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<h1 class="title">geometryengine.cpp Example File</h1>
<span class="subtitle">cube/geometryengine.cpp</span>
<!-- $$$cube/geometryengine.cpp-description -->
<div class="descr"> <a name="details"></a>
<pre class="cpp">
<span class="comment">/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** BSD License Usage
** Alternatively, you may use this file under the terms of the BSD license
** as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
** * Redistributions of source code must retain the above copyright
** notice, this list of conditions and the following disclaimer.
** * Redistributions in binary form must reproduce the above copyright
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****************************************************************************/</span>
<span class="preprocessor">#include "geometryengine.h"</span>
<span class="preprocessor">#include <QVector2D></span>
<span class="preprocessor">#include <QVector3D></span>
<span class="keyword">struct</span> VertexData
{
QVector3D position;
QVector2D texCoord;
};
GeometryEngine<span class="operator">::</span>GeometryEngine()
: indexBuf(<span class="type"><a href="../qtgui/qopenglbuffer.html">QOpenGLBuffer</a></span><span class="operator">::</span>IndexBuffer)
{
initializeOpenGLFunctions();
<span class="comment">// Generate 2 VBOs</span>
arrayBuf<span class="operator">.</span>create();
indexBuf<span class="operator">.</span>create();
<span class="comment">// Initializes cube geometry and transfers it to VBOs</span>
initCubeGeometry();
}
GeometryEngine<span class="operator">::</span><span class="operator">~</span>GeometryEngine()
{
arrayBuf<span class="operator">.</span>destroy();
indexBuf<span class="operator">.</span>destroy();
}
<span class="type">void</span> GeometryEngine<span class="operator">::</span>initCubeGeometry()
{
<span class="comment">// For cube we would need only 8 vertices but we have to</span>
<span class="comment">// duplicate vertex for each face because texture coordinate</span>
<span class="comment">// is different.</span>
VertexData vertices<span class="operator">[</span><span class="operator">]</span> <span class="operator">=</span> {
<span class="comment">// Vertex data for face 0</span>
{QVector3D(<span class="operator">-</span><span class="number">1.0f</span><span class="operator">,</span> <span class="operator">-</span><span class="number">1.0f</span><span class="operator">,</span> <span class="number">1.0f</span>)<span class="operator">,</span> QVector2D(<span class="number">0.0f</span><span class="operator">,</span> <span class="number">0.0f</span>)}<span class="operator">,</span> <span class="comment">// v0</span>
{QVector3D( <span class="number">1.0f</span><span class="operator">,</span> <span class="operator">-</span><span class="number">1.0f</span><span class="operator">,</span> <span class="number">1.0f</span>)<span class="operator">,</span> QVector2D(<span class="number">0.33f</span><span class="operator">,</span> <span class="number">0.0f</span>)}<span class="operator">,</span> <span class="comment">// v1</span>
{QVector3D(<span class="operator">-</span><span class="number">1.0f</span><span class="operator">,</span> <span class="number">1.0f</span><span class="operator">,</span> <span class="number">1.0f</span>)<span class="operator">,</span> QVector2D(<span class="number">0.0f</span><span class="operator">,</span> <span class="number">0.5f</span>)}<span class="operator">,</span> <span class="comment">// v2</span>
{QVector3D( <span class="number">1.0f</span><span class="operator">,</span> <span class="number">1.0f</span><span class="operator">,</span> <span class="number">1.0f</span>)<span class="operator">,</span> QVector2D(<span class="number">0.33f</span><span class="operator">,</span> <span class="number">0.5f</span>)}<span class="operator">,</span> <span class="comment">// v3</span>
<span class="comment">// Vertex data for face 1</span>
{QVector3D( <span class="number">1.0f</span><span class="operator">,</span> <span class="operator">-</span><span class="number">1.0f</span><span class="operator">,</span> <span class="number">1.0f</span>)<span class="operator">,</span> QVector2D( <span class="number">0.0f</span><span class="operator">,</span> <span class="number">0.5f</span>)}<span class="operator">,</span> <span class="comment">// v4</span>
{QVector3D( <span class="number">1.0f</span><span class="operator">,</span> <span class="operator">-</span><span class="number">1.0f</span><span class="operator">,</span> <span class="operator">-</span><span class="number">1.0f</span>)<span class="operator">,</span> QVector2D(<span class="number">0.33f</span><span class="operator">,</span> <span class="number">0.5f</span>)}<span class="operator">,</span> <span class="comment">// v5</span>
