<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <title>libQGLViewer callback example</title> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <link href="../qglviewer.css" rel="stylesheet" type="text/css" /> <link rel="shortcut icon" href="../images/qglviewer.ico" type="image/x-icon" /> <link rel="icon" href="../images/qglviewer.icon.png" type="image/png" /> </head> <body> <div class="banner"> <a class="qindex" href="../index.html">Home</a> <a class="qindex" href="../download.html">Download</a> <a class="qindex highlight" href="index.html">Examples</a> <a class="qindex" href="../refManual/hierarchy.html">Documentation</a> <a class="qindex" href="../developer.html">Developer</a> </div> <h1>The callback example</h1> <center> <img src="../images/callback.jpg" width="330" height="228" alt="callback"/> </center> <p> Using the Qt signal-slot mechanism to connect a QGLViewer to your scene. </p> <p> This very simple application uses the Qt signal-slot callback mechanism to link the QGLViewer and your Scene. The two class hence remain totally independent. The <code>drawNeeded()</code> QGLViewer signal is connected to the Scene <code>drawScene()</code> slot. </p> <h2>callback.h</h2> <!-- Generator: GNU source-highlight 3.1.4 by Lorenzo Bettini http://www.lorenzobettini.it http://www.gnu.org/software/src-highlite --> <pre><tt><b><font color="#000080">#include</font></b> <font color="#FF0000"><qobject.h></font> <b><font color="#0000FF">class</font></b> <font color="#008080">QGLViewer</font><font color="#990000">;</font> <i><font color="#9A1900">// The Scene class must derive from QObject in order to allow a</font></i> <i><font color="#9A1900">// signal slot mechanism.</font></i> <b><font color="#0000FF">class</font></b> <font color="#008080">Scene</font> <font color="#990000">:</font> <b><font color="#0000FF">public</font></b> QObject <font color="#FF0000">{</font> Q_OBJECT <b><font color="#0000FF">public</font></b> <font color="#990000">:</font> <b><font color="#000000">Scene</font></b><font color="#990000">(</font><b><font color="#0000FF">const</font></b> QGLViewer<font color="#990000">*</font> <b><font color="#0000FF">const</font></b> v<font color="#990000">);</font> <b><font color="#0000FF">public</font></b> Q_SLOTS<font color="#990000">:</font> <font color="#009900">void</font> <b><font color="#000000">draw</font></b><font color="#990000">();</font> <font color="#FF0000">}</font><font color="#990000">;</font> </tt></pre> <h2>callback.cpp</h2> <!-- Generator: GNU source-highlight 3.1.4 by Lorenzo Bettini http://www.lorenzobettini.it http://www.gnu.org/software/src-highlite --> <pre><tt><b><font color="#000080">#include</font></b> <font color="#FF0000"><QGLViewer/qglviewer.h></font> <b><font color="#000080">#include</font></b> <font color="#FF0000">"callback.h"</font> <b><font color="#000080">#include</font></b> <font color="#FF0000"><math.h></font> Scene<font color="#990000">::</font><b><font color="#000000">Scene</font></b><font color="#990000">(</font><b><font color="#0000FF">const</font></b> QGLViewer<font color="#990000">*</font> <b><font color="#0000FF">const</font></b> v<font color="#990000">)</font> <font color="#FF0000">{</font> <i><font color="#9A1900">// Connect the viewer signal to our draw slot.</font></i> <b><font color="#000000">connect</font></b><font color="#990000">(</font>v<font color="#990000">,</font> <b><font color="#000000">SIGNAL</font></b><font color="#990000">(</font><b><font color="#000000">drawNeeded</font></b><font color="#990000">()),</font> <b><font color="#0000FF">this</font></b><font color="#990000">,</font> <b><font color="#000000">SLOT</font></b><font color="#990000">(</font><b><font color="#000000">draw</font></b><font color="#990000">()));</font> <font color="#FF0000">}</font> <i><font color="#9A1900">// Draws a spiral</font></i> <font color="#009900">void</font> Scene<font color="#990000">::</font><b><font color="#000000">draw</font></b><font color="#990000">()</font> <font color="#FF0000">{</font> <b><font color="#0000FF">const</font></b> <font