Qt OPenGL 入门教程之五基于QOpenGLWidget 实现3D效果

旧城等待， 2023-06-25 10:11 20阅读 0赞

上一节为白色的正方形通过顶点绘制了颜色，这一小节修改顶点数组，实现3D效果

//myopenglwidget.h
    #ifndef MYOPENGLWIDGET_H
    #define MYOPENGLWIDGET_H
    
    #include <QOpenGLWidget>
    #include <QOpenGLFunctions>
    #include <QOpenGLBuffer>
    
    class QOpenGLShaderProgram;
    
    class MyOpenGLWidget : public QOpenGLWidget, protected QOpenGLFunctions
    {
        Q_OBJECT
    
    public:
        explicit MyOpenGLWidget(QWidget *parent = 0);
    
    protected:
        void initializeGL();
        void paintGL();
        void resizeGL(int width, int height);
    
    private:
        QOpenGLShaderProgram *program;
        QOpenGLBuffer vbo;
    };
    
    #endif // MYOPENGLWIDGET_H
    
    //myopenglwidget.cpp
    #include "myopenglwidget.h"
    #include <QOpenGLShaderProgram>
    
    MyOpenGLWidget::MyOpenGLWidget(QWidget *parent)
        : QOpenGLWidget(parent)
    {
    }
    
    void MyOpenGLWidget::initializeGL()
    {
        // 为当前环境初始化OpenGL函数
        initializeOpenGLFunctions();
    
        // 创建顶点着色器
        QOpenGLShader *vshader = new QOpenGLShader(QOpenGLShader::Vertex, this);
        const char *vsrc =
                "in vec4 vPosition;                        \n"
                "in vec4 vColor;                           \n"
                "out vec4 color;                           \n"
                "uniform mat4 matrix;                      \n"
                "void main() {                             \n"
                "   color = vColor;                        \n"
                "   gl_Position = matrix * vPosition;      \n"
                "}                                         \n";
        vshader->compileSourceCode(vsrc);
        // 创建片段着色器
        QOpenGLShader *fshader = new QOpenGLShader(QOpenGLShader::Fragment, this);
        const char *fsrc =
                "in vec4 color;                             \n"
                "out vec4 fColor;                           \n"
                "void main() {                              \n"
                "   fColor = color;                         \n"
                "}                                          \n";
        fshader->compileSourceCode(fsrc);
    
        // 创建着色器程序
        program = new QOpenGLShaderProgram;
        program->addShader(vshader);
        program->addShader(fshader);
    
        program->link();
        program->bind();
    }
    
    void MyOpenGLWidget::resizeGL(int , int )
    {  
    }
    
    void MyOpenGLWidget::paintGL()
    {
        int w = width();
        int h = height();
        int side = qMin(w, h);
        glViewport((w - side) / 2, (h - side) / 2, side, side);
    
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    
        // 顶点位置
        GLfloat vertices[2][4][3] = {
            { {-0.8f, 0.8f, 0.8f}, {-0.8f, -0.8f, 0.8f}, {0.8f, -0.8f, 0.8f}, {0.8f, 0.8f, 0.8f} },
            { {0.8f, 0.8f, 0.8f}, {0.8f, -0.8f, 0.8f}, {0.8f, -0.8f, -0.8f}, {0.8f, 0.8f, -0.8f} }
        };
    
        vbo.create();
        vbo.bind();
        vbo.allocate(vertices, 48*sizeof(GLfloat));
    
        GLuint vPosition = program->attributeLocation("vPosition");
        program->setAttributeBuffer(vPosition, GL_FLOAT, 0, 3, 0);
        glEnableVertexAttribArray(vPosition);
    
    
        // 顶点颜色
        GLfloat colors[2][4][3] = {
            { {1.0f, 0.0f, 0.0f}, {0.0f, 1.0f, 0.0f}, {0.0f, 0.0f, 1.0f}, {1.0f, 1.0f, 1.0f} },
            { {1.0f, 0.0f, 0.0f}, {0.0f, 1.0f, 0.0f}, {0.0f, 0.0f, 1.0f}, {1.0f, 1.0f, 1.0f} }
        };
        vbo.write(24*sizeof(GLfloat), colors, 24*sizeof(GLfloat));
        GLuint vColor = program->attributeLocation("vColor");
        program->setAttributeBuffer(vColor, GL_FLOAT, 24*sizeof(GLfloat), 3, 0);
        glEnableVertexAttribArray(vColor);
    
        QMatrix4x4 matrix;
        matrix.perspective(45.0f, (GLfloat)w/(GLfloat)h, 0.1f, 100.0f);
        matrix.translate(0, 0, -3);
        matrix.rotate(-60, 0, 1, 0);  //绕Y轴逆时针旋转
        program->setUniformValue("matrix", matrix);
    
    
        // 绘制
        for(int i=0; i<2; i++)
            glDrawArrays(GL_TRIANGLE_FAN, i*4, 4);
    }
    
    
    
    //main.cpp
    #include <QApplication>
    #include "myopenglwidget.h"
    
    int main(int argc, char *argv[])
    {
        QApplication app(argc,argv);
        MyOpenGLWidget w;
        w.resize(400, 300);
        w.show();
        return app.exec();
    }

运行结果：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3A5NDIwMDU0MDU_size_16_color_FFFFFF_t_70][]

[下一节：Qt OPenGL 入门教程之六 基于QOpenGLWidget 3D立方体纹理贴图][Qt OPenGL _ _QOpenGLWidget 3D]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3A5NDIwMDU0MDU_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20191228000404821.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3A5NDIwMDU0MDU=,size_16,color_FFFFFF,t_70
[Qt OPenGL _ _QOpenGLWidget 3D]: https://blog.csdn.net/p942005405/article/details/103739920