OpenGL学习（二）绘制三维图形 固定管线

一.简单步骤

• 考虑顶点数据
• 上色
• 旋转

二.完整代码

myopenglwidget.h

// An highlighted block
#ifndef MYOPENGLWIDGET_H
#define MYOPENGLWIDGET_H
#include <QOpenGLWidget>
#include <QOpenGLFunctions>
#include <QOpenGLShaderProgram>
#include <QtNetwork/QHostInfo>
#include <QtNetwork/QHostAddress>
#include <QtNetwork/QNetworkInterface>
#include <QFile>
#include <QDir>
#include <QImage>
#include <QBuffer>
#include <QKeyEvent>
#include <QTimer>
#include <GL/glu.h>
#include <QMouseEvent>class MyOpenGLWidget : public QOpenGLWidget,protected QOpenGLFunctions  // 可直接使用QOpenGLFunctions中的OpenGL函数
{Q_OBJECT
public:explicit MyOpenGLWidget (QWidget * parent = 0);protected:void initializeGL();void paintGL();void resizeGL(int width,int height);void keyPressEvent(QKeyEvent* e) override;  //Qt键盘事件处理函数void mousePressEvent(QMouseEvent *event) override{if (event->button() == Qt::LeftButton){m_lastPos = event->globalPos() - frameGeometry().topLeft();
//            qDebug() << "Clicked at position: " << m_lastPos;}}void mouseMoveEvent(QMouseEvent *event) override{if (event->buttons() & Qt::LeftButton){QPoint newpos = event->globalPos() - m_lastPos;move(newpos);}}private slots:void rotate() {update();}
private:GLfloat angle;double size_t;bool flag=true;bool fullscreen=false;QPoint m_lastPos;};#endif // MYOPENGLWIDGET_H

 

