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<div class="section" id="using-ringopengl-and-ringfreeglut-for-3d-graphics">
<span id="index-0"></span><h1>Using RingOpenGL and RingFreeGLUT for 3D Graphics<a class="headerlink" href="#using-ringopengl-and-ringfreeglut-for-3d-graphics" title="Permalink to this headline">¶</a></h1>
<p>In this chapter we will learn about using RingOpenGL</p>
<div class="section" id="samples-source-authors">
<span id="index-1"></span><h2>Samples Source (Authors)<a class="headerlink" href="#samples-source-authors" title="Permalink to this headline">¶</a></h2>
<p>The samples in this chapter are based on C Tutorials</p>
<p>from</p>
<ol class="arabic simple">
<li><p><a class="reference external" href="http://www.lighthouse3d.com/tutorials/glut-tutorial/">http://www.lighthouse3d.com/tutorials/glut-tutorial/</a></p></li>
<li><p><a class="reference external" href="http://www.wikihow.com/Make-a-Cube-in-OpenGL">http://www.wikihow.com/Make-a-Cube-in-OpenGL</a></p></li>
</ol>
</div>
<div class="section" id="what-is-ringopengl">
<span id="index-2"></span><h2>What is RingOpenGL?<a class="headerlink" href="#what-is-ringopengl" title="Permalink to this headline">¶</a></h2>
<p>RingOpenGL contains the Ring binding to the OpenGL library</p>
<p>You can learn about OpenGL from : <a class="reference external" href="https://www.opengl.org/">https://www.opengl.org/</a></p>
<p>RingOpenGL comes with support for the next versions</p>
<ul class="simple">
<li><p>OpenGL 1.1</p></li>
<li><p>OpenGL 1.2</p></li>
<li><p>OpenGL 1.3</p></li>
<li><p>OpenGL 1.4</p></li>
<li><p>OpenGL 1.5</p></li>
<li><p>OpenGL 2.0</p></li>
<li><p>OpenGL 2.1</p></li>
<li><p>OpenGL 3.0</p></li>
<li><p>OpenGL 3.2</p></li>
<li><p>OpenGL 3.3</p></li>
<li><p>OpenGL 4.0</p></li>
<li><p>OpenGL 4.1</p></li>
<li><p>OpenGL 4.2</p></li>
<li><p>OpenGL 4.3</p></li>
<li><p>OpenGL 4.4</p></li>
<li><p>OpenGL 4.5</p></li>
<li><p>OpenGL 4.6</p></li>
</ul>
<p>For example, if you want to use OpenGL 2.1 then load RingOpenGL 2.1 library</p>
<div class="highlight-ring notranslate"><div class="highlight"><pre><span></span><span class="k">load</span> <span class="s">"opengl21lib.ring"</span>
</pre></div>
</div>
</div>
<div class="section" id="what-is-ringfreeglut">
<span id="index-3"></span><h2>What is RingFreeGLUT?<a class="headerlink" href="#what-is-ringfreeglut" title="Permalink to this headline">¶</a></h2>
<p>RingFreeGLUT contains the Ring binding to the FreeGLUT library</p>
<p>You can learn about FreeGLUT from : <a class="reference external" href="http://freeglut.sourceforge.net/">http://freeglut.sourceforge.net/</a></p>
<p>To use the RingFreeGLUT library, Just load the library</p>
<div class="highlight-ring notranslate"><div class="highlight"><pre><span></span><span class="k">load</span> <span class="s">"freeglut.ring"</span>
</pre></div>
</div>
</div>
<div class="section" id="the-first-window-using-ringfreeglut">
<span id="index-4"></span><h2>The First Window using RingFreeGLUT<a class="headerlink" href="#the-first-window-using-ringfreeglut" title="Permalink to this headline">¶</a></h2>
<p>Example:</p>
<div class="highlight-ring notranslate"><div class="highlight"><pre><span></span><span class="k">load</span> <span class="s">"freeglut.ring"</span>
<span class="k">func</span> <span class="n">main</span>
<span class="n">glutInit</span><span class="p">()</span>
<span class="n">glutInitDisplayMode</span><span class="p">(</span><span class="n">GLUT_SINGLE</span><span class="p">)</span>
<span class="n">glutInitWindowSize</span><span class="p">(</span><span class="mi">800</span><span class="p">,</span> <span class="mi">600</span><span class="p">)</span>
<span class="n">glutInitWindowPosition</span><span class="p">(</span><span class="mi">100</span><span class="p">,</span> <span class="mi">10</span><span class="p">)</span>
<span class="n">glutCreateWindow</span><span class="p">(</span><span class="s">"RingFreeGLUT - Test 1"</span><span class="p">)</span>
<span class="n">glutDisplayFunc</span><span class="p">(:</span><span class="n">displayCode</span><span class="p">)</span>
<span class="n">glutMainLoop</span><span class="p">()</span>
<span class="k">func</span> <span class="n">displaycode</span>
</pre></div>
</div>
<p>Screen Shot</p>
<img alt="RingFreeGLUT" src="_images/freeglutshot1.png" />
</div>
<div class="section" id="drawing-using-ringopengl">
<span id="index-5"></span><h2>Drawing using RingOpenGL<a class="headerlink" href="#drawing-using-ringopengl" title="Permalink to this headline">¶</a></h2>
<p>Example:</p>
<div class="highlight-ring notranslate"><div class="highlight"><pre><span></span><span class="k">load</span> <span class="s">"freeglut.ring"</span>
<span class="k">load</span> <span class="s">"opengl21lib.ring"</span>
<span class="k">func</span> <span class="n">main</span>
<span class="n">glutInit</span><span class="p">()</span>
<span class="n">glutInitDisplayMode</span><span class="p">(</span><span class="n">GLUT_SINGLE</span><span class="p">)</span>
<span class="n">glutInitWindowSize</span><span class="p">(</span><span class="mi">800</span><span class="p">,</span> <span class="mi">600</span><span class="p">)</span>
<span class="n">glutInitWindowPosition</span><span class="p">(</span><span class="mi">100</span><span class="p">,</span> <span class="mi">10</span><span class="p">)</span>
<span class="n">glutCreateWindow</span><span class="p">(</span><span class="s">"RingFreeGLUT - Test 2"</span><span class="p">)</span>
<span class="n">glutDisplayFunc</span><span class="p">(:</span><span class="n">displayCode</span><span class="p">)</span>
<span class="n">glutMainLoop</span><span class="p">()</span>
<span class="k">func</span> <span class="n">displaycode</span>
<span class="n">glClear</span><span class="p">(</span><span class="n">GL_COLOR_BUFFER_BIT</span><span class="p">)</span>
<span class="n">glColor3f</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span><span class="mi">255</span><span class="p">,</span><span class="mi">0</span><span class="p">)</span>
<span class="n">glBegin</span><span class="p">(</span><span class="n">GL_POLYGON</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span><span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span><span class="mf">0.5</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span><span class="mf">0.5</span><span class="p">,</span> <span class="mf">0.5</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span><span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.5</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glEnd</span><span class="p">()</span>
<span class="n">glColor3f</span><span class="p">(</span><span class="mi">255</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">)</span>
<span class="n">glBegin</span><span class="p">(</span><span class="n">GL_POLYGON</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span><span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span><span class="mf">0.5</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span><span class="o">-</span><span class="mf">0.5</span><span class="p">,</span><span class="o">-</span> <span class="mi">1</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span><span class="mf">0.0</span><span class="p">,</span> <span class="o">-</span><span class="mi">1</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glEnd</span><span class="p">()</span>
<span class="n">glColor3f</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">255</span><span class="p">)</span>
