OpenGL: 绘制图形

OpenGL: 绘制图形

1. 认识头文件

#include <iostream>

标准的输入输出流头文件

#include "math3d.h"

//3D数学库

2. 画正方形

//-----------------画正方形-------------------------

    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
    glClear(GL_COLOR_BUFFER_BIT);
    glColor3f(1.0f, 0.0f, 0.0f);
    glBegin(GL_POLYGON);

    //设置多边形的4个顶点
    glVertex3f(0.25f, 0.25f, 0.0f);
    glVertex3f(0.75f, 0.25f, 0.0f);
    glVertex3f(0.75f, 0.75f, 0.0f);
    glVertex3f(0.25f, 0.75f, 0.0f);
    glEnd();

     glFlush();

画圆

//----------------------画圆---------------------------------

    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
    glClear(GL_COLOR_BUFFER_BIT);
    //设置颜色
    glColor3f(1.0f, 0.0f, 0.0f);
    glBegin(GL_POLYGON);
    const int n = 55;
    const GLfloat R = 0.5f;
    const GLfloat pi = 3.1415926f;
    for (int i = 0; i < n; i++)
    {
        glVertex2f(R*cos(2 * pi / n*i), R*sin(2 * pi / n*i));
    }
    glEnd();
    glFlush();

画五角星

// ------------------------五角形-----------------------------
    const GLfloat Pi = 3.1415926536f;
     GLfloat a = 1 / (2-2*cos(72*Pi/180));
     GLfloat bx = a * cos(18 * Pi/180);
     GLfloat by = a * sin(18 * Pi/180);
     GLfloat cy = -a * cos(18 * Pi/180);
     GLfloat
     PointA[2] = { 0, a },
     PointB[2] = { bx, by },
     PointC[2] = { 0.5, cy },
     PointD[2] = { -0.5, cy },
     PointE[2] = { -bx, by };

     glClear(GL_COLOR_BUFFER_BIT);
     glBegin(GL_LINE_LOOP);
     glVertex2fv(PointA);
     glVertex2fv(PointC);
     glVertex2fv(PointE);
     glVertex2fv(PointB);
     glVertex2fv(PointD);
     glEnd();
     glFlush();

画正炫函数

----------- 画出正弦函数的图形---------------

    const GLfloat factor = 0.1f;
    GLfloat x;
    glClear(GL_COLOR_BUFFER_BIT);
    glBegin(GL_LINES);
    glVertex2f(-1.0f, 0.0f);
    glVertex2f(1.0f, 0.0f);        
    glVertex2f(0.0f, -1.0f);
    glVertex2f(0.0f, 1.0f);    
    glEnd();
    glBegin(GL_LINE_STRIP);
    for(x=-1.0f/factor; x<1.0f/factor; x+=0.01f)
    {
        glVertex2f(x*factor, sin(x)*factor);
    }
    glEnd();
    glFlush();

这次就介绍到这里啦。 GitHub：https://github.com/fzdfy/OpenGL_graphing