problem.4

void drawStar(float r1, float r2, int num, Vec2d c){
Vec2d P;

glColor3f(r1/15,r1/15,r1/15);
glLineWidth(1.5);
//glBegin(GL_LINE_STRIP);
glBegin(GL_TRIANGLE_FAN);
glVertex2f(c.x,c.y);
float ia=rand()%40;
for (int i=0;i<num;i++){
float angle = ia+i*2*PI / num;
if( i%2==0){
P.x = cos(angle) * r1;
P.y = sin(angle) * r1;
}else{
P.x = cos(angle) * r2;
P.y = sin(angle) * r2;
}

glVertex2f(P.x+c.x,P.y+c.y);
}
glVertex2f(r1+c.x,0+c.y);
glEnd();
}

//inside displayFunc()

glBegin(GL_QUADS);
glColor3f(1,1,1);
glVertex2f(0,0);
glVertex2f(windowW,0);
glColor3f(0,0,0);
glVertex2f(windowW,windowH/5);

glVertex2f(0,windowH/5);
glEnd();

srand(43);
for(int i=0;i<100;i++){
float r = rand()%15;
drawStar(r,r-10,10,Vec2d(rand()%windowW,rand()%(4*windowH/5)+windowH/5));
}