color="#009900">float</font> nbSteps <font color="#990000">=</font> <font color="#993399">200.0</font><font color="#990000">;</font> <b><font color="#000000">glBegin</font></b><font color="#990000">(</font>GL_QUAD_STRIP<font color="#990000">);</font> <b><font color="#0000FF">for</font></b> <font color="#990000">(</font><font color="#009900">float</font> i<font color="#990000">=</font><font color="#993399">0</font><font color="#990000">;</font> i<font color="#990000"><</font>nbSteps<font color="#990000">;</font> <font color="#990000">++</font>i<font color="#990000">)</font> <font color="#FF0000">{</font> <font color="#009900">float</font> ratio <font color="#990000">=</font> i<font color="#990000">/</font>nbSteps<font color="#990000">;</font> <font color="#009900">float</font> angle <font color="#990000">=</font> <font color="#993399">21.0</font><font color="#990000">*</font>ratio<font color="#990000">;</font> <font color="#009900">float</font> c <font color="#990000">=</font> <b><font color="#000000">cos</font></b><font color="#990000">(</font>angle<font color="#990000">);</font> <font color="#009900">float</font> s <font color="#990000">=</font> <b><font color="#000000">sin</font></b><font color="#990000">(</font>angle<font color="#990000">);</font> <font color="#009900">float</font> r1 <font color="#990000">=</font> <font color="#993399">1.0</font> <font color="#990000">-</font> <font color="#993399">0.8</font><font color="#990000">*</font>ratio<font color="#990000">;</font> <font color="#009900">float</font> r2 <font color="#990000">=</font> <font color="#993399">0.8</font> <font color="#990000">-</font> <font color="#993399">0.8</font><font color="#990000">*</font>ratio<font color="#990000">;</font> <font color="#009900">float</font> alt <font color="#990000">=</font> ratio <font color="#990000">-</font> <font color="#993399">0.5</font><font color="#990000">;</font> <b><font color="#0000FF">const</font></b> <font color="#009900">float</font> nor <font color="#990000">=</font> <font color="#990000">.</font><font color="#993399">5</font><font color="#990000">;</font> <b><font color="#0000FF">const</font></b> <font color="#009900">float</font> up <font color="#990000">=</font> <b><font color="#000000">sqrt</font></b><font color="#990000">(</font><font color="#993399">1.0</font><font color="#990000">-</font>nor<font color="#990000">*</font>nor<font color="#990000">);</font> <b><font color="#000000">glColor3f</font></b><font color="#990000">(</font><font color="#993399">1.0</font><font color="#990000">-</font>ratio<font color="#990000">,</font> <font color="#993399">0</font><font color="#990000">.</font>2f <font color="#990000">,</font> ratio<font color="#990000">);</font> <b><font color="#000000">glNormal3f</font></b><font color="#990000">(</font>nor<font color="#990000">*</font>c<font color="#990000">,</font> up<font color="#990000">,</font> nor<font color="#990000">*</font>s<font color="#990000">);</font> <b><font color="#000000">glVertex3f</font></b><font color="#990000">(</font>r1<font color="#990000">*</font>c<font color="#990000">,</font> alt<font color="#990000">,</font> r1<font color="#990000">*</font>s<font color="#990000">);</font> <b><font color="#000000">glVertex3f</font></b><font color="#990000">(</font>r2<font color="#990000">*</font>c<font color="#990000">,</font> alt<font color="#990000">+</font><font color="#993399">0.05</font><font color="#990000">,</font> r2<font color="#990000">*</font>s<font color="#990000">);</font> <font color="#FF0000">}</font> <b><font color="#000000">glEnd</font></b><font color="#990000">();</font> <font color="#FF0000">}</font> </tt></pre> <h2>main.cpp</h2> <!