Help to understand expression : toComp(value);

[Zed 248]

Hi there,

rather for help I am seeking understanding what's going on in the following simple case:

When I add a Point Control effect to the layer. The position of this point is absolute. I add a simple expression to it:

toComp(value);

(It seems, that "toWolrld" behaves just the same.)

After this treatment the Point Control seems to be positioned relatively to the layer which is applied on. So when I move the layer, the point moves with it, but the Point can be moved freely as well.

Would you kindly help me to understand why this works? I thought, that everyhting unparented is child of World. So why after this expression it seems to be child of the layer space itself?

Thank you.

[Dan Ebberts]

>The position of this point is absolute.

The value of the Point Control is relative to the upper left corner of the layer. Does that help?

Dan

[Zed 248]

Hi Dan,

thank you for your response. I just don't understand what exactly happens behind that standalone toComp expression. But I don't want to bother you anymore. I would be better to deep dive to the Expression refference.

Take care Dan.

[Dan Ebberts · Accepted solution]

Suppose you create a new 1000x1000 comp and add a new 500x500 solid to it, and add a Point Control to that. The initial value of the Point Control will be [250,250], which will be relative to the upper left corner of the solid, which puts it at the center of the solid (and coincidentally at the center of the comp).

If you now add the toComp(value) expression to the Point Control, it will convert the [250,250] in layer space to comp coordinates, which is the center of the comp, or [500,500]. Since the value is always interpreted as being in layer space [500,500] puts the point at the lower right corner of the solid ([750,750] in comp space).

It's a little confusing, but I suppose the good news is that I can't think of a good reason you'd ever do it that way.

Dan

[UQg]

Apparently, the original experiment was with a shape or text layer. Point controls behave differently for layers with and without a source.

[Zed 248]

Thank you UQg,

will try to figure it out.

[Zed 248]

Awesome Dan,

thank you for your explanation effort!