<span class="n">glBegin</span><span class="p">(</span><span class="n">GL_POLYGON</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span><span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span><span class="o">-</span><span class="mf">0.5</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span><span class="o">-</span><span class="mf">0.5</span><span class="p">,</span><span class="o">-</span> <span class="mf">0.5</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span><span class="mf">0.0</span><span class="p">,</span> <span class="o">-</span><span class="mf">0.5</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glEnd</span><span class="p">()</span>
<span class="n">glFlush</span><span class="p">()</span>
</pre></div>
</div>
<p>Screen Shot</p>
<img alt="RingFreeGLUT" src="_images/freeglutshot2.png" />
</div>
<div class="section" id="the-first-triangle">
<span id="index-6"></span><h2>The First Triangle<a class="headerlink" href="#the-first-triangle" title="Permalink to this headline">¶</a></h2>
<p>Example:</p>
<div class="highlight-ring notranslate"><div class="highlight"><pre><span></span><span class="k">load</span> <span class="s">"freeglut.ring"</span>
<span class="k">load</span> <span class="s">"opengl21lib.ring"</span>
<span class="k">func</span> <span class="n">main</span>
<span class="n">glutInit</span><span class="p">()</span>
<span class="n">glutInitDisplayMode</span><span class="p">(</span><span class="n">GLUT_DEPTH</span> <span class="o">|</span> <span class="n">GLUT_DOUBLE</span> <span class="o">|</span> <span class="n">GLUT_RGBA</span><span class="p">)</span>
<span class="n">glutInitWindowSize</span><span class="p">(</span><span class="mi">320</span><span class="p">,</span><span class="mi">320</span><span class="p">)</span>
<span class="n">glutInitWindowPosition</span><span class="p">(</span><span class="mi">100</span><span class="p">,</span> <span class="mi">10</span><span class="p">)</span>
<span class="n">glutCreateWindow</span><span class="p">(</span><span class="s">"RingFreeGLUT - Test 3"</span><span class="p">)</span>
<span class="n">glutDisplayFunc</span><span class="p">(:</span><span class="n">renderScene</span><span class="p">)</span>
<span class="n">glutMainLoop</span><span class="p">()</span>
<span class="k">func</span> <span class="n">renderScene</span>
<span class="n">glClear</span><span class="p">(</span><span class="n">GL_COLOR_BUFFER_BIT</span> <span class="o">|</span> <span class="n">GL_DEPTH_BUFFER_BIT</span><span class="p">)</span>
<span class="n">glBegin</span><span class="p">(</span><span class="n">GL_TRIANGLES</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span><span class="o">-</span><span class="mf">0.5</span><span class="p">,</span><span class="o">-</span><span class="mf">0.5</span><span class="p">,</span><span class="mf">0.0</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span><span class="mf">0.5</span><span class="p">,</span><span class="mf">0.0</span><span class="p">,</span><span class="mf">0.0</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span><span class="mf">0.0</span><span class="p">,</span><span class="mf">0.5</span><span class="p">,</span><span class="mf">0.0</span><span class="p">)</span>
<span class="n">glEnd</span><span class="p">()</span>
<span class="n">glutSwapBuffers</span><span class="p">()</span>
</pre></div>
</div>
<p>Screen Shot</p>
<img alt="RingFreeGLUT" src="_images/freeglutshot3.png" />
</div>
<div class="section" id="window-resize-event">
<span id="index-7"></span><h2>Window Resize Event<a class="headerlink" href="#window-resize-event" title="Permalink to this headline">¶</a></h2>
<p>Example:</p>
<div class="highlight-ring notranslate"><div class="highlight"><pre><span></span><span class="k">load</span> <span class="s">"freeglut.ring"</span>
<span class="k">load</span> <span class="s">"opengl21lib.ring"</span>
<span class="k">func</span> <span class="n">main</span>
<span class="o">//</span> <span class="n">init</span> <span class="n">GLUT</span> <span class="ow">and</span> <span class="n">create</span> <span class="n">window</span>
<span class="n">glutInit</span><span class="p">()</span>
<span class="n">glutInitDisplayMode</span><span class="p">(</span><span class="n">GLUT_DEPTH</span> <span class="o">|</span> <span class="n">GLUT_DOUBLE</span> <span class="o">|</span> <span class="n">GLUT_RGBA</span><span class="p">)</span>
<span class="n">glutInitWindowPosition</span><span class="p">(</span><span class="mi">100</span><span class="p">,</span><span class="mi">100</span><span class="p">)</span>
<span class="n">glutInitWindowSize</span><span class="p">(</span><span class="mi">320</span><span class="p">,</span><span class="mi">320</span><span class="p">)</span>
<span class="n">glutCreateWindow</span><span class="p">(</span><span class="s">"RingFreeGLUT - Test 4"</span><span class="p">)</span>
<span class="n">glutDisplayFunc</span><span class="p">(:</span><span class="n">renderScene</span><span class="p">)</span>
<span class="n">glutReshapeFunc</span><span class="p">(:</span><span class="n">changeSize</span><span class="p">)</span>
<span class="n">glutMainLoop</span><span class="p">()</span>
<span class="k">func</span> <span class="n">renderScene</span>
<span class="n">glClear</span><span class="p">(</span><span class="n">GL_COLOR_BUFFER_BIT</span> <span class="o">|</span> <span class="n">GL_DEPTH_BUFFER_BIT</span><span class="p">)</span>
<span class="n">glBegin</span><span class="p">(</span><span class="n">GL_TRIANGLES</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span><span class="o">-</span><span class="mi">2</span><span class="p">,</span><span class="o">-</span><span class="mi">2</span><span class="p">,</span><span class="o">-</span><span class="mf">5.0</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span><span class="mi">2</span><span class="p">,</span><span class="mf">0.0</span><span class="p">,</span><span class="o">-</span><span class="mf">5.0</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span><span class="mf">0.0</span><span class="p">,</span><span class="mi">2</span><span class="p">,</span><span class="o">-</span><span class="mf">5.0</span><span class="p">)</span>
<span class="n">glEnd</span><span class="p">()</span>
<span class="n">glutSwapBuffers</span><span class="p">()</span>
<span class="k">func</span> <span class="n">changesize</span>
<span class="n">h</span> <span class="o">=</span> <span class="n">glutEventHeight</span><span class="p">()</span>
<span class="n">w</span> <span class="o">=</span> <span class="n">glutEventWidth</span><span class="p">()</span>
<span class="o">//</span> <span class="n">Prevent</span> <span class="n">a</span> <span class="n">divide</span> <span class="n">by</span> <span class="n">zero</span><span class="p">,</span> <span class="n">when</span> <span class="n">window</span> <span class="n">is</span> <span class="n">too</span> <span class="n">short</span>
<span class="o">//</span> <span class="p">(</span><span class="n">you</span> <span class="n">cant</span> <span class="n">make</span> <span class="n">a</span> <span class="n">window</span> <span class="n">of</span> <span class="n">zero</span> <span class="n">width</span><span class="p">).</span>
<span class="k">if</span> <span class="p">(</span><span class="n">h</span> <span class="o">=</span> <span class="mi">0</span><span class="p">)</span>
<span class="n">h</span> <span class="o">=</span> <span class="mi">1</span>
<span class="k">ok</span>
<span class="n">ratio</span> <span class="o">=</span> <span class="n">w</span> <span class="o">*</span> <span class="mf">1.0</span> <span class="o">/</span> <span class="n">h</span>
<span class="o">//</span> <span class="n">Use</span> <span class="n">the</span> <span class="n">Projection</span> <span class="n">Matrix</span>
