<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> <span class="operator">&</span>XorNode<span class="operator">::</span>textureChange<span class="operator">,</span> <span class="type">Qt</span><span class="operator">::</span>DirectConnection);
}
<span class="type">void</span> preprocess() {
XorBlendState <span class="operator">*</span>state <span class="operator">=</span> m_material<span class="operator">-</span><span class="operator">></span>state();
<span class="comment">// Update the textures from the providers, calling into QSGDynamicTexture if required</span>
<span class="keyword">if</span> (m_provider1) {
state<span class="operator">-</span><span class="operator">></span>texture1 <span class="operator">=</span> m_provider1<span class="operator">-</span><span class="operator">></span>texture();
<span class="keyword">if</span> (<span class="type"><a href="qsgdynamictexture.html">QSGDynamicTexture</a></span> <span class="operator">*</span>dt1 <span class="operator">=</span> qobject_cast<span class="operator"><</span><span class="type"><a href="qsgdynamictexture.html">QSGDynamicTexture</a></span> <span class="operator">*</span><span class="operator">></span>(state<span class="operator">-</span><span class="operator">></span>texture1))
dt1<span class="operator">-</span><span class="operator">></span>updateTexture();
}
<span class="keyword">if</span> (m_provider2) {
state<span class="operator">-</span><span class="operator">></span>texture2 <span class="operator">=</span> m_provider2<span class="operator">-</span><span class="operator">></span>texture();
<span class="keyword">if</span> (<span class="type"><a href="qsgdynamictexture.html">QSGDynamicTexture</a></span> <span class="operator">*</span>dt2 <span class="operator">=</span> qobject_cast<span class="operator"><</span><span class="type"><a href="qsgdynamictexture.html">QSGDynamicTexture</a></span> <span class="operator">*</span><span class="operator">></span>(state<span class="operator">-</span><span class="operator">></span>texture2))
dt2<span class="operator">-</span><span class="operator">></span>updateTexture();
}
<span class="comment">// Remove node from the scene graph if it is there and either texture is missing...</span>
<span class="keyword">if</span> (m_node<span class="operator">.</span>parent() <span class="operator">&</span><span class="operator">&</span> (<span class="operator">!</span>state<span class="operator">-</span><span class="operator">></span>texture1 <span class="operator">|</span><span class="operator">|</span> <span class="operator">!</span>state<span class="operator">-</span><span class="operator">></span>texture2))
removeChildNode(<span class="operator">&</span>m_node);
<span class="comment">// Add it if it is not already there and both textures are present..</span>
<span class="keyword">else</span> <span class="keyword">if</span> (<span class="operator">!</span>m_node<span class="operator">.</span>parent() <span class="operator">&</span><span class="operator">&</span> state<span class="operator">-</span><span class="operator">></span>texture1 <span class="operator">&</span><span class="operator">&</span> state<span class="operator">-</span><span class="operator">></span>texture2)
appendChildNode(<span class="operator">&</span>m_node);
}
<span class="type">void</span> setRect(<span class="keyword">const</span> <span class="type">QRectF</span> <span class="operator">&</span>rect) {
<span class="comment">// Update geometry if it has changed and mark the change in the scene graph.</span>
<span class="keyword">if</span> (m_rect <span class="operator">!</span><span class="operator">=</span> rect) {
m_rect <span class="operator">=</span> rect;
<span class="type"><a href="qsggeometry.html">QSGGeometry</a></span><span class="operator">::</span>updateTexturedRectGeometry(m_node<span class="operator">.</span>geometry()<span class="operator">,</span> m_rect<span class="operator">,</span> <span class="type">QRectF</span>(<span class="number">0</span><span class="operator">,</span> <span class="number">0</span><span class="operator">,</span> <span class="number">1</span><span class="operator">,</span> <span class="number">1</span>));
m_node<span class="operator">.</span>markDirty(<span class="type"><a href="qsgnode.html">QSGNode</a></span><span class="operator">::</span>DirtyGeometry);
}
}
<span class="keyword">public</span> <span class="keyword">slots</span>:
<span class="type">void</span> textureChange() {
<span class="comment">// When our sources change, we will look different, so signal the change to the</span>
<span class="comment">// scene graph.</span>
markDirty(<span class="type"><a href="qsgnode.html">QSGNode</a></span><span class="operator">::</span>DirtyMaterial);
}
<span class="keyword">private</span>:
<span class="type">QRectF</span> m_rect;
<span class="type"><a href="qsgsimplematerial.html">QSGSimpleMaterial</a></span><span class="operator"><</span>XorBlendState<span class="operator">></span> <span class="operator">*</span>m_material;
<span class="type"><a href="qsggeometrynode.html">QSGGeometryNode</a></span> m_node;
<span class="type">QPointer</span><span class="operator"><</span><span class="type"><a href="qsgtextureprovider.html">QSGTextureProvider</a></span><span class="operator">></span> m_provider1;
<span class="type">QPointer</span><span class="operator"><</span><span class="type"><a href="qsgtextureprovider.html">QSGTextureProvider</a></span><span class="operator">></span> m_provider2;
};
