give some explanation about how get first index and position?

[kkjusdoit]

    var p = position - scrollOffset / cellInterval; 
    var firstIndex = Mathf.CeilToInt(p);
    var firstPosition = (Mathf.Ceil(p) - p);// * cellInterval; 

Hi @setchi I'm new learning your code, I have problem to understand above caculation, why this can get first index and position?

[kkjusdoit]

how do you design the formula