Use of Transform, ReplacementTransform and TransformFromCopy

[kekuss]

Hi everyone !

I'm quite a beginner at manim.
I've been struggling with the use of Transform, ReplacementTransform and TransformFromCopy. I read all threads i found on the topic, but it still remains unclear.
e.g. in my video here : https://youtu.be/THxIk51uQO0?t=156

I managed to have the desired effect of scrolling/fadingout using Transform. However, i had to make a copy "by-hand" first to fade it out next.

TransformFromCopy should be best designed to do the job, but I couldn't find a way to fade the copy next.

ReplacementTransform is still mysterious to me beacause it sometimes leaves a copy (when the content is different), and sometimes not (when the content is the same, e.g.
self.play(ReplacementTransform(MathTex(r" \times"), MathTex(r" \times") ) #ReplacementTransform x in line 1 into same symbol x in line 2
I can post more code if needed .

Any help appreciated.

[kekuss]

To all those with the same pb, I found this which helped a lot !