- Qt 5.5
- Qt3D Module
- Qt3D: Tessellation Modes QML Example
- tessellatedquadmesh.cpp Example File
- Qt 5.5.1 Reference Documentation

# tessellatedquadmesh.cpp Example File

tessellation-modes/tessellatedquadmesh.cpp

    /****************************************************************************
    **
    ** Copyright (C) 2014 Klaralvdalens Datakonsult AB (KDAB).
    ** Contact: http://www.qt-project.org/legal
    **
    ** This file is part of the Qt3D module of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:LGPL3$
    ** Commercial License Usage
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    ** GNU Lesser General Public License Usage
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    ** ensure the GNU Lesser General Public License version 3 requirements
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    ** GNU General Public License Usage
    ** Alternatively, this file may be used under the terms of the GNU
    ** General Public License version 2.0 or later as published by the Free
    ** Software Foundation and appearing in the file LICENSE.GPL included in
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    #include "tessellatedquadmesh.h"

    #include <Qt3DRenderer/qattribute.h>
    #include <Qt3DRenderer/qbuffer.h>
    #include <Qt3DRenderer/qgeometry.h>

    class TessellatedGeometry : public Qt3D::QGeometry
    {
        Q_OBJECT
    public:
        TessellatedGeometry(Qt3D::QNode *parent = Q_NULLPTR)
            : Qt3D::QGeometry(parent)
            , m_positionAttribute(new Qt3D::QAttribute(this))
            , m_vertexBuffer(new Qt3D::QBuffer(Qt3D::QBuffer::VertexBuffer, this))
        {
            const float positionData[] = {
                -0.8f, -0.8f, 0.0f,
                 0.8f, -0.8f, 0.0f,
                 0.8f,  0.8f, 0.0f,
                -0.8f,  0.8f, 0.0f
            };

            const int nVerts = 4;
            const int size = nVerts * 3 * sizeof(float);
            QByteArray positionBytes;
            positionBytes.resize(size);
            memcpy(positionBytes.data(), positionData, size);

            m_vertexBuffer->setData(positionBytes);

            m_positionAttribute->setName(Qt3D::QAttribute::defaultPositionAttributeName());
            m_positionAttribute->setDataType(Qt3D::QAttribute::Float);
            m_positionAttribute->setDataSize(3);
            m_positionAttribute->setCount(nVerts);
            m_positionAttribute->setByteStride(3 * sizeof(float));
            m_positionAttribute->setBuffer(m_vertexBuffer);

            setVerticesPerPatch(4);
            addAttribute(m_positionAttribute);
        }

    private:
        Qt3D::QAttribute *m_positionAttribute;
        Qt3D::QBuffer *m_vertexBuffer;
    };

    TessellatedQuadMesh::TessellatedQuadMesh(Qt3D::QNode *parent)
        : Qt3D::QGeometryRenderer(parent)
    {
        setPrimitiveType(Qt3D::QGeometryRenderer::Patches);
        setGeometry(new TessellatedGeometry(this));
    }

    TessellatedQuadMesh::~TessellatedQuadMesh()
    {
        QNode::cleanup();
    }

    #include "tessellatedquadmesh.moc"