Qt OpenGL 3D 编程入门-swift-CSS教程网

Qt OpenGL 3D 编程入门

Qt 提供了强大的 OpenGL 集成功能，使得在 Qt 应用中实现 3D 图形变得更加简单。以下是使用 Qt 进行 OpenGL 3D 编程的基础知识。

1. 环境配置

创建 Qt 项目

新建 Qt Widgets Application 项目
在 .pro 文件中添加 OpenGL 模块：

qmake

QT       += core gui opengl

基本 OpenGL 窗口类

Qt 提供了 QOpenGLWidget 作为 OpenGL 渲染的基础组件。

openglwidget.h

#ifndef OPENGLWIDGET_H
#define OPENGLWIDGET_H

#include <QOpenGLWidget>
#include <QOpenGLFunctions_3_3_Core>
#include <QOpenGLVertexArrayObject>
#include <QOpenGLBuffer>
#include <QOpenGLShaderProgram>
#include <QOpenGLTexture>
#include <QTime>

class OpenGLWidget : public QOpenGLWidget, protected QOpenGLFunctions_3_3_Core
{
    Q_OBJECT
public:
    explicit OpenGLWidget(QWidget *parent = nullptr);
    ~OpenGLWidget();

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

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

private:
    QOpenGLVertexArrayObject vao;
    QOpenGLBuffer vbo{QOpenGLBuffer::VertexBuffer};
    QOpenGLBuffer ebo{QOpenGLBuffer::IndexBuffer};
    QOpenGLShaderProgram shaderProgram;
    QOpenGLTexture *texture;
    QTime time;
    QPoint lastMousePos;
    float xRot = 0.0f;
    float yRot = 0.0f;
    float zRot = 0.0f;
    float zoom = -5.0f;
};

#endif // OPENGLWIDGET_H

2. 基本框架实现

openglwidget.cpp

#include "openglwidget.h"
#include <QDebug>
#include <QMouseEvent>
#include <QImage>

OpenGLWidget::OpenGLWidget(QWidget *parent) : QOpenGLWidget(parent)
{
    setFocusPolicy(Qt::StrongFocus);
    setMouseTracking(true);
    time.start();
}

OpenGLWidget::~OpenGLWidget()
{
    makeCurrent();
    vao.destroy();
    vbo.destroy();
    ebo.destroy();
    delete texture;
    doneCurrent();
}

void OpenGLWidget::initializeGL()
{
    initializeOpenGLFunctions();
    glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
    glEnable(GL_DEPTH_TEST);

    // 立方体顶点数据 (位置 + 颜色 + 纹理坐标)
    float scale = 2.0f;
    float vertices[] = {
        // 前面
        -0.5f*scale, -0.5f*scale,  0.5f*scale,  1.0f, 0.0f, 0.0f, 1.0f,  0.0f, 0.0f,
        0.5f*scale, -0.5f*scale,  0.5f*scale,  0.0f, 1.0f, 0.0f, 1.0f,  1.0f, 0.0f,
        0.5f*scale,  0.5f*scale,  0.5f*scale,  0.0f, 0.0f, 1.0f, 1.0f,  1.0f, 1.0f,
        -0.5f*scale,  0.5f*scale,  0.5f*scale,  1.0f, 1.0f, 0.0f, 1.0f,  0.0f, 1.0f,

        // 后面
        -0.5f*scale, -0.5f*scale, -0.5f*scale,  1.0f, 0.0f, 1.0f, 1.0f,  1.0f, 0.0f,
        0.5f*scale, -0.5f*scale, -0.5f*scale,  0.0f, 1.0f, 1.0f, 1.0f,  0.0f, 0.0f,
        0.5f*scale,  0.5f*scale, -0.5f*scale,  1.0f, 1.0f, 1.0f, 1.0f,  0.0f, 1.0f,
        -0.5f*scale,  0.5f*scale, -0.5f*scale,  0.5f, 0.5f, 0.5f, 1.0f,  1.0f, 1.0f,

