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<td >Qt 5.12</td><td ><a href="qt3d-index.html">Qt 3D</a></td><td >Qt 3D: Simple C++ Example</td></tr></table><table class="buildversion"><tr>
<td id="buildversion" width="100%" align="right"><a href="qt3d-index.html">Qt 5.12.2 Reference Documentation</a></td>
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<h3><a name="toc">Contents</a></h3>
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<li class="level1"><a href="#running-the-example">Running the Example</a></li>
<li class="level1"><a href="#setting-up-the-scene">Setting Up the Scene</a></li>
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<h1 class="title">Qt 3D: Simple C++ Example</h1>
<span class="subtitle"></span>
<!-- $$$simple-cpp-brief -->
<p>A C++ application that demonstrates how to render a scene in Qt 3D.</p>
<!-- @@@simple-cpp -->
<!-- $$$simple-cpp-description -->
<div class="descr"> <a name="details"></a>
<p class="centerAlign"><img src="images/simple-cpp.png" alt="" /></p><p><i>Simple</i> demonstrates how to render a scene in Qt 3D.</p>
<a name="running-the-example"></a>
<h2 id="running-the-example">Running the Example</h2>
<p>To run the example from Qt Creator, open the <b>Welcome</b> mode and select the example from <b>Examples</b>. For more information, visit Building and Running an Example.</p>
<a name="setting-up-the-scene"></a>
<h2 id="setting-up-the-scene">Setting Up the Scene</h2>
<p>We set up the scene in the <i>main.cpp</i> file.</p>
<p>To be able to use the classes and functions in the Q3D Core, Q3D Render, Qt 3D Input, and Qt 3D Extras modules, we must include the classes:</p>
<pre class="cpp">
<span class="preprocessor">#include <Qt3DCore/QEntity></span>
<span class="preprocessor">#include <Qt3DRender/QCamera></span>
<span class="preprocessor">#include <Qt3DRender/QCameraLens></span>
<span class="preprocessor">#include <Qt3DCore/QTransform></span>
<span class="preprocessor">#include <Qt3DCore/QAspectEngine></span>
<span class="preprocessor">#include <Qt3DInput/QInputAspect></span>
<span class="preprocessor">#include <Qt3DRender/QRenderAspect></span>
<span class="preprocessor">#include <Qt3DExtras/QForwardRenderer></span>
<span class="preprocessor">#include <Qt3DExtras/QPhongMaterial></span>
<span class="preprocessor">#include <Qt3DExtras/QCylinderMesh></span>
<span class="preprocessor">#include <Qt3DExtras/QSphereMesh></span>
<span class="preprocessor">#include <Qt3DExtras/QTorusMesh></span>
</pre>
<p>First, we set up the scene and specify its root entity:</p>
<pre class="cpp">
<span class="type"><a href="qt3dcore-module.html">Qt3DCore</a></span><span class="operator">::</span><span class="type">QEntity</span> <span class="operator">*</span>createScene()
{
<span class="type"><a href="qt3dcore-module.html">Qt3DCore</a></span><span class="operator">::</span><span class="type">QEntity</span> <span class="operator">*</span>rootEntity <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qt3dcore-module.html">Qt3DCore</a></span><span class="operator">::</span><span class="type">QEntity</span>;
</pre>
<p>We specify the material to use for Phong rendering:</p>
<pre class="cpp">
<span class="type"><a href="qt3drender-module.html">Qt3DRender</a></span><span class="operator">::</span><span class="type">QMaterial</span> <span class="operator">*</span>material <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qt3dextras-sub-qt3d.html">Qt3DExtras</a></span><span class="operator">::</span><span class="type">QPhongMaterial</span>(rootEntity);
</pre>
<p>The root entity is just an empty shell and its behavior is defined by the components that it references. We specify the torus entity and its mesh, transform, and material components:</p>
<pre class="cpp">
<span class="type"><a href="qt3dcore-module.html">Qt3DCore</a></span><span class="operator">::</span><span class="type">QEntity</span> <span class="operator">*</span>torusEntity <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qt3dcore-module.html">Qt3DCore</a></span><span class="operator">::</span><span class="type">QEntity</span>(rootEntity);
<span class="type"><a href="qt3dextras-sub-qt3d.html">Qt3DExtras</a></span><span class="operator">::</span><span class="type">QTorusMesh</span> <span class="operator">*</span>torusMesh <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qt3dextras-sub-qt3d.html">Qt3DExtras</a></span><span class="operator">::</span><span class="type">QTorusMesh</span>;
