Here is the Projekt that i want to make:
Another thing is that i want to reuse this method in other projekts,for example if the bars are colored diffrentry then in the screenshot i provided.
I would be really gratefull if someone could give me a step by step guide on how to do that cause im rather new to Aftereffects and expressions.
Thanks in advance!
-Tom-
16
Replies
I don't know how you set up your lighting effect layer. You mentioned Keylight but that effect is usually used to separate foreground elements on footage that has a consistent background color. To make a scenario using some kind of keying effect I would have to see the layer and know all of the modified properties and your workflow.
If all you want to do to is generate some kind of glow every time one of the white bars intersects with the moving piano roll by far the easiest solution is to have the entire animated piano roll on a single layer, duplicate the layer, create a shape layer that covers just the intersection of the piano keys and the piano roll layer, use that as a track matte, then add a glow effect and/or some blur and color effects to the masked top copy of the piano roll layer. Something as simple as this:
If you want to use the "sampleImage" expression method to detect where the intersection takes place and control something like lens flare brightness then look at this solution presented by Dan Ebberts: Using Sample Image
You will end up with a lot more complex composition but a different look. Something like this:
The problem with this approach is that effect(index) does not seem to work as I would expect it to so you have to manually rename every instance of the lens flare, and every image sample takes time to calculate, so this approach would much slower to render.
Let me know exactly how you created your Keylight layer and how you expect to add the lighting effect to each layer and maybe I can help but I think your workflow may be a lot more complicated than it needs to be.
To get that custom lighting effect to work you'll have to get rid of the pre-comp put all of those layers in the main comp. If you then move the anchor point of each of those layers directly over the appropriate piano key you can add an expression to each layer to change the opacity based on the layer position. If you duplicate the piano roll layer, turn it into a guide layer, and add directional blur, you can ramp the opacity up and down instead of just turning it on and off. The comp would look something like this:
And here's the expression:
target = thisComp.layer("Piano Roll 2");
point = thisLayer.position;
alpha = target.sampleImage(point,[3.5, 3.5])[3];
linear(alpha, 0, 1, 0, 100)
It's not going to render very fast, but it will work.
You could make it work with all of the lighting effects on a single layer and modify the expression to adjust the values of each parameter by modifying the point variable and the tMin, tMax, Value1, and Value2 portion of the expression. It all depends on what you want to do and which parameters you want to animate. You could even add a bunch of nulls to the comp and use the position property of the nulls as the point variable. There are a lot of ways to go but I think this is the easiest.
Here's a sample comp that is greatly simplified: https://www.dropbox.com/s/mxsr09uer2zf0js/piano%20roll.aep?dl=0
(if your browser adds a .txt extension when you download the file just delete it.)
I dont know i did everything you said but the keylight layers arent showing up, the opacity is at 0% all the time.
Maybe it has something to do with moving all the layers to the main comp like you said but i dont know what you mean by that i only have one comp.
The anchor point is not in the center of the red rectangle. It should be. The opacity seems to be reversed. I notice you are using blue [2] instead of red. The test layer is also not at 100% scale.
Try soloing the Piano 2 layer and make it visible so you can actually see the area you are sampling. Make sure that the Info Panel is open and expanded and set to decimal:
then mouse over the solid part of the piano roll and check out the maximum value for the color with the highest number. In this sample, the highest value is Red [1] at .9569. In this sample:
the highest value is still red at 0.6078
This means that I should change the tMax value in the linear expression from 1 to .6078.
In your video the opacity of the test layer changes but it does not line up with the visible layers. This tells me that the Piano Roll 2 layer is not at it's default position scale and rotation values. Here's what I would do to continue the test.
Fix the anchor point, make sure that the test layer and the layer you are sampling are visible by soloing both layers so you can actually see what is being sampled, Turn on Transparency grid so you can see any transparency, but I don't think there is any and if the highest color value you see is red and something like .4403 change the expression to this:
target = thisComp.layer("Piano Roll 2");
point = thisLayer.position;
alpha = target.sampleImage(point,[.5, .5])[0];
linear(alpha, 0, .4403, 0, 100)
As long as the layer you are sampling has not been moved or scaled this expression should work and the test layer's opacity should be 100% when its anchor point moves over anything that has a red value of at least .4403.
If the layer has been scaled or moved from the default position you can just select it and pre-compose. That is a lot easier than adding layer space transformations to the expression.
OK i think i know what the problem was all the time.
In the Piano Roll that i was using is a green and a blue bar over the dropping notes wich you didnt see because i expanded the timeline so that you could see all the details of the layers.
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