float InvSqrt(float x){
   float xhalf = 0.5f * x;
   int i = *(int*)&x;            // store floating-point bits in integer
   i = 0x5f3759df - (i >> 1);    // initial guess for Newton's method
   x = *(float*)&i;              // convert new bits into float
   x = x*(1.5f - xhalf*x*x);     // One round of Newton's method
   return x;
}

function checkangle(x2,y2,x1,y1) {
    var angle = Math.atan((x2-x1)/(y1-y2))/(Math.PI/180);
    if(y2 > y1) {
        angle += 180;
    }
    if(angle < 0) {
        angle += 360;
    }
    return angle
}