QT点云显示--基于QOpenGLWidget和QOpenGLFunctions实现

一、实现功能

1、网格显示

2、坐标轴显示

3、鼠标操作旋转、平移、缩放

4、点云显示

之前写了一篇基于QGLWidget实现，此版本的功能接口基本保持一致，方便对比

QT点云显示--基于QGLWidget实现_Jason~shen的博客-CSDN博客1、网格显示2、坐标轴显示3、鼠标操作旋转、平移、缩放4、点云显示。https://blog.csdn.net/qq_40602000/article/details/128293336?spm=1001.2014.3001.5501

QGLWidget与QOpenGLWidget的区别:

1、QGLWidget中是直接调用opengl指令，个人觉得比较方便，逻辑清晰，可以了解opengl底层的接口；

2、QOpenGLWidget是调用QOpenGLFunctions中封装接口，从Qt5.4开始，Qt推荐使用QOpenGLWidget和QOpenGL类。

二、实现效果

 

 

 

三、实现方法

细节待补充

完整代码

PointCloudOpenGLWidget.h

#ifndef BASEOPENGLWIDGET_H
#define BASEOPENGLWIDGET_H

#include <QOpenGLWidget>
#include <QOpenGLFunctions_3_3_Core>
#include <QOpenGLShaderProgram>
#include <QOpenGLTexture>
#include <QMouseEvent>

#include "opengllib_global.h"

class OPENGLLIBSHARED_EXPORT PointCloudOpenGLWidget: public QOpenGLWidget, public QOpenGLFunctions_3_3_Core
{
    Q_OBJECT
public:
    PointCloudOpenGLWidget(QWidget *parent = 0);
    ~PointCloudOpenGLWidget();
    void updatePoints(const QVector<QVector3D> &points);
    void loadCsvFile(const QString &path);

protected:
    void initializeGL() override;
    void paintGL() override;
    void resizeGL(int width, int height) override;

    void mousePressEvent(QMouseEvent *event) override;
    void mouseMoveEvent(QMouseEvent *event) override;
    void wheelEvent(QWheelEvent *event);

    virtual unsigned int drawMeshline(float size, int count);
    virtual void drawCooraxis(float length);
    virtual unsigned int drawPointdata(std::vector<float> &pointVertexs);

protected:
    QOpenGLShaderProgram m_shaderProgramMesh;
    QOpenGLShaderProgram m_shaderProgramAxis;
    QOpenGLShaderProgram m_shaderProgramPoint;

    unsigned int m_VBO_MeshLine;
    unsigned int m_VAO_MeshLine;

    unsigned int m_VBO_Axis;
    unsigned int m_VAO_Axis;

    unsigned int m_VBO_Point;
    unsigned int m_VAO_Point;

    std::vector<float> m_pointData;
    unsigned int m_pointCount;

    unsigned int m_vertexCount;

    float m_xRotate;
    float m_zRotate;
    float m_xTrans;
    float m_yTrans;
    float m_zoom;

    QPoint   lastPos;
};

PointCloudOpenGLWidget.cpp

#include "PointCloudOpenGLWidget.h"
#include <QDebug>

PointCloudOpenGLWidget::PointCloudOpenGLWidget(QWidget *parent)
    : QOpenGLWidget(parent)
{
    m_xRotate = -30.0;
    m_zRotate = 100.0;
    m_xTrans = 0.0;
    m_yTrans = 0.0;
    m_zoom = 45.0;
}

PointCloudOpenGLWidget::~PointCloudOpenGLWidget()
{
    makeCurrent();
    glDeleteBuffers(1, &m_VBO_MeshLine);
    glDeleteVertexArrays(1, &m_VAO_MeshLine);

    glDeleteBuffers(1, &m_VBO_Axis);
    glDeleteVertexArrays(1, &m_VAO_Axis);

    glDeleteBuffers(1, &m_VBO_Point);
    glDeleteVertexArrays(1, &m_VAO_Point);

    m_shaderProgramMesh.release();
    m_shaderProgramAxis.release();
    m_shaderProgramPoint.release();

    doneCurrent();
    qDebug() << __FUNCTION__;
}

void PointCloudOpenGLWidget::updatePoints(const QVector<QVector3D> &points)
{
    m_pointData.clear();
    for(auto vector3D : points)
    {
        m_pointData.push_back(vector3D.x());
        m_pointData.push_back(vector3D.y());
        m_pointData.push_back(vector3D.z());
        m_pointData.push_back(1);
    }
}

void PointCloudOpenGLWidget::loadCsvFile(const QString &path)
{
    m_pointData.clear();
    QFile inFile(path);
    if (inFile.open(QIODevice::ReadOnly))
    {
        QTextStream stream_text(&inFile);
        while (!stream_text.atEnd())
        {
            QString line = stream_text.readLine();
            QStringList strSplit = line.split(",");

            double x = strSplit.value(0).toDouble();
            double y = strSplit.value(1).toDouble();
            double z = strSplit.value(2).toDouble();
            m_pointData.push_back(x);
            m_pointData.push_back(y);
            m_pointData.push_back(z);
            m_pointData.push_back(1);
        }
        inFile.close();
    }
}

void PointCloudOpenGLWidget::initializeGL()
{
    initializeOpenGLFunctions();

