qt3d自定义生成mesh图形

qt中提供的基础的QMesh

  • 方形体 - Qt3DExtras::QConeMesh
  • 圆锥体 - Qt3DExtras::QCuboidMesh
  • 圆柱体 - Qt3DExtras::QCylinderMesh
  • 文本 - Qt3DExtras::QExtrudedTextMesh
  • 平面 - Qt3DExtras::QPlaneMesh
  • 球体 - Qt3DExtras::QSphereMesh
  • 圆环 - Qt3DExtras::QTorusMesh
  • 外部加载 - Qt3DRender::QMesh 从各种格式的外部文件加载网格数据。
    都继承于QGeometryRenderer类。而QGeometryRenderer继承于Qt3DCore::QComponent。很容易知道mesh网格数据是作为组件增加到渲染中的。

在这里插入图片描述
红色上面是qt自带绘制出来的3d模型。下面部分是自定义生成空心圆柱体的3d模型,涉及到重写这些类。

查看qt自带mesh分别怎么用的,和提供了什么

SceneModifier::SceneModifier(Qt3DCore::QEntity *rootEntity)
    : m_rootEntity(rootEntity)
{
    // Torus shape data
    //! [0]
    m_torus = new Qt3DExtras::QTorusMesh();
    m_torus->setRadius(1.0f);
    m_torus->setMinorRadius(0.4f);
    m_torus->setRings(100);
    m_torus->setSlices(20);
    //! [0]

    // TorusMesh Transform
    //! [1]
    Qt3DCore::QTransform *torusTransform = new Qt3DCore::QTransform();
    torusTransform->setScale(1.0f);
    torusTransform->setRotation(QQuaternion::fromAxisAndAngle(QVector3D(0.0f, 1.0f, 0.0f), 25.0f));
    torusTransform->setTranslation(QVector3D(5.0f, 4.0f, 0.0f));
    //! [1]

    //! [2]
    Qt3DExtras::QPhongMaterial *torusMaterial = new Qt3DExtras::QPhongMaterial();
    torusMaterial->setDiffuse(QColor(QRgb(0xbeb32b)));
    //! [2]

    // Torus
    //! [3]
    m_torusEntity = new Qt3DCore::QEntity(m_rootEntity);
    m_torusEntity->addComponent(m_torus);
    m_torusEntity->addComponent(torusMaterial);
    m_torusEntity->addComponent(torusTransform);
    Qt3DRender::QObjectPicker *pickerTorus = new Qt3DRender::QObjectPicker(m_torusEntity);
    m_torusEntity->addComponent(pickerTorus);
    connect(pickerTorus, &Qt3DRender::QObjectPicker::clicked, this, &SceneModifier::handlePickerClicked);
    //! [3]

    // Cone shape data
    Qt3DExtras::QConeMesh *cone = new Qt3DExtras::QConeMesh();
    cone->setTopRadius(0.5);
    cone->setBottomRadius(1);
    cone->setLength(3);
    cone->setRings(50);
    cone->setSlices(20);

    // ConeMesh Transform
    Qt3DCore::QTransform *coneTransform = new Qt3DCore::QTransform();
    coneTransform->setScale(1.5f);
    coneTransform->setRotation(QQuaternion::fromAxisAndAngle(QVector3D(1.0f, 0.0f, 0.0f), 45.0f));
    coneTransform->setTranslation(QVector3D(0.0f, 4.0f, -1.5));

    Qt3DExtras::QPhongMaterial *coneMaterial = new Qt3DExtras::QPhongMaterial();
    coneMaterial->setDiffuse(QColor(QRgb(0x928327)));

    // Cone
    m_coneEntity = new Qt3DCore::QEntity(m_rootEntity);
    m_coneEntity->addComponent(cone);
    m_coneEntity->addComponent(coneMaterial);
    m_coneEntity->addComponent(coneTransform);

    // Cylinder shape data
    Qt3DExtras::QCylinderMesh *cylinder = new Qt3DExtras::QCylinderMesh();
    cylinder->setRadius(1);
    cylinder->setLength(3);
    cylinder->setRings(24);
    cylinder->setSlices(24);

