Yes i already fix it myself. But still no make sense to me, sorry.
As i said, it create already the boxes and just gives me the opacity to latest boxes. What i try basically is to control the opacity by distance.
Means, each last 3 for example to keep the opacity like your example, but need to me change all this.
Example:
We have 10 boxes: Last 3 opacity like your example.
We back the touch a bit, so we have now 5 boxes.. Same as above, last 3 opacity.
All it's about touch distance between first creation and touch.x touch.y
Maybe it's a bit complex, but basically this is the main reason, this is what looking.
Thanks again for your time and help!