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  • Expression and Masking

    Posted by Brad Strickman on March 30, 2007 at 5:59 pm

    I am trying to make a curtain that subtly blows in the wind. Fractal noise on a solid is working great except for one issue. The bottom of the solid remains a hard edge. Is there a way to make it so the fractal noise expands beyond the edges of the solid? My other idea is to create a mask and then add a wiggle expression to its shape. Is that possible? Any suggestions? Thanks

    Brad Strickman replied 19 years, 1 month ago 5 Members · 10 Replies
  • 10 Replies
  • Darby Edelen

    March 30, 2007 at 6:58 pm

    If you pre-compose the curtain and make sure that there is transparent space around the curtain layer (easiest way might be scale it down 5%) in the pre-comp the displacement map should displace the ‘edges’ of the curtain.

  • Adolfo Rozenfeld

    March 30, 2007 at 7:10 pm

    You can’t apply wiggle() to a mask path, because the nodes’ locations aren’t exposed to expressions.

    In CS3 you’ll be able to apply the Wiggle Paths operator (sounds pretty good, doesn’t it?) to a bezier shape path, which is identical and compatible with mask paths.

    Adolfo Rozenfeld
    Buenos Aires – Argentina
    https://www.adolforozenfeld.com
    adolfo(AT)adolforozenfeld.com

  • Brad Strickman

    March 30, 2007 at 9:12 pm

    I attempted scaling and precomposing and the same problem exists. The bottom edge of the curtain remains static. Any other ideas?

  • Darby Edelen

    March 30, 2007 at 9:27 pm

    [bdstric] “I attempted scaling and precomposing and the same problem exists. The bottom edge of the curtain remains static. Any other ideas?”

    Nope, but I still have the same idea =)

    You go the order wrong there, pre-comp and then scale inside that pre-comp… The goal is to make a layer (a pre-comp) that has your curtain solid in it but with a buffer of at least 20 pixels of transparency surrounding it. So if your curtain layer is 720×480 and your displacement is 720×480, pre-comp your curtain layer into a 720×480 composition then scale it down so that the curtain layer is about 700×460 inside a 720×480 comp. Then the displacement map will displace the entire 720×480 pre-comp. You’ll still have ‘hard edges’ but those ‘hard edges’ will be on the transparent pixels at the border of the 720×480 pre-comp (so you won’t see any hard edges).

    Note that the 20 pixel buffer I mention here is pretty arbitrary, it really depends on your maximum displacement values in the displacement map effect. A 20 pixel buffer would work for a maximum displacement of up to 20.

  • Ronaldo

    March 30, 2007 at 11:25 pm

    This may not be very helpful to you but Cinema 4D has a great was to do this. If you have access to it, let me know and I’ll fill you in.
    All the best.

    All the best

  • Mike Clasby

    March 31, 2007 at 1:10 am

    You can wiggle a mask’s verticies with expressions, it’s a little round about, see this:

    https://forums.creativecow.net/cgi-bin/new_read_post.cgi?forumid=2&postid=897730

  • Adolfo Rozenfeld

    March 31, 2007 at 2:40 am

    Expressions can’t access mask nodes directly. Scripting can, as the link you mention shows.

    Adolfo Rozenfeld
    Buenos Aires – Argentina
    https://www.adolforozenfeld.com
    adolfo(AT)adolforozenfeld.com

  • Mike Clasby

    March 31, 2007 at 3:52 am

    And an excellent script it is too.

  • Adolfo Rozenfeld

    March 31, 2007 at 6:59 am

    True 🙂

    Adolfo Rozenfeld
    Buenos Aires – Argentina
    https://www.adolforozenfeld.com
    adolfo(AT)adolforozenfeld.com

  • Brad Strickman

    March 31, 2007 at 10:10 pm

    Thanks for clarifying. It looks really good.

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