<span class="n">glMatrixMode</span><span class="p">(</span><span class="n">GL_PROJECTION</span><span class="p">)</span>
<span class="o">//</span> <span class="n">Reset</span> <span class="n">Matrix</span>
<span class="n">glLoadIdentity</span><span class="p">()</span>
<span class="o">//</span> <span class="n">Set</span> <span class="n">the</span> <span class="n">viewport</span> <span class="k">to</span> <span class="n">be</span> <span class="n">the</span> <span class="n">entire</span> <span class="n">window</span>
<span class="n">glViewport</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="n">w</span><span class="p">,</span> <span class="n">h</span><span class="p">)</span>
<span class="o">//</span> <span class="n">Set</span> <span class="n">the</span> <span class="n">correct</span> <span class="n">perspective</span><span class="p">.</span>
<span class="n">gluPerspective</span><span class="p">(</span><span class="mi">45</span><span class="p">,</span><span class="n">ratio</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">100</span><span class="p">)</span>
<span class="o">//</span> <span class="k">Get</span> <span class="n">Back</span> <span class="k">to</span> <span class="n">the</span> <span class="n">Modelview</span>
<span class="n">glMatrixMode</span><span class="p">(</span><span class="n">GL_MODELVIEW</span><span class="p">)</span>
</pre></div>
</div>
</div>
<div class="section" id="triangle-rotation">
<span id="index-8"></span><h2>Triangle Rotation<a class="headerlink" href="#triangle-rotation" title="Permalink to this headline">¶</a></h2>
<p>Example:</p>
<div class="highlight-ring notranslate"><div class="highlight"><pre><span></span><span class="k">load</span> <span class="s">"freeglut.ring"</span>
<span class="k">load</span> <span class="s">"opengl21lib.ring"</span>
<span class="n">angle</span> <span class="o">=</span> <span class="mi">0</span>
<span class="k">func</span> <span class="n">main</span>
<span class="o">//</span> <span class="n">init</span> <span class="n">GLUT</span> <span class="ow">and</span> <span class="n">create</span> <span class="n">window</span>
<span class="n">glutInit</span><span class="p">()</span>
<span class="n">glutInitDisplayMode</span><span class="p">(</span><span class="n">GLUT_DEPTH</span> <span class="o">|</span> <span class="n">GLUT_DOUBLE</span> <span class="o">|</span> <span class="n">GLUT_RGBA</span><span class="p">)</span>
<span class="n">glutInitWindowPosition</span><span class="p">(</span><span class="mi">100</span><span class="p">,</span><span class="mi">100</span><span class="p">)</span>
<span class="n">glutInitWindowSize</span><span class="p">(</span><span class="mi">320</span><span class="p">,</span><span class="mi">320</span><span class="p">)</span>
<span class="n">glutCreateWindow</span><span class="p">(</span><span class="s">"RingFreeGLUT - Test 5"</span><span class="p">)</span>
<span class="n">glutDisplayFunc</span><span class="p">(:</span><span class="n">renderScene</span><span class="p">)</span>
<span class="n">glutReshapeFunc</span><span class="p">(:</span><span class="n">changeSize</span><span class="p">)</span>
<span class="n">glutIdleFunc</span><span class="p">(:</span><span class="n">renderScene</span><span class="p">)</span>
<span class="n">glutMainLoop</span><span class="p">()</span>
<span class="k">func</span> <span class="n">renderScene</span>
<span class="o">//</span> <span class="n">Clear</span> <span class="n">Color</span> <span class="ow">and</span> <span class="n">Depth</span> <span class="n">Buffers</span>
<span class="n">glClear</span><span class="p">(</span><span class="n">GL_COLOR_BUFFER_BIT</span> <span class="o">|</span> <span class="n">GL_DEPTH_BUFFER_BIT</span><span class="p">)</span>
<span class="o">//</span> <span class="n">Reset</span> <span class="n">transformations</span>
<span class="n">glLoadIdentity</span><span class="p">()</span>
<span class="o">//</span> <span class="n">Set</span> <span class="n">the</span> <span class="n">camera</span>
<span class="n">gluLookAt</span><span class="p">(</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">10.0</span><span class="p">,</span>
<span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span>
<span class="mf">0.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glRotatef</span><span class="p">(</span><span class="n">angle</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glBegin</span><span class="p">(</span><span class="n">GL_TRIANGLES</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span><span class="o">-</span><span class="mf">2.0</span><span class="p">,</span><span class="o">-</span><span class="mf">2.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span> <span class="mf">2.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">2.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glEnd</span><span class="p">()</span>
<span class="n">angle</span><span class="o">+=</span><span class="mf">0.1</span>
<span class="n">glutSwapBuffers</span><span class="p">();</span>
<span class="k">func</span> <span class="n">changesize</span>
<span class="n">h</span> <span class="o">=</span> <span class="n">glutEventHeight</span><span class="p">()</span>
<span class="n">w</span> <span class="o">=</span> <span class="n">glutEventWidth</span><span class="p">()</span>
<span class="o">//</span> <span class="n">Prevent</span> <span class="n">a</span> <span class="n">divide</span> <span class="n">by</span> <span class="n">zero</span><span class="p">,</span> <span class="n">when</span> <span class="n">window</span> <span class="n">is</span> <span class="n">too</span> <span class="n">short</span>
<span class="o">//</span> <span class="p">(</span><span class="n">you</span> <span class="n">cant</span> <span class="n">make</span> <span class="n">a</span> <span class="n">window</span> <span class="n">of</span> <span class="n">zero</span> <span class="n">width</span><span class="p">).</span>
<span class="k">if</span> <span class="p">(</span><span class="n">h</span> <span class="o">=</span> <span class="mi">0</span><span class="p">)</span>
<span class="n">h</span> <span class="o">=</span> <span class="mi">1</span>
<span class="k">ok</span>
<span class="n">ratio</span> <span class="o">=</span> <span class="n">w</span> <span class="o">*</span> <span class="mf">1.0</span> <span class="o">/</span> <span class="n">h</span>
<span class="o">//</span> <span class="n">Use</span> <span class="n">the</span> <span class="n">Projection</span> <span class="n">Matrix</span>
<span class="n">glMatrixMode</span><span class="p">(</span><span class="n">GL_PROJECTION</span><span class="p">)</span>
<span class="o">//</span> <span class="n">Reset</span> <span class="n">Matrix</span>
<span class="n">glLoadIdentity</span><span class="p">()</span>
<span class="o">//</span> <span class="n">Set</span> <span class="n">the</span> <span class="n">viewport</span> <span class="k">to</span> <span class="n">be</span> <span class="n">the</span> <span class="n">entire</span> <span class="n">window</span>
<span class="n">glViewport</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="n">w</span><span class="p">,</span> <span class="n">h</span><span class="p">)</span>
<span class="o">//</span> <span class="n">Set</span> <span class="n">the</span> <span class="n">correct</span> <span class="n">perspective</span><span class="p">.</span>
<span class="n">gluPerspective</span><span class="p">(</span><span class="mi">45</span><span class="p">,</span><span class="n">ratio</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">100</span><span class="p">)</span>
