https://editor.p5js.org/Pilou/sketches/PE_HwNoXH
I remake for more clear thing for me 
And I have forgotten to increase the name of previous versions so they are devastated!
Here not yet drop…
you must obtain a variation of that in change t between (1-50) on the fly inside the code …or anything you want!
Next I will try to put your code…for drop an image against an yet existing one!