XorBlender<span class="operator">::</span>XorBlender(<span class="type"><a href="qquickitem.html">QQuickItem</a></span> <span class="operator">*</span>parent)
: <span class="type"><a href="qquickitem.html">QQuickItem</a></span>(parent)
<span class="operator">,</span> m_source1(<span class="number">0</span>)
<span class="operator">,</span> m_source2(<span class="number">0</span>)
<span class="operator">,</span> m_source1Changed(<span class="keyword">false</span>)
<span class="operator">,</span> m_source2Changed(<span class="keyword">false</span>)
{
setFlag(ItemHasContents<span class="operator">,</span> <span class="keyword">true</span>);
}
<span class="type">void</span> XorBlender<span class="operator">::</span>setSource1(<span class="type"><a href="qquickitem.html">QQuickItem</a></span> <span class="operator">*</span>i)
{
<span class="keyword">if</span> (i <span class="operator">=</span><span class="operator">=</span> m_source1)
<span class="keyword">return</span>;
m_source1 <span class="operator">=</span> i;
<span class="keyword">emit</span> source1Changed(m_source1);
m_source1Changed <span class="operator">=</span> <span class="keyword">true</span>;
update();
}
<span class="type">void</span> XorBlender<span class="operator">::</span>setSource2(<span class="type"><a href="qquickitem.html">QQuickItem</a></span> <span class="operator">*</span>i)
{
<span class="keyword">if</span> (i <span class="operator">=</span><span class="operator">=</span> m_source2)
<span class="keyword">return</span>;
m_source2 <span class="operator">=</span> i;
<span class="keyword">emit</span> source2Changed(m_source2);
m_source2Changed <span class="operator">=</span> <span class="keyword">true</span>;
update();
}
<span class="type"><a href="qsgnode.html">QSGNode</a></span> <span class="operator">*</span>XorBlender<span class="operator">::</span>updatePaintNode(<span class="type"><a href="qsgnode.html">QSGNode</a></span> <span class="operator">*</span>old<span class="operator">,</span> UpdatePaintNodeData <span class="operator">*</span>)
{
<span class="comment">// Check if our input is valid and abort if not, deleting the old node.</span>
bool abort <span class="operator">=</span> <span class="keyword">false</span>;
<span class="keyword">if</span> (<span class="operator">!</span>m_source1 <span class="operator">|</span><span class="operator">|</span> <span class="operator">!</span>m_source1<span class="operator">-</span><span class="operator">></span>isTextureProvider()) {
qDebug() <span class="operator"><</span><span class="operator"><</span> <span class="string">"source1 is missing or not a texture provider"</span>;
abort <span class="operator">=</span> <span class="keyword">true</span>;
}
<span class="keyword">if</span> (<span class="operator">!</span>m_source2 <span class="operator">|</span><span class="operator">|</span> <span class="operator">!</span>m_source2<span class="operator">-</span><span class="operator">></span>isTextureProvider()) {
qDebug() <span class="operator"><</span><span class="operator"><</span> <span class="string">"source2 is missing or not a texture provider"</span>;
abort <span class="operator">=</span> <span class="keyword">true</span>;
}
<span class="keyword">if</span> (abort) {
<span class="keyword">delete</span> old;
<span class="keyword">return</span> <span class="number">0</span>;
}
XorNode <span class="operator">*</span>node <span class="operator">=</span> <span class="keyword">static_cast</span><span class="operator"><</span>XorNode <span class="operator">*</span><span class="operator">></span>(old);
<span class="comment">// If the sources have changed, recreate the nodes</span>
<span class="keyword">if</span> (m_source1Changed <span class="operator">|</span><span class="operator">|</span> m_source2Changed) {
<span class="keyword">delete</span> node;
node <span class="operator">=</span> <span class="number">0</span>;
m_source1Changed <span class="operator">=</span> <span class="keyword">false</span>;
m_source2Changed <span class="operator">=</span> <span class="keyword">false</span>;
}
<span class="comment">// Create a new XorNode for us to render with.</span>
<span class="keyword">if</span> (<span class="operator">!</span>node)
node <span class="operator">=</span> <span class="keyword">new</span> XorNode(m_source1<span class="operator">-</span><span class="operator">></span>textureProvider()<span class="operator">,</span> m_source2<span class="operator">-</span><span class="operator">></span>textureProvider());
<span class="comment">// Update the geometry of the node to match the new bounding rect</span>
node<span class="operator">-</span><span class="operator">></span>setRect(boundingRect());
<span class="keyword">return</span> node;
}
<span class="preprocessor">#include "xorblender.moc"</span>
</pre>
</div>
<!-- @@@scenegraph/twotextureproviders/xorblender.cpp -->
</div>
</div>
</div>
</div>
</div>
<div class="footer">
<p>
<acronym title="Copyright">©</acronym> 2017 The Qt Company Ltd.
Documentation contributions included herein are the copyrights of
their respective owners.<br> The documentation provided herein is licensed under the terms of the <a href="http://www.gnu.org/licenses/fdl.html">GNU Free Documentation License version 1.3</a> as published by the Free Software Foundation.<br> Qt and respective logos are trademarks of The Qt Company Ltd. in Finland and/or other countries worldwide. All other trademarks are property
of their respective owners. </p>
</div>
</body>
</html>
