- Qt 5.5
- Qt OpenGL
- Hello GL2 Example
- logo.cpp Example File
- Qt 5.5.1 Reference Documentation

# logo.cpp Example File

hellogl2/logo.cpp

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the examples of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:BSD$
    ** 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
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    **     contributors may be used to endorse or promote products derived
    **     from this software without specific prior written permission.
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    #include "logo.h"
    #include <qmath.h>

    Logo::Logo()
        : m_count(0)
    {
        m_data.resize(2500 * 6);

        const GLfloat x1 = +0.06f;
        const GLfloat y1 = -0.14f;
        const GLfloat x2 = +0.14f;
        const GLfloat y2 = -0.06f;
        const GLfloat x3 = +0.08f;
        const GLfloat y3 = +0.00f;
        const GLfloat x4 = +0.30f;
        const GLfloat y4 = +0.22f;

        quad(x1, y1, x2, y2, y2, x2, y1, x1);
        quad(x3, y3, x4, y4, y4, x4, y3, x3);

        extrude(x1, y1, x2, y2);
        extrude(x2, y2, y2, x2);
        extrude(y2, x2, y1, x1);
        extrude(y1, x1, x1, y1);
        extrude(x3, y3, x4, y4);
        extrude(x4, y4, y4, x4);
        extrude(y4, x4, y3, x3);

        const int NumSectors = 100;

        for (int i = 0; i < NumSectors; ++i) {
            GLfloat angle = (i * 2 * M_PI) / NumSectors;
            GLfloat angleSin = qSin(angle);
            GLfloat angleCos = qCos(angle);
            const GLfloat x5 = 0.30f * angleSin;
            const GLfloat y5 = 0.30f * angleCos;
            const GLfloat x6 = 0.20f * angleSin;
            const GLfloat y6 = 0.20f * angleCos;

            angle = ((i + 1) * 2 * M_PI) / NumSectors;
            angleSin = qSin(angle);
            angleCos = qCos(angle);
            const GLfloat x7 = 0.20f * angleSin;
            const GLfloat y7 = 0.20f * angleCos;
            const GLfloat x8 = 0.30f * angleSin;
            const GLfloat y8 = 0.30f * angleCos;

            quad(x5, y5, x6, y6, x7, y7, x8, y8);

            extrude(x6, y6, x7, y7);
            extrude(x8, y8, x5, y5);
        }
    }

    void Logo::add(const QVector3D &v, const QVector3D &n)
    {
        GLfloat *p = m_data.data() + m_count;
        *p++ = v.x();
        *p++ = v.y();
        *p++ = v.z();
        *p++ = n.x();
        *p++ = n.y();
        *p++ = n.z();
        m_count += 6;
    }

    void Logo::quad(GLfloat x1, GLfloat y1, GLfloat x2, GLfloat y2, GLfloat x3, GLfloat y3, GLfloat x4, GLfloat y4)
    {
        QVector3D n = QVector3D::normal(QVector3D(x4 - x1, y4 - y1, 0.0f), QVector3D(x2 - x1, y2 - y1, 0.0f));

        add(QVector3D(x1, y1, -0.05f), n);
        add(QVector3D(x4, y4, -0.05f), n);
        add(QVector3D(x2, y2, -0.05f), n);

        add(QVector3D(x3, y3, -0.05f), n);
        add(QVector3D(x2, y2, -0.05f), n);
        add(QVector3D(x4, y4, -0.05f), n);

        n = QVector3D::normal(QVector3D(x1 - x4, y1 - y4, 0.0f), QVector3D(x2 - x4, y2 - y4, 0.0f));

        add(QVector3D(x4, y4, 0.05f), n);
        add(QVector3D(x1, y1, 0.05f), n);
        add(QVector3D(x2, y2, 0.05f), n);

        add(QVector3D(x2, y2, 0.05f), n);
        add(QVector3D(x3, y3, 0.05f), n);
        add(QVector3D(x4, y4, 0.05f), n);
    }

    void Logo::extrude(GLfloat x1, GLfloat y1, GLfloat x2, GLfloat y2)
    {
        QVector3D n = QVector3D::normal(QVector3D(0.0f, 0.0f, -0.1f), QVector3D(x2 - x1, y2 - y1, 0.0f));

        add(QVector3D(x1, y1, +0.05f), n);
        add(QVector3D(x1, y1, -0.05f), n);
        add(QVector3D(x2, y2, +0.05f), n);

        add(QVector3D(x2, y2, -0.05f), n);
        add(QVector3D(x2, y2, +0.05f), n);
        add(QVector3D(x1, y1, -0.05f), n);
    }