stadium platform sight view

hello, am quite new to grasshopper, am trying to build a parametric platform section to calculate the sight curve while dimensioning.
The definition is done very roughly, probably can be half of it if done properly, but this is not the question I have now. I am rather trying to add an auto detect component between the head group and the view lines, which is the final purpose of the all thing. Any idea about the components to use? Am usinc CCX component but am stuck on how to exclude the intersection between the heads and their own line view. Maybe it's easy and am just lazy.