    // CylinderMesh Transform
    Qt3DCore::QTransform *cylinderTransform = new Qt3DCore::QTransform();
    cylinderTransform->setScale(1.5f);
    cylinderTransform->setRotation(QQuaternion::fromAxisAndAngle(QVector3D(1.0f, 0.0f, 0.0f), 45.0f));
    cylinderTransform->setTranslation(QVector3D(-5.0f, 4.0f, -1.5));

    Qt3DExtras::QPhongMaterial *cylinderMaterial = new Qt3DExtras::QPhongMaterial();
    cylinderMaterial->setDiffuse(QColor(QRgb(0x928327)));

    // Cylinder
    m_cylinderEntity = new Qt3DCore::QEntity(m_rootEntity);
    m_cylinderEntity->addComponent(cylinder);
    m_cylinderEntity->addComponent(cylinderMaterial);
    m_cylinderEntity->addComponent(cylinderTransform);

    // Cuboid shape data
    Qt3DExtras::QCuboidMesh *cuboid = new Qt3DExtras::QCuboidMesh();

    // CuboidMesh Transform
    Qt3DCore::QTransform *cuboidTransform = new Qt3DCore::QTransform();
    cuboidTransform->setScale(2.0f);
    cuboidTransform->setTranslation(QVector3D(5.0f, -4.0f, 0.0f));

    Qt3DExtras::QPhongMaterial *cuboidMaterial = new Qt3DExtras::QPhongMaterial();
    cuboidMaterial->setDiffuse(QColor(QRgb(0x665423)));

    //Cuboid
    m_cuboidEntity = new Qt3DCore::QEntity(m_rootEntity);
    m_cuboidEntity->addComponent(cuboid);
    m_cuboidEntity->addComponent(cuboidMaterial);
    m_cuboidEntity->addComponent(cuboidTransform);
    Qt3DRender::QObjectPicker *pickerCuboid = new Qt3DRender::QObjectPicker(m_cuboidEntity);
    m_cuboidEntity->addComponent(pickerCuboid);
    connect(pickerCuboid, &Qt3DRender::QObjectPicker::clicked, this, &SceneModifier::handlePickerClicked);

    // Plane shape data
    Qt3DExtras::QPlaneMesh *planeMesh = new Qt3DExtras::QPlaneMesh();
    planeMesh->setWidth(2);
    planeMesh->setHeight(2);

    // Plane mesh transform
    Qt3DCore::QTransform *planeTransform = new Qt3DCore::QTransform();
    planeTransform->setScale(1.3f);
    planeTransform->setRotation(QQuaternion::fromAxisAndAngle(QVector3D(1.0f, 0.0f, 0.0f), 45.0f));
    planeTransform->setTranslation(QVector3D(0.0f, -4.0f, 0.0f));

    Qt3DExtras::QPhongMaterial *planeMaterial = new Qt3DExtras::QPhongMaterial();
    planeMaterial->setDiffuse(QColor(QRgb(0xa69929)));

    // Plane
    m_planeEntity = new Qt3DCore::QEntity(m_rootEntity);
    m_planeEntity->addComponent(planeMesh);
    m_planeEntity->addComponent(planeMaterial);
    m_planeEntity->addComponent(planeTransform);

    // Sphere shape data
    Qt3DExtras::QSphereMesh *sphereMesh = new Qt3DExtras::QSphereMesh();
    sphereMesh->setRings(20);
    sphereMesh->setSlices(20);
    sphereMesh->setRadius(2);

    // Sphere mesh transform
    Qt3DCore::QTransform *sphereTransform = new Qt3DCore::QTransform();

    sphereTransform->setScale(1.3f);
    sphereTransform->setTranslation(QVector3D(-5.0f, -4.0f, 0.0f));

    Qt3DExtras::QPhongMaterial *sphereMaterial = new Qt3DExtras::QPhongMaterial();
    sphereMaterial->setDiffuse(QColor(QRgb(0xa69929)));

    // Sphere
    m_sphereEntity = new Qt3DCore::QEntity(m_rootEntity);
    m_sphereEntity->addComponent(sphereMesh);
    m_sphereEntity->addComponent(sphereMaterial);
    m_sphereEntity->addComponent(sphereTransform);

