Vẽ Măt Trăng

#include 
#include "stdlib.h" 
#include "string.h"
#include "math.h"
#include "glut.h"

#define P 3.14159265358979
#define RAD(goc) ((goc)*(P/180.0))
struct colorentry
{
	unsigned char red;
	unsigned char green;
	unsigned char blue;
	colorentry(unsigned char _r,unsigned char _g,unsigned char _b)
	{ red = _r; green = _g; blue = _b; }
};
void vecungtron(int xc,int yc,int st_a,int en_a,int r)
{
	int n=100;
	while((en_a - st_a) <0) en_a += 360;
	float da =RAD((en_a - st_a)%360)/n;
	glColor3ub(255,255,0);
	glBegin(GL_POLYGON);
	{
		for(int i=0;i		{
			glVertex2f(xc+r*cos(RAD(st_a)+i*da),yc+r*
				sin(RAD(st_a)+i*da));
		}
	}
	glEnd();
}

void veelip(int xc,int yc,int rx,int ry,int st_a,int en_a)
{
	int n=100;
	//float da=2*P/n;
	while((en_a - st_a) <0) en_a += 360;
	float da =RAD((en_a - st_a)%360)/n;
	glColor3ub(255,255,255);
	glBegin(GL_POLYGON);
	{
		for(int i=0;i		{
			int x=xc+rx*cos(RAD(st_a)+i*da);
			int y=yc+ry*sin(RAD(st_a)+i*da);
			glVertex2f(x,y);
		}
	}
	glEnd();

}
void mydisplay()
{
	glClear(GL_COLOR_BUFFER_BIT); 
	
	vecungtron(250,250,90,275,200);
	veelip(250,250,125,200,90,275);
	glFlush();
	glutSwapBuffers();
}

void OnSize(int width, int height)
{
	glViewport(0,0,width,height);

	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluOrtho2D(0,width,0,height);
}

void main()
{
	/* Thiet lap thuoc tinh cua so */
	glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGB);
	glutInitWindowPosition(100,150);
	glutInitWindowSize(640,480);

	/* Tao cua so */
	glutCreateWindow("MAT TRANG!");

	/* Mot so lenh khoi tao */
	//glutDisplayFunc(mydisplay);
	glClearColor(1.0,1.0,1.0,0.0);

	/* Dang ky su kien */
	glutDisplayFunc(mydisplay);
	//glutKeyboardFunc(OnKeyDown);
	glutReshapeFunc(OnSize);

	//glutTimerFunc(100,OnTime,5);
	//glutIdleFunc(OnDraw);

	/* Vong lap thong diep */
	glutMainLoop();
}