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Activity Forums Apple Final Cut Pro Legacy Changing Viewable Portion of Masked Box in Motion 4

  • Changing Viewable Portion of Masked Box in Motion 4

    Posted by Matt Smith on April 16, 2014 at 4:44 pm

    Hi Everyone.

    I have a screenshot of a map with an animated bezier line that I’ve drawn over top. However, I only want to focus on the front of the line as it moves. So I’ve created a mask box to cut out the rest of the map. The problem is that the line then moves out of the view once it leaves the mask. Can anyone suggest a technique that would allow me to mask the map, and then have it follow along with the line, in the viewable portion? I can attach a video to show what I’m talking about if that would help. Thanks!

    Mark Suszko replied 12 years, 5 months ago 2 Members · 3 Replies
  • 3 Replies
  • Mark Suszko

    April 16, 2014 at 4:57 pm

    Animate the actual virtual camera to follow the progress of the line.

  • Matt Smith

    April 16, 2014 at 6:04 pm

    I’ve tried that. But animating the camera, unless I’m missing something, moves everything visible. So when I do that, even the mask box moves. If I tell the camera to move left or up or what have you, it moves everything and defeats the purpose. I thought it would be as simple as animating the camera.

  • Mark Suszko

    April 16, 2014 at 7:02 pm

    If the camera is keyframed to move across the map as if flying above the front of the growing line, I don’t see why you need a mask then.

    If you use a bezier path for your travel arrow, you don’t need to mask it off to make the old part of the line disappear: you can just keyframe the parameters called first point offset and last point offset. The first two stills here show what that looks like.

    Now, the tail disappears as it follows the arrow head…

    And if you select a new camera, and say “yes” to “do you want a 3-d camera?” You get a keyframable camera that you can fly over the map, chasing the moving arrow head. Here’s a grab from that:

    Is this kind of what you’re after, or did I misinterpret?

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