<span class="o">//</span> <span class="k">Get</span> <span class="n">Back</span> <span class="k">to</span> <span class="n">the</span> <span class="n">Modelview</span>
<span class="n">glMatrixMode</span><span class="p">(</span><span class="n">GL_MODELVIEW</span><span class="p">)</span>
</pre></div>
</div>
<p>Screen Shot</p>
<img alt="RingFreeGLUT" src="_images/freeglutshot4.png" />
</div>
<div class="section" id="keyboard-events-and-colors">
<span id="index-9"></span><h2>Keyboard Events and Colors<a class="headerlink" href="#keyboard-events-and-colors" title="Permalink to this headline">¶</a></h2>
<p>Example:</p>
<div class="highlight-ring notranslate"><div class="highlight"><pre><span></span><span class="k">load</span> <span class="s">"freeglut.ring"</span>
<span class="k">load</span> <span class="s">"opengl21lib.ring"</span>
<span class="n">angle</span> <span class="o">=</span> <span class="mi">0</span>
<span class="n">red</span><span class="o">=</span><span class="mf">1.0</span>
<span class="n">blue</span><span class="o">=</span><span class="mf">1.0</span>
<span class="n">green</span><span class="o">=</span><span class="mf">1.0</span>
<span class="k">func</span> <span class="n">main</span>
<span class="o">//</span> <span class="n">init</span> <span class="n">GLUT</span> <span class="ow">and</span> <span class="n">create</span> <span class="n">window</span>
<span class="n">glutInit</span><span class="p">()</span>
<span class="n">glutInitDisplayMode</span><span class="p">(</span><span class="n">GLUT_DEPTH</span> <span class="o">|</span> <span class="n">GLUT_DOUBLE</span> <span class="o">|</span> <span class="n">GLUT_RGBA</span><span class="p">)</span>
<span class="n">glutInitWindowPosition</span><span class="p">(</span><span class="mi">100</span><span class="p">,</span><span class="mi">100</span><span class="p">)</span>
<span class="n">glutInitWindowSize</span><span class="p">(</span><span class="mi">320</span><span class="p">,</span><span class="mi">320</span><span class="p">)</span>
<span class="n">glutCreateWindow</span><span class="p">(</span><span class="s">"RingFreeGLUT - Test 6"</span><span class="p">)</span>
<span class="n">glutDisplayFunc</span><span class="p">(:</span><span class="n">renderScene</span><span class="p">)</span>
<span class="n">glutReshapeFunc</span><span class="p">(:</span><span class="n">changeSize</span><span class="p">)</span>
<span class="n">glutIdleFunc</span><span class="p">(:</span><span class="n">renderScene</span><span class="p">)</span>
<span class="o">//</span> <span class="n">here</span> <span class="n">are</span> <span class="n">the</span> <span class="k">new</span> <span class="n">entries</span>
<span class="n">glutKeyboardFunc</span><span class="p">(:</span><span class="n">processNormalKeys</span><span class="p">)</span>
<span class="n">glutSpecialFunc</span><span class="p">(:</span><span class="n">processSpecialKeys</span><span class="p">)</span>
<span class="n">glutMainLoop</span><span class="p">()</span>
<span class="k">func</span> <span class="n">renderScene</span>
<span class="o">//</span> <span class="n">Clear</span> <span class="n">Color</span> <span class="ow">and</span> <span class="n">Depth</span> <span class="n">Buffers</span>
<span class="n">glClear</span><span class="p">(</span><span class="n">GL_COLOR_BUFFER_BIT</span> <span class="o">|</span> <span class="n">GL_DEPTH_BUFFER_BIT</span><span class="p">)</span>
<span class="o">//</span> <span class="n">Reset</span> <span class="n">transformations</span>
<span class="n">glLoadIdentity</span><span class="p">()</span>
<span class="o">//</span> <span class="n">Set</span> <span class="n">the</span> <span class="n">camera</span>
<span class="n">gluLookAt</span><span class="p">(</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">10.0</span><span class="p">,</span>
<span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span>
<span class="mf">0.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glRotatef</span><span class="p">(</span><span class="n">angle</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glColor3f</span><span class="p">(</span><span class="n">red</span><span class="p">,</span><span class="n">green</span><span class="p">,</span><span class="n">blue</span><span class="p">);</span>
<span class="n">glBegin</span><span class="p">(</span><span class="n">GL_TRIANGLES</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span><span class="o">-</span><span class="mf">2.0</span><span class="p">,</span><span class="o">-</span><span class="mf">2.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span> <span class="mf">2.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">2.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glEnd</span><span class="p">()</span>
<span class="n">angle</span><span class="o">+=</span><span class="mf">0.1</span>
<span class="n">glutSwapBuffers</span><span class="p">();</span>
<span class="k">func</span> <span class="n">changesize</span>
<span class="n">h</span> <span class="o">=</span> <span class="n">glutEventHeight</span><span class="p">()</span>
<span class="n">w</span> <span class="o">=</span> <span class="n">glutEventWidth</span><span class="p">()</span>
<span class="o">//</span> <span class="n">Prevent</span> <span class="n">a</span> <span class="n">divide</span> <span class="n">by</span> <span class="n">zero</span><span class="p">,</span> <span class="n">when</span> <span class="n">window</span> <span class="n">is</span> <span class="n">too</span> <span class="n">short</span>
<span class="o">//</span> <span class="p">(</span><span class="n">you</span> <span class="n">cant</span> <span class="n">make</span> <span class="n">a</span> <span class="n">window</span> <span class="n">of</span> <span class="n">zero</span> <span class="n">width</span><span class="p">).</span>
<span class="k">if</span> <span class="p">(</span><span class="n">h</span> <span class="o">=</span> <span class="mi">0</span><span class="p">)</span>
<span class="n">h</span> <span class="o">=</span> <span class="mi">1</span>
<span class="k">ok</span>
<span class="n">ratio</span> <span class="o">=</span> <span class="n">w</span> <span class="o">*</span> <span class="mf">1.0</span> <span class="o">/</span> <span class="n">h</span>
<span class="o">//</span> <span class="n">Use</span> <span class="n">the</span> <span class="n">Projection</span> <span class="n">Matrix</span>
<span class="n">glMatrixMode</span><span class="p">(</span><span class="n">GL_PROJECTION</span><span class="p">)</span>
<span class="o">//</span> <span class="n">Reset</span> <span class="n">Matrix</span>
<span class="n">glLoadIdentity</span><span class="p">()</span>
<span class="o">//</span> <span class="n">Set</span> <span class="n">the</span> <span class="n">viewport</span> <span class="k">to</span> <span class="n">be</span> <span class="n">the</span> <span class="n">entire</span> <span class="n">window</span>
<span class="n">glViewport</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="n">w</span><span class="p">,</span> <span class="n">h</span><span class="p">)</span>
<span class="o">//</span> <span class="n">Set</span> <span class="n">the</span> <span class="n">correct</span> <span class="n">perspective</span><span class="p">.</span>
<span class="n">gluPerspective</span><span class="p">(</span><span class="mi">45</span><span class="p">,</span><span class="n">ratio</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">100</span><span class="p">)</span>
<span class="o">//</span> <span class="k">Get</span> <span class="n">Back</span> <span class="k">to</span> <span class="n">the</span> <span class="n">Modelview</span>