    //textMesh
    Qt3DExtras::QExtrudedTextMesh* textMesh = new Qt3DExtras::QExtrudedTextMesh();
    textMesh->setDepth(.1f);
    textMesh->setText("Qt3d自带的shapes");

    Qt3DCore::QTransform *textTransform = new Qt3DCore::QTransform();
    textTransform->setScale(1.5f);
    textTransform->setRotation(QQuaternion::fromAxisAndAngle(QVector3D(1.0f, 0.0f, 0.0f), 45.0f));
    textTransform->setTranslation(QVector3D(-6.0f, 8.0f, 0.0f));

    Qt3DExtras::QPhongMaterial *textMaterial = new Qt3DExtras::QPhongMaterial();
    textMaterial->setDiffuse(QColor(QRgb(0x928327)));

    //
    Qt3DCore::QEntity* textEntity = new Qt3DCore::QEntity(m_rootEntity);
    textEntity->addComponent(textMesh);
    textEntity->addComponent(textMaterial);
    textEntity->addComponent(textTransform);

//==============================================================================
    //DHollowCylinderMesh 自定义空心圆柱mesh
    Qt3DExtras::DHollowCylinderMesh* dcylinder = new Qt3DExtras::DHollowCylinderMesh();
    dcylinder->setSlices(100);
    dcylinder->setRings(100);
    dcylinder->setLength(3);
    dcylinder->setOuterRadius(5);
    dcylinder->setInnerRadius(2.5f);

    Qt3DCore::QTransform *dcylinderTransform = new Qt3DCore::QTransform();
    dcylinderTransform->setScale(1.5f);
    dcylinderTransform->setRotation(QQuaternion::fromAxisAndAngle(QVector3D(1.0f, 0.0f, 0.0f), 45.0f));
    dcylinderTransform->setTranslation(QVector3D(0.0f, -15.0f, 0.0f));

    Qt3DExtras::QPhongMaterial *dcylinderMaterial = new Qt3DExtras::QPhongMaterial();
    dcylinderMaterial->setDiffuse(QColor(QRgb(0x928327)));

    Qt3DCore::QEntity* dcylinderEntity = new Qt3DCore::QEntity(m_rootEntity);
    dcylinderEntity->addComponent(dcylinder);
    dcylinderEntity->addComponent(dcylinderMaterial);
    dcylinderEntity->addComponent(dcylinderTransform);
}

自定义图形 (空心圆柱体)

DHollowCylinderMesh.h

#ifndef DHOLLOWCYLINDERMESH_H
#define DHOLLOWCYLINDERMESH_H


#include <Qt3DExtras/qt3dextras_global.h>
#include <Qt3DRender/qgeometryrenderer.h>

QT_BEGIN_NAMESPACE
namespace Qt3DExtras {
class Q_3DEXTRASSHARED_EXPORT DHollowCylinderMesh : public Qt3DRender::QGeometryRenderer
{
    Q_OBJECT
    Q_PROPERTY(int rings READ rings WRITE setRings NOTIFY ringsChanged)
    Q_PROPERTY(int slices READ slices WRITE setSlices NOTIFY slicesChanged)
    Q_PROPERTY(float outerRadius READ outerRadius WRITE setOuterRadius NOTIFY outerRadiusChanged);
    Q_PROPERTY(float innerRadius READ innerRadius WRITE setInnerRadius NOTIFY innerRadiusChanged);
    Q_PROPERTY(float length READ length WRITE setLength NOTIFY lengthChanged)
public:
    explicit DHollowCylinderMesh(Qt3DCore::QNode *parent = nullptr);
    ~DHollowCylinderMesh();
    int rings() const;
    int slices() const;
    float length() const;
    float outerRadius() const;
    float innerRadius() const;
public Q_SLOTS:
    void setRings(int rings);
    void setSlices(int slices);
    void setLength(float length);
    void setOuterRadius(float radius);
    void setInnerRadius(float radius);
Q_SIGNALS:
    void ringsChanged(int rings);
    void slicesChanged(int slices);
    void lengthChanged(float length);
    void outerRadiusChanged(float radius);
    void innerRadiusChanged(float radius);
private:
    // As this is a default provided geometry renderer, no one should be able
    // to modify the QGeometryRenderer's properties
    void setInstanceCount(int instanceCount);
    void setVertexCount(int vertexCount);
    void setIndexOffset(int indexOffset);
    void setFirstInstance(int firstInstance);
    void setRestartIndexValue(int index);
    void setPrimitiveRestartEnabled(bool enabled);
    void setGeometry(Qt3DRender::QGeometry *geometry);
    void setPrimitiveType(PrimitiveType primitiveType);
};
} // namespace Qt3DRender
QT_END_NAMESPACE