 myopenglwidget.cpp

#include "myopenglwidget.h"MyOpenGLWidget::MyOpenGLWidget(QWidget *parent): QOpenGLWidget(parent)
{setGeometry(1550,0,100,100);               //设置窗口大小、位置resize(50,50);// 去掉当前窗口的标题栏setWindowFlags(Qt::FramelessWindowHint | Qt::WindowStaysOnTopHint);//隐藏标题栏并且设置窗口悬浮在所有程序之上setAttribute(Qt::WA_TranslucentBackground);//设置背景透明
//    setWindowFlags(Qt::WindowStaysOnTopHint);angle = 0;size_t=0;QTimer *timer = new QTimer(this);connect(timer, SIGNAL(timeout()), this, SLOT(rotate()));timer->start(20);foreach(const QHostAddress& hostAddress,QNetworkInterface::allAddresses())//对于所有检测到的地址if ( hostAddress != QHostAddress::LocalHost && hostAddress.toIPv4Address() )//如果格式为IPv4则输出qDebug()<<hostAddress.toString();}void MyOpenGLWidget::initializeGL()
{initializeOpenGLFunctions();//    glClearColor(0.5, 0.5, 0.5, 0.0);glClearDepth(1.0);  //设置深度缓存glEnable(GL_DEPTH_TEST);    //启动深度测试glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);glDepthFunc(GL_LEQUAL); //所作深度测试的类型glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);  //真正精细的透视修正，告诉OPenGL我们希望进行最好的透视修正，这会十分轻微的影响性能，但使得透视图看起来好一点
}void MyOpenGLWidget::paintGL()
{glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);//用于清除颜色缓冲区和深度缓冲区，以便开始绘制新的帧。glLoadIdentity();//用于将当前矩阵重置为单位矩阵，即将模型视图矩阵设置为初始状态。glScalef(size_t,size_t,size_t);//进行缩放变换，将物体的大小缩小为原来的0.2倍。glRotatef(angle, 0.0f, 1.0f, 0.0f);//是进行旋转变换，围绕Y轴旋转angle度。其中，angle是一个变量，可以控制旋转的角度。// 启用混合glEnable(GL_BLEND);glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);// 启用Alpha测试glEnable(GL_ALPHA_TEST);glAlphaFunc(GL_GREATER, 0.0f);glBegin(GL_TRIANGLES);//前侧面glColor3f(1.0, 0.0, 0.0);glVertex3f(0.0, 1.0, 0.0);      //上顶点glColor3f(0.0, 1.0, 0.0);glVertex3f(-1.0, -1.0, 1.0);    //左下顶点glColor3f(0.0, 0.0, 1.0);glVertex3f(1.0, -1.0, 1.0);     //右下顶点//前侧面下glColor3f(0.0, 1.0, 0.0);glVertex3f(-1.0, -1.0, 1.0);    //左下顶点glColor3f(1.0, 0.0, 0.0);glVertex3f(0.0, -3.0, 0.0);      //下顶点glColor3f(0.0, 0.0, 1.0);glVertex3f(1.0, -1.0, 1.0);     //右下顶点//右侧面glColor3f(1.0, 0.0, 0.0);glVertex3f(0.0, 1.0, 0.0);      //上顶点glColor3f(0.0, 0.0, 1.0);glVertex3f(1.0, -1.0, 1.0);     //左下顶点glColor3f(0.0, 1.0, 0.0);glVertex3f(1.0, -1.0, -1.0);    //右下顶点//右侧面下glColor3f(0.0, 0.0, 1.0);glVertex3f(1.0, -1.0, 1.0);     //左下顶点glColor3f(1.0, 0.0, 0.0);glVertex3f(0.0, -3.0, 0.0);      //上顶点glColor3f(0.0, 1.0, 0.0);glVertex3f(1.0, -1.0, -1.0);    //右下顶点//后侧面glColor3f(1.0, 0.0, 0.0);glVertex3f(0.0, 1.0, 0.0);      //上顶点glColor3f(0.0, 1.0, 0.0);glVertex3f(1.0, -1.0, -1.0);    //左下顶点glColor3f(0.0, 0.0, 1.0);glVertex3f(-1.0, -1.0, -1.0);   //右下顶点//后侧面下glColor3f(0.0, 1.0, 0.0);glVertex3f(1.0, -1.0, -1.0);    //左下顶点glColor3f(1.0, 0.0, 0.0);glVertex3f(0.0, -3.0, 0.0);      //上顶点glColor3f(0.0, 0.0, 1.0);glVertex3f(-1.0, -1.0, -1.0);   //右下顶点//左侧面glColor3f(1.0, 0.0, 0.0);glVertex3f(0.0, 1.0, 0.0);      //上顶点glColor3f(0.0, 0.0, 1.0);glVertex3f(-1.0, -1.0, -1.0);   //左下顶点glColor3f(0.0, 1.0, 0.0);glVertex3f(-1.0, -1.0, 1.0);    //右下顶点//左侧面下glColor3f(0.0, 0.0, 1.0);glVertex3f(-1.0, -1.0, -1.0);   //左下顶点glColor3f(1.0, 0.0, 0.0);glVertex3f(0.0, -3.0, 0.0);      //上顶点glColor3f(0.0, 1.0, 0.0);glVertex3f(-1.0, -1.0, 1.0);    //右下顶点glEnd();if(size_t>=0.5){flag=false;}else if(size_t==0){flag=true;}angle += 2;if(flag){size_t+=0.001;}else{size_t-=0.001;}
}void MyOpenGLWidget::resizeGL(int w, int h)
{glViewport(0, 0, w, h);//使用当前屏幕的宽和高来设置视口glMatrixMode(GL_PROJECTION);glLoadIdentity();glMatrixMode(GL_MODELVIEW);glLoadIdentity();}
void MyOpenGLWidget::keyPressEvent(QKeyEvent* e)
{switch (e->key()) {case Qt::Key_Q: {fullscreen = !fullscreen;if(fullscreen) {showFullScreen();}else {showNormal();setGeometry(500,500,640,480);}update();break;}//case Qt::Key_Qcase Qt::Key_Escape: {close();}//Qt::Key_Escape}//switch (e->key())
}