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<title>libQGLViewer cameraLight example</title>
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<h1>The cameraLight example</h1>
<center>
<img src="../images/cameraLight.jpg" width="330" height="228" alt="cameraLight"/>
</center>
<p>
This example shows how to position a GL_LIGHT on the camera.
</p>
<p>
A spot light position and direction are set so that they always match the
camera's current setup.
</p>
<p>
This is done using the <code>camera->position()</code> and <code>camera->viewDirection()</code>
methods which return values expressed in the world coordinates system.
</p>
<h2>cameraLight.h</h2>
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<pre><tt><b><font color="#000080">#include</font></b> <font color="#FF0000"><QGLViewer/qglviewer.h></font>
<b><font color="#0000FF">class</font></b> Viewer <font color="#990000">:</font> <b><font color="#0000FF">public</font></b> QGLViewer
<font color="#FF0000">{</font>
<b><font color="#0000FF">protected</font></b> <font color="#990000">:</font>
<b><font color="#0000FF">virtual</font></b> <font color="#009900">void</font> <b><font color="#000000">draw</font></b><font color="#990000">();</font>
<b><font color="#0000FF">virtual</font></b> <font color="#009900">void</font> <b><font color="#000000">init</font></b><font color="#990000">();</font>
<b><font color="#0000FF">virtual</font></b> QString <b><font color="#000000">helpString</font></b><font color="#990000">()</font> <b><font color="#0000FF">const</font></b><font color="#990000">;</font>
<b><font color="#0000FF">private</font></b> <font color="#990000">:</font>
<b><font color="#0000FF">virtual</font></b> <font color="#009900">void</font> <b><font color="#000000">drawSpiral</font></b><font color="#990000">();</font>
<font color="#FF0000">}</font><font color="#990000">;</font>
</tt></pre>
<h2>cameraLight.cpp</h2>
<!-- Generator: GNU source-highlight 2.4
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<pre><tt><b><font color="#000080">#include</font></b> <font color="#FF0000">"cameraLight.h"</font>
<b><font color="#0000FF">using</font></b> <b><font color="#0000FF">namespace</font></b> std<font color="#990000">;</font>
<b><font color="#0000FF">using</font></b> <b><font color="#0000FF">namespace</font></b> qglviewer<font color="#990000">;</font>
<font color="#009900">void</font> Viewer<font color="#990000">::</font><b><font color="#000000">draw</font></b><font color="#990000">()</font>
<font color="#FF0000">{</font>
<i><font color="#9A1900">// Place light at camera position</font></i>
<b><font color="#0000FF">const</font></b> Vec cameraPos <font color="#990000">=</font> <b><font color="#000000">camera</font></b><font color="#990000">()-></font><b><font color="#000000">position</font></b><font color="#990000">();</font>
<b><font color="#0000FF">const</font></b> GLfloat pos<font color="#990000">[</font><font color="#993399">4</font><font color="#990000">]</font> <font color="#990000">=</font> <font color="#FF0000">{</font>cameraPos<font color="#990000">[</font><font color="#993399">0</font><font color="#990000">],</font> cameraPos<font color="#990000">[</font><font color="#993399">1</font><font color="#990000">],</font> cameraPos<font color="#990000">[</font><font color="#993399">2</font><font color="#990000">],</font> <font color="#993399">1.0</font><font color="#FF0000">}</font><font color="#990000">;</font>
<b><font color="#000000">glLightfv</font></b><font color="#990000">(</font>GL_LIGHT1<font color="#990000">,</font> GL_POSITION<font color="#990000">,</font> pos<font color="#990000">);</font>
<i><font color="#9A1900">// Orientate light along view direction</font></i>
<b><font color="#000000">glLightfv</font></b><font color="#990000">(</font>GL_LIGHT1<font color="#990000">,</font> GL_SPOT_DIRECTION<font color="#990000">,</font> <b><font color="#000000">camera</font></b><font color="#990000">()-></font><b><font color="#000000">viewDirection</font></b><font color="#990000">());</font>
<b><font color="#000000">drawSpiral</font></b><font color="#990000">();</font>
