void drawGrid( void )
{
for(int i=0;i<windowW;i+=10){
glColor3f(0.8,0.8,0.8);
glBegin(GL_LINES);
glVertex2f(i,0);
glVertex2f(i,windowH);
glEnd();
}


for(int i=0;i<windowH;i+=10){
glColor3f(0.8,0.8,0.8);
glBegin(GL_LINES);
glVertex2f(0,i);
glVertex2f(windowW,i);
glEnd();
}

for(int i=0;i<windowW;i+=10){
for(int j=0;j<windowH;j+=10){
glPointSize(3);
glBegin(GL_POINTS);
glVertex2f(i,j);
glEnd();
}
}

}