{QVector3D( <span class="number">1.0f</span><span class="operator">,</span> <span class="number">1.0f</span><span class="operator">,</span> <span class="number">1.0f</span>)<span class="operator">,</span> QVector2D(<span class="number">0.0f</span><span class="operator">,</span> <span class="number">1.0f</span>)}<span class="operator">,</span> <span class="comment">// v6</span>
{QVector3D( <span class="number">1.0f</span><span class="operator">,</span> <span class="number">1.0f</span><span class="operator">,</span> <span class="operator">-</span><span class="number">1.0f</span>)<span class="operator">,</span> QVector2D(<span class="number">0.33f</span><span class="operator">,</span> <span class="number">1.0f</span>)}<span class="operator">,</span> <span class="comment">// v7</span>
<span class="comment">// Vertex data for face 2</span>
{QVector3D( <span class="number">1.0f</span><span class="operator">,</span> <span class="operator">-</span><span class="number">1.0f</span><span class="operator">,</span> <span class="operator">-</span><span class="number">1.0f</span>)<span class="operator">,</span> QVector2D(<span class="number">0.66f</span><span class="operator">,</span> <span class="number">0.5f</span>)}<span class="operator">,</span> <span class="comment">// v8</span>
{QVector3D(<span class="operator">-</span><span class="number">1.0f</span><span class="operator">,</span> <span class="operator">-</span><span class="number">1.0f</span><span class="operator">,</span> <span class="operator">-</span><span class="number">1.0f</span>)<span class="operator">,</span> QVector2D(<span class="number">1.0f</span><span class="operator">,</span> <span class="number">0.5f</span>)}<span class="operator">,</span> <span class="comment">// v9</span>
{QVector3D( <span class="number">1.0f</span><span class="operator">,</span> <span class="number">1.0f</span><span class="operator">,</span> <span class="operator">-</span><span class="number">1.0f</span>)<span class="operator">,</span> QVector2D(<span class="number">0.66f</span><span class="operator">,</span> <span class="number">1.0f</span>)}<span class="operator">,</span> <span class="comment">// v10</span>
{QVector3D(<span class="operator">-</span><span class="number">1.0f</span><span class="operator">,</span> <span class="number">1.0f</span><span class="operator">,</span> <span class="operator">-</span><span class="number">1.0f</span>)<span class="operator">,</span> QVector2D(<span class="number">1.0f</span><span class="operator">,</span> <span class="number">1.0f</span>)}<span class="operator">,</span> <span class="comment">// v11</span>
<span class="comment">// Vertex data for face 3</span>
{QVector3D(<span class="operator">-</span><span class="number">1.0f</span><span class="operator">,</span> <span class="operator">-</span><span class="number">1.0f</span><span class="operator">,</span> <span class="operator">-</span><span class="number">1.0f</span>)<span class="operator">,</span> QVector2D(<span class="number">0.66f</span><span class="operator">,</span> <span class="number">0.0f</span>)}<span class="operator">,</span> <span class="comment">// v12</span>
{QVector3D(<span class="operator">-</span><span class="number">1.0f</span><span class="operator">,</span> <span class="operator">-</span><span class="number">1.0f</span><span class="operator">,</span> <span class="number">1.0f</span>)<span class="operator">,</span> QVector2D(<span class="number">1.0f</span><span class="operator">,</span> <span class="number">0.0f</span>)}<span class="operator">,</span> <span class="comment">// v13</span>
{QVector3D(<span class="operator">-</span><span class="number">1.0f</span><span class="operator">,</span> <span class="number">1.0f</span><span class="operator">,</span> <span class="operator">-</span><span class="number">1.0f</span>)<span class="operator">,</span> QVector2D(<span class="number">0.66f</span><span class="operator">,</span> <span class="number">0.5f</span>)}<span class="operator">,</span> <span class="comment">// v14</span>
{QVector3D(<span class="operator">-</span><span class="number">1.0f</span><span class="operator">,</span> <span class="number">1.0f</span><span class="operator">,</span> <span class="number">1.0f</span>)<span class="operator">,</span> QVector2D(<span class="number">1.0f</span><span class="operator">,</span> <span class="number">0.5f</span>)}<span class="operator">,</span> <span class="comment">// v15</span>
<span class="comment">// Vertex data for face 4</span>
{QVector3D(<span class="operator">-</span><span class="number">1.0f</span><span class="operator">,</span> <span class="operator">-</span><span class="number">1.0f</span><span class="operator">,</span> <span class="operator">-</span><span class="number">1.0f</span>)<span class="operator">,</span> QVector2D(<span class="number">0.33f</span><span class="operator">,</span> <span class="number">0.0f</span>)}<span class="operator">,</span> <span class="comment">// v16</span>