<font color="#FF0000">}</font>
<i><font color="#9A1900">// Draws a spiral</font></i>
<font color="#009900">void</font> Viewer<font color="#990000">::</font><b><font color="#000000">drawSpiral</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">1000.0</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">int</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>
<b><font color="#0000FF">const</font></b> <font color="#009900">float</font> ratio <font color="#990000">=</font> i<font color="#990000">/</font>nbSteps<font color="#990000">;</font>
<b><font color="#0000FF">const</font></b> <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>
<b><font color="#0000FF">const</font></b> <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>
<b><font color="#0000FF">const</font></b> <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>
<b><font color="#0000FF">const</font></b> <font color="#009900">float</font> r1 <font color="#990000">=</font> <font color="#993399">1.0</font> <font color="#990000">-</font> <font color="#993399">0</font><font color="#990000">.</font>8f<font color="#990000">*</font>ratio<font color="#990000">;</font>
<b><font color="#0000FF">const</font></b> <font color="#009900">float</font> r2 <font color="#990000">=</font> <font color="#993399">0</font><font color="#990000">.</font>8f <font color="#990000">-</font> <font color="#993399">0</font><font color="#990000">.</font>8f<font color="#990000">*</font>ratio<font color="#990000">;</font>
<b><font color="#0000FF">const</font></b> <font color="#009900">float</font> alt <font color="#990000">=</font> ratio <font color="#990000">-</font> <font color="#993399">0</font><font color="#990000">.</font>5f<font color="#990000">;</font>
<b><font color="#0000FF">const</font></b> <font color="#009900">float</font> nor <font color="#990000">=</font> <font color="#993399">0</font><font color="#990000">.</font>5f<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</font><font color="#990000">.</font>05f<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>
<font color="#009900">void</font> Viewer<font color="#990000">::</font><b><font color="#000000">init</font></b><font color="#990000">()</font>
<font color="#FF0000">{</font>
<i><font color="#9A1900">// Light setup</font></i>
<b><font color="#000000">glDisable</font></b><font color="#990000">(</font>GL_LIGHT0<font color="#990000">);</font>
<b><font color="#000000">glEnable</font></b><font color="#990000">(</font>GL_LIGHT1<font color="#990000">);</font>
<i><font color="#9A1900">// Light default parameters</font></i>
<b><font color="#0000FF">const</font></b> GLfloat light_ambient<font color="#990000">[</font><font color="#993399">4</font><font color="#990000">]</font> <font color="#990000">=</font> <font color="#FF0000">{</font><font color="#993399">1.0</font><font color="#990000">,</font> <font color="#993399">1.0</font><font color="#990000">,</font> <font color="#993399">1.0</font><font color="#990000">,</font> <font color="#993399">1.0</font><font color="#FF0000">}</font><font color="#990000">;</font>
<b><font color="#0000FF">const</font></b> GLfloat light_specular<font color="#990000">[</font><font color="#993399">4</font><font color="#990000">]</font> <font color="#990000">=</font> <font color="#FF0000">{</font><font color="#993399">1.0</font><font color="#990000">,</font> <font color="#993399">1.0</font><font color="#990000">,</font> <font color="#993399">1.0</font><font color="#990000">,</font> <font color="#993399">1.0</font><font color="#FF0000">}</font><font color="#990000">;</font>
<b><font color="#0000FF">const</font></b> GLfloat light_diffuse<font color="#990000">[</font><font color="#993399">4</font><font color="#990000">]</font> <font color="#990000">=</font> <font color="#FF0000">{</font><font color="#993399">1.0</font><font color="#990000">,</font> <font color="#993399">1.0</font><font color="#990000">,</font> <font color="#993399">1.0</font><font color="#990000">,</font> <font color="#993399">1.0</font><font color="#FF0000">}</font><font color="#990000">;</font>
