Adding track data to Polygon, maintain centre

I have a polygon mask.
I have track data from a Tracker Node.

I want to add the track data to the polygon, so that it moves across with the image, but without messing up the starting position of the polygon.

I get as far as making the polygon successfully move with the track data, but the problem is it aligns it's centre to the track's centre, so the polygon ends up the wrong place, and I cannot for the love_of_all_things_holy find a way to offset it to where it should be.

I know you should be able to do this and I'm just being thick, but I'm banging my head against my desk trying to make this work..

Any advice appreciated.

Cheers.

The easiest way to do this is in the future is by connecting the polygon centre *before* creating the mask.
One way (and there will be some others as well, but I can't remember which at the moment) to off-set the centre in this case is by using an off-set modifier. Just right-click on the polygon center and choose 'modify with off-set position' then in that modifier connect the center to your tracking data and use the off-set cross to put the mask where you need it to be.

The easiest way to do this is in the future is by connecting the polygon centre *before* creating the mask.
One way (and there will be some others as well, but I can't remember which at the moment) to off-set the centre in this case is by using an off-set modifier. Just right-click on the polygon center and choose 'modify with off-set position' then in that modifier connect the center to your tracking data and use the off-set cross to put the mask where you need it to be.

thank you!