-- Generator: GNU source-highlight 3.1.4 by Lorenzo Bettini http://www.lorenzobettini.it http://www.gnu.org/software/src-highlite --> <pre><tt><b><font color="#000080">#include</font></b> <font color="#FF0000">"callback.h"</font> <b><font color="#000080">#include</font></b> <font color="#FF0000"><QGLViewer/qglviewer.h></font> <b><font color="#000080">#include</font></b> <font color="#FF0000"><qapplication.h></font> <b><font color="#000080">#include</font></b> <font color="#FF0000"><qmessagebox.h></font> <b><font color="#0000FF">using</font></b> <b><font color="#0000FF">namespace</font></b> std<font color="#990000">;</font> <font color="#009900">void</font> <b><font color="#000000">help</font></b><font color="#990000">()</font> <font color="#FF0000">{</font> <font color="#008080">QString</font> <b><font color="#000000">text</font></b><font color="#990000">(</font><font color="#FF0000">"<h2>C a l l b a c k</h2>"</font><font color="#990000">);</font> text <font color="#990000">+=</font> <font color="#FF0000">"This example is conceptually the same as simpleViewer.<br>"</font><font color="#990000">;</font> text <font color="#990000">+=</font> <font color="#FF0000">"The difference is that it uses the Qt signal/slot mechanism "</font><font color="#990000">;</font> text <font color="#990000">+=</font> <font color="#FF0000">"instead of deriving the QGLViewer class. "</font><font color="#990000">;</font> text <font color="#990000">+=</font> <font color="#FF0000">"The QGLViewer::drawNeeded() signal is connected to the Scene::draw() method. "</font><font color="#990000">;</font> text <font color="#990000">+=</font> <font color="#FF0000">"The two classes are otherwise completely independant."</font><font color="#990000">;</font> QMessageBox<font color="#990000">::</font><b><font color="#000000">information</font></b><font color="#990000">(</font>NULL<font color="#990000">,</font> <font color="#FF0000">"Callback exemple"</font><font color="#990000">,</font> text<font color="#990000">);</font> <font color="#FF0000">}</font> <font color="#009900">int</font> <b><font color="#000000">main</font></b><font color="#990000">(</font><font color="#009900">int</font> argc<font color="#990000">,</font> <font color="#009900">char</font><font color="#990000">**</font> argv<font color="#990000">)</font> <font color="#FF0000">{</font> <font color="#008080">QApplication</font> <b><font color="#000000">application</font></b><font color="#990000">(</font>argc<font color="#990000">,</font>argv<font color="#990000">);</font> <i><font color="#9A1900">// Instantiate the viewer.</font></i> <font color="#008080">QGLViewer</font> viewer<font color="#990000">;</font> <i><font color="#9A1900">// Restore the previous viewer state.</font></i> viewer<font color="#990000">.</font><b><font color="#000000">restoreStateFromFile</font></b><font color="#990000">();</font> <i><font color="#9A1900">// Create a scene, giving a pointer to the associated viewer.</font></i> <font color="#008080">Scene</font> <b><font color="#000000">s</font></b><font color="#990000">(&</font>viewer<font color="#990000">);</font> <b><font color="#000080">#if</font></b> QT_VERSION <font color="#990000"><</font> <font color="#993399">0x040000</font> application<font color="#990000">.</font><b><font color="#000000">setMainWidget</font></b><font color="#990000">(&</font>viewer<font color="#990000">);</font> <b><font color="#000080">#else</font></b> viewer<font color="#990000">.</font><b><font color="#000000">setWindowTitle</font></b><font color="#990000">(</font><font color="#FF0000">"callback"</font><font color="#990000">);</font> <b><font color="#000080">#endif</font></b> <b><font color="#000000">help</font></b><font color="#990000">();</font> viewer<font color="#990000">.</font><b><font color="#000000">show</font></b><font color="#990000">();</font> <b><font color="#0000FF">return</font></b> application<font color="#990000">.</font><b><font color="#000000">exec</font></b><font color="#990000">();</font> <font color="#FF0000">}</font> </tt></pre> <p> Back to the <a href="index.html">examples main page</a>. </p> <p> <a href="http://validator.w3.org/check/referer"><img src="../images/xhtml.png" alt="Valid XHTML 1.0!" height="31" width="88"/></a> <a href="http://jigsaw.w3.org/css-validator/check/referer"><img src="../images/css.gif" width="88" height="31" alt="Valid CSS!"/></a> <i>Last modified on Monday, December 06, 2010.</i> </p> </body> </html>