Qt5使用openGL，进行3d绘图

https://blog.csdn.net/qq_35703848/article/details/79819854　

　1、

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QOpenGLWindow>
#include <QOpenGLFunctions>

class Widget : public QOpenGLWindow,protected QOpenGLFunctions
{
    Q_OBJECT

public:
  //  Widget(QWidget *parent = 0);
  //使用时，直接Widget w;即可。
    ~Widget(){};

    void initializeGL()
    {
        initializeOpenGLFunctions();
        glClearColor(0.0f,0.0f,0.0f,0.0f);
    }
    void resizeGL(int width, int height){} //若无需对高、宽进行处理，此函数可省
    void paintGL()
    {
        glClear(GL_COLOR_BUFFER_BIT);
    }
};

#endif // WIDGET_H

2、使用QGLWidget

#ifndef OPENGLWIDGET_H
#define OPENGLWIDGET_H
#include <QtOpenGL>

class OpenglWidget : public QGLWidget
{
public:
    OpenglWidget(QWidget *parent=0);
protected:
    void initializeGL();
    void initWidget();
    void paintGL();
    void resizeGL(int width, int height);
private:
    GLfloat angle;
    GLfloat angle1;
};
#endif // OPENGLWIDGET_H

#include "widget.h"

OpenglWidget::OpenglWidget(QWidget *parent):QGLWidget(parent)
{
    initWidget();
    initializeGL();
}
void OpenglWidget::initializeGL()
{
    //设置着色模式，平滑的
    glShadeModel(GL_SMOOTH);
    //清除掉之前的所有颜色
    glClearColor(0.0,0.0,0.0,0.0);
    //深度缓存,设置初始值为1.0，小于1.0的部分是可见的
    glClearDepth(1.0);
    //启动OPenGL的相关功能，由参数决定，这里指
    //（启用了之后，OpenGL在绘制的时候就会检查，当前像素前面是否有别的像素，如果别的像素挡道了它，那它就不会绘制，也就是说，OpenGL就只绘制最前面的一层）
    glEnable(GL_DEPTH_TEST);
    //制定深度缓存比较值
    //这里参数指的是如果输入的深度值小于或者等于参考值则通过
    glDepthFunc(GL_LEQUAL);

    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);

}

void OpenglWidget::initWidget()
{
    //从屏幕上（400，400）为起始点，显示一个640*400的界面
    setGeometry(400,200,640,480);
    setWindowTitle("My OPenGL");
}

void OpenglWidget::paintGL()
{
    //清除颜色缓冲和深度缓冲
    glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
    //将当前点移置屏幕中心，相当于复位的操作
    glLoadIdentity();
    //平移函数,参数指的是分别从X轴，Y轴，Z轴平移
    glTranslatef(-1.5,0.0,-6.0);


    glRotated(angle,0.0,1.0,0.0);
    //创建图元，是绘制什么图形的接口，参数是绘制多边形的意思
    glBegin(GL_QUADS);
    //设置顶点值（f代表浮点），三维空间坐标
    glColor3f( 1.0, 0.0, 0.0 );
    glBegin( GL_QUADS );

       glColor3f(1, 0, 0);
       glVertex3f(-1,1,1);
       glVertex3f(-1,1,-1);
       glVertex3f(-1,-1,-1);
       glVertex3f(-1,-1,1);

       glColor3f(0, 0, 1);
       glVertex3f(-1,1,-1);
       glVertex3f(-1,-1,-1);
       glVertex3f(1,-1,-1);
       glVertex3f(1,1,-1);

       glColor3f(0, 1, 0);
       glVertex3f(1,1,-1);
       glVertex3f(1,-1,-1);
       glVertex3f(1,-1,1);
       glVertex3f(1,1,1);

       glColor3f(0, 0, 1);
       glVertex3f(1,-1,1);
       glVertex3f(1,1,1);
       glVertex3f(-1,1,1);
       glVertex3f(-1,-1,1);

       glColor3f(0, 1, 0);
       glVertex3f(-1,1,1);
       glVertex3f(1,1,1);
       glVertex3f(1,1,-1);
       glVertex3f(-1,1,-1);

       glColor3f(0, 0, 1);
       glVertex3f(-1,-1,1);
       glVertex3f(-1,-1,-1);
       glVertex3f(1,-1,-1);
       glVertex3f(1,-1,1);
       glEnd();

       glLoadIdentity();

      glTranslatef(1.5,0.0,-6.0);
      glRotatef( angle1,0.0,1.0,0.0);

      glBegin( GL_TRIANGLES );

      glColor3f( 1.0, 0.0, 0.0 );
      glVertex3f(  0.0,  1.0,  0.0 );
      glColor3f( 0.0, 0.0, 1.0 );
      glVertex3f( -1.0, -1.0, -1.0 );
      glColor3f( 0.0, 1.0, 0.0 );
      glVertex3f( -1.0, -1.0,  1.0 );

      glColor3f( 1.0, 0.0, 0.0 );
      glVertex3f(  0.0,  1.0,  0.0 );
      glColor3f( 0.0, 0.0, 1.0 );
      glVertex3f(  1.0, -1.0,  1.0 );
      glColor3f( 0.0, 1.0, 0.0 );
      glVertex3f(  1.0, -1.0, -1.0 );

      glColor3f( 1.0, 0.0, 0.0 );
      glVertex3f(  0.0,  1.0,  0.0 );
      glColor3f( 0.0, 1.0, 0.0 );
      glVertex3f( -1.0, -1.0,  1.0 );
      glColor3f( 0.0, 0.0, 1.0 );
      glVertex3f(  1.0, -1.0,  1.0 );


      glColor3f( 1.0, 0.0, 0.0 );
      glVertex3f(  0.0,  1.0,  0.0 );
      glColor3f( 0.0, 1.0, 0.0 );
      glVertex3f(  1.0, -1.0, -1.0 );
      glColor3f( 0.0, 0.0, 1.0 );
      glVertex3f( -1.0, -1.0, -1.0 );

      glEnd();

    angle+=70;
    angle1+=10;

}

void OpenglWidget::resizeGL(int width, int height)
{
    if(0==height)
        height=1;
    //告诉绘制到窗体的哪个位置
    glViewport(0,0,width,height);
    // 设置矩阵模式，参数是设置为投影矩阵
    glMatrixMode(GL_PROJECTION);
    //复位操作
    glLoadIdentity();

    GLdouble aspectRatio=(GLfloat)width/(GLfloat)height;
    GLdouble rFov=45.0*3.14159265/180.0;
    GLdouble zNear=0.1;
    GLdouble zFar=100.0;
    //调用glFrustum，生成矩阵与当前矩阵相乘，生成透视效果
    glFrustum(-zNear*tan(rFov/2.0)*aspectRatio,
              zNear*tan(rFov/2.0)*aspectRatio,
              -zNear*tan(rFov/2.0),
              zNear*tan(rFov/2.0),
              zNear,zFar);
    //切回模型视图矩阵
    glMatrixMode(GL_MODELVIEW);
    //复位
    glLoadIdentity();
}