strange linear

[Dan Ebberts]

The second parameter to linear() needs to be less than the third parameter.

Try changing your second expression to this:

linear(comp(“Aiguille PC”).layer(“Aiguille”).transform.rotation,-360,0,-270,90)

Dan

[Lucia Bastenhof]

I don’t understand quite well. You write : “The second parameter to linear() needs to be less than the third parameter. “. But 0 is more than -270 ?
Did you want to say : “The first parameter to linear() needs to be less than the second parameter.” ?

Anyway, I tried it, but the returned values remain different :
– time1 : A=-30 , B=-150
– time2 : A=-270 , B=90
– time3 : A=-193,2 , B=13,2
I learn the order is important, time2 is different, but there remain 2 deep questions :
1/ Why are the returned values different ?
2/ The result is half good, half wrong. Basically, the expression is written on the opacity parameter of a layer-object, and this object appears now, indeed, when encountering the scanner-line.
But its behavior remains strange : its opacity is on and off like with a wiggle. ?

For full information, here’s the entire expression :

===========================
sldval = degreesToRadians(180-linear(comp(“Aiguille PC”).layer(“Aiguille”).transform.rotation,-360, 0,-270, 90));
object = transform.position;

x0 = thisComp.layer(“grid”).transform.anchorPoint[0];
y0 = thisComp.layer(“grid”).transform.anchorPoint[1];

rayon = length(thisComp.layer(“grid”).transform.anchorPoint,object);

xA = x0 + rayon * Math.cos(-sldval );
yA = y0 + rayon * Math.sin(-sldval );

aiguille = [xA,yA];

dist = length(aiguille,object);

if((dist > 0) && (dist < 10)){ 100; }else{ 0; } ================================== The source parameter is coming from another comp ("linear(comp(“Aiguille PC”).layer…..) but I don’t think that it’s the cause of this behavior.

Do you have an answer to one of those 2 questions ?

THANKS !! 🙂

[Dan Ebberts]

It’s still not clear to me what you’re trying to do, but the way you have it set up, as comp(“Aiguille PC”).layer(“Aiguille”).transform.rotation varies from 180 to 540, sldval will go from 90 to -270. Is that not what you want?

Dan

[Lucia Bastenhof]

Hi,

I made a little rendering so that you can have a glance at it.
Here it is : https://fr.youtube.com/watch?v=IJWqxMeX5ls

I followed a tutorial by Maltaannon, to make a radar, and an object that becomes visible only when encountering the radar.
I then tried to make my own one, and to make it really like I wanted, I needed to make the radar line by a different way, in a precomp.

The line A I talked about is the tutorial one, and it works perfectly of course, that is to say the object appears when asked.
The line B is my own radar line, and I try to adapt the expression.

It seems to be more difficult than I thought, but if I learn something, that’s OK. That’s why I’m still trying to solve it.

As you can see in the video, the object remains visible quite a long time, and it reacts like with a wiggle on the opacity. But what’s good now (with the first changes you suggested) is that it appears at the right moments, when encountering the radar.

With the values you suggested in your last message, I made some attempts, changing :
– the rotation values (at first,0 -> -360) to 540 -> 180, and to 360 -> 0 ;
– the values of the linear in the expression following the new ones, trying 90,-270 and -270, 90.
But the results are worse : the same wiggling reaction, and it appears only one time instead of 3 (the 2nd time only).

Do you understand what’s wrong with all that ?

Thank you.

[Dan Ebberts]

I don’t, but my hunch would be that it’s something in the other part of the expression. My suggestion would be to apply the expression to a slider, turn on the graph editor, comment different portions of the expression in and out until you find the piece that’s introducing the wiggle.

Dan

[Lucia Bastenhof]

I’ll try some tweakings tomorrow. But what’s strange is that the rest of the expression works perfectly when applied with the first linear…