QOpenGLShaderProgram 空心矩形, 背景透明, 完善代码列子

很高兴为您解答这个问题。以下是创建具有空心矩形和透明背景的 QOpenGLShaderProgram 的完整代码示例：

#include <QCoreApplication>
#include <QSurfaceFormat>
#include <QOpenGLFunctions>
#include <QOpenGLShaderProgram>
#include <QOpenGLWidget>

class QTransparentRectangleWidget : public QOpenGLWidget, protected QOpenGLFunctions
{
public:
    void initializeGL()
    {
        // 设置 OpenGL 的清除颜色为全透明
        glClearColor(0, 0, 0, 0);

        // 初始化 OpenGL 函数
        initializeOpenGLFunctions();

        // 加载顶点和片段着色器
        m_program.addShaderFromSourceCode(QOpenGLShader::Vertex, "#version 330\n"
                "layout (location = 0) in vec2 position;\n"
                "uniform mat4 projectionMatrix;\n"
                "void main()\n"
                "{\n"
                "    gl_Position = projectionMatrix * vec4(position, 0.0, 1.0);\n"
                "}\n");

        m_program.addShaderFromSourceCode(QOpenGLShader::Fragment, "#version 330\n"
                "out vec4 FragColor;\n"
                "uniform vec4 color;\n"
                "void main()\n"
                "{\n"
                "    FragColor = color;\n"
                "}\n");

        // 绑定属性
        m_program.bindAttributeLocation("position", 0);

        // 编译和链接着色器程序
        bool programLinked = m_program.link();
        Q_ASSERT(programLinked);
        (void)programLinked;

        // 生成和绑定一个顶点缓冲区对象
        glGenBuffers(1, &m_vbo);
        glBindBuffer(GL_ARRAY_BUFFER, m_vbo);

        // 设定顶点属性
        glEnableVertexAttribArray(0);
        glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 0, nullptr);
    }

    void resizeGL(int w, int h)
    {
        glViewport(0, 0, w, h);
        m_projectionMatrix.setToIdentity();
        m_projectionMatrix.ortho(0, w, h, 0, -1, 1);
    }

    void paintGL()
    {
        // 清除颜色缓存
        glClear(GL_COLOR_BUFFER_BIT);

        // 使用着色器程序
        m_program.bind();

        // 传递 Uniform 值
        m_program.setUniformValue("projectionMatrix", m_projectionMatrix);
        m_program.setUniformValue("color", QColor(255, 0, 0, 127));

        // 画一个空心矩形
        const GLfloat vertices[] = {
            50.0f, 50.0f,
            200.0f, 50.0f,
            200.0f, 200.0f,
            50.0f, 200.0f,
            50.0f, 50.0f
        };
        glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
        glDrawArrays(GL_LINE_STRIP, 0, 5);
    }

private:
    QOpenGLShaderProgram m_program;
    GLuint m_vbo;
    QMatrix4x4 m_projectionMatrix;
};

int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_UseOpenGLES);
    QCoreApplication::setAttribute(Qt::AA_ShareOpenGLContexts);
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
    QCoreApplication::setAttribute(Qt::AA_UseHighDpiPixmaps);

    QSurfaceFormat format;
    format.setDepthBufferSize(24);
    QSurfaceFormat::setDefaultFormat(format);

    QApplication a(argc, argv);

    QTransparentRectangleWidget widget;
    widget.resize(400, 400);
    widget.show();

    return a.exec();
}

希望这个代码示例对您有所帮助！