#endif // DHOLLOWCYLINDERMESH_H

DHollowCylinderMesh.cpp

#include "dhollowcylindermesh.h"
#include "dhollowcylindergeometry.h"


#ifndef _USE_MATH_DEFINES
# define _USE_MATH_DEFINES // For MSVC
#endif

#include <Qt3DRender/qbuffer.h>
#include <Qt3DRender/qbufferdatagenerator.h>
#include <Qt3DRender/qattribute.h>
#include <QtGui/QVector3D>
#include <qmath.h>


QT_BEGIN_NAMESPACE
using namespace Qt3DRender;
namespace Qt3DExtras {
/*!
 * \class Qt3DExtras::DHollowCylinderMesh
   \ingroup qt3d-extras-geometries
 * \inheaderfile Qt3DExtras/DHollowCylinderMesh
 * \inmodule Qt3DExtras
 *
 * \inherits Qt3DRender::QGeometryRenderer
 *
 * \brief A hollowCylinderMesh mesh.
 */
/*!
 * Constructs a new DHollowCylinderMesh with \a parent.
 */
DHollowCylinderMesh::DHollowCylinderMesh(QNode *parent)
    : QGeometryRenderer(parent)
{
    DHollowCylinderGeometry *geometry = new DHollowCylinderGeometry(this);
    QObject::connect(geometry, &DHollowCylinderGeometry::outerRadiusChanged, this, &DHollowCylinderMesh::outerRadiusChanged);
    QObject::connect(geometry, &DHollowCylinderGeometry::innerRadiusChanged, this, &DHollowCylinderMesh::innerRadiusChanged);
    QObject::connect(geometry, &DHollowCylinderGeometry::ringsChanged, this, &DHollowCylinderMesh::ringsChanged);
    QObject::connect(geometry, &DHollowCylinderGeometry::slicesChanged, this, &DHollowCylinderMesh::slicesChanged);
    QObject::connect(geometry, &DHollowCylinderGeometry::lengthChanged, this, &DHollowCylinderMesh::lengthChanged);
    QGeometryRenderer::setGeometry(geometry);
}

DHollowCylinderMesh::~DHollowCylinderMesh()
{
}
void DHollowCylinderMesh::setRings(int rings)
{
    static_cast<DHollowCylinderGeometry *>(geometry())->setRings(rings);
}
void DHollowCylinderMesh::setSlices(int slices)
{
    static_cast<DHollowCylinderGeometry *>(geometry())->setSlices(slices);
}

void DHollowCylinderMesh::setLength(float length)
{
    static_cast<DHollowCylinderGeometry *>(geometry())->setLength(length);
}
void DHollowCylinderMesh::setOuterRadius(float radius)
{
    static_cast<DHollowCylinderGeometry *>(geometry())->setOuterRadius(radius);
}
void DHollowCylinderMesh::setInnerRadius(float radius)
{
    static_cast<DHollowCylinderGeometry *>(geometry())->setInnerRadius(radius);
}

int DHollowCylinderMesh::rings() const
{
    return static_cast<DHollowCylinderGeometry *>(geometry())->rings();
}

int DHollowCylinderMesh::slices() const
{
    return static_cast<DHollowCylinderGeometry *>(geometry())->slices();
}

float DHollowCylinderMesh::length() const
{
    return static_cast<DHollowCylinderGeometry *>(geometry())->length();
}

float DHollowCylinderMesh::outerRadius() const
{
    return static_cast<DHollowCylinderGeometry *>(geometry())->outerRadius();
}

float DHollowCylinderMesh::innerRadius() const
{
    return static_cast<DHollowCylinderGeometry *>(geometry())->outerRadius();
}


