Material: How to set a Custom Rotation's pivot point to the same location as 'zoomed in'/aligned texture?

terrain-grass-alphadem.jpg

I have a material that has a few different settings to alter which part of a texture and opacity mask is displayed via parameters. I want to add rotation as a parameter also but when using a custom rotator it rotates the entire base BMP pictured above, or does other incorrect things depending on where in the line it is placed.

How can I set the pivot point for the rotation to be in exactly the same place as where my opacity mask is centered?

You can test with the asset above and the basic setup below, its an extremely simple but I just can’t figure this part out.

Hey, I just ran across the same problem. Have you been able to figure it out? Your help is much appreciated.