        // 左面
        -0.5f*scale, -0.5f*scale, -0.5f*scale,  0.6f, 0.0f, 0.0f, 1.0f,  0.0f, 0.0f,
        -0.5f*scale, -0.5f*scale,  0.5f*scale,  0.6f, 0.0f, 0.0f, 1.0f,  1.0f, 0.0f,
        -0.5f*scale,  0.5f*scale,  0.5f*scale,  0.6f, 0.0f, 0.0f, 1.0f,  1.0f, 1.0f,
        -0.5f*scale,  0.5f*scale, -0.5f*scale,  0.6f, 0.0f, 0.0f, 1.0f,  0.0f, 1.0f,

        // 右面
        0.5f*scale, -0.5f*scale, -0.5f*scale,  1.0f, 0.2f, 0.2f, 1.0f,  1.0f, 0.0f,
        0.5f*scale, -0.5f*scale,  0.5f*scale,  1.0f, 0.2f, 0.2f, 1.0f,  0.0f, 0.0f,
        0.5f*scale,  0.5f*scale,  0.5f*scale,  1.0f, 0.2f, 0.2f, 1.0f,  0.0f, 1.0f,
        0.5f*scale,  0.5f*scale, -0.5f*scale,  1.0f, 0.2f, 0.2f, 1.0f,  1.0f, 1.0f,

        // 顶面
        -0.5f*scale,  0.5f*scale,  0.5f*scale,  1.0f, 0.1f, 0.1f, 1.0f,  0.0f, 0.0f,
        0.5f*scale,  0.5f*scale,  0.5f*scale,  1.0f, 0.1f, 0.1f, 1.0f,  1.0f, 0.0f,
        0.5f*scale,  0.5f*scale, -0.5f*scale,  1.0f, 0.1f, 0.1f, 1.0f,  1.0f, 1.0f,
        -0.5f*scale,  0.5f*scale, -0.5f*scale,  1.0f, 0.1f, 0.1f, 1.0f,  0.0f, 1.0f,

        // 底面
        -0.5f*scale, -0.5f*scale,  0.5f*scale,  0.5f, 0.0f, 0.0f, 1.0f,  0.0f, 0.0f,
        0.5f*scale, -0.5f*scale,  0.5f*scale,  0.5f, 0.0f, 0.0f, 1.0f,  1.0f, 0.0f,
        0.5f*scale, -0.5f*scale, -0.5f*scale,  0.5f, 0.0f, 0.0f, 1.0f,  1.0f, 1.0f,
        -0.5f*scale, -0.5f*scale, -0.5f*scale,  0.5f, 0.0f, 0.0f, 1.0f,  0.0f, 1.0f
    };

    // 索引数据保持不变
    unsigned int indices[] = {
        0, 1, 2, 2, 3, 0,
        4, 5, 6, 6, 7, 4,
        8, 9, 10, 10, 11, 8,
        12, 13, 14, 14, 15, 12,
        16, 17, 18, 18, 19, 16,
        20, 21, 22, 22, 23, 20
    };

    // 初始化 VAO, VBO 和 EBO
    vao.create();
    vbo.create();
    ebo.create();

    vao.bind();
    vbo.bind();
    vbo.allocate(vertices, sizeof(vertices));
    ebo.bind();
    ebo.allocate(indices, sizeof(indices));

    // 顶点着色器
    const char *vertexShaderSource = R"(
        #version 330 core
        layout(location = 0) in vec3 aPos;
        layout(location = 1) in vec4 aColor;
        layout(location = 2) in vec2 aTexCoord;
        out vec4 ourColor;
        out vec2 TexCoord;
        uniform mat4 model;
        uniform mat4 view;
        uniform mat4 projection;
        void main()
        {
            gl_Position = projection * view * model * vec4(aPos, 1.0);
            ourColor = aColor;
            TexCoord = aTexCoord;
        }
    )";

    // 片段着色器
    const char *fragmentShaderSource = R"(
        #version 330 core
        in vec4 ourColor;
        in vec2 TexCoord;
        out vec4 FragColor;
        uniform sampler2D texture1;
        void main()
        {
            vec4 texColor = texture(texture1, TexCoord);
            FragColor = texColor * ourColor;
        }
    )";