<span class="n">glMatrixMode</span><span class="p">(</span><span class="n">GL_MODELVIEW</span><span class="p">)</span>
<span class="k">func</span> <span class="n">processNormalKeys</span>
<span class="n">key</span> <span class="o">=</span> <span class="n">GLUTEventKey</span><span class="p">()</span>
<span class="k">if</span> <span class="n">key</span> <span class="o">=</span> <span class="mi">27</span>
<span class="n">shutdown</span><span class="p">()</span>
<span class="k">ok</span>
<span class="k">func</span> <span class="n">processSpecialKeys</span>
<span class="n">key</span> <span class="o">=</span> <span class="n">GLUTEventKey</span><span class="p">()</span>
<span class="k">switch</span> <span class="n">key</span>
<span class="k">on</span> <span class="n">GLUT_KEY_F1</span>
<span class="n">red</span> <span class="o">=</span> <span class="mf">1.0</span>
<span class="n">green</span> <span class="o">=</span> <span class="mf">0.0</span>
<span class="n">blue</span> <span class="o">=</span> <span class="mf">0.0</span>
<span class="k">on</span> <span class="n">GLUT_KEY_F2</span>
<span class="n">red</span> <span class="o">=</span> <span class="mf">0.0</span>
<span class="n">green</span> <span class="o">=</span> <span class="mf">1.0</span>
<span class="n">blue</span> <span class="o">=</span> <span class="mf">0.0</span>
<span class="k">on</span> <span class="n">GLUT_KEY_F3</span>
<span class="n">red</span> <span class="o">=</span> <span class="mf">0.0</span>
<span class="n">green</span> <span class="o">=</span> <span class="mf">0.0</span>
<span class="n">blue</span> <span class="o">=</span> <span class="mf">1.0</span>
<span class="k">off</span>
</pre></div>
</div>
<p>Screen Shot</p>
<img alt="RingFreeGLUT" src="_images/freeglutshot5.png" />
</div>
<div class="section" id="the-camera">
<span id="index-10"></span><h2>The Camera<a class="headerlink" href="#the-camera" title="Permalink to this headline">¶</a></h2>
<p>Example:</p>
<div class="highlight-ring notranslate"><div class="highlight"><pre><span></span><span class="k">load</span> <span class="s">"freeglut.ring"</span>
<span class="k">load</span> <span class="s">"opengl21lib.ring"</span>
<span class="o">//</span> <span class="n">angle</span> <span class="n">of</span> <span class="n">rotation</span> <span class="k">for</span> <span class="n">the</span> <span class="n">camera</span> <span class="n">direction</span>
<span class="n">angle</span><span class="o">=</span><span class="mf">0.0</span>
<span class="o">//</span> <span class="n">actual</span> <span class="n">vector</span> <span class="n">representing</span> <span class="n">the</span> <span class="n">camera</span><span class="sc">'s direction</span>
<span class="n">lx</span><span class="o">=</span><span class="mf">0.0</span>
<span class="n">lz</span><span class="o">=-</span><span class="mf">1.0</span>
<span class="o">//</span> <span class="n">XZ</span> <span class="n">position</span> <span class="n">of</span> <span class="n">the</span> <span class="n">camera</span>
<span class="n">x</span><span class="o">=</span><span class="mf">0.0</span>
<span class="n">z</span><span class="o">=</span><span class="mf">5.0</span>
<span class="k">func</span> <span class="n">drawSnowMan</span>
<span class="n">glColor3f</span><span class="p">(</span><span class="mf">1.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">)</span>
<span class="o">//</span> <span class="n">Draw</span> <span class="n">Body</span>
<span class="n">glTranslatef</span><span class="p">(</span><span class="mf">0.0</span> <span class="p">,</span><span class="mf">0.75</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glutSolidSphere</span><span class="p">(</span><span class="mf">0.75</span><span class="p">,</span><span class="mi">20</span><span class="p">,</span><span class="mi">20</span><span class="p">)</span>
<span class="o">//</span> <span class="n">Draw</span> <span class="n">Head</span>
<span class="n">glTranslatef</span><span class="p">(</span><span class="mf">0.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glutSolidSphere</span><span class="p">(</span><span class="mf">0.25</span><span class="p">,</span><span class="mi">20</span><span class="p">,</span><span class="mi">20</span><span class="p">)</span>
<span class="o">//</span> <span class="n">Draw</span> <span class="n">Eyes</span>
<span class="n">glPushMatrix</span><span class="p">()</span>
<span class="n">glColor3f</span><span class="p">(</span><span class="mf">0.0</span><span class="p">,</span><span class="mf">0.0</span><span class="p">,</span><span class="mf">0.0</span><span class="p">)</span>
<span class="n">glTranslatef</span><span class="p">(</span><span class="mf">0.05</span><span class="p">,</span> <span class="mf">0.10</span><span class="p">,</span> <span class="mf">0.18</span><span class="p">)</span>
<span class="n">glutSolidSphere</span><span class="p">(</span><span class="mf">0.05</span><span class="p">,</span><span class="mi">10</span><span class="p">,</span><span class="mi">10</span><span class="p">)</span>
<span class="n">glTranslatef</span><span class="p">(</span><span class="o">-</span><span class="mf">0.1</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glutSolidSphere</span><span class="p">(</span><span class="mf">0.05</span><span class="p">,</span><span class="mi">10</span><span class="p">,</span><span class="mi">10</span><span class="p">)</span>
<span class="n">glPopMatrix</span><span class="p">()</span>
<span class="o">//</span> <span class="n">Draw</span> <span class="n">Nose</span>
<span class="n">glColor3f</span><span class="p">(</span><span class="mf">1.0</span><span class="p">,</span> <span class="mf">0.5</span> <span class="p">,</span> <span class="mf">0.5</span><span class="p">)</span>
<span class="n">glutSolidCone</span><span class="p">(</span><span class="mf">0.08</span><span class="p">,</span><span class="mf">0.5</span><span class="p">,</span><span class="mi">10</span><span class="p">,</span><span class="mi">2</span><span class="p">)</span>
<span class="k">func</span> <span class="n">changeSize</span>
<span class="n">w</span> <span class="o">=</span> <span class="n">glutEventWidth</span><span class="p">()</span>
<span class="n">h</span> <span class="o">=</span> <span class="n">glutEventHeight</span><span class="p">()</span>
<span class="o">//</span> <span class="n">Prevent</span> <span class="n">a</span> <span class="n">divide</span> <span class="n">by</span> <span class="n">zero</span><span class="p">,</span> <span class="n">when</span> <span class="n">window</span> <span class="n">is</span> <span class="n">too</span> <span class="n">short</span>
<span class="o">//</span> <span class="p">(</span><span class="n">you</span> <span class="n">cant</span> <span class="n">make</span> <span class="n">a</span> <span class="n">window</span> <span class="n">of</span> <span class="n">zero</span> <span class="n">width</span><span class="p">).</span>
<span class="k">if</span> <span class="n">h</span> <span class="o">=</span> <span class="mi">0</span>
<span class="n">h</span> <span class="o">=</span> <span class="mi">1</span>
<span class="k">ok</span>
<span class="n">ratio</span> <span class="o">=</span> <span class="n">w</span> <span class="o">*</span> <span class="mf">1.0</span> <span class="o">/</span> <span class="n">h</span>
<span class="o">//</span> <span class="n">Use</span> <span class="n">the</span> <span class="n">Projection</span> <span class="n">Matrix</span>
<span class="n">glMatrixMode</span><span class="p">(</span><span class="n">GL_PROJECTION</span><span class="p">)</span>
<span class="o">//</span> <span class="n">Reset</span> <span class="n">Matrix</span>