    // enable depth_test
    glEnable(GL_DEPTH_TEST);

    // link meshline shaders   vs文件为顶点着色器  fs为片段着色器
    m_shaderProgramMesh.addShaderFromSourceFile(QOpenGLShader::Vertex,
            ":/opengl/shader/shader_mesh.vs");
    m_shaderProgramMesh.addShaderFromSourceFile(QOpenGLShader::Fragment,
            ":/opengl/shader/shader_mesh.fs");
    m_shaderProgramMesh.link();

    // link coordinate axis shaders
    m_shaderProgramAxis.addShaderFromSourceFile(QOpenGLShader::Vertex,
            ":/opengl/shader/shader_axis.vs");
    m_shaderProgramAxis.addShaderFromSourceFile(QOpenGLShader::Fragment,
            ":/opengl/shader/shader_axis.fs");
    m_shaderProgramAxis.link();

    // link pointcloud shaders
    m_shaderProgramPoint.addShaderFromSourceFile(QOpenGLShader::Vertex,
            ":/opengl/shader/shader_point.vs");
    m_shaderProgramPoint.addShaderFromSourceFile(QOpenGLShader::Fragment,
            ":/opengl/shader/shader_point.fs");
    m_shaderProgramPoint.link();

    m_vertexCount = drawMeshline(2.0, 16);
    m_pointCount = drawPointdata(m_pointData);
    qDebug() << "point_count" << m_pointCount;
    drawCooraxis(4.0);
}

void PointCloudOpenGLWidget::paintGL()
{
    glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    /*
       为了将坐标从一个坐标系转换到另一个坐标系，需要用到几个转换矩阵，
       分别是模型(Model)、视图(View)、投影(Projection)三个矩阵。
    */
    QMatrix4x4 projection, view, model;
    //透视矩阵变换
    projection.perspective(m_zoom, (float)width() / (float)height(), 1.0f, 100.0f);

    // eye：摄像机位置  center：摄像机看的点位 up：摄像机上方的朝向
    view.lookAt(QVector3D(0.0, 0.0, 50.0), QVector3D(0.0, 0.0, 1.0), QVector3D(0.0, 1.0, 0.0));

    model.translate(m_xTrans, m_yTrans, 0.0);
    model.rotate(m_xRotate, 1.0, 0.0, 0.0);
    model.rotate(m_zRotate, 0.0, 0.0, 1.0);

    m_shaderProgramMesh.bind();
    m_shaderProgramMesh.setUniformValue("projection", projection);
    m_shaderProgramMesh.setUniformValue("view", view);
    m_shaderProgramMesh.setUniformValue("model", model);

    m_shaderProgramAxis.bind();
    m_shaderProgramAxis.setUniformValue("projection", projection);
    m_shaderProgramAxis.setUniformValue("view", view);
    m_shaderProgramAxis.setUniformValue("model", model);

    m_shaderProgramPoint.bind();
    m_shaderProgramPoint.setUniformValue("projection", projection);
    m_shaderProgramPoint.setUniformValue("view", view);
    m_shaderProgramPoint.setUniformValue("model", model);

    //画网格
    m_shaderProgramMesh.bind();
    glBindVertexArray(m_VAO_MeshLine);
    glLineWidth(1.0f);
    glDrawArrays(GL_LINES, 0, m_vertexCount);

    //画坐标轴
    m_shaderProgramAxis.bind();
    glBindVertexArray(m_VAO_Axis);
    glLineWidth(5.0f);
    glDrawArrays(GL_LINES, 0, 6);

    //画点云
    m_shaderProgramPoint.bind();
    glBindVertexArray(m_VAO_Point);
    glPointSize(1.0f);
    glDrawArrays(GL_POINTS, 0, m_pointCount);
}

void PointCloudOpenGLWidget::resizeGL(int width, int height)
{
    glViewport(0, 0, width, height);
}

void PointCloudOpenGLWidget::mousePressEvent(QMouseEvent *event)
{
    lastPos = event->pos();
}

void PointCloudOpenGLWidget::mouseMoveEvent(QMouseEvent *event)
{
    int dx = event->pos().x() - lastPos.x();
    int dy = event->pos().y() - lastPos.y();
    if (event->buttons() & Qt::LeftButton)
    {
        m_xRotate = m_xRotate + 0.3 * dy;
        m_zRotate = m_zRotate + 0.3 * dx;

