[Darby Edelen]

You’ve tried this with some standard fonts like Helvetica or Arial, correct? And you have no effects applied to the text layer?

Darby Edelen

[Darby Edelen]

The description you’ve provided of your desired behavior is a little ambiguous.

Can you give a more detailed description of how the line should move randomly? From the look of your current expression it seems that the line is choosing random start and end points but moving continuously between them. If, however, the start and end points of each loop are required to be the same then the start and end points will no longer appear random.

Based on your current description and the approach you were taking with your expression this is what I came up with:

segDur = .5;
minVal = [64,0];
maxVal = [64, thisComp.height];
loop = time % segDur;
seed = Math.floor(loop);
segStart = 0;
seedRandom(seed,true);
startVal = random(minVal,maxVal);
seedRandom(seed+1,true);
endVal = random(minVal,maxVal);
if(loop < segStart + segDur / 2) ease(loop,segStart,segStart + segDur / 2, startVal, endVal);
else ease(loop, segStart + segDur / 2, segStart + segDur, endVal, startVal);

But as you can see this doesn’t appear random. A clearer description of the desired behavior is probably required.

Darby Edelen

[Darby Edelen]

I’m assuming you’re using the Expression node in Nuke to do that. That’s an entirely different beast than AE expressions and is used for a different purpose.

However, the example you posted can be done by clever use of effects, blend modes and pre-composing.

In the specific case you mentioned you could use Shift Channels to bring the Red into each of the RGB channels, use Levels to multiply the values by 1.5 (set the output white to 1.5), use Shift Channels on a duplicate to bring the Green into the RGB channels, put that duplicate above the Red and set it’s blend mode to Divide, create a new solid at the top of the timeline with RGB values of [0.8,0.8,0.8] and set it to the Multiply blend mode. You now have your alpha value, you just need to pre-compose it and use it as a matte.

Some of the details in the above method can be altered but the basic idea is the same as the expression node in Nuke. As far as computers are concerned the colors are just numbers. You can modify them with effects and blend modes the same way you would with mathematical operators. Several of the blend modes are named after mathematical operators (Add, Subtract, Multiply, Divide) for a reason!

Of course this should all be done in 32bpc (as Nuke does) to preserve values. It’s not as easy and certainly not as flexible as the Expression node (good luck finding “Square Root” or trigonometric blend modes) but the basics are definitely achievable.

Darby Edelen

[Darby Edelen]

Something like this should work:

firstKey = key(1).time;
offset = effect("Slider Control")("Slider");
valueAtTime(time + firstKey - offset);

Although that will return an error if the property doesn’t have at least 1 keyframe. A try/catch statement could be used to prevent that error:

try{
firstKey = key(1).time;
offset = effect("Slider Control")("Slider");
valueAtTime(time + firstKey - offset);
}
catch(err){
value;
}

Darby Edelen

[Darby Edelen]

Here are a couple of other options:

-Apply the Channels > Shift Channels effect to the layer and set Take Alpha From to Full On. The masks will still be in Add mode but they will have no effect on the alpha of the layer.

-Apply a layer sized rectangular mask in Add mode. The fastest way to do that is to select the rectangular mask tool, select the layer and then double click the rectangular mask tool in the toolbar.

In either case you’d simply remove/disable the effect or layer sized mask when you’re done.

Darby Edelen

[Darby Edelen]

Boomerang is just describing the effect that occurs when the spatial bezier handles of two keyframes fight against each other. This happens not only when the keyframes are identical but also when there is a relatively large/fast motion into/out of a set of keyframes that are relatively close to one another.

It’s possible this isn’t what you’re experiencing, but try setting the spatial interpolation of the keyframes to linear anyway and see if that helps.

Darby Edelen

[Darby Edelen]

Masking outside of the frame is no problem.

It’s not uncommon to move masks outside of the composition boundaries when they are no longer needed.

I think your issue is only related to the size or position of the layer that you are masking. You want the layer to fill the composition.

Darby Edelen

[Darby Edelen]

Is there anything inside the pre-comp that could be causing that? Have you purged your caches recently?

Darby Edelen

[Darby Edelen]

It looks like your mask goes beyond the edge of the layer it’s applied to.

If that’s the case then there are a couple of possible solutions. One is to use the pan behind tool to move the layer without changing the position of the mask. The other is to apply a fill effect and set the fill mask property to the mask in question (or check all masks if that works for your purpose).

Darby Edelen

[Darby Edelen]

The first two things that come to mind are the layer quality setting (make sure it’s best and not draft) and alpha settings if you’re rendering with an alpha (try premultiplied instead of straight).

These are both not likely but they’re the first things that come to mind without more information.

Darby Edelen