QT6 使用OpenGL库画两个不同外形的立方体（1）

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已于 2024-10-17 17:34:27 修改 · 747 阅读

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#c++ #OpenGL #Qt6 #几何学 #3d

于 2022-09-14 00:33:31 首次发布

QT6 使用OpenGL库画两个不同外形的立方体

首先准备两幅图片，分别如下

然后新建一个工程，不用窗体。分别新建如下代码：

文档结构如下：

two_cube.pro

QT += core gui widgets opengl openglwidgets

TARGET = cube
TEMPLATE = app

SOURCES += main.cpp

SOURCES += \
    mainwidget.cpp \
    geometryengine.cpp

HEADERS += \
    mainwidget.h \
    geometryengine.h

RESOURCES += \
    shaders.qrc \
    textures.qrc

# install
target.path = $$[QT_INSTALL_EXAMPLES]/opengl/cube
INSTALLS += target

GEOMETRYENGINE_H

#ifndef GEOMETRYENGINE_H
#define GEOMETRYENGINE_H

#include <QOpenGLFunctions>
#include <QOpenGLShaderProgram>
#include <QOpenGLBuffer>

class GeometryEngine : protected QOpenGLFunctions
{
public:
    GeometryEngine();
    virtual ~GeometryEngine();

    void drawCubeGeometry(QOpenGLShaderProgram *program);
    void drawCubeGeometry2(QOpenGLShaderProgram *program);


private:
    void initCubeGeometry();

    QOpenGLBuffer arrayBuf;
    QOpenGLBuffer indexBuf;

    QOpenGLBuffer arrayBuf2;
};

#endif // GEOMETRYENGINE_H

MAINWIDGET_H

#ifndef MAINWIDGET_H
#define MAINWIDGET_H

#include "geometryengine.h"

#include <QOpenGLWidget>
#include <QOpenGLFunctions>
#include <QMatrix4x4>
#include <QQuaternion>
#include <QVector2D>
#include <QBasicTimer>
#include <QOpenGLShaderProgram>
#include <QOpenGLTexture>

class GeometryEngine;

class MainWidget : public QOpenGLWidget, protected QOpenGLFunctions
{
    Q_OBJECT

public:
    using QOpenGLWidget::QOpenGLWidget;
    ~MainWidget();

protected:
    void mousePressEvent(QMouseEvent *e) override;
    void mouseReleaseEvent(QMouseEvent *e) override;
    void timerEvent(QTimerEvent *e) override;

    void initializeGL() override;
    void resizeGL(int w, int h) override;
    void paintGL() override;

    void initShaders();
    void initTextures();

private:
    QBasicTimer timer;
    QOpenGLShaderProgram program;
    QOpenGLShaderProgram program2;
    GeometryEngine *geometries = nullptr;

    QOpenGLTexture *texture = nullptr;
    QOpenGLTexture *texture2 = nullptr;

    QMatrix4x4 projection;
    QMatrix4x4 projection2;

    QVector2D mousePressPosition;
    QVector3D rotationAxis;
    qreal angularSpeed = 0;
    QQuaternion rotation;
    QQuaternion rotation2;
};

#endif // MAINWIDGET_H

geometryengine.cpp

#include "geometryengine.h"

#include <QVector2D>
#include <QVector3D>

struct VertexData
{
    QVector3D position;
    QVector2D texCoord;
};

//! [0]
GeometryEngine::GeometryEngine()
    : indexBuf(QOpenGLBuffer::IndexBuffer)
{
    initializeOpenGLFunctions();

    // Generate 2 VBOs
    arrayBuf.create();
    arrayBuf2.create();
    indexBuf.create();

    // Initializes cube geometry and transfers it to VBOs
    initCubeGeometry();
}

GeometryEngine::~GeometryEngine()
{
    arrayBuf.destroy();
    arrayBuf2.destroy();
    indexBuf.destroy();
}
//! [0]

void GeometryEngine::initCubeGeometry()
{
    // For cube we would need only 8 vertices but we have to
    // duplicate vertex for each face because texture coordinate
    // is different.
    VertexData vertices[] = {


        // Vertex data for face 0
        {QVector3D(-1.0f, -1.0f,  1.0f), QVector2D(0.0f, 0.0f)},  // v0
        {QVector3D( 1.0f, -1.0f,  1.0f), QVector2D(0.33f, 0.0f)}, // v1
        {QVector3D(-1.0f,  1.0f,  1.0f), QVector2D(0.0f, 0.5f)},  // v2
        {QVector3D( 1.0f,  1.0f,  1.0f), QVector2D(0.33f, 0.5f)}, // v3

        // Vertex data for face 1
        {QVector3D( 1.0f, -1.0f,  1.0f), QVector2D( 0.0f, 0.5f)}, // v4
        {QVector3D( 1.0f, -1.0f, -1.0f), QVector2D(0.33f, 0.5f)}, // v5
        {QVector3D( 1.0f,  1.0f,  1.0f), QVector2D(0.0f, 1.0f)},  // v6
        {QVector3D( 1.0f,  1.0f, -1.0f), QVector2D(0.33f, 1.0f)}, // v7

        // Vertex data for face 2
        {QVector3D( 1.0f, -1.0f, -1.0f), QVector2D(0.66f, 0.5f)}, // v8
        {QVector3D(-1.0f, -1.0f, -1.0f)