    // 编译着色器
    shaderProgram.addShaderFromSourceCode(QOpenGLShader::Vertex, vertexShaderSource);
    shaderProgram.addShaderFromSourceCode(QOpenGLShader::Fragment, fragmentShaderSource);
    if (!shaderProgram.link()) {
        qDebug() << "Shader Program Link Error:" << shaderProgram.log();
        return;
    }

    shaderProgram.bind();

    // 设置顶点属性指针
    shaderProgram.setAttributeBuffer(0, GL_FLOAT, 0, 3, 9 * sizeof(float));
    shaderProgram.enableAttributeArray(0);
    shaderProgram.setAttributeBuffer(1, GL_FLOAT, 3 * sizeof(float), 4, 9 * sizeof(float));
    shaderProgram.enableAttributeArray(1);
    shaderProgram.setAttributeBuffer(2, GL_FLOAT, 7 * sizeof(float), 2, 9 * sizeof(float));
    shaderProgram.enableAttributeArray(2);

    // 加载纹理
    QImage img(":/textures/test.jpeg");
    if (img.isNull()) {
        qDebug() << "Failed to load texture image!";
        img = QImage(2, 2, QImage::Format_RGB32);
        img.fill(Qt::red);
    }

    texture = new QOpenGLTexture(img.mirrored());
    texture->setMinificationFilter(QOpenGLTexture::Linear);
    texture->setMagnificationFilter(QOpenGLTexture::Linear);
    texture->setWrapMode(QOpenGLTexture::Repeat);

    shaderProgram.setUniformValue("texture1", 0);

    vao.release();
    shaderProgram.release();
}

void OpenGLWidget::resizeGL(int w, int h)
{
    glViewport(0, 0, w, h);
}

void OpenGLWidget::paintGL()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    shaderProgram.bind();
    vao.bind();
    texture->bind(0);

    QMatrix4x4 model;
    QMatrix4x4 view;
    QMatrix4x4 projection;

    model.rotate(xRot, 1.0f, 0.0f, 0.0f);
    model.rotate(yRot, 0.0f, 1.0f, 0.0f);
    model.rotate(zRot, 0.0f, 0.0f, 1.0f);
    view.translate(0.0f, 0.0f, zoom);
    projection.perspective(45.0f, width() / float(height()), 0.1f, 100.0f);

    shaderProgram.setUniformValue("model", model);
    shaderProgram.setUniformValue("view", view);
    shaderProgram.setUniformValue("projection", projection);

    glDrawElements(GL_TRIANGLES, 36, GL_UNSIGNED_INT, 0);

    texture->release();
    vao.release();
    shaderProgram.release();

    zRot += 0.5f;
    if (zRot > 360.0f) zRot -= 360.0f;
    //update();
}

void OpenGLWidget::mousePressEvent(QMouseEvent *event)
{
    lastMousePos = event->pos();
}

void OpenGLWidget::mouseMoveEvent(QMouseEvent *event)
{
    if (event->buttons() & Qt::LeftButton) {
        float dx = event->pos().x() - lastMousePos.x();
        float dy = event->pos().y() - lastMousePos.y();
        xRot += dy;
        yRot += dx;
        lastMousePos = event->pos();
        update();
    }
}

void OpenGLWidget::wheelEvent(QWheelEvent *event)
{
    float delta = event->angleDelta().y() / 120.0f;
    zoom += delta * 0.5f;
    zoom = qBound(-10.0f, zoom, -1.0f);
    update();
}

