x_ray(t) = y * ctg(w*t)
y = constant vertical distance from center of screen to bottom of screen
w = some constant parameter adjusting constant angular speed
dx_ray(t)/dt = (-y * w) / sin^2(wt)
d2x_ray(t)/dt2 = (2 * w * w * y * cos(wt)) / (sin^3(wt))
-> x_ray(t) is the x position of ray (ray's begin).
-> there's a need to modify x_ray(t) parameters because x,y screen coordinates are really x,-y
-> dx_ray(t)/dt = speed, it's chaning, because...
-> d2x_ray(t)/dt2 = (2 * w * w * y * cos(wt)) / (sin^3(wt)) ... acceleration is not a constant value.
Ergo, x_tank(t) = y * ctg(w*t) to make x_tank in synch with x_ray.