Qt3D绘制线占用太多内存

Question

如何用QT3D画线？如何删除画好的线条？我发现下面的代码会占用太多的内存，如果你画很多线，尽管它可以工作。此方法只为绘制一条线分配了太多的存储空间，并且不会释放这些存储空间。如果你使用删除指针，那么它崩溃了。如何解决这个问题？

#include <Qt3DCore/QEntity>
#include <Qt3DCore/QTransform>
#include <Qt3DExtras/QPhongMaterial>
#include <Qt3DRender/QAttribute>
#include <Qt3DRender/QBuffer>
#include <Qt3DRender/QGeometry>

drawLine(const QVector3D &start, const QVector3D &end, const QColor &color)
{
    if(!m_bShow) {
        return;
    }

    auto *geometry = new Qt3DRender::QGeometry(m_pRootEntity);
    QByteArray bufferBytes;
    bufferBytes.resize(3*2*sizeof (float));
    float *pos = reinterpret_cast<float*>(bufferBytes.data());
    *pos++ = start.x();
    *pos++ = start.y();
    *pos++ = start.z();
    *pos++ = end.x();
    *pos++ = end.y();
    *pos++ = end.z();

    auto *buf = new Qt3DRender::QBuffer(geometry);
    buf->setData(bufferBytes);

    auto *positionAttribute = new Qt3DRender::QAttribute(geometry);
    positionAttribute->setName(Qt3DRender::QAttribute::defaultPositionAttributeName());
    positionAttribute->setVertexBaseType(Qt3DRender::QAttribute::Float);
    positionAttribute->setVertexSize(3);
    positionAttribute->setAttributeType(Qt3DRender::QAttribute::VertexAttribute);
    positionAttribute->setBuffer(buf);
    positionAttribute->setByteStride(3 * sizeof(float));
    positionAttribute->setCount(2);
    geometry->addAttribute(positionAttribute); // We add the vertices in the geometry

    //connectivity between vertices
    QByteArray indexBytes;
    indexBytes.resize(2 * sizeof(unsigned int)); // start to end
    unsigned int *indices = reinterpret_cast<unsigned int*>(indexBytes.data());
    *indices++ = 0;
    *indices++ = 1;
    auto *indexBuffer = new Qt3DRender::QBuffer(geometry);
    indexBuffer->setData(indexBytes);

    auto *indexAttribute = new Qt3DRender::QAttribute(geometry);
    indexAttribute->setVertexBaseType(Qt3DRender::QAttribute::UnsignedInt);
    indexAttribute->setAttributeType(Qt3DRender::QAttribute::IndexAttribute);
    indexAttribute->setBuffer(indexBuffer);
    indexAttribute->setCount(2);
    geometry->addAttribute(indexAttribute); // We add the indices linking the points in the geometry

    //mesh
    auto *line = new Qt3DRender::QGeometryRenderer(m_pRootEntity);
    line->setGeometry(geometry);
    line->setPrimitiveType(Qt3DRender::QGeometryRenderer::Lines);

    //material
    auto *material = new Qt3DExtras::QDiffuseSpecularMaterial(m_pRootEntity);
    material->setAmbient(color);

    auto *lineEntity = new Qt3DCore::QEntity(m_pRootEntity);

    lineEntity->addComponent(line);
    lineEntity->addComponent(material);
}

Answer 1

最后，我解决了这个问题。
首先，将line实体放入容器:
m_LineEntityList.push_back(lineEntity)，
然后移除line实体的组件：

 while(!m_lineEntityList.isEmpty()) {
    Qt3DCore::QEntity* pEntity = m_lineEntityList.last();
    Qt3DCore::QComponentVector entityVector = pEntity->components();
    while (!entityVector.isEmpty()) {
        pEntity->removeComponent(entityVector.last());
        entityVector.pop_back();
    }
    m_lineEntityList.pop_back();
}