3. 渲染 3D 立方体

准备顶点数据

  // 立方体顶点数据 (位置 + 颜色 + 纹理坐标)
    float scale = 2.0f;
    float vertices[] = {
        // 前面
        -0.5f*scale, -0.5f*scale,  0.5f*scale,  1.0f, 0.0f, 0.0f, 1.0f,  0.0f, 0.0f,
        0.5f*scale, -0.5f*scale,  0.5f*scale,  0.0f, 1.0f, 0.0f, 1.0f,  1.0f, 0.0f,
        0.5f*scale,  0.5f*scale,  0.5f*scale,  0.0f, 0.0f, 1.0f, 1.0f,  1.0f, 1.0f,
        -0.5f*scale,  0.5f*scale,  0.5f*scale,  1.0f, 1.0f, 0.0f, 1.0f,  0.0f, 1.0f,

        // 后面
        -0.5f*scale, -0.5f*scale, -0.5f*scale,  1.0f, 0.0f, 1.0f, 1.0f,  1.0f, 0.0f,
        0.5f*scale, -0.5f*scale, -0.5f*scale,  0.0f, 1.0f, 1.0f, 1.0f,  0.0f, 0.0f,
        0.5f*scale,  0.5f*scale, -0.5f*scale,  1.0f, 1.0f, 1.0f, 1.0f,  0.0f, 1.0f,
        -0.5f*scale,  0.5f*scale, -0.5f*scale,  0.5f, 0.5f, 0.5f, 1.0f,  1.0f, 1.0f,

        // 左面
        -0.5f*scale, -0.5f*scale, -0.5f*scale,  0.6f, 0.0f, 0.0f, 1.0f,  0.0f, 0.0f,
        -0.5f*scale, -0.5f*scale,  0.5f*scale,  0.6f, 0.0f, 0.0f, 1.0f,  1.0f, 0.0f,
        -0.5f*scale,  0.5f*scale,  0.5f*scale,  0.6f, 0.0f, 0.0f, 1.0f,  1.0f, 1.0f,
        -0.5f*scale,  0.5f*scale, -0.5f*scale,  0.6f, 0.0f, 0.0f, 1.0f,  0.0f, 1.0f,

        // 右面
        0.5f*scale, -0.5f*scale, -0.5f*scale,  1.0f, 0.2f, 0.2f, 1.0f,  1.0f, 0.0f,
        0.5f*scale, -0.5f*scale,  0.5f*scale,  1.0f, 0.2f, 0.2f, 1.0f,  0.0f, 0.0f,
        0.5f*scale,  0.5f*scale,  0.5f*scale,  1.0f, 0.2f, 0.2f, 1.0f,  0.0f, 1.0f,
        0.5f*scale,  0.5f*scale, -0.5f*scale,  1.0f, 0.2f, 0.2f, 1.0f,  1.0f, 1.0f,

        // 顶面
        -0.5f*scale,  0.5f*scale,  0.5f*scale,  1.0f, 0.1f, 0.1f, 1.0f,  0.0f, 0.0f,
        0.5f*scale,  0.5f*scale,  0.5f*scale,  1.0f, 0.1f, 0.1f, 1.0f,  1.0f, 0.0f,
        0.5f*scale,  0.5f*scale, -0.5f*scale,  1.0f, 0.1f, 0.1f, 1.0f,  1.0f, 1.0f,
        -0.5f*scale,  0.5f*scale, -0.5f*scale,  1.0f, 0.1f, 0.1f, 1.0f,  0.0f, 1.0f,

        // 底面
        -0.5f*scale, -0.5f*scale,  0.5f*scale,  0.5f, 0.0f, 0.0f, 1.0f,  0.0f, 0.0f,
        0.5f*scale, -0.5f*scale,  0.5f*scale,  0.5f, 0.0f, 0.0f, 1.0f,  1.0f, 0.0f,
        0.5f*scale, -0.5f*scale, -0.5f*scale,  0.5f, 0.0f, 0.0f, 1.0f,  1.0f, 1.0f,
        -0.5f*scale, -0.5f*scale, -0.5f*scale,  0.5f, 0.0f, 0.0f, 1.0f,  0.0f, 1.0f
    };

    // 索引数据保持不变
    unsigned int indices[] = {
        0, 1, 2, 2, 3, 0,
        4, 5, 6, 6, 7, 4,
        8, 9, 10, 10, 11, 8,
        12, 13, 14, 14, 15, 12,
        16, 17, 18, 18, 19, 16,
        20, 21, 22, 22, 23, 20
    };