<span class="n">glLoadIdentity</span><span class="p">()</span>
<span class="o">//</span> <span class="n">Set</span> <span class="n">the</span> <span class="n">viewport</span> <span class="k">to</span> <span class="n">be</span> <span class="n">the</span> <span class="n">entire</span> <span class="n">window</span>
<span class="n">glViewport</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="n">w</span><span class="p">,</span> <span class="n">h</span><span class="p">)</span>
<span class="o">//</span> <span class="n">Set</span> <span class="n">the</span> <span class="n">correct</span> <span class="n">perspective</span><span class="p">.</span>
<span class="n">gluPerspective</span><span class="p">(</span><span class="mf">45.0</span><span class="p">,</span> <span class="n">ratio</span><span class="p">,</span> <span class="mf">0.1</span><span class="p">,</span> <span class="mf">100.0</span><span class="p">);</span>
<span class="o">//</span> <span class="k">Get</span> <span class="n">Back</span> <span class="k">to</span> <span class="n">the</span> <span class="n">Modelview</span>
<span class="n">glMatrixMode</span><span class="p">(</span><span class="n">GL_MODELVIEW</span><span class="p">)</span>
<span class="k">func</span> <span class="n">processNormalKeys</span>
<span class="n">key</span> <span class="o">=</span> <span class="n">glutEventKey</span><span class="p">()</span>
<span class="k">if</span> <span class="n">key</span> <span class="o">=</span> <span class="mi">27</span>
<span class="n">shutdown</span><span class="p">()</span>
<span class="k">ok</span>
<span class="k">func</span> <span class="n">renderScene</span>
<span class="o">//</span> <span class="n">Clear</span> <span class="n">Color</span> <span class="ow">and</span> <span class="n">Depth</span> <span class="n">Buffers</span>
<span class="n">glClear</span><span class="p">(</span><span class="n">GL_COLOR_BUFFER_BIT</span> <span class="o">|</span> <span class="n">GL_DEPTH_BUFFER_BIT</span><span class="p">)</span>
<span class="o">//</span> <span class="n">Reset</span> <span class="n">transformations</span>
<span class="n">glLoadIdentity</span><span class="p">()</span>
<span class="o">//</span> <span class="n">Set</span> <span class="n">the</span> <span class="n">camera</span>
<span class="n">gluLookAt</span><span class="p">(</span> <span class="n">x</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">,</span> <span class="n">z</span><span class="p">,</span>
<span class="n">x</span><span class="o">+</span><span class="n">lx</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">,</span> <span class="n">z</span><span class="o">+</span><span class="n">lz</span><span class="p">,</span>
<span class="mf">0.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="o">//</span> <span class="n">Draw</span> <span class="n">ground</span>
<span class="n">glColor3f</span><span class="p">(</span><span class="mf">0.9</span><span class="p">,</span> <span class="mf">0.9</span><span class="p">,</span> <span class="mf">0.9</span><span class="p">)</span>
<span class="n">glBegin</span><span class="p">(</span><span class="n">GL_QUADS</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span><span class="o">-</span><span class="mf">100.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="o">-</span><span class="mf">100.0</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span><span class="o">-</span><span class="mf">100.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">100.0</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span> <span class="mf">100.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">100.0</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span> <span class="mf">100.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="o">-</span><span class="mf">100.0</span><span class="p">)</span>
<span class="n">glEnd</span><span class="p">()</span>
<span class="o">//</span> <span class="n">Draw</span> <span class="mi">36</span> <span class="n">SnowMen</span>
<span class="k">for</span> <span class="n">i</span> <span class="o">=</span> <span class="o">-</span><span class="mi">3</span> <span class="k">to</span> <span class="mi">2</span>
<span class="k">for</span> <span class="n">j</span><span class="o">=-</span><span class="mi">3</span> <span class="k">to</span> <span class="mi">2</span>
<span class="n">glPushMatrix</span><span class="p">()</span>
<span class="n">glTranslatef</span><span class="p">(</span><span class="n">i</span><span class="o">*</span><span class="mf">10.0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="n">j</span> <span class="o">*</span> <span class="mf">10.0</span><span class="p">)</span>
<span class="n">drawSnowMan</span><span class="p">()</span>
<span class="n">glPopMatrix</span><span class="p">()</span>
<span class="k">next</span>
<span class="k">next</span>
<span class="n">glutSwapBuffers</span><span class="p">()</span>
<span class="k">func</span> <span class="n">processSpecialKeys</span>
<span class="n">key</span> <span class="o">=</span> <span class="n">glutEventKey</span><span class="p">()</span>
<span class="n">fraction</span> <span class="o">=</span> <span class="mf">0.1</span>
<span class="k">switch</span> <span class="n">key</span>
<span class="k">on</span> <span class="n">GLUT_KEY_LEFT</span>
<span class="n">angle</span> <span class="o">-=</span> <span class="mf">0.01</span>
<span class="n">lx</span> <span class="o">=</span> <span class="n">sin</span><span class="p">(</span><span class="n">angle</span><span class="p">)</span>
<span class="n">lz</span> <span class="o">=</span> <span class="o">-</span><span class="n">cos</span><span class="p">(</span><span class="n">angle</span><span class="p">)</span>
<span class="k">on</span> <span class="n">GLUT_KEY_RIGHT</span>
<span class="n">angle</span> <span class="o">+=</span> <span class="mf">0.01</span>
<span class="n">lx</span> <span class="o">=</span> <span class="n">sin</span><span class="p">(</span><span class="n">angle</span><span class="p">)</span>
<span class="n">lz</span> <span class="o">=</span> <span class="o">-</span><span class="n">cos</span><span class="p">(</span><span class="n">angle</span><span class="p">)</span>
<span class="k">on</span> <span class="n">GLUT_KEY_UP</span>
<span class="n">x</span> <span class="o">+=</span> <span class="n">lx</span> <span class="o">*</span> <span class="n">fraction</span>
<span class="n">z</span> <span class="o">+=</span> <span class="n">lz</span> <span class="o">*</span> <span class="n">fraction</span>
<span class="k">on</span> <span class="n">GLUT_KEY_DOWN</span>
<span class="n">x</span> <span class="o">-=</span> <span class="n">lx</span> <span class="o">*</span> <span class="n">fraction</span>
<span class="n">z</span> <span class="o">-=</span> <span class="n">lz</span> <span class="o">*</span> <span class="n">fraction</span>
<span class="k">off</span>
<span class="k">func</span> <span class="n">main</span>
<span class="o">//</span> <span class="n">init</span> <span class="n">GLUT</span> <span class="ow">and</span> <span class="n">create</span> <span class="n">window</span>
<span class="n">glutInit</span><span class="p">()</span>
<span class="n">glutInitDisplayMode</span><span class="p">(</span><span class="n">GLUT_DEPTH</span> <span class="o">|</span> <span class="n">GLUT_DOUBLE</span> <span class="o">|</span> <span class="n">GLUT_RGBA</span><span class="p">)</span>
<span class="n">glutInitWindowPosition</span><span class="p">(</span><span class="mi">100</span><span class="p">,</span><span class="mi">100</span><span class="p">)</span>
<span class="n">glutInitWindowSize</span><span class="p">(</span><span class="mi">320</span><span class="p">,</span><span class="mi">320</span><span class="p">)</span>