{QVector3D( <span class="number">1.0f</span><span class="operator">,</span> <span class="operator">-</span><span class="number">1.0f</span><span class="operator">,</span> <span class="operator">-</span><span class="number">1.0f</span>)<span class="operator">,</span> QVector2D(<span class="number">0.66f</span><span class="operator">,</span> <span class="number">0.0f</span>)}<span class="operator">,</span> <span class="comment">// v17</span>
{QVector3D(<span class="operator">-</span><span class="number">1.0f</span><span class="operator">,</span> <span class="operator">-</span><span class="number">1.0f</span><span class="operator">,</span> <span class="number">1.0f</span>)<span class="operator">,</span> QVector2D(<span class="number">0.33f</span><span class="operator">,</span> <span class="number">0.5f</span>)}<span class="operator">,</span> <span class="comment">// v18</span>
{QVector3D( <span class="number">1.0f</span><span class="operator">,</span> <span class="operator">-</span><span class="number">1.0f</span><span class="operator">,</span> <span class="number">1.0f</span>)<span class="operator">,</span> QVector2D(<span class="number">0.66f</span><span class="operator">,</span> <span class="number">0.5f</span>)}<span class="operator">,</span> <span class="comment">// v19</span>
<span class="comment">// Vertex data for face 5</span>
{QVector3D(<span class="operator">-</span><span class="number">1.0f</span><span class="operator">,</span> <span class="number">1.0f</span><span class="operator">,</span> <span class="number">1.0f</span>)<span class="operator">,</span> QVector2D(<span class="number">0.33f</span><span class="operator">,</span> <span class="number">0.5f</span>)}<span class="operator">,</span> <span class="comment">// v20</span>
{QVector3D( <span class="number">1.0f</span><span class="operator">,</span> <span class="number">1.0f</span><span class="operator">,</span> <span class="number">1.0f</span>)<span class="operator">,</span> QVector2D(<span class="number">0.66f</span><span class="operator">,</span> <span class="number">0.5f</span>)}<span class="operator">,</span> <span class="comment">// v21</span>
{QVector3D(<span class="operator">-</span><span class="number">1.0f</span><span class="operator">,</span> <span class="number">1.0f</span><span class="operator">,</span> <span class="operator">-</span><span class="number">1.0f</span>)<span class="operator">,</span> QVector2D(<span class="number">0.33f</span><span class="operator">,</span> <span class="number">1.0f</span>)}<span class="operator">,</span> <span class="comment">// v22</span>
{QVector3D( <span class="number">1.0f</span><span class="operator">,</span> <span class="number">1.0f</span><span class="operator">,</span> <span class="operator">-</span><span class="number">1.0f</span>)<span class="operator">,</span> QVector2D(<span class="number">0.66f</span><span class="operator">,</span> <span class="number">1.0f</span>)} <span class="comment">// v23</span>
};
<span class="comment">// Indices for drawing cube faces using triangle strips.</span>
<span class="comment">// Triangle strips can be connected by duplicating indices</span>
<span class="comment">// between the strips. If connecting strips have opposite</span>
<span class="comment">// vertex order then last index of the first strip and first</span>
<span class="comment">// index of the second strip needs to be duplicated. If</span>
<span class="comment">// connecting strips have same vertex order then only last</span>
<span class="comment">// index of the first strip needs to be duplicated.</span>
GLushort indices<span class="operator">[</span><span class="operator">]</span> <span class="operator">=</span> {
<span class="number">0</span><span class="operator">,</span> <span class="number">1</span><span class="operator">,</span> <span class="number">2</span><span class="operator">,</span> <span class="number">3</span><span class="operator">,</span> <span class="number">3</span><span class="operator">,</span> <span class="comment">// Face 0 - triangle strip ( v0, v1, v2, v3)</span>
<span class="number">4</span><span class="operator">,</span> <span class="number">4</span><span class="operator">,</span> <span class="number">5</span><span class="operator">,</span> <span class="number">6</span><span class="operator">,</span> <span class="number">7</span><span class="operator">,</span> <span class="number">7</span><span class="operator">,</span> <span class="comment">// Face 1 - triangle strip ( v4, v5, v6, v7)</span>
