void rotate(){

Vec2d array[]= {

Vec2d (400,400),

Vec2d (800,400),

Vec2d (800,800),

Vec2d (400,800)

//Vec2d (200,400)

};

// printf( "%f\n", mouseX);

float a =mouseX;// degrees to rotate

Vec2d centerPoint (600,600);

Vec2d xp,yp;

xp.x = d_cos(a);

xp.y = d_sin(a);

yp.x = -1 * d_sin(a);

yp.y = d_cos(a);

for(int i = 0;i< 4;i++){ 

Vec2d currentPoint= array[i]  - centerPoint; //centers it to middle

//printf( "hello \n");

if (2 % i == 0){

printf( "hello %d\n",i);

 currentPoint = xp * currentPoint.x + yp * currentPoint.y;

}

currentPoint = currentPoint + centerPoint; // center back in?

//printf( "new points xy  %f%f\n", currentPoint.x,currentPoint.y);

glVertex2f(currentPoint.x,currentPoint.y);// put points

}

}