Help: Sun Shading definition

Hello,

I am trying to develope a sun shading panel system that responds to sunlight. 

Basicly the panel is meant to block the sun's rays relative to the measure of direct sunlight and  gradually open (preforate) as the sun rays angle increase to the surface surface normal.

I have two diffenet definitions (1.Grid 2.Srf), I am working on however both are having similar issues.

I am an ametuer in grasshopper, please help!

NOTE:

I am using a vector on an arch(crv) as an atraction point to simulate sun path rays.

1. Limit inner polygon(crv) to srf edges [A sort of range input]

2. Range attempt for angle... should be:

? > 90 degree angle then Polygon (Radius) should be 0. 
? < 90 degree angle should be equal to angle/srf area to = Polygon (Radius)

Below is the model space view...