<span class="number">8</span><span class="operator">,</span> <span class="number">8</span><span class="operator">,</span> <span class="number">9</span><span class="operator">,</span> <span class="number">10</span><span class="operator">,</span> <span class="number">11</span><span class="operator">,</span> <span class="number">11</span><span class="operator">,</span> <span class="comment">// Face 2 - triangle strip ( v8, v9, v10, v11)</span>
<span class="number">12</span><span class="operator">,</span> <span class="number">12</span><span class="operator">,</span> <span class="number">13</span><span class="operator">,</span> <span class="number">14</span><span class="operator">,</span> <span class="number">15</span><span class="operator">,</span> <span class="number">15</span><span class="operator">,</span> <span class="comment">// Face 3 - triangle strip (v12, v13, v14, v15)</span>
<span class="number">16</span><span class="operator">,</span> <span class="number">16</span><span class="operator">,</span> <span class="number">17</span><span class="operator">,</span> <span class="number">18</span><span class="operator">,</span> <span class="number">19</span><span class="operator">,</span> <span class="number">19</span><span class="operator">,</span> <span class="comment">// Face 4 - triangle strip (v16, v17, v18, v19)</span>
<span class="number">20</span><span class="operator">,</span> <span class="number">20</span><span class="operator">,</span> <span class="number">21</span><span class="operator">,</span> <span class="number">22</span><span class="operator">,</span> <span class="number">23</span> <span class="comment">// Face 5 - triangle strip (v20, v21, v22, v23)</span>
};
<span class="comment">// Transfer vertex data to VBO 0</span>
arrayBuf<span class="operator">.</span>bind();
arrayBuf<span class="operator">.</span>allocate(vertices<span class="operator">,</span> <span class="number">24</span> <span class="operator">*</span> <span class="keyword">sizeof</span>(VertexData));
<span class="comment">// Transfer index data to VBO 1</span>
indexBuf<span class="operator">.</span>bind();
indexBuf<span class="operator">.</span>allocate(indices<span class="operator">,</span> <span class="number">34</span> <span class="operator">*</span> <span class="keyword">sizeof</span>(GLushort));
}
<span class="type">void</span> GeometryEngine<span class="operator">::</span>drawCubeGeometry(<span class="type"><a href="../qtgui/qopenglshaderprogram.html">QOpenGLShaderProgram</a></span> <span class="operator">*</span>program)
{
<span class="comment">// Tell OpenGL which VBOs to use</span>
arrayBuf<span class="operator">.</span>bind();
indexBuf<span class="operator">.</span>bind();
<span class="comment">// Offset for position</span>
quintptr offset <span class="operator">=</span> <span class="number">0</span>;
<span class="comment">// Tell OpenGL programmable pipeline how to locate vertex position data</span>
<span class="type">int</span> vertexLocation <span class="operator">=</span> program<span class="operator">-</span><span class="operator">></span>attributeLocation(<span class="string">"a_position"</span>);
program<span class="operator">-</span><span class="operator">></span>enableAttributeArray(vertexLocation);
program<span class="operator">-</span><span class="operator">></span>setAttributeBuffer(vertexLocation<span class="operator">,</span> GL_FLOAT<span class="operator">,</span> offset<span class="operator">,</span> <span class="number">3</span><span class="operator">,</span> <span class="keyword">sizeof</span>(VertexData));
<span class="comment">// Offset for texture coordinate</span>
offset <span class="operator">+</span><span class="operator">=</span> <span class="keyword">sizeof</span>(QVector3D);
<span class="comment">// Tell OpenGL programmable pipeline how to locate vertex texture coordinate data</span>
<span class="type">int</span> texcoordLocation <span class="operator">=</span> program<span class="operator">-</span><span class="operator">></span>attributeLocation(<span class="string">"a_texcoord"</span>);
program<span class="operator">-</span><span class="operator">></span>enableAttributeArray(texcoordLocation);
program<span class="operator">-</span><span class="operator">></span>setAttributeBuffer(texcoordLocation<span class="operator">,</span> GL_FLOAT<span class="operator">,</span> offset<span class="operator">,</span> <span class="number">2</span><span class="operator">,</span> <span class="keyword">sizeof</span>(VertexData));
<span class="comment">// Draw cube geometry using indices from VBO 1</span>
glDrawElements(GL_TRIANGLE_STRIP<span class="operator">,</span> <span class="number">34</span><span class="operator">,</span> GL_UNSIGNED_SHORT<span class="operator">,</span> <span class="number">0</span>);
}
</pre>
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<!-- @@@cube/geometryengine.cpp -->
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