torusMesh<span class="operator">-</span><span class="operator">></span>setRadius(<span class="number">5</span>);
torusMesh<span class="operator">-</span><span class="operator">></span>setMinorRadius(<span class="number">1</span>);
torusMesh<span class="operator">-</span><span class="operator">></span>setRings(<span class="number">100</span>);
torusMesh<span class="operator">-</span><span class="operator">></span>setSlices(<span class="number">20</span>);
<span class="type"><a href="qt3dcore-module.html">Qt3DCore</a></span><span class="operator">::</span><span class="type">QTransform</span> <span class="operator">*</span>torusTransform <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qt3dcore-module.html">Qt3DCore</a></span><span class="operator">::</span><span class="type">QTransform</span>;
torusTransform<span class="operator">-</span><span class="operator">></span>setScale3D(QVector3D(<span class="number">1.5</span><span class="operator">,</span> <span class="number">1</span><span class="operator">,</span> <span class="number">0.5</span>));
torusTransform<span class="operator">-</span><span class="operator">></span>setRotation(<span class="type">QQuaternion</span><span class="operator">::</span>fromAxisAndAngle(QVector3D(<span class="number">1</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">45.0f</span>));
torusEntity<span class="operator">-</span><span class="operator">></span>addComponent(torusMesh);
torusEntity<span class="operator">-</span><span class="operator">></span>addComponent(torusTransform);
torusEntity<span class="operator">-</span><span class="operator">></span>addComponent(material);
</pre>
<p>We also specify a sphere entity and its components:</p>
<pre class="cpp">
<span class="type"><a href="qt3dcore-module.html">Qt3DCore</a></span><span class="operator">::</span><span class="type">QEntity</span> <span class="operator">*</span>sphereEntity <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qt3dcore-module.html">Qt3DCore</a></span><span class="operator">::</span><span class="type">QEntity</span>(rootEntity);
<span class="type"><a href="qt3dextras-sub-qt3d.html">Qt3DExtras</a></span><span class="operator">::</span><span class="type">QSphereMesh</span> <span class="operator">*</span>sphereMesh <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qt3dextras-sub-qt3d.html">Qt3DExtras</a></span><span class="operator">::</span><span class="type">QSphereMesh</span>;
sphereMesh<span class="operator">-</span><span class="operator">></span>setRadius(<span class="number">3</span>);
<span class="type"><a href="qt3dcore-module.html">Qt3DCore</a></span><span class="operator">::</span><span class="type">QTransform</span> <span class="operator">*</span>sphereTransform <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qt3dcore-module.html">Qt3DCore</a></span><span class="operator">::</span><span class="type">QTransform</span>;
OrbitTransformController <span class="operator">*</span>controller <span class="operator">=</span> <span class="keyword">new</span> OrbitTransformController(sphereTransform);
controller<span class="operator">-</span><span class="operator">></span>setTarget(sphereTransform);
controller<span class="operator">-</span><span class="operator">></span>setRadius(<span class="number">20.0f</span>);
<span class="type">QPropertyAnimation</span> <span class="operator">*</span>sphereRotateTransformAnimation <span class="operator">=</span> <span class="keyword">new</span> <span class="type">QPropertyAnimation</span>(sphereTransform);
sphereRotateTransformAnimation<span class="operator">-</span><span class="operator">></span>setTargetObject(controller);
sphereRotateTransformAnimation<span class="operator">-</span><span class="operator">></span>setPropertyName(<span class="string">"angle"</span>);
sphereRotateTransformAnimation<span class="operator">-</span><span class="operator">></span>setStartValue(<span class="type">QVariant</span><span class="operator">::</span>fromValue(<span class="number">0</span>));
sphereRotateTransformAnimation<span class="operator">-</span><span class="operator">></span>setEndValue(<span class="type">QVariant</span><span class="operator">::</span>fromValue(<span class="number">360</span>));