初始化 VAO, VBO 和 EBO

    // 初始化 VAO, VBO 和 EBO
    vao.create();
    vbo.create();
    ebo.create();

    vao.bind();
    vbo.bind();
    vbo.allocate(vertices, sizeof(vertices));
    ebo.bind();
    ebo.allocate(indices, sizeof(indices));

创建着色器程序

 // 顶点着色器
    const char *vertexShaderSource = R"(
        #version 330 core
        layout(location = 0) in vec3 aPos;
        layout(location = 1) in vec4 aColor;
        layout(location = 2) in vec2 aTexCoord;
        out vec4 ourColor;
        out vec2 TexCoord;
        uniform mat4 model;
        uniform mat4 view;
        uniform mat4 projection;
        void main()
        {
            gl_Position = projection * view * model * vec4(aPos, 1.0);
            ourColor = aColor;
            TexCoord = aTexCoord;
        }
    )";

    // 编译着色器
    shaderProgram.addShaderFromSourceCode(QOpenGLShader::Vertex, vertexShaderSource);

 // 片段着色器
    const char *fragmentShaderSource = R"(
        #version 330 core
        in vec4 ourColor;
        in vec2 TexCoord;
        out vec4 FragColor;
        uniform sampler2D texture1;
        void main()
        {
            vec4 texColor = texture(texture1, TexCoord);
            FragColor = texColor * ourColor;
        }
    )";

 shaderProgram.addShaderFromSourceCode(QOpenGLShader::Fragment, fragmentShaderSource);

4. 实现 3D 渲染

void OpenGLWidget::paintGL()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    shaderProgram.bind();
    vao.bind();
    texture->bind(0);

    QMatrix4x4 model;
    QMatrix4x4 view;
    QMatrix4x4 projection;

    model.rotate(xRot, 1.0f, 0.0f, 0.0f);
    model.rotate(yRot, 0.0f, 1.0f, 0.0f);
    model.rotate(zRot, 0.0f, 0.0f, 1.0f);
    view.translate(0.0f, 0.0f, zoom);
    projection.perspective(45.0f, width() / float(height()), 0.1f, 100.0f);

    shaderProgram.setUniformValue("model", model);
    shaderProgram.setUniformValue("view", view);
    shaderProgram.setUniformValue("projection", projection);

    glDrawElements(GL_TRIANGLES, 36, GL_UNSIGNED_INT, 0);

    texture->release();
    vao.release();
    shaderProgram.release();

    zRot += 0.5f;
    if (zRot > 360.0f) zRot -= 360.0f;
}

5. 添加纹理

加载纹理

 // 加载纹理
    QImage img(":/textures/test.jpeg");
    if (img.isNull()) {
        qDebug() << "Failed to load texture image!";
        img = QImage(2, 2, QImage::Format_RGB32);
        img.fill(Qt::red);
    }

    texture = new QOpenGLTexture(img.mirrored());
    texture->setMinificationFilter(QOpenGLTexture::Linear);
    texture->setMagnificationFilter(QOpenGLTexture::Linear);
    texture->setWrapMode(QOpenGLTexture::Repeat);

    shaderProgram.setUniformValue("texture1", 0);

更新顶点属性指针

    // 设置顶点属性指针
    shaderProgram.setAttributeBuffer(0, GL_FLOAT, 0, 3, 9 * sizeof(float));
    shaderProgram.enableAttributeArray(0);
    shaderProgram.setAttributeBuffer(1, GL_FLOAT, 3 * sizeof(float), 4, 9 * sizeof(float));
    shaderProgram.enableAttributeArray(1);
    shaderProgram.setAttributeBuffer(2, GL_FLOAT, 7 * sizeof(float), 2, 9 * sizeof(float));
    shaderProgram.enableAttributeArray(2);

完整工程代码：

https://gitee.***/byxdaz/opengl3d-instance

运行效果图：

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