利用OpenGL 绘制基本图元 五角星

实验1：利用OpenGL 绘制基本图元

1、实验要求和目的：

a、掌握vc++程序开发环境，熟悉OpenGL基本程序结构。

b、掌握基本图元的绘制方法。

2、实验内容：

a、点、线、三角形、多边形的绘制

3、实验步骤：

a、OpenGL相关库文件的安装；

b、新建工程，OpenGL相关.lib链接，.cpp文件中包含相关.h文件

c、输入、调试、运行OpenGL绘制基本图元的程序。

d、设计五角星（填充）及过渡色扇面（三角，四角）的生成算法的实现程序。

4、实验代码

#include

#include

#include

#include

#include

voidmyDraw() {

glClear (GL_COLOR_BUFFER_BIT);

glColor3f (0.0, 0.0, 1.0);

glPointSize(1.0);

/*

假设五角星外接圆半径为1，有一个角朝上，以五角星中心为原点:

则五个角顶点坐标分别为(按顺时针)：

A（0,1）

B(cos18°,sin18°)

C(cos54°,-sin54°)

D(-cos54°,-sin54°)

E(-cos18°,sin18°)

假设t为内部五边形外接圆半径，

t=(1+tan^2(18°))/(3-tan^2(18°))，即0.3819660112501

则五个顶点所对应的坐标为(即内部五边形的五个顶点)：

BB(-t*cos18°,-t*sin18°)3

CC(-t*cos54°,t*sin54°) 2

DD(t*cos54°,t*sin54°) 1

AA(0,-t) 4

EE(t*cos18°,-t*sin18°)5

*/

//up

glBegin(GL_TRIANGLES); // 绘制三角形

glVertex3f( 0.0f, 1.0f, 0.0f); // 上顶点

glVertex3f(0.38f*cos(54*3.14/180.0),0.38f*sin(54*3.14/180.0), 0.0f); // 1 glVertex3f(-0.38f*cos(54*3.14/180.0),0.38f*sin(54*3.14/180.0),0.0f); // 2 glEnd();

glColor3f (0.0, 1.0, 1.0);

//left-up

glBegin(GL_TRIANGLES); // 绘制三角形

glVertex3f( -1.0f*cos(18*3.14/180.0), 1.0*sin(18*3.14/180.0), 0.0f); //

glVertex3f(-0.38f*cos(54*3.14/180.0),0.38f*sin(54*3.14/180.0),0.0f);//2 glVertex3f(-0.38f*cos(18*3.14/180.0),-0.38f*sin(18*3.14/180.0),0.0f); // 3 glEnd();

glColor3f (1.0, 0.0, 1.0);

//left-down

glBegin(GL_TRIANGLES); // 绘制三角形

glVertex3f( -1.0f*cos(54*3.14/180.0), -1.0*sin(54*3.14/180.0), 0.0f); //

glVertex3f(-0.38f*cos(18*3.14/180.0),-0.38f*sin(18*3.14/180.0),0.0f); //3 glVertex3f(0.0,-0.38f, 0.0f); // 4

glEnd();

glColor3f (0.0, 1.0, 0.0);

//right-down

glBegin(GL_TRIANGLES); // 绘制三角形

glVertex3f(1.0f*cos(54*3.14/180.0),-1.0f*sin(54*3.14/180.0), 0.0f);

glVertex3f(0.0,-0.38f, 0.0f); // 4

glVertex3f(0.38f*cos(18*3.14/180.0),-0.38f*sin(18*3.14/180.0),0.0f); // 5

glEnd();

glColor3f (1.0, 0.4, 0.5);

//right-up

glBegin(GL_TRIANGLES); // 绘制三角形

glVertex3f( 1.0f*cos(18*3.14/180.0), 1.0*sin(18*3.14/180.0), 0.0f); //

glVertex3f(0.38f*cos(18*3.14/180.0),-0.38f*sin(18*3.14/180.0),0.0f); // 5 glVertex3f(0.38f*cos(54*3.14/180.0),0.38f*sin(54*3.14/180.0), 0.0f); // 1 glEnd();

glColor3f (0.5, 1.0, 1.0);

glBegin(GL_POLYGON);

glVertex3f(0.38f*cos(54*3.14/180.0),0.38f*sin(54*3.14/180.0), 0.0f); // 1 glVertex3f(-0.38f*cos(54*3.14/180.0),0.38f*sin(54*3.14/180.0),0.0f); // 2 glVertex3f(-0.38f*cos(18*3.14/180.0),-0.38f*sin(18*3.14/180.0),0.0f); //3 glVertex3f(0.0,-0.38f, 0.0f); // 4

glVertex3f(0.38f*cos(18*3.14/180.0),-0.38f*sin(18*3.14/180.0),0.0f); // 5 glEnd();

glFlush();

}

int main(intargc, char* argv[]) {

glutInit(&argc, argv);

glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);

glutInitWindowSize(500, 500);

glutInitWindowPosition(0,0);

glutCreateWindow("Sterpinski Triangle");

glutDisplayFunc(myDraw);

glutMainLoop();

return 0;

}