Firstly, is it possible to use the light intensity value as an input? I would like to use the light intensity as the driving factor for opacity so that when in the dark the particles are completely transparent however in the light they’re opaque. The problem I’m having is even in pitch black they seem to still be lit slightly somehow, as shown in the screenshot below.
The second question is, is it also possible to control the scattering of light within a particle? I’m not sure if this is done on purpose or not, but when light enters a particle it seems to scatter within the particle causing adjacent particles to become lit, and hence starting a chain reaction which leads to particles being lit when exposed light isn’t accessible to the particle. You can see what I mean in the below screenshot, in the majority of the undercover space the particles are receiving no light (well, “no light”, as what I discussed in my first question), however near the ceiling they seem to be receiving light from a non-existent light source (actually a directional light source, however the ceiling should still be blocking the light). I suspected this is due to particles which are spawned above the ceiling (the system spawns the particles in a volume from (500, 500, 500) to (-500, -500, -500)) leaking light into adjacent particles, and somehow light is being leaked through the surface.
However, upon further analysis it appears no matter if I move the particle system beneath the ceiling so none spawn above or in the ceiling, it still occurs. As a third question, anyone got any ideas for why this is occurring?