        if (m_xRotate > 30.0f)
        {
            m_xRotate = 30.0f;
        }
        if (m_xRotate < -120.0f)
        {
            m_xRotate = -120.0f;
        }
        update();
    }
    else if (event->buttons() & Qt::MidButton)
    {
        m_xTrans = m_xTrans + 0.1 * dx;
        m_yTrans = m_yTrans - 0.1 * dy;
        update();
    }
    lastPos = event->pos();
}

void PointCloudOpenGLWidget::wheelEvent(QWheelEvent *event)
{
    auto scroll_offest = event->angleDelta().y() / 120;
    m_zoom = m_zoom - (float)scroll_offest;

    if (m_zoom < 1.0f)    /* 放大限制 */
    {
        m_zoom = 1.0f;
    }

    if (m_zoom > 80.0f)
    {
        m_zoom = 80.0f;
    }

    update();
}

unsigned int PointCloudOpenGLWidget::drawMeshline(float size, int count)
{
    std::vector<float> mesh_vertexs;
    unsigned int vertex_count = 0;

    float start = count * (size / 2);
    float posX = start, posZ = start;

    for (int i = 0; i <= count; ++i)
    {
        mesh_vertexs.push_back(posX);
        mesh_vertexs.push_back(start);
        mesh_vertexs.push_back(0);

        mesh_vertexs.push_back(posX);
        mesh_vertexs.push_back(-start);
        mesh_vertexs.push_back(0);

        mesh_vertexs.push_back(start);
        mesh_vertexs.push_back(posZ);
        mesh_vertexs.push_back(0);

        mesh_vertexs.push_back(-start);
        mesh_vertexs.push_back(posZ);
        mesh_vertexs.push_back(0);

        posX = posX - size;
        posZ = posZ - size;
    }

    glGenVertexArrays(1, &m_VAO_MeshLine);
    glGenBuffers(1, &m_VBO_MeshLine);

    glBindVertexArray(m_VAO_MeshLine);

    glBindBuffer(GL_ARRAY_BUFFER, m_VBO_MeshLine);

    glBufferData(GL_ARRAY_BUFFER, mesh_vertexs.size() * sizeof(float), &mesh_vertexs[0], GL_STATIC_DRAW);

    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void *)0);
    glEnableVertexAttribArray(0);

    glBindBuffer(GL_ARRAY_BUFFER, 0);

    glBindVertexArray(0);

    vertex_count = (int)mesh_vertexs.size() / 3;

    return vertex_count;
}

void PointCloudOpenGLWidget::drawCooraxis(float length)
{
    std::vector<float> axis_vertexs =
    {
        //x,y ,z ,r, g, b
        0.0, 0.0, 0.0, 1.0, 0.0, 0.0,
        length, 0.0, 0.0, 1.0, 0.0, 0.0,
        0.0, 0.0, 0.0, 0.0, 1.0, 0.0,
        0.0, length, 0.0, 0.0, 1.0, 0.0,
        0.0, 0.0, 0.0, 0.0, 0.0, 1.0,
        0.0, 0.0, length, 0.0, 0.0, 1.0,
    };

    glGenVertexArrays(1, &m_VAO_Axis);
    glGenBuffers(1, &m_VBO_Axis);

    glBindVertexArray(m_VAO_Axis);

    glBindBuffer(GL_ARRAY_BUFFER, m_VBO_Axis);
    glBufferData(GL_ARRAY_BUFFER, axis_vertexs.size() * sizeof(float), &axis_vertexs[0], GL_STATIC_DRAW);

    // 位置属性
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void *)0);
    glEnableVertexAttribArray(0);

    // 颜色属性
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void *)(3 * sizeof(float)));
    glEnableVertexAttribArray(1);

    glBindBuffer(GL_ARRAY_BUFFER, 0);

    glBindVertexArray(0);
}

unsigned int PointCloudOpenGLWidget::drawPointdata(std::vector<float> &pointVertexs)
{
    unsigned int point_count = 0;

    glGenVertexArrays(1, &m_VAO_Point);
    glGenBuffers(1, &m_VBO_Point);

    glBindVertexArray(m_VAO_Point);

    glBindBuffer(GL_ARRAY_BUFFER, m_VBO_Point);
    glBufferData(GL_ARRAY_BUFFER, pointVertexs.size() * sizeof(float), &pointVertexs[0], GL_STATIC_DRAW);

    // 位置属性
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 4 * sizeof(float), (void *)0);
    glEnableVertexAttribArray(0);

// 颜色属性
    glVertexAttribPointer(1, 1, GL_FLOAT, GL_FALSE, 4 * sizeof(float), (void *)(3 * sizeof(float)));
    glEnableVertexAttribArray(1);

    glBindBuffer(GL_ARRAY_BUFFER, 0);

    glBindVertexArray(0);

    point_count = (unsigned int)pointVertexs.size() / 4;

    return point_count;
}