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Forums Adobe After Effects NEED GUIDANCE! with expression scripting!

  • NEED GUIDANCE! with expression scripting!

     Gould Lin updated 3 years, 6 months ago 3 Members · 15 Posts
  • Kalleheikki Kannisto

    October 19, 2018 at 6:11 pm

    The layer emitter will have to be selected separately for each instance of Particular. You won’t be able to precomp multiple instances of Particular and use a layer emitter that is outside that precomp.

    Kalleheikki Kannisto
    Senior Graphic Designer

  • Daniel Nam

    October 21, 2018 at 7:00 am

    Thank you!
    I just added layers to do multiple effects! It takes little more time to render but I am really satisfied with the result!
    I have one more question!

    Like the picture above, I want to make my piano keyboard light up with the shadows from the black keys.
    When I record a video with top-down angle and add optical flare effect, it lights up the background but does not create shadows of the black piano keys like the picture above.
    I think this has to do something with 3d.. stuff.
    Is this possible to do in after effects?

  • Kalleheikki Kannisto

    October 21, 2018 at 8:12 am

    Possible, yes; easy, no.

    Had I known at the start you wanted to include that effect as well, I would have steered you toward the more complicated route of having a row of lights at the top of the keyboard, because you could use it for this effect.

    I can think of two ways to accomplish a resemblance of this in AE without any extra plugins or 3D:

    0A) In either case, you need a layer with just the black keys on it. A white solid with masks for each of the key would work.
    0B) In either case, you need a point at the top of each key (black and white) where you sample the black and white piano roll emitter layer with a sampleImage() expression to determine if it is black or white (round it to one or the other). You could attach this expression to a row of nulls, each null sampling the point directly behind it.

    1A) In option one you would also have a light source at the location of each of the keys, at the top, which would light up depending on the value of the sampleImage() at the previous step
    1B) The white solid from 0A would have to be a 3D layer, and you would need another white solid layer behind it to catch the shadows from the keys. Making the solids white allows you to composite the over the keyboard in Multiply mode to get the shadows. (If that doesn’t work too well, you can try gray solids and Overlay mode or even dark gray solids with Screen or Add.)

    2) It might be possible to do this with a series of CC light rays effects, the centers of each placed in the same fashion at the top of each key and triggered by the sampleImage() results and using the black-keys solid to generate shadows. The layers would be 2D in this case. It would be a more complex matter to get an output that you can overlay on the keys. My guess is it would have to be in the Add transfer mode.

    I’d personally go with the lights solution, knowing with greater certainty that it would work.

    It is not going to be a simple operation either way.

    Kalleheikki Kannisto
    Senior Graphic Designer

  • Kalleheikki Kannisto

    October 21, 2018 at 8:27 am

    This concurrent thread in the expression forum has a pretty ready-looking solution for the sampleImage() code you need
    https://forums.creativecow.net/thread/227/40057

    Kalleheikki Kannisto
    Senior Graphic Designer

  • Gould Lin

    November 7, 2018 at 11:02 am

    Hi ~~
    may I ask how to use optical flares to create the shiny blink point like the following fugure?
    Is it possible to created only by optical flares?
    Or need some extra effect (plugins) ?

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