<span class="n">glutCreateWindow</span><span class="p">(</span><span class="s">"RingFreeGLUT - Test 7"</span><span class="p">)</span>
<span class="o">//</span> <span class="n">register</span> <span class="n">callbacks</span>
<span class="n">glutDisplayFunc</span><span class="p">(:</span><span class="n">renderScene</span><span class="p">)</span>
<span class="n">glutReshapeFunc</span><span class="p">(:</span><span class="n">changeSize</span><span class="p">)</span>
<span class="n">glutIdleFunc</span><span class="p">(:</span><span class="n">renderScene</span><span class="p">)</span>
<span class="n">glutKeyboardFunc</span><span class="p">(:</span><span class="n">processNormalKeys</span><span class="p">)</span>
<span class="n">glutSpecialFunc</span><span class="p">(:</span><span class="n">processSpecialKeys</span><span class="p">)</span>
<span class="o">//</span> <span class="n">OpenGL</span> <span class="n">init</span>
<span class="n">glEnable</span><span class="p">(</span><span class="n">GL_DEPTH_TEST</span><span class="p">)</span>
<span class="o">//</span> <span class="n">enter</span> <span class="n">GLUT</span> <span class="n">event</span> <span class="n">processing</span> <span class="n">cycle</span>
<span class="n">glutMainLoop</span><span class="p">()</span>
</pre></div>
</div>
<p>Screen Shot</p>
<img alt="RingFreeGLUT" src="_images/freeglutshot6.png" />
<p>Another Example:</p>
<div class="highlight-ring notranslate"><div class="highlight"><pre><span></span><span class="k">load</span> <span class="s">"freeglut.ring"</span>
<span class="k">load</span> <span class="s">"opengl21lib.ring"</span>
<span class="o">//</span> <span class="n">angle</span> <span class="n">of</span> <span class="n">rotation</span> <span class="k">for</span> <span class="n">the</span> <span class="n">camera</span> <span class="n">direction</span>
<span class="n">angle</span> <span class="o">=</span> <span class="mf">0.0</span>
<span class="o">//</span> <span class="n">actual</span> <span class="n">vector</span> <span class="n">representing</span> <span class="n">the</span> <span class="n">camera</span><span class="sc">'s direction</span>
<span class="n">lx</span><span class="o">=</span><span class="mf">0.0</span> <span class="n">lz</span><span class="o">=-</span><span class="mf">1.0</span>
<span class="o">//</span> <span class="n">XZ</span> <span class="n">position</span> <span class="n">of</span> <span class="n">the</span> <span class="n">camera</span>
<span class="n">x</span><span class="o">=</span><span class="mf">0.0</span> <span class="n">z</span><span class="o">=</span><span class="mf">5.0</span>
<span class="o">//</span> <span class="n">the</span> <span class="n">key</span> <span class="n">states</span><span class="p">.</span> <span class="n">These</span> <span class="n">variables</span> <span class="n">will</span> <span class="n">be</span> <span class="n">zero</span>
<span class="o">//</span><span class="n">when</span> <span class="n">no</span> <span class="n">key</span> <span class="n">is</span> <span class="n">being</span> <span class="n">presses</span>
<span class="n">deltaAngle</span> <span class="o">=</span> <span class="mf">0.0</span>
<span class="n">deltaMove</span> <span class="o">=</span> <span class="mi">0</span>
<span class="k">func</span> <span class="n">changeSize</span>
<span class="n">w</span> <span class="o">=</span> <span class="n">glutEventWidth</span><span class="p">()</span>
<span class="n">h</span> <span class="o">=</span> <span class="n">glutEventHeight</span><span class="p">()</span>
<span class="o">//</span> <span class="n">Prevent</span> <span class="n">a</span> <span class="n">divide</span> <span class="n">by</span> <span class="n">zero</span><span class="p">,</span> <span class="n">when</span> <span class="n">window</span> <span class="n">is</span> <span class="n">too</span> <span class="n">short</span>
<span class="o">//</span> <span class="p">(</span><span class="n">you</span> <span class="n">cant</span> <span class="n">make</span> <span class="n">a</span> <span class="n">window</span> <span class="n">of</span> <span class="n">zero</span> <span class="n">width</span><span class="p">).</span>
<span class="k">if</span> <span class="n">h</span> <span class="o">=</span> <span class="mi">0</span>
<span class="n">h</span> <span class="o">=</span> <span class="mi">1</span>
<span class="k">ok</span>
<span class="n">ratio</span> <span class="o">=</span> <span class="n">w</span> <span class="o">*</span> <span class="mf">1.0</span> <span class="o">/</span> <span class="n">h</span>
<span class="o">//</span> <span class="n">Use</span> <span class="n">the</span> <span class="n">Projection</span> <span class="n">Matrix</span>
<span class="n">glMatrixMode</span><span class="p">(</span><span class="n">GL_PROJECTION</span><span class="p">)</span>
<span class="o">//</span> <span class="n">Reset</span> <span class="n">Matrix</span>
<span class="n">glLoadIdentity</span><span class="p">()</span>
<span class="o">//</span> <span class="n">Set</span> <span class="n">the</span> <span class="n">viewport</span> <span class="k">to</span> <span class="n">be</span> <span class="n">the</span> <span class="n">entire</span> <span class="n">window</span>
<span class="n">glViewport</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="n">w</span><span class="p">,</span> <span class="n">h</span><span class="p">)</span>
<span class="o">//</span> <span class="n">Set</span> <span class="n">the</span> <span class="n">correct</span> <span class="n">perspective</span><span class="p">.</span>
<span class="n">gluPerspective</span><span class="p">(</span><span class="mf">45.0</span><span class="p">,</span> <span class="n">ratio</span><span class="p">,</span> <span class="mf">0.1</span><span class="p">,</span> <span class="mf">100.0</span><span class="p">)</span>
<span class="o">//</span> <span class="k">Get</span> <span class="n">Back</span> <span class="k">to</span> <span class="n">the</span> <span class="n">Modelview</span>
<span class="n">glMatrixMode</span><span class="p">(</span><span class="n">GL_MODELVIEW</span><span class="p">)</span>
<span class="k">func</span> <span class="n">drawSnowMan</span>
<span class="n">glColor3f</span><span class="p">(</span><span class="mf">1.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">)</span>
<span class="o">//</span> <span class="n">Draw</span> <span class="n">Body</span>
<span class="n">glTranslatef</span><span class="p">(</span><span class="mf">0.0</span> <span class="p">,</span><span class="mf">0.75</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glutSolidSphere</span><span class="p">(</span><span class="mf">0.75</span><span class="p">,</span><span class="mi">20</span><span class="p">,</span><span class="mi">20</span><span class="p">)</span>
<span class="o">//</span> <span class="n">Draw</span> <span class="n">Head</span>
<span class="n">glTranslatef</span><span class="p">(</span><span class="mf">0.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glutSolidSphere</span><span class="p">(</span><span class="mf">0.25</span><span class="p">,</span><span class="mi">20</span><span class="p">,</span><span class="mi">20</span><span class="p">)</span>
<span class="o">//</span> <span class="n">Draw</span> <span class="n">Eyes</span>
<span class="n">glPushMatrix</span><span class="p">()</span>
<span class="n">glColor3f</span><span class="p">(</span><span class="mf">0.0</span><span class="p">,</span><span class="mf">0.0</span><span class="p">,</span><span class="mf">0.0</span><span class="p">)</span>
