Auto-aligning anchor point with “sourceRectAtTime()” aligns point incorrectly

Posted by Pau Amer on September 17, 2021 at 12:53 am

I have a preset with text layers animated with expressions because I’m going to use it alot and I don’t want to manually set each keyframe when text is changed.

Because of this, I have 4 keyframes, two for IN and two for OUT. The text is under a shape layer that acts as a MATE.

Obvsiusly, I have to set the anchor point for the text layer, wich is set at the middle of the left side of the layer using “sourceRectatTime()”. When doing this in a normal layer without animations driven by expressions, it works correctly. When I do it in this text layer, it doesn’t work properly. The anchor point is set slightly over the middle and it offsets al the layer, unaligning all the design.

I attached one screencap to show the issue and make it more graphical.

The code I use for the text layer is the following one (first example slides text from top to bottom, second example slides from left and goes backwards):

And a download link for sample I made, wich has the same issue: https://drive.google.com/file/d/1iY8ik97dJst-aFUEaaMsiENi4zwWjUjR/view?usp=sharing

// customBezier(time, startTime, endTime, startValue, endingValue, beizerPoints);
function customBezier(t,tMin,tMax,value1,value2,bezierPoints){
    if(arguments.length!==6)return value;
    var a=value2-value1;
    var b=tMax-tMin;
    var c=clamp((t-tMin)/b,0,1);
    if(!(bezierPoints instanceof Array)||bezierPoints.length!==4)bezierPoints=[0,0,1,1];
    return a*h(c,bezierPoints)+value1;
    function h(f,g){var x=3*g[0];
        var j=3*(g[2]-g[0])-x;var k=1-x-j;
        var l=3*g[1];var m=3*(g[3]-g[1])-l;
        var n=1-l-m;var d=f;for(var i=0;i<5;i++){var z=d*(x+d*(j+d*k))-f;
            if(Math.abs(z)<1e-3)break;d-=z/(x+d*(2*j+3*k*d));
            }
        return d*(l+d*(m+d*n));
        }
    }
var w = thisLayer.sourceRectAtTime(time, false);
if(time<key(2).time) {
    customBezier(time, key(1).time, key(2).time, [w.left, w.height*1.20], [w.left, w.top/2], [.39,.01,.4,.99]);
} else {
    customBezier(time, key(3).time, key(4).time, [w.left, w.top/2], [w.left, -w.height*2], [.39,.01,.4,.99]);
}

// customBezier(time, startTime, endTime, startValue, endingValue, beizerPoints);
function customBezier(t,tMin,tMax,value1,value2,bezierPoints){
    if(arguments.length!==6)return value;
    var a=value2-value1;
    var b=tMax-tMin;
    var c=clamp((t-tMin)/b,0,1);
    if(!(bezierPoints instanceof Array)||bezierPoints.length!==4)bezierPoints=[0,0,1,1];
    return a*h(c,bezierPoints)+value1;
    function h(f,g){var x=3*g[0];
        var j=3*(g[2]-g[0])-x;var k=1-x-j;
        var l=3*g[1];var m=3*(g[3]-g[1])-l;
        var n=1-l-m;var d=f;for(var i=0;i<5;i++){var z=d*(x+d*(j+d*k))-f;
            if(Math.abs(z)<1e-3)break;d-=z/(x+d*(2*j+3*k*d));
            }
        return d*(l+d*(m+d*n));
        }
    }
var w = thisLayer.sourceRectAtTime(time, false);
if(time<key(2).time) {
    customBezier(time, key(1).time, key(2).time, [w.width, w.top/2], [0, w.top/2], [.39,.01,.4,.99]);
} else {
    customBezier(time, key(3).time, key(4).time, [0, w.top/2], [w.width, w.top/2], [.39,.01,.4,.99]);
}

Pau Amer replied 4 years, 10 months ago 2 Members · 6 Replies

6 Replies

Andrei Popa
September 17, 2021 at 7:36 am

I have tried your expression on a text layer and it works fine unless I use stroke. If I use any stroke, the text goes a bit off. The thicker the stroke, the bigger the difference.
Pau Amer
September 17, 2021 at 7:55 am

I have no issue when using capital letters. A text like “ABC” is not a problem, but when I do “ABCEfg” it turns weird because “g” and “f” are changing the layer dimensions. Have you tried it? I think this can be software bug…
Andrei Popa
September 17, 2021 at 8:25 am

I think the anchor point in your picture is correct, and it is the left boundary of the layer, boundary given by the dot of the i.
Pau Amer
September 17, 2021 at 9:12 am

If the anchor point it’s correct I don’t understand why it’s not positioned over the square underneath of it. I tried the “sourceRectAtTime()” without animations or anything else and it does center correctly.

I’ve given you permission to download the files, if you want to give a look.
Andrei Popa
September 17, 2021 at 10:57 am
Oh, you meant vertically? I am sorry, I missunderstood the issue. You need to replace the
```
w.top/2
```
with
```
w.top+w.height/2
```
This means that you start fromt he top point, then add half the height of the rectangle.
Pau Amer
September 17, 2021 at 11:16 am

Thank you so much… It really helped me. I’m having a hard time learning sourceRectAtTime()…

Thank you!

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Auto-aligning anchor point with “sourceRectAtTime()” aligns point incorrectly