- Qt 5.5
- Qt Widgets
- Boxes
- roundedbox.cpp Example File
- Qt 5.5.1 Reference Documentation

# roundedbox.cpp Example File

graphicsview/boxes/roundedbox.cpp

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the demonstration applications of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:LGPL21$
    ** Commercial License Usage
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    ** GNU Lesser General Public License Usage
    ** Alternatively, this file may be used under the terms of the GNU Lesser
    ** General Public License version 2.1 or version 3 as published by the Free
    ** Software Foundation and appearing in the file LICENSE.LGPLv21 and
    ** LICENSE.LGPLv3 included in the packaging of this file. Please review the
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    ****************************************************************************/

    #include "roundedbox.h"

    //============================================================================//
    //                                P3T2N3Vertex                                //
    //============================================================================//

    VertexDescription P3T2N3Vertex::description[] = {
        {VertexDescription::Position, GL_FLOAT, SIZE_OF_MEMBER(P3T2N3Vertex, position) / sizeof(float), 0, 0},
        {VertexDescription::TexCoord, GL_FLOAT, SIZE_OF_MEMBER(P3T2N3Vertex, texCoord) / sizeof(float), sizeof(QVector3D), 0},
        {VertexDescription::Normal, GL_FLOAT, SIZE_OF_MEMBER(P3T2N3Vertex, normal) / sizeof(float), sizeof(QVector3D) + sizeof(QVector2D), 0},

        {VertexDescription::Null, 0, 0, 0, 0},
    };

    //============================================================================//
    //                                GLRoundedBox                                //
    //============================================================================//

    float lerp(float a, float b, float t)
    {
        return a * (1.0f - t) + b * t;
    }

    GLRoundedBox::GLRoundedBox(float r, float scale, int n)
        : GLTriangleMesh<P3T2N3Vertex, unsigned short>((n+2)*(n+3)*4, (n+1)*(n+1)*24+36+72*(n+1))
    {
        int vidx = 0, iidx = 0;
        int vertexCountPerCorner = (n + 2) * (n + 3) / 2;

        P3T2N3Vertex *vp = m_vb.lock();
        unsigned short *ip = m_ib.lock();

        if (!vp || !ip) {
            qWarning("GLRoundedBox::GLRoundedBox: Failed to lock vertex buffer and/or index buffer.");
            m_ib.unlock();
            m_vb.unlock();
            return;
        }

        for (int corner = 0; corner < 8; ++corner) {
            QVector3D centre(corner & 1 ? 1.0f : -1.0f,
                    corner & 2 ? 1.0f : -1.0f,
                    corner & 4 ? 1.0f : -1.0f);
            int winding = (corner & 1) ^ ((corner >> 1) & 1) ^ (corner >> 2);
            int offsX = ((corner ^ 1) - corner) * vertexCountPerCorner;
            int offsY = ((corner ^ 2) - corner) * vertexCountPerCorner;
            int offsZ = ((corner ^ 4) - corner) * vertexCountPerCorner;

            // Face polygons
            if (winding) {
                ip[iidx++] = vidx;
                ip[iidx++] = vidx + offsX;
                ip[iidx++] = vidx + offsY;

                ip[iidx++] = vidx + vertexCountPerCorner - n - 2;
                ip[iidx++] = vidx + vertexCountPerCorner - n - 2 + offsY;
                ip[iidx++] = vidx + vertexCountPerCorner - n - 2 + offsZ;

                ip[iidx++] = vidx + vertexCountPerCorner - 1;
                ip[iidx++] = vidx + vertexCountPerCorner - 1 + offsZ;
                ip[iidx++] = vidx + vertexCountPerCorner - 1 + offsX;
            }

            for (int i = 0; i < n + 2; ++i) {

                // Edge polygons
                if (winding && i < n + 1) {
                    ip[iidx++] = vidx + i + 1;
                    ip[iidx++] = vidx;
                    ip[iidx++] = vidx + offsY + i + 1;
                    ip[iidx++] = vidx + offsY;
                    ip[iidx++] = vidx + offsY + i + 1;
                    ip[iidx++] = vidx;

                    ip[iidx++] = vidx + i;
                    ip[iidx++] = vidx + 2 * i + 2;
                    ip[iidx++] = vidx + i + offsX;
                    ip[iidx++] = vidx + 2 * i + offsX + 2;
                    ip[iidx++] = vidx + i + offsX;
                    ip[iidx++] = vidx + 2 * i + 2;

                    ip[iidx++] = (corner + 1) * vertexCountPerCorner - 1 - i;
                    ip[iidx++] = (corner + 1) * vertexCountPerCorner - 2 - i;
                    ip[iidx++] = (corner + 1) * vertexCountPerCorner - 1 - i + offsZ;
                    ip[iidx++] = (corner + 1) * vertexCountPerCorner - 2 - i + offsZ;
                    ip[iidx++] = (corner + 1) * vertexCountPerCorner - 1 - i + offsZ;
                    ip[iidx++] = (corner + 1) * vertexCountPerCorner - 2 - i;
                }

                for (int j = 0; j <= i; ++j) {
                    QVector3D normal = QVector3D(i - j, j, n + 1 - i).normalized();
                    QVector3D offset(0.5f - r, 0.5f - r, 0.5f - r);
                    QVector3D pos = centre * (offset + r * normal);

                    vp[vidx].position = scale * pos;
                    vp[vidx].normal = centre * normal;
                    vp[vidx].texCoord = QVector2D(pos.x() + 0.5f, pos.y() + 0.5f);

                    // Corner polygons
                    if (i < n + 1) {
                        ip[iidx++] = vidx;
                        ip[iidx++] = vidx + i + 2 - winding;
                        ip[iidx++] = vidx + i + 1 + winding;
                    }
                    if (i < n) {
                        ip[iidx++] = vidx + i + 1 + winding;
                        ip[iidx++] = vidx + i + 2 - winding;
                        ip[iidx++] = vidx + 2 * i + 4;
                    }

                    ++vidx;
                }
            }

        }

        m_ib.unlock();
        m_vb.unlock();
    }