<span class="n">glTranslatef</span><span class="p">(</span><span class="mf">0.05</span><span class="p">,</span> <span class="mf">0.10</span><span class="p">,</span> <span class="mf">0.18</span><span class="p">)</span>
<span class="n">glutSolidSphere</span><span class="p">(</span><span class="mf">0.05</span><span class="p">,</span><span class="mi">10</span><span class="p">,</span><span class="mi">10</span><span class="p">)</span>
<span class="n">glTranslatef</span><span class="p">(</span><span class="o">-</span><span class="mf">0.1</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glutSolidSphere</span><span class="p">(</span><span class="mf">0.05</span><span class="p">,</span><span class="mi">10</span><span class="p">,</span><span class="mi">10</span><span class="p">)</span>
<span class="n">glPopMatrix</span><span class="p">()</span>
<span class="o">//</span> <span class="n">Draw</span> <span class="n">Nose</span>
<span class="n">glColor3f</span><span class="p">(</span><span class="mf">1.0</span><span class="p">,</span> <span class="mf">0.5</span> <span class="p">,</span> <span class="mf">0.5</span><span class="p">)</span>
<span class="n">glRotatef</span><span class="p">(</span><span class="mf">0.0</span><span class="p">,</span><span class="mf">1.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">glutSolidCone</span><span class="p">(</span><span class="mf">0.08</span><span class="p">,</span><span class="mf">0.5</span><span class="p">,</span><span class="mi">10</span><span class="p">,</span><span class="mi">2</span><span class="p">)</span>
<span class="k">func</span> <span class="n">computePos</span> <span class="n">deltaMove</span>
<span class="n">x</span> <span class="o">+=</span> <span class="n">deltaMove</span> <span class="o">*</span> <span class="n">lx</span> <span class="o">*</span> <span class="mf">0.1</span>
<span class="n">z</span> <span class="o">+=</span> <span class="n">deltaMove</span> <span class="o">*</span> <span class="n">lz</span> <span class="o">*</span> <span class="mf">0.1</span>
<span class="k">func</span> <span class="n">computeDir</span> <span class="n">deltaAngle</span>
<span class="n">angle</span> <span class="o">+=</span> <span class="n">deltaAngle</span>
<span class="n">lx</span> <span class="o">=</span> <span class="n">sin</span><span class="p">(</span><span class="n">angle</span><span class="p">)</span>
<span class="n">lz</span> <span class="o">=</span> <span class="o">-</span><span class="n">cos</span><span class="p">(</span><span class="n">angle</span><span class="p">)</span>
<span class="k">func</span> <span class="n">renderScene</span>
<span class="k">if</span> <span class="n">deltaMove</span>
<span class="n">computePos</span><span class="p">(</span><span class="n">deltaMove</span><span class="p">)</span>
<span class="k">ok</span>
<span class="k">if</span> <span class="n">deltaAngle</span>
<span class="n">computeDir</span><span class="p">(</span><span class="n">deltaAngle</span><span class="p">)</span>
<span class="k">ok</span>
<span class="o">//</span> <span class="n">Clear</span> <span class="n">Color</span> <span class="ow">and</span> <span class="n">Depth</span> <span class="n">Buffers</span>
<span class="n">glClear</span><span class="p">(</span><span class="n">GL_COLOR_BUFFER_BIT</span> <span class="o">|</span> <span class="n">GL_DEPTH_BUFFER_BIT</span><span class="p">)</span>
<span class="o">//</span> <span class="n">Reset</span> <span class="n">transformations</span>
<span class="n">glLoadIdentity</span><span class="p">()</span>
<span class="o">//</span> <span class="n">Set</span> <span class="n">the</span> <span class="n">camera</span>
<span class="n">gluLookAt</span><span class="p">(</span> <span class="n">x</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">,</span> <span class="n">z</span><span class="p">,</span>
<span class="n">x</span><span class="o">+</span><span class="n">lx</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">,</span> <span class="n">z</span><span class="o">+</span><span class="n">lz</span><span class="p">,</span>
<span class="mf">0.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="o">//</span> <span class="n">Draw</span> <span class="n">ground</span>
<span class="n">glColor3f</span><span class="p">(</span><span class="mf">0.9</span><span class="p">,</span> <span class="mf">0.9</span><span class="p">,</span> <span class="mf">0.9</span><span class="p">)</span>
<span class="n">glBegin</span><span class="p">(</span><span class="n">GL_QUADS</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span><span class="o">-</span><span class="mf">100.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="o">-</span><span class="mf">100.0</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span><span class="o">-</span><span class="mf">100.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">100.0</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span> <span class="mf">100.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="mf">100.0</span><span class="p">)</span>
<span class="n">glVertex3f</span><span class="p">(</span> <span class="mf">100.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">,</span> <span class="o">-</span><span class="mf">100.0</span><span class="p">)</span>
<span class="n">glEnd</span><span class="p">()</span>
<span class="o">//</span> <span class="n">Draw</span> <span class="mi">36</span> <span class="n">SnowMen</span>
<span class="k">for</span> <span class="n">i</span> <span class="o">=</span> <span class="o">-</span><span class="mi">3</span> <span class="k">to</span> <span class="mi">2</span>
<span class="k">for</span> <span class="n">j</span><span class="o">=-</span><span class="mi">3</span> <span class="k">to</span> <span class="mi">2</span>
<span class="n">glPushMatrix</span><span class="p">()</span>
<span class="n">glTranslatef</span><span class="p">(</span><span class="n">i</span><span class="o">*</span><span class="mf">10.0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="n">j</span> <span class="o">*</span> <span class="mf">10.0</span><span class="p">)</span>
<span class="n">drawSnowMan</span><span class="p">()</span>
<span class="n">glPopMatrix</span><span class="p">()</span>
<span class="k">next</span>
<span class="k">next</span>
<span class="n">glutSwapBuffers</span><span class="p">()</span>
<span class="k">func</span> <span class="n">pressKey</span>
<span class="n">key</span> <span class="o">=</span> <span class="n">glutEventKey</span><span class="p">()</span>
<span class="n">xx</span> <span class="o">=</span> <span class="n">glutEventX</span><span class="p">()</span>
<span class="n">yy</span> <span class="o">=</span> <span class="n">glutEventY</span><span class="p">()</span>
<span class="k">switch</span> <span class="n">key</span>
<span class="k">on</span> <span class="n">GLUT_KEY_LEFT</span>
<span class="n">deltaAngle</span> <span class="o">=</span> <span class="o">-</span><span class="mf">0.01</span>
<span class="k">on</span> <span class="n">GLUT_KEY_RIGHT</span>
<span class="n">deltaAngle</span> <span class="o">=</span> <span class="mf">0.01</span>
<span class="k">on</span> <span class="n">GLUT_KEY_UP</span>
<span class="n">deltaMove</span> <span class="o">=</span> <span class="mf">0.5</span>
<span class="k">on</span> <span class="n">GLUT_KEY_DOWN</span>
<span class="n">deltaMove</span> <span class="o">=</span> <span class="o">-</span><span class="mf">0.5</span>
<span class="k">off</span>
<span class="k">func</span> <span class="n">releaseKey</span>
<span class="n">key</span> <span class="o">=</span> <span class="n">glutEventKey</span><span class="p">()</span>
<span class="k">switch</span> <span class="n">key</span>