Question: Why does my object interact with the simulated rays at all?
Background: I want to create a material that allows perfect specular transmission in one direction and no transmission or reflection in the other direction. I built the following BRTD function and .cal file for this purpose:
void BRTDfunc testing
10 refl_red refl_grn refl_blu trans_red trans_grn trans_blu 0 0 0 testingBRTDf.cal
9 0 0 0 0 0 0 0 0 0
(Note in file “(x)” is just one of these symbols >>> *)
refl_red = if(Nz, 0 (x) RdotP, 0 (x) RdotP);
refl_grn = if(Nz, 0 (x) RdotP, 0 (x) RdotP);
refl_blu = if(Nz, 0 (x) RdotP, 0 (x) RdotP);
trans_red = if(Nz, 1 (x) RdotP, 0 (x) RdotP);
trans_grn = if(Nz, 1 (x) RdotP, 0 (x) RdotP);
trans_blu = if(Nz, 1 (x) RdotP, 0 (x) RdotP);
To validate this material I rendered the following:
And this resulted in the following test mesh results:
However, when I ran the simulation without the material present I got results roughly 15% higher:
Since any rays that pass through the material should only receive a factor of 1, why does the presence of the material reduce the energy on the test mesh by 15% and how can I remove this behavior?