Mr. Gaskin writes in to the blog:
…wouldn’t it be great if we were able to *rotate* the mask-shape filter. That way I could selectively isolate diagonals or keyframe the mask-shape on a changing shape in the shot.
Having a look at this idea points up the problem: you can’t use FXScript to modify the values used in the controls. I’ve come up with a plugin that gives this sort of control, but there’s a limit to the user interface: You can set your eight points up where you want them to be. If you want to rotate that matte, using keyframes for example, the new position of the points changed by the rotation cannot be put into the controls of the filter.
That means if you want to keyframe the rotation, scale and position of your matte to follow a specific feature in your clip and the shape of the feature changes, the points that you manipulate on screen won’t match the edge of your matte:
In this case, the matte has been scaled and repositioned so that the edges don’t line up with the control points. The control points on screen define the shape of the matte, other controls describe the location, size and rotation of the matte. You can change the View Mode to ‘Wireframe’ to get better control of the shape by seeing how moving a point changes the line that defines the edge of the matte:
Copy the ‘Alex4D 8-Point Matte v1.fcfcc’ file into one of two places on your computer:
Your Startup HD/Library/Application Support/Final Cut Pro System Support/Plugins
Your Startup HD/Users/your name/Library/Preferences/Final Cut Pro User Data/Plugins/
(Your Startup HD/Users/your name/Library/Application Support/Final Cut Express Support/Plugins for Final Cut Express users)
Restart Final Cut, and you’ll see the filter in the ‘Matte’ section of ‘Video Filters’