Use comp marker to simply play a pre-comp

[NBA Shaun]

I have done tons of search query's on this... it seems so simple on the surface, but can't nail it.

1- I have a simple y-pos animation in a precomp -- to transition from a blank screen to the screen full with content

2- I have a parent-comp with two comp-markers, that will trigger the appropriate nested precomps to play real-time

• Scene 1 will already be on screen, so the first marker triggers scene 2, and the second marker triggers scene 3
• Marker should trigger the scene to play from frame 1 in realtime - no stretching time. Just like a powerpoint presentation... I click my mouse, and the slide plays as it's been set up
  

I am using the comp below to time three-scenes for each of  3-digital signage boards (FCP, VCP, ICP) simultaneously.

3- My approach and the problem

• After research I'm assuming I'm correct that Linear( ) would be the way to approach this
• Here is the expression I came up with

var compWithMarker = comp("Proof_DS_");

var show2 = compWithMarker.marker.key("Show2").time;
var show3 = compWithMarker.marker.key("Show3").time;

linear(time,show2,100,0,100)​

• The problem is with this expression it is "stretching time" -- albeit by a tiny amount, but I need it to be realtime

• I time remapped the precomp.
• With the current expression, it triggers on-time (at 5.00 seconds)
• When the playhead is at 10.00 seconds --- only 5.00 seconds should have elapsed (or as AE math shows it as 5.01 seconds)
• Why is the precomp's time-remap showing 5.08 seconds have elapsed?  How do I get it to play in realtime? 
  

Thank you!

[Dan Ebberts · Accepted solution]

Try it this way:

var compWithMarker = comp("Proof_DS_");

var show2 = compWithMarker.marker.key("Show2").time;
var show3 = compWithMarker.marker.key("Show3").time;
time < show2 ? 0 : time - show2

[NBA Shaun]

Oh my goodness, thank you so much -- it worked! 

I have never seen either a question mark, or a colon in an expression line.

Do you care to elaborate what is going on here?  If not, no worries, it works, and I am grateful for your help Dan.

[Dan Ebberts]

It's just the ternary conditional JavaScript operator. If the condition (the part before the ?) is true, it does what's between the ? and the : -- otherwise it does what's after the :

So once the current time reaches the marker, it uses time - show2, before that it holds at 0.

Dan

[NBA Shaun]

So it's just short hand for if/then?
? = if
: = then

That's awesome!

[Dan Ebberts]

It's the same as this:

if (time < show2) { 0 } else { time - show2 }

Dan

[NBA Shaun]

Thank you!