<b><font color="#000000">glLightf</font></b><font color="#990000">(</font> GL_LIGHT1<font color="#990000">,</font> GL_SPOT_EXPONENT<font color="#990000">,</font> <font color="#993399">3.0</font><font color="#990000">);</font>
<b><font color="#000000">glLightf</font></b><font color="#990000">(</font> GL_LIGHT1<font color="#990000">,</font> GL_SPOT_CUTOFF<font color="#990000">,</font> <font color="#993399">10.0</font><font color="#990000">);</font>
<b><font color="#000000">glLightf</font></b><font color="#990000">(</font> GL_LIGHT1<font color="#990000">,</font> GL_CONSTANT_ATTENUATION<font color="#990000">,</font> <font color="#993399">0</font><font color="#990000">.</font>1f<font color="#990000">);</font>
<b><font color="#000000">glLightf</font></b><font color="#990000">(</font> GL_LIGHT1<font color="#990000">,</font> GL_LINEAR_ATTENUATION<font color="#990000">,</font> <font color="#993399">0</font><font color="#990000">.</font>3f<font color="#990000">);</font>
<b><font color="#000000">glLightf</font></b><font color="#990000">(</font> GL_LIGHT1<font color="#990000">,</font> GL_QUADRATIC_ATTENUATION<font color="#990000">,</font> <font color="#993399">0</font><font color="#990000">.</font>3f<font color="#990000">);</font>
<b><font color="#000000">glLightfv</font></b><font color="#990000">(</font>GL_LIGHT1<font color="#990000">,</font> GL_AMBIENT<font color="#990000">,</font> light_ambient<font color="#990000">);</font>
<b><font color="#000000">glLightfv</font></b><font color="#990000">(</font>GL_LIGHT1<font color="#990000">,</font> GL_SPECULAR<font color="#990000">,</font> light_specular<font color="#990000">);</font>
<b><font color="#000000">glLightfv</font></b><font color="#990000">(</font>GL_LIGHT1<font color="#990000">,</font> GL_DIFFUSE<font color="#990000">,</font> light_diffuse<font color="#990000">);</font>
<i><font color="#9A1900">// Restore previous viewer state.</font></i>
<b><font color="#000000">restoreStateFromFile</font></b><font color="#990000">();</font>
<i><font color="#9A1900">// Opens help window</font></i>
<b><font color="#000000">help</font></b><font color="#990000">();</font>
<font color="#FF0000">}</font>
QString Viewer<font color="#990000">::</font><b><font color="#000000">helpString</font></b><font color="#990000">()</font> <b><font color="#0000FF">const</font></b>
<font color="#FF0000">{</font>
QString <b><font color="#000000">text</font></b><font color="#990000">(</font><font color="#FF0000">"<h2>C a m e r a L i g h t</h2>"</font><font color="#990000">);</font>
text <font color="#990000">+=</font> <font color="#FF0000">"See the <b>Mouse</b> tab and the documentation web pages for details.<br><br>"</font><font color="#990000">;</font>
text <font color="#990000">+=</font> <font color="#FF0000">"Press <b>Escape</b> to exit the viewer."</font><font color="#990000">;</font>
<b><font color="#0000FF">return</font></b> text<font color="#990000">;</font>
<font color="#FF0000">}</font>
</tt></pre>
<h2>main.cpp</h2>
<!-- Generator: GNU source-highlight 2.4
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">"cameraLight.h"</font>
<b><font color="#000080">#include</font></b> <font color="#FF0000"><qapplication.h></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>
<i><font color="#9A1900">// Read command lines arguments.</font></i>
QApplication <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>
Viewer viewer<font color="#990000">;</font>
<b><font color="#000080">#if</font></b> QT_VERSION <font color="#990000"><</font> <font color="#993399">0x040000</font>
<i><font color="#9A1900">// Set the viewer as the application main widget.</font></i>
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">"cameraLight"</font><font color="#990000">);</font>
<b><font color="#000080">#endif</font></b>
<i><font color="#9A1900">// Make the viewer window visible on screen.</font></i>
viewer<font color="#990000">.</font><b><font color="#000000">show</font></b><font color="#990000">();</font>
<i><font color="#9A1900">// Run main loop.</font></i>
<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>
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