[Dan Ebberts]

I think it’s here now, under Chapter resources:

https://routledgetextbooks.com/textbooks/_author/geduld-9780240809366/resources.php

[Dan Ebberts]

I found this one on stackoverflow:

function calculate_age(birth_month,birth_day,birth_year)
{
    today_date = new Date();
    today_year = today_date.getFullYear();
    today_month = today_date.getMonth();
    today_day = today_date.getDate();
    age = today_year - birth_year;
    if ( today_month < (birth_month - 1))
    {
        age--;
    }
    if (((birth_month - 1) == today_month) && (today_day < birth_day))
    {
        age--;
    }
    return age;
}

[Dan Ebberts]

Yes, you can add an expression to a keyframed property, but the expression has to supply the property’s value at all frames, not just at a particular keyframe. You might be able to achieve the desired result, especially if the keyframes are linear, or you’re willing to accept the easing provided by ease(), easeIn(), or easeOut() expressions. However, it gets trickier if you need to preserve some custom easing.

[Dan Ebberts]

While I guess it’s possible, this particular expression probably wouldn’t be a good candidate for inputs controlling the total distance traveled. Based on those entries and given values for launch angle, elasticity, gravity, friction, and number of bounces, you could calculate the launch velocity required to give you that result, but it would be messy.

[Dan Ebberts]

Thanks for the kind words! I appreciate it.

[Dan Ebberts]

To do that, I think you have to build the property spec path on the fly, like this:

var myComp = app.project.activeItem;
var myProps = myComp.selectedProperties;
for (var p = 0; p < myProps.length; p++){
	var myLayers = myComp.selectedLayers;
	for (var l = 0; l < myLayers.length; l++){
		var myProp = myProps[p];
		var myPropString = "";
		while (myProp.parentProperty !== null){
			var name = "\"" + myProp.name + "\"";
			myPropString = ".property" + "(" + name + ")" + myPropString;
			myProp = myProp.parentProperty;
		}
		if (myPropString != ""){
			eval("var myActualProp = myComp.layer('"  + myLayers[l].name  + "')" + myPropString + ";");
			myActualProp.selected = true;
		}
	}
};

[Dan Ebberts]

I’m not sure, but if you’re planning on looping this through multiple layers, I think you first need to save the state of which layers and properties are currently selected, because the actions of your function will change that. So you’d need to restore those selections each time through the loop, or change the function to expect layer names and property path specs. It could be tricky, and a little messy.

[Dan Ebberts]

Good point. Are you making sure in your loop that only the property you want to move is selected? It seems like you could get cascading mess if you’re not really tidy about that.

[Dan Ebberts]

Have you considered using .moveTo() instead of executeCommand() ?

[Dan Ebberts]

sourceRectAtTime() won’t detect the zero-alpha areas of precomp layers.

You could always convert the anchor point expression to keyframes. That might help.