set spline point at screen space position

yo,

ok i have this setup where ive made a massive canvas and placed a spline box on it. So later i control the position of the canvas and have the spline box move with it.

However i am placing the points of the spline at runtime and i am feeding it screen space coordinates to make the point positions.

However when it places the spline points it is using the coordinates of the massive canvas, so in fact the splines appear in the top left area of the big canvas, and not within the screen space at all.

So basically, the splines appear in the right shape, but they are offset by the large canvas. Does anyone know how to make the splines ignore the size of the canvas they are being placed on and just take screen space pixel positions instead?

thanks, Sam