} // namespace Qt3DExtras
QT_END_NAMESPACE

DHollowCylinderGeometry.h

#ifndef DHOLLOWCYLINDERGEOMETRY_H
#define DHOLLOWCYLINDERGEOMETRY_H

#include <Qt3DExtras/qt3dextras_global.h>
#include <Qt3DRender/qgeometry.h>

QT_BEGIN_NAMESPACE
namespace Qt3DRender {
class QAttribute;
class QBuffer;
} // namespace Qt3DRender
namespace Qt3DExtras {

class Q_3DEXTRASSHARED_EXPORT DHollowCylinderGeometry : public Qt3DRender::QGeometry
{
    Q_OBJECT
    Q_PROPERTY(int rings READ rings WRITE setRings NOTIFY ringsChanged)
    Q_PROPERTY(int slices READ slices WRITE setSlices NOTIFY slicesChanged)
    Q_PROPERTY(float innerRadius READ innerRadius WRITE setInnerRadius NOTIFY innerRadiusChanged)
    Q_PROPERTY(float outerRadius READ outerRadius WRITE setOuterRadius NOTIFY outerRadiusChanged)
    Q_PROPERTY(float length READ length WRITE setLength NOTIFY lengthChanged)
    Q_PROPERTY(Qt3DRender::QAttribute *positionAttribute READ positionAttribute CONSTANT)
    Q_PROPERTY(Qt3DRender::QAttribute *normalAttribute READ normalAttribute CONSTANT)
    Q_PROPERTY(Qt3DRender::QAttribute *texCoordAttribute READ texCoordAttribute CONSTANT)
    Q_PROPERTY(Qt3DRender::QAttribute *indexAttribute READ indexAttribute CONSTANT)
public:
    explicit DHollowCylinderGeometry(QNode *parent = nullptr);
    ~DHollowCylinderGeometry();
    void updateVertices();
    void updateIndices();
    int rings() const;
    int slices() const;
    float innerRadius() const;
    float outerRadius() const;
    float length() const;
    Qt3DRender::QAttribute *positionAttribute() const;
    Qt3DRender::QAttribute *normalAttribute() const;
    Qt3DRender::QAttribute *texCoordAttribute() const;
    Qt3DRender::QAttribute *indexAttribute() const;
public Q_SLOTS:
    void setRings(int rings);
    void setSlices(int slices);
    void setLength(float length);
    void setOuterRadius(float radius);
    void setInnerRadius(float radius);

Q_SIGNALS:
    void radiusChanged(float radius);
    void ringsChanged(int rings);
    void slicesChanged(int slices);
    void lengthChanged(float length);
    void outerRadiusChanged(float radius);
    void innerRadiusChanged(float radius);

private:
    //Q_DECLARE_PRIVATE(QCylinderGeometry)
    void init();

    int m_rings;
    int m_slices;
    float m_length;
    float m_outerRadius;
    float m_innerRadius;

    Qt3DRender::QAttribute *m_positionAttribute;
    Qt3DRender::QAttribute *m_normalAttribute;
    Qt3DRender::QAttribute *m_texCoordAttribute;
    Qt3DRender::QAttribute *m_indexAttribute;
    Qt3DRender::QBuffer *m_vertexBuffer;
    Qt3DRender::QBuffer *m_indexBuffer;
};
} // Qt3DExtras
QT_END_NAMESPACE