sphereRotateTransformAnimation<span class="operator">-</span><span class="operator">></span>setDuration(<span class="number">10000</span>);
sphereRotateTransformAnimation<span class="operator">-</span><span class="operator">></span>setLoopCount(<span class="operator">-</span><span class="number">1</span>);
sphereRotateTransformAnimation<span class="operator">-</span><span class="operator">></span>start();
sphereEntity<span class="operator">-</span><span class="operator">></span>addComponent(sphereMesh);
sphereEntity<span class="operator">-</span><span class="operator">></span>addComponent(sphereTransform);
sphereEntity<span class="operator">-</span><span class="operator">></span>addComponent(material);
</pre>
<p>We use a property animation to animate the sphere transform.</p>
<p>Finally, we initialize a Qt GUI application that uses a Qt 3D window:</p>
<pre class="cpp">
<span class="type">int</span> main(<span class="type">int</span> argc<span class="operator">,</span> <span class="type">char</span><span class="operator">*</span> argv<span class="operator">[</span><span class="operator">]</span>)
{
<span class="type">QGuiApplication</span> app(argc<span class="operator">,</span> argv);
<span class="type"><a href="qt3dextras-sub-qt3d.html">Qt3DExtras</a></span><span class="operator">::</span><span class="type">Qt3DWindow</span> view;
<span class="type"><a href="qt3dcore-module.html">Qt3DCore</a></span><span class="operator">::</span><span class="type">QEntity</span> <span class="operator">*</span>scene <span class="operator">=</span> createScene();
<span class="comment">// Camera</span>
<span class="type"><a href="qt3drender-module.html">Qt3DRender</a></span><span class="operator">::</span><span class="type">QCamera</span> <span class="operator">*</span>camera <span class="operator">=</span> view<span class="operator">.</span>camera();
camera<span class="operator">-</span><span class="operator">></span>lens()<span class="operator">-</span><span class="operator">></span>setPerspectiveProjection(<span class="number">45.0f</span><span class="operator">,</span> <span class="number">16.0f</span><span class="operator">/</span><span class="number">9.0f</span><span class="operator">,</span> <span class="number">0.1f</span><span class="operator">,</span> <span class="number">1000.0f</span>);
camera<span class="operator">-</span><span class="operator">></span>setPosition(QVector3D(<span class="number">0</span><span class="operator">,</span> <span class="number">0</span><span class="operator">,</span> <span class="number">40.0f</span>));
camera<span class="operator">-</span><span class="operator">></span>setViewCenter(QVector3D(<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="comment">// For camera controls</span>
<span class="type"><a href="qt3dextras-sub-qt3d.html">Qt3DExtras</a></span><span class="operator">::</span><span class="type">QOrbitCameraController</span> <span class="operator">*</span>camController <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qt3dextras-sub-qt3d.html">Qt3DExtras</a></span><span class="operator">::</span><span class="type">QOrbitCameraController</span>(scene);
camController<span class="operator">-</span><span class="operator">></span>setLinearSpeed( <span class="number">50.0f</span> );
camController<span class="operator">-</span><span class="operator">></span>setLookSpeed( <span class="number">180.0f</span> );
camController<span class="operator">-</span><span class="operator">></span>setCamera(camera);
view<span class="operator">.</span>setRootEntity(scene);
view<span class="operator">.</span>show();
<span class="keyword">return</span> app<span class="operator">.</span>exec();
}
</pre>
<p>Files:</p>
<ul>
<li><a href="qt3d-simple-cpp-main-cpp.html">simple-cpp/main.cpp</a></li>
<li><a href="qt3d-simple-cpp-orbittransformcontroller-cpp.html">simple-cpp/orbittransformcontroller.cpp</a></li>
<li><a href="qt3d-simple-cpp-orbittransformcontroller-h.html">simple-cpp/orbittransformcontroller.h</a></li>
<li><a href="qt3d-simple-cpp-simple-cpp-pro.html">simple-cpp/simple-cpp.pro</a></li>
</ul>
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<!-- @@@simple-cpp -->
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