Some basic questions and issues after some days of utilisation.

[Adrien21902085hshs]

Hello,

I'm in a period where I'm trying to create a motion a day. It's very cool because it allows me to confront a lot of problems that I find the solution either by myself or by searching.

I come to you because I find myself without solutions or answers for questions I have:

- I noticed a difference between the "Set Matte" which is an effect, and the "Track Matte" integrated in the timeline. Even if my effect is set with "sources, masks and effects", it takes the alpha of the base layer. My solution is to copy the base layer and put it in front of the second layer I'm trying to alpha. The problem is a large number of layers. So these two ways of doing things are quite different?

- I have a problem often with the "center" property of many effects. For example, I have a ramp with two points. I have a shape layer with a circle which is the layer that hosts my ramp grandient. If I make a move, my gradient points stay at their initial location. So I say to myself that I will link via the expression panel the position of each of its points to the position of my circle. Except that at this moment they are placed at the location of my anchor.My only solution was to create this gradient in another shape, to make a composition, and this composition that I trace mattes with my circle that I also put parent (so many more layers and manipulation). The other problem is that I wanted to animate these points of large, now I have to go into my composition with my gradients to modify and I have no view of the rest of my global composition.
So: how to link to a parent the position of effect points (without it being attached to the anchor part but just to the movement).

- I have trouble understanding what is going on between positions and anchors sometimes. For example always with this story of gradation.
I tell myself that I'm going to create two nulls that will serve as parents for the two effect points of my gradient. So far so good, the anchor points of my null layers are indeed those of my gradient points. As soon as I link the null with another shape that moves, my effect points move outside my composition, (even if the property position of the effect points are well indicated in red and are the same as those of my nulls which move well as they should).

These little problems are at the heart of many doubts in the middle of my work and each time I have to find ways to work around them that seem long and tedious.

Thank you in advance for your concerns,
If you want some pictures, don't hesitate.
Or even a discord discussion with a screen share. 🙂

[Mylenium]

None of what you experience is out of the ordinary. It's just how AE works. Effects always reference layer coordinates while at the same time this principle falls apart with shape layers because they are just comp-sized containers for the vector rasterization engine. Same for your track matte issues. And, to put it directly, from your description you are making the typical mistake of considering pre-composing the enemy and trying to do as much as possible in the same comp/ on the same layer which simply cannot work given how the render pipeline works. Instead you need to consider it a regular part of the workflow and plan your project accordingly. Aside from the abstract explanations laid out in the online help and what we can tell you here on this forum this is simply a matter of of experience. The more projects you do, the more you'll understand these minutia and eventually it will simply "click" and no longer be a problem.

Mylenium

[Adrien21902085hshs]

Thanks for your answer. It's my feeling too, After Effects is a software which ask time and experience.
But sometimes when something specific escapes us, it can become frustrating because it doesn't seem clear.

So, to put the ramp grandient in a precomposition and this precompistion used to track matte in a shape is the right way to use After Effects at last... But I stay on my position, when i want to move my gradient points for exemple, i need to go in the precomposition to modify blindly..

But during writting I thought : I can display the composition and the precomposition at the same time... ahah

[Kyle Hamrick]

re: Track Mattes / Set Matte

Yes, the Set Matte effect works differently from Track Mattes, though they have some overlapping functionality. 

Here's a good overview of Track Mattes, respecting the recent updates to this feature: https://youtu.be/rvAXZl8Ypus 

Here's a good overview of Set Matte: https://www.youtube.com/watch?v=zfmuXUgATpo

Personally, I mostly end up using Set Matte for textures (like in Jake's example), or to matte a layer with itself. (Example, you get a logo from a client with a white background instead of transparent; you could possibly use Set Matte, set to luminance, to use the layer's own white/black values to cut itself out.) It does have a "gotcha," in that it requires your layer and matte source to have the same dimensions (which usually means pre-composing). In short, this new Track Matte functionality makes a lot of what Set Matte *used* to be needed for obsolete, so if you can't understand how to make it work quite yet, direct your energy at Track Mattes. 

[Adrien21902085hshs]

Thanks I will watch these two videos ! You're perfect !

[Kyle Hamrick]

re: Anchor Point vs Position (Parenting) & Point Controls in Effects

These two are related issues, relying on an understanding of "Composition Space" vs "Layer Space."

This stuff can be a little tricky to wrap your head around at first (and takes a while to write out explanations). Fortunately, I've explained these concepts in videos already, so I'll just refer you there to start:

This video will both explain this concept of Comp Space vs Layer Space, and also offer some solutions to common questions:

https://www.youtube.com/live/xeBrtrrKDVA

A short summary:

Position is actually the position of the layer's Anchor Point in Composition Space.

...until you parent that layer to something. The child layer's Position is now the position of its Anchor Point in the Parent layer's Layer Space. (That's why the Position value changes when you parent a layer.) The Point controls within effects add another layer of complication here (a different but similar issue, which can also be combined with the above idea to make it even more confusing - ha!)

Hopefully the above video will point you in the right direction - once you've got your head wrapped around that, let us know if you have more questions!

[Adrien21902085hshs]

Oww thank you, I will watch this video.
I understand : it  can become a real headache ahah

"Position is actually the position of the layer's Anchor Point in Composition Space.

...until you parent that layer to something. The child layer's Position is now the position of its Anchor Point in the Parent layer's Layer Space. "

Isn't the parent space the same as the child space since they share the same composition?
I think the video will explain this to me.

Quick question: how would you have solved this problem on your side for the effect points follow the animation of the object in which the effect comes from?

[Kyle Hamrick]

I cover that exact question in the linked video!

In most cases, you can also solve this without expressions by pre-composing your layer before applying the affect, but using expressions feels like the most efficient and editable solution to me. 

[Adrien21902085hshs]

Thanks ! 🙂