#endif // DHOLLOWCYLINDERGEOMETRY_H

<think>我们正在讨论Qt3D编程相关的内容。用户之前询问的是关于在Qt中为3D网格模型边缘生成新平面的方法,这是一个比较专业的3D图形处理问题。 根据我的知识,Qt3D模块(Qt3D)是一个强大的框架,支持3D渲染和计算。生成新平面通常涉及到网格处理,如边缘检测、几何构造等。 在Qt3D中,网格由顶点和面(通常是三角形)组成。要为边缘生成新平面,可能的步骤包括: 1. 边缘检测:找出网格的所有边缘(即只被一个三角形边共享的边)。 2. 为每个边缘生成新的平面:通常,新平面可以垂直于边缘或者沿着某个方向延伸。具体方法取决于需求(如生成厚度、生成连接面等)。 实现方法可能包括: - 使用Qt3D提供的网格类(如QGeometry、QAttribute)来访问和修改网格数据。 - 编写自定义的几何处理器(可以继承自Qt3D::QNode)来创建新的几何图形。 - 对于每个检测到的边缘,计算新平面的顶点(例如,沿边缘法线方向延伸形成四边形面,或者根据相邻面的法线生成新的连接面)。 具体步骤: a. 提取网格的所有边,并标记哪些边是边界边(只属于一个三角形)。 b. 对于每个边界边,可以生成一个四边形(两个新的顶点)来形成新的平面。例如,将边向某个方向(如法线方向)拉伸一段距离,形成新的面。 c. 将这些新生成的四边形添加到原始网格中,或者创建一个新的网格。 注意:生成新平面可能会改变网格的拓扑结构。 由于这是一个复杂的操作,可能需要使用线性代数(向量、矩阵)进行顶点位置的计算。Qt3D使用右手坐标系,计算时需要注意。 参考代码结构(伪代码): ```cpp // 假设我们有一个网格,其几何数据由QGeometry表示 QGeometry *originalGeometry = ...; // 获取原始几何体的顶点和索引数据 QVector<QVector3D> vertices = ...; // 顶点列表 QVector<ushort> indices = ...; // 索引列表(三角形列表) // 步骤1: 检测边界边 // 使用一个映射来记录每条边(用顶点索引对表示,小的索引在前)出现的次数 QMap<Edge, int> edgeCount; for (int i = 0; i < indices.size(); i += 3) { ushort idx0 = indices[i]; ushort idx1 = indices[i+1]; ushort idx2 = indices[i+2]; // 三条边 Edge e1(min(idx0, idx1), max(idx0, idx1)); Edge e2(min(idx1, idx2), max(idx1, idx2)); Edge e3(min(idx2, idx0), max(idx2, idx0)); edgeCount[e1]++; edgeCount[e2]++; edgeCount[e3]++; } // 边界边集合 QList<Edge> boundaryEdges; for (auto it = edgeCount.begin(); it != edgeCount.end(); ++it) { if (it.value() == 1) { boundaryEdges.append(it.key()); } } // 步骤2: 为每个边界边生成新平面(这里以沿法线方向拉伸为例) // 假设我们有一个法线方向,可以是整个网格的平均法线,或者根据相邻面计算 // 为了简单,这里假设使用固定方向(例如(0,1,0))或根据每个边的相邻面计算 // 生成新的顶点和索引 QVector<QVector3D> newVertices = vertices; // 原始顶点 QVector<ushort> newIndices = indices; // 原始索引 QVector3D extrusionDir(0, 1, 0); // 拉伸方向,实际中可能需要根据具体情况计算 float extrusionLength = 1.0f; for (const Edge &edge : boundaryEdges) { QVector3D v0 = vertices[edge.first]; QVector3D v1 = vertices[edge.second]; // 计算拉伸后的两个新顶点 QVector3D v2 = v0 + extrusionDir * extrusionLength; QVector3D v3 = v1 + extrusionDir * extrusionLength; // 添加新顶点 int idx2 = newVertices.size(); newVertices.append(v2); int idx3 = idx2 + 1; newVertices.append(v3); // 构建两个三角形(四边形由两个三角形组成) // 三角形1: v0, v1, v2 newIndices.append(edge.first); newIndices.append(edge.second); newIndices.append(idx2); // 三角形2: v2, v1, v3 newIndices.append(idx2); newIndices.append(edge.second); newIndices.append(idx3); } // 步骤3: 使用newVertices和newIndices创建新的几何体 ``` 以上只是一个简单的示例,实际应用中可能需要考虑: - 拉伸方向(通常使用相邻面的法线平均值) - 新平面与原有网格的平滑连接 - 避免自相交 另外,Qt3D提供了自定义几何体的方法,可以参考Qt官方文档中关于自定义几何体的示例。 