Reflected light not passing through transparent materials

[MafiaMoe]

I am trying to add windows to my scene using just a transparency material in Unity 5. The problem I am running into is the bounced/reflected lighting from a directional light source is not coming through the window at all, leaving my room extremely dark if no interior lighting is provided. I am using Unity Free.

To better explain, below are some images of the scene.

Here are two rooms side by side, the left with a highly transparent window (very dark) and the right with no window.

To show no light is making it through the ‘window’ here is an image showing 2 sets of light probes on the inside and outside of the transparent materials. The black probes on the inside show no light passing through the window, while those on the outside are well lit from the outside.

I would provide a 3rd image showing the view from inside the dark room looking out, but since only 2 images are allowed just imagine a window looking out on a bland white topography. It shows that indeed both the inside and outside facing panels are visibly transparent.

Any help would be greatly appreciated as I hope to have some ‘power outage’ situations with limited internal light sources for this game. Thank you,

[FortisVenaliter]

The way shadows are calculated is binary. Either there’s a shadow from the light or there isn’t. Unity does some magic with smoothing that allows for soft shadows, and sometimes some dithering for transparency, but it can’t get past that basic requirement. So, what you need to do is disable the cast shadows setting on the renderer component of the windows. That way, the building will cast shadows, but the windows will not.

[PeeMan]

I know it’s a bit late but for people who come across this thread should know.

The solution is to create a custom Lightmap Parameter and in it’s inspector setting you will find “Is Transparent”, tick that and assign it to the mesh that is transparent and GI light will pass through.