相关问题: 1. 在Qt3D中,如何计算网格的法线向量? 2. 除了边界拉伸,还有哪些方法可以为网格添加新的几何结构? 3. 如何在Qt3D中实现网格的实时编辑和更新? 注意:用户的问题是关于“生成新平面”,上述方法生成的是垂直于拉伸方向的平面(实际上是一个侧面,由两个三角形组成)。如果用户想要生成的是与边界边共面的平面,那么方法会不同(例如,将边界边作为新平面的一条边,然后指定另外两个顶点)。具体需求可能需要进一步明确。 由于用户没有提供具体场景,我们假设是为边界边生成一个垂直的平面(即增加厚度或裙边效果)。如果是要在边界处生成一个扩展的平面(比如补洞),则需要不同的方法。 </think>### Qt中为3D网格模型边缘生成新平面的实现方法 在Qt(特别是Qt 3D模块)中为3D网格模型边缘生成新平面,主要涉及网格数据处理和几何扩展技术。以下是关键实现步骤和方法: --- #### 1. **边缘检测与数据提取** - **边界边识别** 通过遍历网格三角形,标记只属于一个三角形的边(边界边): ```cpp QHash<Edge, int> edgeCount; // 边结构体: (minVertIndex, maxVertIndex) for (const Triangle &tri : mesh.triangles()) { countEdge(edgeCount, tri.v1, tri.v2); countEdge(edgeCount, tri.v2, tri.v3); countEdge(edgeCount, tri.v3, tri.v1); } QVector<Edge> boundaryEdges; for (auto it = edgeCount.begin(); it != edgeCount.end(); ++it) { if (it.value() == 1) boundaryEdges.append(it.key()); } ``` - **法线计算** 计算边界边的平均法线方向(用于平面生成方向): ```cpp QVector3D calculateEdgeNormal(const Edge &e) { // 获取共享该边的三角形法线均值 return (adjacentTriangles[e].normal1 + adjacentTriangles[e].normal2).normalized(); } ``` --- #### 2. **平面生成算法** - **垂直拉伸法**(最常用) 沿边界边法线方向延伸生成新四边形平面: ```cpp float thickness = 0.1f; // 拉伸厚度 for (const Edge &e : boundaryEdges) { QVector3D v1 = originalVertices[e.v1]; QVector3D v2 = originalVertices[e.v2]; QVector3D normal = edgeNormals[e]; QVector3D v3 = v1 + normal * thickness; QVector3D v4 = v2 + normal * thickness; // 添加新四边形 (v1,v2,v4,v3) addQuad(newVertices, newIndices, v1, v2, v4, v3); } ``` - **轮廓膨胀法** 对边缘顶点沿法线方向进行径向扩展: ```cpp for (int i = 0; i < boundaryVertices.size(); ++i) { QVector3D displacement = vertexNormals[i] * expandRadius; newVertices.append(originalVertices[i] + displacement); } // 连接新旧顶点生成新面片 ``` --- #### 3. **与Qt 3D模块集成** - **几何数据更新** 创建新的`QGeometryRenderer`加载扩展后的网格: ```cpp Qt3DExtras::QPlaneMesh *newPlane = new Qt3DExtras::QPlaneMesh; QAttribute *positionAttr = new QAttribute(newVerticesBuffer, QAttribute::defaultPositionAttributeName(), QAttribute::Float, 3); newPlane->geometry()->addAttribute(positionAttr); ``` - **实体化渲染** 附加材质和变换组件: ```cpp Qt3DCore::QEntity *planeEntity = new Qt3DCore::QEntity(root); planeEntity->addComponent(newPlane); planeEntity->addComponent(new Qt3DExtras::QPhongMaterial()); ``` --- #### 4. **优化建议** - **破洞修补**:使用`Delaunay三角剖分`连接边界点生成连续平面 - **性能优化**:对大型网格使用`OpenCL`或`Compute Shader`加速计算 - **平滑处理**:在边缘交接处添加`Bezier曲线`过渡面 > **关键库依赖**: > - 核心计算:`Qt3DExtras`、`Qt3DRender` > - 高级操作:`CGAL`(计算几何库)或`OpenMesh` > - 可视化调试:`Qt3DWindow`和`Scene3D` ---
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